Eriodictyol Attenuates LPS-Induced Neuroinflammation, Amyloidogenesis, and Cognitive Impairments via the Inhibition of NF-κB in Male C57BL/6J Mice and BV2 Microglial Cells

Actinobacillus pleuropneumoniae infection activates IL-1β expression in porcine alveolar macrophages via β-amyloid production

Actinobacillus pleuropneumoniae (A. pleuropneumoniae), a porcine respiratory tract pathogen, causes porcine pleuropneumonia. Porcine alveolar macrophages (PAMs) play a crucial role during A. pleuropneumoniae infection. Amyloid precursor protein (APP) can be cleaved by β- and γ-secretase to produce β-amyloid (Aβ). APP and Aβ are associated with the inflammatory response. They activate microglia and astrocytes to secrete IL-1β, IL-6, and other cytokines. In this study, we found that during the interaction between A. pleuropneumoniae and PAMs, the two-component system CpxAR upregulates wecA expression, increasing lipopolysaccharide (LPS) production. LPS promotes APP production and cleavage to generate Aβ. The Aβ activates NF-κB, leading to increased IL-1β expression. We hypothesize that A. pleuropneumoniae infection of PAMs regulates APP production and cleavage to control Aβ levels. Different quantities of Aβ induce PAMs to produce varying amounts of cytokines, leading to different pathological processes in porcine pleuropneumonia.

Research Progress in the Molecular Mechanism of NLRP3 Inflammasome in Alzheimer's Disease and Regulation by Natural Plant Products

Alzheimer's disease (AD) is a prominent neurodegenerative disorder affecting the central nervous system in the elderly. Current understanding of AD primarily centers on the gradual decline in cognitive and memory functions, believed to be influenced by factors including mitochondrial dysfunction, β-amyloid aggregation, and neuroinflammation. Emerging research indicates that neuroinflammation plays a significant role in the development of AD, with the inflammasome potentially mediating inflammatory responses that contribute to neurodegeneration. Recent studies in AD pathology have identified a novel form of inflammasome referred to as NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome. Pathological alterations closely associated with NLRP3 inflammasome activation have been observed in the brain tissues of AD patients, transgenic mice, and in vitro neurocyte models. Numerous studies have demonstrated the potent neuroprotective properties of natural plant products (NPPs) against NLRP3 inflammasome-mediated AD pathology. This review provides a comprehensive examination of the NLRP3 inflammasome, its involvement in AD pathology, and the mechanisms underlying the therapeutic effects of NPP targeting the NLRP3 inflammasome.

Narirutin attenuates LPS-induced neuroinflammatory responses in both microglial cells and wild-type mice

BACKGROUND

Microglia-induced neuroinflammation plays a key role in the etiology and progression of neurodegenerative diseases. Narirutin, a flavanone glycoside naturally present in citrus fruits, demonstrates anti-oxidant and anti-inflammatory properties. This study aimed to investigate the effects and underlying mechanisms of narirutin in inhibiting microglia-mediated neuroinflammation.

METHODS

The neuroprotective and anti-neuroinflammatory properties of narirutin were evaluated using both lipopolysaccharide (LPS)-stimulated BV-2 cells and mouse models. Real-time quantitative PCR, western blot analysis (WB), enzyme-linked immunosorbent assay, immunofluorescence staining, and flow cytometry were performed to assess the effects of narirutin on LPS-induced neuroinflammation. Transcriptomic analysis was conducted to identify narirutin-regulated differentially expressed genes in LPS-activated BV-2 cells. In addition, behavioral assessments comprising the open field test, forced swim test, and tail suspension test were performed to evaluate the impact of narirutin on LPS-induced sickness behavior. Neuroinflammation was assessed using WB and immunohistochemistry. Oxidative stress levels were quantified by measuring superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration.

RESULTS

Narirutin demonstrated dose-dependent inhibition of LPS-induced pro-inflammatory cytokine production. This anti-inflammatory effect was mediated through suppression of the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways. Behavioral assessments revealed that narirutin administration significantly ameliorated LPS-induced sickness behaviors in the mouse model. Furthermore, narirutin administration suppressed microglial activation, enhanced superoxide dismutase (SOD) activity, and reduced malondialdehyde (MDA) levels in the brain tissues of treated mice.

CONCLUSION

Our results demonstrate that narirutin significantly downregulates LPS-induced neuroinflammatory responses both in vitro and in vivo, suggesting its potential as a therapeutic agent for neuroinflammatory disorders.

Role of Flavonoids in Protecting Against Neurodegenerative Diseases-Possible Mechanisms of Action

Neurodegenerative and mood disorders represent growing medical and social problems, many of which are produced by oxidative stress, neuroinflammation, disruption in the metabolism of various neurotransmitters, and some disturbances in lipid/carbohydrate homeostasis. Biologically active plant compounds, including flavonoids, have been shown to exert a positive impact on central nervous system function. This review assesses the studies of naturally occurring flavonoids belonging to various polyphenol subclasses and their mechanisms of neuroprotective action, especially against neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. Most of the studied phytochemicals possess anti-oxidative, anti-inflammatory, and neuroprotective properties. These phytochemicals have been considered as compounds that reduce the risk of developing Alzheimer's and Parkinson's diseases and can be used in the treatment of neurological diseases. The neuroprotective actions of some flavonoids may entail mechanisms that regulate reactive oxygen species generation and modify inflammatory pathways, and they should be considered as therapeutic agents.

Associations between flavonoids intake and sleep disorders: A survey-weighted cross-section study from NHANES

OBJECTIVE

This study aimed to evaluate the associations between flavonoid intake and sleep disorders.

METHODS

A cross-sectional study was conducted using data from the National Health and Nutrition Examination Survey (2007-2010, 2017-2018). Intake data for 29 flavonoids were derived from the average of two 24-hour dietary recall interviews. Sleep disorders and sleep duration were the outcome measures. Dummy variables were used to account for missing covariate values. Survey-weighted generalized linear models and survey-weighted restricted cubic splines were applied to explore the associations between flavonoid intake and sleep disorders/sleep duration. Sensitivity and stratified analyses were performed to verify the robustness of results and examine potential subgroup differences.

RESULTS

A total of 10,162 participants were included. After adjusting for covariates, isorhamnetin intake was inversely associated with sleep disorders. The odds ratios (OR) for sleep disorder were 0.944 (95% CI: 0.893-0.999) for continuous isorhamnetin intake and 0.754 (95% CI: 0.651-0.874, Ptrend<0.001) for the highest tertile. Luteolin intake, both continuous and in tertiles, was also significantly inversely associated with sleep disorders (continuous OR=0.903, 95% CI: 0.822-0.991; tertiles OR= 0.851, 95% CI: 0.732-0.989, Ptrend=0.031). Isorhamnetin intake, categorized by tertiles, was positively correlated with sleep duration (β=0.125, 95% CI: 0.042-0.208, Ptrend=0.004), with a non-linear relationship identified (Pnon-linear=0.0001). Sensitivity analysis confirmed the robustness of the results, and stratified analysis showed that luteolin's effect varied across different body mass index levels, while isorhamnetin's effect differed by age, gender, and race.

CONCLUSION

Isorhamnetin and luteolin exhibit a significant negative correlation with sleep disorders. Isorhamnetin is linked to an increase in sleep duration. Additionally, both isorhamnetin and eriodictyol demonstrate a notable non-linear relationship with sleep duration.

Albiflorin ameliorates neuroinflammation and exerts neuroprotective effects in Parkinson's disease models

BACKGROUND

Albiflorin isolated from Paeoniae Alba Radix can cross the blood-brain barrier (BBB) and possesses analgesia, anticonvulsant, anti-inflammatory, and hepatoprotective properties. This study investigates albiflorin functions and related mechanisms in Parkinson's disease (PD) pathogenesis.

METHODS

Cellular and animal models of PD were constructed. Cell viability and apoptosis were detected by CCK-8 assays. Levels of Iba-1 and TH were measured by immunofluorescence staining, western blotting, and immunohistochemistry staining. Levels of pro-inflammatory mediators and pathway-related genes were measured by western blotting and RT-qPCR. Locomotor activity of mice was examined by open field test, rod climbing test, and rod rotating test.

RESULTS

For in vitro analysis, albiflorin inhibited LPS-induced microglial activation and neuroinflammation. Additionally, albiflorin inactivated NF-κB and MAPK pathways in LPS-treated BV2 cells. Moreover, albiflorin attenuated neurotoxicity mediated by LPS-stimulated microglia. For in vivo analysis, albiflorin improved MPTP-induced locomotor activity deficits and reduced MPTP-induced dopaminergic neuron loss. In parallel, albiflorin inhibited activated microglia-mediated neuroinflammation in MPTP-treated mice.

CONCLUSION

Albiflorin mitigates neuronal apoptosis and improves behavioral impairments in MPTP-induced PD mouse model through inhibition of activated microglia-mediated neuroinflammation via the NF-κB and MAPK pathways.

Role of Flavonoids in Mitigating the Pathological Complexities and Treatment Hurdles in Alzheimer's Disease

With the passage of time, people step toward old age and become more prone to several diseases associated with the age. One such is Alzheimer's disease (AD) which results into neuronal damage and dementia with the progression of age. The existing therapeutics has been hindered by various enkindles like less eminent between remote populations, affordability issues and toxicity profiles. Moreover, lack of suitable therapeutic option further worsens the quality of life in older population. Developing an efficient therapeutic intervention to cure AD is still a challenge for medical fraternity. Recently, alternative approaches attain the attention of researchers to focus on plant-based therapy in mitigating AD. In this context, flavonoids gained centrality as a feasible treatment in modifying various neurological deficits. This review mainly focuses on the pathological facets and economic burden of AD. Furthermore, we have explored the possible mechanism of flavonoids with the preclinical and clinical aspects for curing AD. Flavonoids being potential therapeutic, target the pathogenic factors of AD such as oxidative stress, inflammation, metal toxicity, Aβ accumulation, modulate neurotransmission and insulin signaling. In this review, we emphasized on potential neuroprotective effects of flavonoids in AD pathology, with focus on both experimental and clinical findings. While preclinical studies suggest promising therapeutic benefits, clinical data remains limited and inconclusive. Thus, further high-quality clinical trials are necessary to validate the efficacy of flavonoids in AD. The study aim is to promote the plant-based therapies and encourage people to add flavonoids to regular diet to avail the beneficial effects in preventive therapy for AD.

Nobiletin and Eriodictyol Suppress Release of IL-1β, CXCL8, IL-6, and MMP-9 from LPS, SARS-CoV-2 Spike Protein, and Ochratoxin A-Stimulated Human Microglia

Neuroinflammation is involved in various neurological and neurodegenerative disorders in which the activation of microglia is one of the key factors. In this study, we examined the anti-inflammatory effects of the flavonoids nobiletin (5,6,7,8,3',4'-hexamethoxyflavone) and eriodictyol (3',4',5,7-tetraxydroxyflavanone) on human microglia cell line activation stimulated by either lipopolysaccharide (LPS), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) full-length Spike protein (FL-Spike), or the mycotoxin ochratoxin A (OTA). Human microglia were preincubated with the flavonoids (10, 50, and 100 µM) for 2 h, following which, they were stimulated for 24 h. The inflammatory mediators interleukin-1 beta (IL-1β), chemokine (C-X-C motif) ligand 8 (CXCL8), IL-6, and matrix metalloproteinase-9 (MMP-9) were quantified in the cell culture supernatant by enzyme-linked immunosorbent assay (ELISA). Both nobiletin and eriodictyol significantly inhibited the LPS, FL-Spike, and OTA-stimulated release of IL-1β, CXCL8, IL-6, and MMP-9 at 50 and 100 µM, while, in most cases, nobiletin was also effective at 10 µM, with the most pronounced reductions at 100 µM. These findings suggest that both nobiletin and eriodictyol are potent inhibitors of the pathogen-stimulated microglial release of inflammatory mediators, highlighting their potential for therapeutic application in neuroinflammatory diseases, such as long COVID.

Isoamericanin A ameliorates neuronal damage and alleviates vascular cognitive impairments by inhibiting oxidative stress through activation of the Nrf2 pathway

Oxidative stress is critically involved in the cognitive dysfunction and neuronal progressive degeneration in the vascular cognitive impairment (VCI). The natural lignan molecular isoamericanin A (ISOA) containing multiple hydroxyl groups has great potential for suppressing oxidative stress in VCI. The primary objective of this study was to delve into the pharmacological properties of ISOA against VCI, as well as to elucidate the mechanisms driving this effect from the perspective of antioxidative stress. Transient bilateral common carotid arteries occlusion (tBCCAO) mice model and hydrogen peroxide (H2O2) treated N2a cells were employed in vivo and in vitro, respectively. Behavioral tests showed that ISOA (5, 10 mg/kg) treatment alleviated learning, memorizing, and recognition in tBCCAO model mice. ISOA alleviated the neuronal damages by increasing the number of NeuN-positive cells, decreasing the TUNEL-positive cells density, up-regulating MAP-2 expression, lighting the damage of neuronal nucleus and synapse. Mechanistically, we found that ISOA reduced the oxidative stress in neurons, which manifested by reduction on the expressions of superoxide, H2O2, intercellular reactive oxygen species (ROS) and malondialdehyde (MDA) level, and up-regulations on the expressions of anti-oxidant enzymes superoxide dismutase, heme oxygenase-1, glutathione peroxidase 4, glutathione, and NAD(P)H: quinone oxidoreductase 1. Further investigation showed that ISOA activated nuclear factor erythroid 2-related factor 2 (Nrf2) pathway by downregulating the expression of kelch-like ECH-associated protein 1, upregulating the nuclear translocation and expression of Nrf2, and augmenting antioxidant response elements (ARE) promotor activity. The ISOA-mediated promotion on ARE promotor activity and anti-oxidant enzymes expressions, and suppression on superoxide and ROS expressions and MDA levels were weakened by pharmacological inhibition or genetic knockdown of Nrf2. These effects were enhanced after knockdown Keap1 in H2O2-treated cells. Our study demonstrates that ISOA alleviates the cognitive impairments and neuronal loss in VCI by attenuating oxidative stress through promoting the activation of Nrf2 pathway.

The Extraction, Biosynthesis, Health-Promoting and Therapeutic Properties of Natural Flavanone Eriodictyol

Eriodictyol is a flavanone compound commonly found in several edible plants. Ultrasound-assisted extraction and high-performance liquid chromatography (HPLC) are commonly used methods for the separation and analysis of eriodictyol. Many studies show that some micro-organisms can produce eriodictyol as a host. What is more, eriodictyol has a wide range of health benefits, including skincare, neuroprotective, hypoglycemic, anti-inflammatory, and antioxidant activities. In addition, the therapeutic properties of eriodictyol are cardioprotective, hepatoprotective, anticancer, with protective effects on the lungs and kidneys, and so on. This review examines the extraction, biosynthesis, and health and therapeutic properties of the natural compound eriodictyol and its value in medicine and food.

Hesperidin alleviated dendritic spines through inhibiting ferritinophagy via HERC2-NCOA4 ubiquitination in CUMS mice

BACKGROUND

Depression has been linked to ferritinophagy-induced synaptic damage, which affects the emotional circuitry and can ultimately lead to depressive symptoms. It has been suggested that Hesperidin might improve depression disorders. However, the relationship between the therapeutic effects of the sympathetic nervous system in alleviating depression-like behaviors and ferritinophagy is still unknown.

PURPOSE

The objective of this study is to investigate the possible impact of Hesperidin in alleviating dendritic spines through the inhibition of ferritinophagy via HERC2-NCOA4 ubiquitination in mice exposed to chronic unpredictable mild stress (CUMS).

METHODS

C57BL/6 and NCOA4+/+ mice were exposed to CUMS for 42 days. During the last 3 weeks of the CUMS procedure, the mice were administered Hesperidin (50, 100, 200 g/kg/d) or fluoxetine (10 mg/kg/d) once daily. Following the behavioral tests, Golgi staining, tissue iron concentration test, and perls staining were conducted to assess the therapeutic effect of Hesperidin. Additionally, ultrahigh-performance liquid chromatography-high-resolution tandem mass spectrometry (UPLC-Q-TOF/MS) and ultrahigh-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was utilized to analyze the metabolic components of Hesperidin in both blood and brain tissue. To investigate mechanism of Hesperidin, the cells were subjected to different concentrations of Hesperidin (25, 50, 100 µM), its metabolites (Eriodictyol (10, 20, 50 µM), Homoeriodictyol (0.1, 0.5, 1 µM)) and si-HERC2. Furthermore, HERC2-NCOA4 ubiquitination, and ferritinophagy-related proteins was explored through techniques such as western blot, immunofluorescence, co-immunoprecipitation, and molecular docking.

RESULTS

Hesperidin has demonstrated the potential to alleviate symptoms of depression by regulating dendritic spines through the inhibition of NCOA4-ferritinophagy, while NCOA4 overexpression could reverse these results. Importantly, the content of Hesperidin metabolites (Homoeriodictyol and Eriodictyol) was relatively high in brain tissue. The Hesperidin and its metabolites, Eriodictyol and Homoeriodictyol, were able to regulate GluR2 and SYN protein expression. Additionally, they inhibited ferritinophagy involving NCOA4, P62, LC3, and FTH. but this phenomenon was reversed by si-HERC2 following Hesperidin and its metabolite administration. Furthermore, the binding of HERC2 and NCOA4 protein was found to be inhibited by Hesperidin and its metabolites.

CONCLUSIONS

Hesperidin alleviated dendritic spines through inhibiting ferritinophagy via HERC2-NCOA4 ubiquitination in CUMS mice.

Neuroprotective effects and mechanisms of action of artemisinin in retinal ganglion cells in a mouse model of traumatic optic neuropathy

Introduction

Traumatic optic neuropathy is known to be a critical condition that can cause blindness; however, the specific mechanism underlying optic nerve injury is unclear. Recent studies have reported that artemisinin, considered vital in malaria treatment, can also be used to treat neurodegenerative diseases; however, its precise role and mechanism of action remain unknown. Therefore, in this study, we aimed to investigate the impact and probable mechanism of action of artemisinin in retinal ganglion cells (RGCs) in a mouse model of traumatic optic neuropathy induced by optic nerve crush (ONC).

Methods

ONC was induced in the left eye of mice by short-term clamping of the optic nerve; oral artemisinin was administered daily. The neuroprotective effect of the drug was assessed using Tuj-1 staining in RGCs. In addition, the inflammatory response and the expression levels of phosphorylated tau protein and tau oligomers were observed using RT-qPCR, TUNEL assay, and fluorescence staining to investigate the underlying mechanisms.

Results

Artemisinin increased the survival rate of RGCs 14 days after ONC. Artemisinin significantly reduced the levels of inflammatory factors such as CXCL10, CXCR3, and IL-1β in the retina and decreased the apoptosis of RGCs. Moreover, downregulation of the phosphorylation of tau proteins and the expression of tau oligomers were observed after artemisinin treatment.

Conclusion

Our results suggest that artemisinin can increase the survival rate of RGCs after ONC and reduce their apoptosis. This effect may be achieved by inhibiting the inflammatory response it triggers and downregulating tau protein phosphorylation and tau oligomer expression. These findings suggest the potential application of artemisinin as a therapeutic agent for neuropathy.

Cedrol supplementation ameliorates memory deficits by regulating neuro-inflammation and cholinergic function in lipopolysaccharide-induced cognitive impairment in rats

BACKGROUND

Cedrol, a sesquiterpene alcohol, is found in a high amount in several conifers. It possess several beneficial health effects, including antioxidant and anti-inflammatory properties. Objective: This study evaluates the neuroprotective role of cedrol against lipopolysaccharide (LPS)-induced neuroinflammation and memory loss in rats.

METHODS

Wistar rats were treated with cedrol (7.5, 15, and 30 mg/kg, oral, two weeks). During the last week, the rats (except for the control group) were treated with LPS (intraperitoneal injection, 1 mg/kg) to induce memory impairment. After that, the animals were subjected to behavioral studies (Morris water maze and passive avoidance) and biochemical assessments.

RESULTS

Our results showed a significant decrease in learning and memory function-in LPS-induced rats which were reversed by cedrol. Also, there was a significant increase in the cerebral levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and malondialdehyde (MDA) as well as acetylcholinesterase (AChE) activity in LPS-treated rats. Besides, a significant reduction in total thiol and superoxide dismutase levels was observed in LPS-treated rats. However, cedrol significantly decreased the brain level of AChE, TNF-α, and IL-1β. Administration of cedrol also restored the oxidative stress markers.

CONCLUSION

the beneficial effects of cedrol against LPS-induced memory impairment could be due to antioxidant activities and modulation of neuro-inflammatory mediators.

Natural polyphenol: Their pathogenesis-targeting therapeutic potential in Alzheimer's disease

Alzheimer's disease (AD) is a detrimental neurodegenerative disease affecting the elderly. Clinically, it is characterized by progressive memory decline and subsequent loss of broader cognitive functions. Current drugs provide only symptomatic relief but do not have profound disease-modifying effects. There is an unmet need to identify novel pharmacological agents for AD therapy. Neuropathologically, the characteristic hallmarks of the disease are extracellular senile plaques containing amyloid β-peptides and intracellular neurofibrillary tangles containing hyperphosphorylated microtubule-associated protein tau. Simultaneously, oxidative stress, neuroinflammation and mitochondrial dysfunction in specific brain regions are early events during the process of AD pathologic changes and are associated with Aβ/tau toxicity. Here, we first summarized probable pathogenic mechanisms leading to neurodegeneration and hopefully identify pathways that serve as specific targets to improve therapy for AD. We then reviewed the mechanisms that underlie disease-modifying effects of natural polyphenols, with a focus on nuclear factor erythroid 2-related factor 2 activators for AD treatment. Lastly, we discussed challenges in the preclinical to clinical translation of natural polyphenols. In conclusion, there is evidence that natural polyphenols can be therapeutically useful in AD through their multifaceted mechanism of action. However, more clinical studies are needed to confirm these effects.

Eriodictyol inhibits the motility, angiogenesis and tumor growth of hepatocellular carcinoma via NLRP3 inflammasome inactivation

NLRP3 involves in the development of hepatocellular carcinoma (HCC). Eriodictyol has shown its inhibitory effect on HCC cell proliferation. However, the underlying mechanism of eriodictyol in HCC is still unclear. This study aimed to explore the effect of and mechanism of eriodictyol on HCC. In this study, compared with eriodictyol (0 μM) group, eriodictyol significantly suppressed HepG2 cells (eriodictyol of 25, 50 and 100 μM) and Huh-7 cells (eriodictyol of 50 and 100 μM) viability, invasion, tube formation, metastasis-related genes MMP3, MMP16 and angiogenesis regulator VEGFA expressions with IC50 of 45.63 μM and 78.26 μM in vitro, respectively. Besides, eriodictyol significantly repressed NLRP3 expression, and reduced the protein levels of NLRP3 inflammasome-related proteins, adapter protein ASC, caspase-1, interleukin (IL)-18, and IL-1β in HepG2 (eriodictyol of 25, 50 and 100 μM) and Huh-7 cells (eriodictyol of 50 and 100 μM), respectively. Meanwhile, compared with control group, NLRP3 overexpression reversed the anti-metastatic effects of 100 μM eriodictyol on HCC cells invasion, tube formation, and metastasis-related genes MMP3, MMP16 and angiogenesis regulator VEGFA expressions, whereas NLRP3 knockdown enhanced the anti-metastatic effects of 100 μM eriodictyol on HCC cells. In vivo, compared with control group, eriodictyol significantly reduced the tumor growth, liver damage, inhibited the activation of NLRP3 inflammasome, and improved liver function, whereas NLRP3 overexpressing neutralized the anti-tumor effects of eriodictyol and degraded liver function. Hence, eriodictyol inhibited HCC cell viability, motility, angiogenesis and tumor growth via NLRP3 inflammasome inactivation both in vitro and in vivo.

Synthesis and evaluation of butylphthalide-scutellarein hybrids as multifunctional agents for the treatment of Alzheimer's disease

A series of butylphthalide and scutellarein hybrids 3-(alkyl/alkenyl) hydroxyphthalide derivatives were designed, synthesized and evaluated as multifunctional agents against Alzheimer's disease. In vitro bioactivity assays indicated that most of the compounds displayed excellent antioxidant activity and moderate to good inhibition activities of self-induced Aβ1-42 aggregation. Among them, compound 7c was demonstrated as a potential and balanced multifunctional candidate displaying the best inhibitory effects on self- and Cu2+-induced Aβ1-42 aggregation (90.2 % and 35.4 %, respectively) and moderate activity for disaggregation of Aβ1-42 aggregation (42.5 %). In addition, 7c also displayed excellent antioxidant (2.42 Trolox equivalents), metal ions chelating, oxidative stress alleviation, neuroprotective and anti-neuroinflammatory activities. Furthermore, in vivo study demonstrated that 7c could ameliorate the learning and memory impairment induced by sodium nitrite and Aβ1-42 in the step-down passive avoidance test. These balanced multifunctional profiles supporting compound 7c as a novel potential candidate for the treatment of AD.

Pyrolae herba alleviates cognitive impairment via hippocampal TREM2 signaling modulating neuroinflammation and neurogenesis in lipopolysaccharide-treated mice

ETHNOPHARMACOLOGICAL RELEVANC

Pyrolae herba (PH), a kind of Chinese herb, has been identified to have an anti-inflammatory effect, while the potential for treating cognitive impairment (CI), as well as the underlying mechanisms, is unclear. Currently, the interaction between neuroinflammation and neural function play a critical role in pathophysiology of CI.

AIM OF THE STUDY

To elucidate therapeutic effect of PH for CI as well as its underlying mechanisms with LPS-treated mice model.

METHODS AND MATERIALS

In this study, male C57BL6/J mice received lipopolysaccharide (LPS) injection for 10 days to establish CI model and were administrated with PH for 14 days. We used piracetam as a positive control. Memory and spatial function was tested by Morris water maze (MWM). The level of inflammation-related cytokines (TNF-α, IL-1β, IL-10, IL-6) were determined by enzyme-linked immunosorbent assay (ELISA) in serum and western blot in hippocampus. Immunofluorescence (IF) was used to measure the levels of ionized calcium binding linker molecule 1 (IBA-1), glial fibrillary acidic protein (GFAP), BrdU, Ki67 and doublecortin (DCX) in hippocampus. The mRNA sequencing was used to screen the potential target of PH with therapeutic CI. Reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the gene alteration of triggering receptor expressed on myeloid cells 2 (TREM2) in hippocampus. We used western blot to determine protein expressions of TREM2 and its related signaling, as well as synaptic proteins in hippocampus.

RESULTS

The results revealed that LPS contributed to CI, and PH or piracetam treatment significantly ameliorated CI in MWM test. LPS contributed to increasing expressions of TNF-α and IL-1β in serum and hippocampus, which both reversed by PH or piracetam. PH or piracetam could inhibit the activation of glial cells including microglia and astrocyte in the hippocampus in LPS-induced CI model. The mRNA sequencing and RT-PCR results showed that LPS significantly increased the gene expression of TREM2, which was reversed by PH. The alteration of TREM2 expression was the most significant among the 10 genes (TREM2, Slc24a2, Ptch2, Gck, Il1rapl1, Cadps2, Btbd11, Secisbp2l, Tenm3 and Prepl) in hippocampus. Protein results showed that LPS upregulated the expressions of TREM2 and its related proteins including DAP12, spleen tyrosine kinase (SYK) phosphorylation and ADAM 10, which were all reversed by PH or piracetam in hippocampus. Furthermore, LPS was capable of reducing the expression of BrdU and DCX co-labeled positive cells in hippocampal dentate gyrus (DG), which was reversed only by PH. Moreover, PH or piracetam treatment significantly increased the expression of Ki67 and DCX co-labeled positive cells in hippocampal DG. The expression of synapsin1 was obviously decreased by LPS and was significantly reversed by PH or piracetam.

CONCLUSIONS

PH could alleviate CI by suppressing the secretion of pro-inflammatory cytokines and mitigating astrocyte activity by restraining microglia's activation in hippocampus, further facilitating neurogenesis and proliferation, thereby enhancing pre-synaptic protein. This study highlighted on the clinical application of PH, which might promote the use of phytomedicine in CI patients.

Metabolic Regulations of Smilax china L. against β-Amyloid Toxicity in Caenorhabditis elegans

Smilax china L. (Chinaroot) is a natural herb that has multiple uses, such as being used to make tea and food. Both its roots and leaves have different uses due to their unique components. In this study, we analyzed the extract of S. china. roots using LC-HRMS and evaluated the neuroprotective effects and metabolic regulation of S. china on Caenorhabditis elegans. Chinaroot extract prolonged the life span of healthy nematodes, delayed the paralysis time of transgenic CL4176, and reduced the level of β-amyloid deposition in transgenic CL2006. The comprehensive analysis of metabolomics and qRT-PCR revealed that Chinaroot extract exerted neuroprotective effects through the valine, leucine and isoleucine degradation and fatty acid degradation pathways. Moreover, we first discovered that the expressions of T09B4.8, ech-7, and agxt-1 were linked to the neuroprotective effects of Chinaroot. The material exerted neuroprotective effects by modulating metabolic abnormalities in AD model C. elegans. Our study provides a new foundation for the development of functional food properties and functions.

The Potential Mechanism of Eriodictyol in Treating Alzheimer's Disease: A Study on Computer-assisted Investigational Strategies

BACKGROUND

At present, drug development for treating Alzheimer's disease (AD) is still highly challenging. Eriodictyol (ERD) has shown great potential in treating AD, but its molecular mechanism is unknown.

OBJECTIVE

We aimed to explore the potential targets and mechanisms of ERD in the treatment of AD through network pharmacology, molecular docking, and molecular dynamics simulations.

METHODS

ERD-related targets were predicted based on the CTD, SEA, PharmMapper, Swiss TargetPrediction, and ETCM databases, and AD-related targets were predicted through the TTD, OMIM, DrugBank, GeneCards, Disgenet, and PharmGKB databases. Protein-protein interaction, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomics analyses (KEGG) were used to analyse the potential targets and key pathways of the anti-AD effect of ERD. Subsequently, potential DEGs affected by AD were analysed using the AlzData database, and their relationships with ERD were evaluated through molecular docking and molecular dynamics simulations.

RESULTS

A total of 198 ERD-related targets, 3716 AD-related targets, and 122 intersecting targets were identified. GO annotation analysis revealed 1497 biological processes, 78 cellular components, and 132 molecular functions of 15 core targets. KEGG enrichment analysis identified 168 signalling pathways. We ultimately identified 9 DEGs associated with AD through analysis of the AlzData data. Molecular docking results showed good affinity between the selected targets and ERD, with PTGS2, HSP90AA1, and BCL2. The interactions were confirmed by molecular dynamics simulations.

CONCLUSION

ERD exerts anti-AD effects through multiple targets, pathways, and levels, providing a theoretical foundation and valuable reference for the development of ERD as a natural anti-AD drug.

Ilexchinene, a new seco-ursane triterpenoid from the leaves of Ilex chinensis with therapeutic effect on neuroinflammation by attenuating the MAPK/NF-κB signaling pathway

BACKGROUND

Neuroinflammation is a vital factor participating in the whole pathogenetic process of diverse neurodegenerative disorders, but accessible clinical drugs are still insufficient due to their inefficacy and side effects. Triterpenoids are reported to possess potential anti-neuroinflammatory activities, and the leaves of Ilex chinensis are a commonly used herbal medicine containing many ursane-type and oleanane-type triterpenoids. However, the novel triterpenoids from I. chinensis and their underlying mechanisms are still elusive.

PURPOSE

To isolate novel seco-ursane triterpenoids with anti-neuroinflammatory effects from the leaves of I. chinensis and reveal their underlying mechanisms.

STUDY DESIGN AND METHODS

The novel compound was purified by column chromatography and identified by comprehensive spectroscopic experiments. The LPS-induced BV-2 cell model and LPS-induced acute murine brain inflammation model were used to assess the anti-neuroinflammatory effect of the structure and further understand its underlying mechanisms by cell viability, ELISA, Western blot analysis, qRT‒PCR analysis, behavior analysis, H&E staining, and immunofluorescence staining experiments.

RESULTS

Ilexchinene is a novel ursane-type triterpenoid with a rare 18,19-seco-ring skeleton that was first isolated and identified from I. chinensis. Ilexchinene evidently reduced the overexpression of inflammatory substances in vitro. A mechanistic study suggested that ilexchinene could decrease NF-κB activation to prevent the formation of the NLRP3 inflammasome in the early neuroinflammatory response; in addition, it could prevent the phosphorylation of ERK and JNK. In vivo, ilexchinene remarkably improved LPS-induced mouse behavioral deficits and diminished the number of overactivated microglial cells. Furthermore, ilexchinene evidently diminished the overexpression of inflammatory substances in mouse brains. A mechanistic study confirmed that ilexchinene markedly suppressed the MAPK/NF-κB pathway to relieve the neuroinflammatory response.

CONCLUSION

We identified a novel 18,19-seco-ursane triterpenoid from the leaves of I. chinensis and revealed its underlying mechanism of neuroinflammation for the first time. These findings suggest that ilexchinene might possess promising therapeutic effects in neuroinflammation.

Knockdown and inhibition of hippocampal GPR17 attenuates lipopolysaccharide-induced cognitive impairment in mice

BACKGROUND

Previously we reported that inhibition of GPR17 prevents amyloid β 1-42 (Aβ1-42)-induced cognitive impairment in mice. However, the role of GPR17 on cognition is still largely unknown.

METHODS

Herein, we used a mouse model of cognitive impairment induced by lipopolysaccharide (LPS) to further investigate the role of GPR17 in cognition and its potential mechanism. The mice were pretreated with GPR17 shRNA lentivirus and cangrelor by microinjection into the dentate gyrus (DG) region of the hippocampus. After 21 days, LPS (0.25 mg/kg, i.p.) was administered for 7 days. Animal behavioral tests as well as pathological and biochemical assays were performed to evaluate the cognitive function in mice.

RESULTS

LPS exposure resulted in a significant increase in GPR17 expression at both protein and mRNA levels in the hippocampus. Gene reduction and pharmacological blockade of GPR17 improved cognitive impairment in both the Morris water maze and novel object recognition tests. Knockdown and inhibition of GPR17 inhibited Aβ production, decreased the expression of NF-κB p65, increased CREB phosphorylation and elevated BDNF expression, suppressed the accumulation of pro-inflammatory cytokines, inhibited Glial cells (microglia and astrocytes) activation, and increased Bcl-2, PSD-95, and SYN expression, reduced Bax expression as well as decreased caspase-3 activity and TUNEL-positive cells in the hippocampus of LPS-treated mice. Notably, knockdown and inhibition of GPR17 not only provided protective effects against cholinergic dysfunction but also facilitated the regulation of oxidative stress. In addition, cangrelor pretreatment can effectively inhibit the expression of inflammatory cytokines by suppressing NF-κB/CREB/BDNF signaling in BV-2 cells stimulated by LPS. However, activation of hippocampal GPR17 with MDL-29951 induced cognitive impairment in normal mice.

CONCLUSIONS

These observations indicate that GPR17 may possess a neuroprotective effect against LPS-induced cognition deficits, and neuroinflammation by modulation of NF-κB/CREB/BDNF signaling in mice, indicating that GPR17 may be a promising new target for the prevention and treatment of AD.

Eriodictyol Alleviated LPS/D-GalN-Induced Acute Liver Injury by Inhibiting Oxidative Stress and Cell Apoptosis via PI3K/AKT Signaling Pathway

Eriodictyol occurs naturally in a variety of fruits and vegetables, and has drawn significant attention for its potential health benefits. This study aims to look into the effects of eriodictyol on acute liver injury (ALI) induced by LPS/D-GalN and elucidate its potential molecular biological mechanisms. A total of 47 targets were predicted for the treatment of ALI with eriodictyol, and the PI3K/AKT signaling pathway played a key role in the anti-ALI processing of this drug. The in vivo experiment showed that eriodictyol can effectively reduce liver function-related biochemical indicators such as ALT, AST, and AKP. Eriodictyol can also up-regulate the levels of SOD and GSH, and inhibit the release of IL-1β, IL-6, and TNF-α. Additionally, TUNEL staining, immunohistochemistry, and RT-PCR experiments showed that eriodictyol activated the PI3K/AKT pathway and decreased the expression of Bax, caspase3, and caspase8 while increasing the expression of Bcl-2 m-RNA. Finally, molecular docking experiments and molecular dynamics simulations confirmed the stable binding between eriodictyol and PI3K, AKT molecules. This study showed that eriodictyol can activate the PI3K/AKT signaling pathway to alleviate ALI-related oxidative stress and apoptosis.

Targeting impaired nutrient sensing via the sirtuin pathway with novel compounds to prevent or treat dementia: A systematic review

BACKGROUND

Dementia is prevalent in aged populations and is associated with disability and distress for those affected. Therapeutic benefits of drugs targeting dementia are small. Impaired nutrient sensing pathways have been implicated in the pathogenesis of dementia and may offer a novel treatment target.

AIMS

This systematic review collated evidence for novel therapeutic compounds that modify nutrient sensing pathways, particularly the sirtuin pathway, in preventing cognitive decline or improving cognition in normal ageing, mild cognitive impairment (MCI), and dementia.

METHODS

PubMed, Embase and Web of Science databases were searched using key search terms. Articles were screened using Covidence systematic review software. The risk of bias was assessed using the Systematic Review Center for Laboratory animal Experimentation (SYRCLE)'s risk of bias tool for animal studies and Cochrane Risk of Bias tool v 2.0 for human studies.

RESULTS

Out of 3841 articles, 68 were included describing 38 different novel therapeutic compounds that modulate the nutrient sensing pathway via the sirtuin pathway. In animal models (58 studies), all investigated novel therapeutic compounds showed cognitive benefits. Ten studies were human intervention trials targeting normal ageing (1 study) and dementia populations (9 studies). Direct sirtuin (silent mating type information regulation 2 homolog) 1 (SIRT1) activators Resveratrol and Nicotinamide derivatives improved cognitive outcomes among human subjects with normal cognition and MCI.

CONCLUSION

Animal studies support that modulation of the sirtuin pathway has the potential to improve cognitive outcomes. Overall, there is a clear lack of translation from animal models to human populations.

6-Aminoflavone Activates Nrf2 to Inhibit the Phospho-JNK/TNF-α Signaling Pathway to Reduce Amyloid Burden in an Aging Mouse Model

In the current study, we examined the antioxidant activity and anti-amyloidogenic potential of 6-aminoflavone in an adult mice model of d-galactose-induced aging. Male albino eight-week-old mice were assigned into four groups: 1. the control group (saline-treated), 2. d-galactose-treated mice (100 mg/kg/day, intravenously) for eight weeks, 3. d-galactose-treated mice (100 mg/kg/day, intravenously for eight weeks) and 6-AF-treated mice (30 mg/kg/day, intravenously for the final four weeks), and 4. 6-AF-treated mice (30 mg/kg/day i.p. for four weeks). We conducted many assays for antioxidant enzymes, including lipid peroxidation, catalase, glutathione (GSH), peroxidase (POD), and sulfoxide dismutase (SOD) (LPO). Western blotting was used to assess protein expression while the Morris water maze (MWM) and Y-maze (YM) were used to study behavior. The findings show that 6-AF greatly improved neuronal synapse and memory impairment brought on by d-galactose and it significantly inhibited BACE1 to reduce the amyloidogenic pathway of A (both amyloid β production and aggregation) by upregulating Nrf2 proteins (validated through molecular docking studies) and suppressing phosphorylated JNK and TNF-α proteins in adult albino mice's brain homogenates. These findings suggest that 6-AF, through the Nrf2/p-JNK/TNF-α signaling pathway, can diminish the oxidative stress caused by d-galactose, as well as the amyloidogenic route of A formation and memory impairment.

Study on the mechanism of Shujin Tongluo granules in treating cervical spondylosis based on network pharmacology and molecular docking

BACKGROUND

To investigate the potential active ingredients and possible mechanisms of Shujin Tongluo granules (SJTLG) in the treatment of cervical spondylosis (CS) by network pharmacology and molecular docking.

METHODS

The active ingredients and potential targets of SJTLG were obtained through databases such as traditional Chinese medicine system (TCMSP) and BATMAN-traditional Chinese medicine (TCM), and the relevant human targets of CS were identified through databases such as OMIM, GeneCards, and DisGeNET. The intersection targets were imported into STRING for protein-protein interaction (PPI) analysis. The obtained data were imported into Cytoscape 3.9.0 software for visualization, and module analysis was performed using the MCODE plug-in. The representative targets were screened through the Metascape website for pathway enrichment analysis in Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Cytoscape software was used to build networks such as "drug-compound-target" and "drug-compound-target-pathway." Finally, the key targets were selected for molecular docking with the corresponding compounds by Autodock Tools 1.5.7 and visualized by PyMol.

RESULTS

A total of 132 active compounds and 996 targets from SJTLG and 678 targets from CS were screened with 116 intersection targets. The key targets were AKT1, GAPDH, ALB, IL-6, TP53, TNF, VEGFA, IL-1β, EGFR, HSP90AA1, ESR1, and JUN. The results of GO and KEGG enrichment analysis showed that the treatment of CS was mainly related to biological processes such as cellular response to nitrogen compound, cellular response to organonitrogen compound, and positive regulation of locomotion, and the targets were mainly focused on pathways in cancer, Kaposi sarcoma-associated herpesvirus infection, PI3K-Akt signaling pathway, lipid, and atherosclerosis. Molecular docking results showed that the minimum binding energy between the core targets and the corresponding compound was <-5.0 kcal·mol-1.

CONCLUSION

This study preliminarily elucidates the potential active ingredients and mechanism of anti-inflammatory, analgesic, microcirculation improvement, vasodilation, osteoporosis inhibition and nerve nutrition effects of SJTLG in the treatment of CS and provides a reference for its clinical application.

Therapeutic targeting of Ras/Raf/MAPK pathway by natural products: A systematic and mechanistic approach for neurodegeneration

BACKGROUND

Multiple dysregulated pathways are behind the pathogenesis of neurodegenerative diseases (NDDs); however, the crucial targets are still unknown. Oxidative stress, apoptosis, autophagy, and inflammation are the most dominant pathways that strongly influence neurodegeneration. In this way, targeting the Ras/Raf/mitogen-activated protein kinases (MAPKs) pathway appears to be a developing strategy for combating NDDs like Parkinson's disease, Alzheimer's disease, stroke, aging, and other NDDs. Accordingly, plant secondary metabolites have shown promising potentials for the simultaneous modulation of the Ras/Raf/MAPKs pathway and play an essential role in NDDs. MAPKs include p38 MAPK, extracellular signal-regulated kinase 1/2 (ERK 1/2), and c-Jun N-terminal kinase (JNK), which are important molecular players in neurodegeneration. Ras/Raf, which is located the upstream of MAPK pathway influences the initiation and progression of neurodegeneration and is regulated by natural products.

PURPOSE

Thus, the present study aimed to investigate the neuroprotective roles of plant- and marine-derived secondary metabolites against several NDDs through the modulation of the Ras/Raf/MAPK signaling pathway.

STUDY DESIGN AND METHODS

A systematic and comprehensive review was performed to highlight the modulatory roles of natural products on the Ras/Raf/MAPK signaling pathway in NDDs, according to the PRISMA guideline, using scholarly electronic databases, including PubMed, Scopus, and Web of Sciences. Associated reference lists were also searched for the literature review.

RESULTS

From a total of 1495 results, finally 107 articles were included in the present study. The results show that several natural compounds such as alkaloid, phenolic, terpenoids, and nanoformulation were shown to have modulatory effects on the Ras/Raf/MAPKs pathway.

CONCLUSION

Natural products are promising multi-targeted agents with on NDDs through Ras/Raf/MAPKs pathway. Nevertheless, additional and complementary studies are necessary to check its efficacy and potential side effects.

A Comparison between High-Performance Countercurrent Chromatography and Fast-Centrifugal Partition Chromatography for a One-Step Isolation of Flavonoids from Peanut Hulls Supported by a Conductor like Screening Model for Real Solvents

Peanut hulls (Arachis hypogaea, Leguminosae), which are a side stream of global peanut processing, are rich in bioactive flavonoids such as luteolin, eriodictyol, and 5,7-dihydroxychromone. This study aimed to isolate these flavonoid derivatives by liquid-liquid chromatography with as few steps as possible. To this end, luteolin, eriodictyol and 5,7-dihydroxychromone were isolated from peanut hulls using two different techniques, high-performance countercurrent chromatography (HPCCC) and fast-centrifugal partition chromatography (FCPC). The suitability of the biphasic solvent system composed of n-hexane/ethyl acetate/methanol/water (1.0/1.0/1.0/1.5; v/v/v/v) was determined by the Conductor like Screening Model for Real Solvents (COSMO-RS), which allowed the partition ratio K_D-values of the three main flavonoids to be calculated. After a one-step HPCCC separation of ~1000 mg of an ethanolic peanut hull extract, 15 mg of luteolin and 8 mg of eriodictyol were isolated with purities over 96%. Furthermore, 3 mg of 5,7-dihydroxychromone could be isolated after purification by semi-preparative reversed-phase liquid chromatography (semi-prep. HPLC) in purity of over 99%. The compounds were identified by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance spectroscopy (NMR).

Mechanisms of ferroptosis in Alzheimer's disease and therapeutic effects of natural plant products: A review

Neurodegenerative diseases, such as Alzheimer's disease (AD), are characterized by massive loss of specific neurons. It is a progressive disabling, severe and fatal complex disease. Due to its complex pathogenesis and limitations of clinical treatment strategies, it poses a serious medical challenge and medical burden worldwide. The pathogenesis of AD is not clear, and its potential biological mechanisms include aggregation of soluble amyloid to form insoluble amyloid plaques, abnormal phosphorylation of tau protein and formation of intracellular neurofibrillary tangles (NFT), neuroinflammation, ferroptosis, oxidative stress and metal ion disorders. Among them, ferroptosis is a newly discovered programmed cell death induced by iron-dependent lipid peroxidation and reactive oxygen species. Recent studies have shown that ferroptosis is closely related to AD, but the mechanism remains unclear. It may be induced by iron metabolism, amino acid metabolism and lipid metabolism affecting the accumulation of iron ions. Some iron chelating agents (deferoxamine, deferiprone), chloroiodohydroxyquine and its derivatives, antioxidants (vitamin E, lipoic acid, selenium), chloroiodohydroxyquine and its derivatives Fer-1, tet, etc. have been shown in animal studies to be effective in AD and exert neuroprotective effects. This review summarizes the mechanism of ferroptosis in AD and the regulation of natural plant products on ferroptosis in AD, in order to provide reference information for future research on the development of ferroptosis inhibitors.

Response Surface Optimization of Extraction Conditions for the Active Components with High Acetylcholinesterase Inhibitory Activity and Identification of Key Metabolites from Acer truncatum Seed Oil Residue

The State Council of China has called for the comprehensive development and utilization of Acer truncatum resources. However, research on one of its by-products, namely seed oil residue (ASR), from seed oil extraction is seriously insufficient, resulting in a waste of these precious resources. We aimed to optimize the conditions of ultrasound-assisted extraction (UAE) using a response surface methodology to obtain high acetylcholinesterase (AChE) inhibitory components from ASR and to tentatively identify the active metabolites in ASR using non-targeted metabolomics. Based on the results of the independent variables test, the interaction effects of three key extracting variables, including methanol concentration, ultrasonic time, and material-to-liquid ratio, were further investigated using the Box-Behnken design (BBD) to obtain prior active components with high AChE inhibitory activity. UPLC-QTOF-MS combined with a multivariate method was used to analyze the metabolites in ASR and investigate the causes of activity differences. Based on the current study, the optimal conditions for UAE were as follows: methanol concentration of 85.06%, ultrasonic time of 39.1 min, and material-to-liquid ratio of 1.06:10 (g/mL). Under these optimal conditions, the obtained extracts show strong inhibitions against AChE with half maximal inhibitory concentration (IC₅₀) values ranging from 0.375 to 0.459 µg/mL according to an Ellman's method evaluation. Furthermore, 55 metabolites were identified from the ASR extracted using methanol in different concentrations, and 9 biomarkers were subsequently identified as potential compounds responsible for the observed AChE inhibition. The active extracts have potential to be used for the development of functional foods with positive effects on Alzheimer's disease owing to their high AChE inhibition activity. Altogether, this study provides insights into promoting the comprehensive utilization of A. truncatum resources.

UPLC-QTOF-MS-based metabolomics and chemometrics studies of geographically diverse Acer truncatum leaves: A traditional herbal tea in Northern China

Traditionally in Northern China, Acer truncatum leaves (ATL) have been used as herbal tea, now consumed worldwide. Few studies have reported ATL metabolites from different areas and their correlation with the environment. Thus, metabolomic analyses were conducted on ATL collected from twelve locations throughout four environmental zones in Northern China to understand the phytochemical differences with regards to environmental conditions. Sixty-four compounds, mostly flavonoids (FLAs) and gallic acid-containing natural products (GANPs), were characterized, including 34 previously unreported constituents from A. truncatum. Twenty-two markers were useful to differentiate ATL from the four environmental zones. Humidity, temperature, and sunshine duration are the predominant factors affecting FLAs and GANPs levels. Sunshine duration was positively correlated with eriodictyol (r = 0.994, p < 0.01), and humidity negatively with epicatechin gallate (r = -0.960, p < 0.05). These findings provide insights into ATL phytochemistry, aiding cultivation of A. truncatum tea with higher potential health benefits.

Discovery of novel 2-hydroxyl-4-benzyloxybenzyl aniline derivatives as potential multifunctional agents for the treatment of Parkinson's disease

To discover novel multifunctional agents for the treatment of Parkinson's disease, a series of 2-hydroxyl-4-benzyloxybenzyl aniline derivatives was designed, synthesized and evaluated. The biological screening indicated that representative compound 6h possessed excellent MAO-B inhibition (IC₅₀ = 0.014 μM), high antioxidant activity (ORAC = 2.14 Trolox equivalent), good metal chelating ability, appropriate BBB permeability and significant neuroprotective effect. Additionally, 6h exhibited great ability to alleviate the neuroinflammtion by suppressing the activation of NF-κB pathway in vitro. Furthermore, 6h can also ameliorate MPTP induced Parkinson's disease symptoms in mice by improving the dopamine level and repressing oxidative damage. These results indicated that compound 6h was a promising candidate for further development against PD.

Therapeutic potential of natural molecules against Alzheimer's disease via SIRT1 modulation

Alzheimer's disease (AD) is a neurodegenerative disease mainly characterized by progressive cognitive dysfunction and memory impairment. Recent studies have shown that regulating silent information regulator 1 (SIRT1) expression has a significant neuroprotective effect, and SIRT1 may become a new therapeutic target for AD. Natural molecules are an important source of drug development for use in AD therapy and may regulate a wide range of biological events by regulating SIRT1 as well as other SIRT1-mediated signaling pathways. This review aims to summarize the correlation between SIRT1 and AD and to identify in vivo and in vitro studies investigating the anti-AD properties of natural molecules as modulators of SIRT1 and SIRT1-mediated signaling pathways. A literature search was conducted for studies published between January 2000 and October 2022 using various literature databases, including Web of Science, PubMed, Google Scholar, Science Direct, and EMBASE. Natural molecules, such as resveratrol, quercetin, icariin, bisdemethoxycurcumin, dihydromyricetin, salidroside, patchouli, sesamin, rhein, ligustilide, tetramethoxyflavanone, 1-theanine, schisandrin, curcumin, betaine, pterostilbene, ampelopsin, schisanhenol, and eriodictyol, have the potential to modulate SIRT1 and SIRT1 signaling pathways, thereby combating AD. The natural molecules modulating SIRT1 discussed in this review provide a potentially novel multi-mechanistic therapeutic strategy for AD. However, future clinical trials need to be conducted to further investigate their beneficial properties and to determine the safety and efficacy of SIRT1 natural activators against AD.

Eriodictyol: a review of its pharmacological activities and molecular mechanisms related to ischemic stroke

Ischemic stroke (IS) is characterized by a prominent mortality and disability rate, which has increased the burden on the global economy to a certain extent. Meanwhile, patients benefit little from the limited clinical strategies of intravenous alteplase and thrombectomy due to the limited therapeutic window. Given this, it is urgent to study new therapeutic methods to intervene in these patients. Eriodyctiol (ERD) is a major natural flavonoid, which widely exists in fruits, vegetables, and medicinal herbs, and has various pharmacological properties. It has been reported that ERD can maintain homeostasis in organisms by exerting neuroprotective and vascular protective effects. Therefore, more and more studies have focused on the pharmacological activity and mechanism of ERD in IS. This paper provides an overview of the plant sources, phytochemical properties, pharmacokinetics, and pathogenesis, as well as the pharmacological effects and mechanisms of ERD in IS. To date, preclinical studies on ERD in diverse cell lines and animal models have established the idea of ERD as a feasible agent capable of specifically ameliorating IS. The molecular mechanisms of ERD to prevent or reduce IS are mainly based on the inhibition of inflammation, oxidative stress, autophagy and apoptosis. Nevertheless, the mechanism of ERD against IS is flawed and needs more exploration by the research community. Moreover, well-designed clinical trials are needed to increase the scientific validity of the beneficial effects of ERD against IS.

Anti-inflammatory actions of β-funaltrexamine in a mouse model of lipopolysaccharide-induced inflammation

Neuroinflammation is involved in a wide range of brain disorders, thus there is great interest in identifying novel anti-inflammatory agents to include in therapeutic strategies. Our previous in vitro studies revealed that beta-funaltrexamine (β-FNA), a well-characterized selective mu-opioid receptor (MOR) antagonist, inhibits inflammatory signaling in human astroglial cells, albeit through an apparent MOR-independent mechanism. We also previously determined that lipopolysaccharide (LPS)-induced sickness behavior and neuroinflammation in mice are prevented by pretreatment with β-FNA. Herein we investigated the temporal importance of β-FNA treatment in this pre-clinical model of LPS-induced neuroinflammation. Adult, male C57BL/6J mice were administered an i.p. injection of LPS followed by treatment (i.p. injection) with β-FNA immediately or 4 h post-LPS. Sickness behavior was assessed using an open-field test, followed by assessment of inflammatory signaling in the brain, spleen, and plasma. Levels of inflammatory chemokines/cytokines (interferon γ-induced protein, CXCL10; monocyte chemotactic protein 1, CCL2; and interleukin-6, IL-6) in tissues were measured using an enzyme-linked immunosorbent assay and nuclear factor-kappa B (NFκB), p38 mitogen activated kinase (p38 MAPK), and glial fibrillary acidic protein (GFAP) expression were measured by western blot. LPS-induced sickness behavior and chemokine expression were inhibited more effectively when β-FNA treatment occurred immediately after LPS administration, as opposed to 4 h post-LPS; and β-FNA-mediated effects were time-dependent as evidenced by inhibition at 24 h, but not at 8 h. The inhibitory effects of β-FNA on chemokine expression were more evident in the brain versus the spleen or plasma. LPS-induced NFκB-p65 and p38 MAPK expression in the brain and spleen were inhibited at 8 and 24 h post-LPS. These findings extend our understanding of the anti-inflammatory effects of β-FNA and warrant further investigation into its therapeutic potential.

Neurological disorders of COVID-19: insights to applications of natural products from plants and microorganisms

In addition to the typical respiratory manifestations, various disorders including involvement of the nerve system have been detected in COVID-19 ranging from 22 to 36%. Although growing records are focusing on neurological aspects of COVID-19, the pathophysiological mechanisms and related therapeutic methods remain obscure. Considering the increased concerns of SARS-CoV-2 potential for more serious neuroinvasion conditions, the present review attempts to focus on the neuroprotective effects of natural compounds as the principle source of therapeutics inhibiting multiple steps of the SARS-CoV-2 infection cycle. The great majority of the natural products with anti-SARS-CoV-2 activity mainly inhibit the attachment, entry and gene expression rather than the replication, assembly, or release. Although microbial-derived natural products comprise 38.5% of the known natural products with neuroprotective effects following viral infection, the neuroprotective potential of the majority of microorganisms is still undiscovered. Among natural products, chrysin, huperzine A, ginsenoside Rg1, pterostilbene, and terrein have shown potent in vitro neuroprotective activity and can be promising for new or repurpose drugs for neurological complications of SARS-CoV-2.

Interdisciplinary Approaches to Deal with Alzheimer's Disease-From Bench to Bedside: What Feasible Options Do Already Exist Today?

Alzheimer's disease is one of the most common neurodegenerative diseases in the western population. The incidence of this disease increases with age. Rising life expectancy and the resulting increase in the ratio of elderly in the population are likely to exacerbate socioeconomic problems. Alzheimer's disease is a multifactorial disease. In addition to amyloidogenic processing leading to plaques, and tau pathology, but also other molecular causes such as oxidative stress or inflammation play a crucial role. We summarize the molecular mechanisms leading to Alzheimer's disease and which potential interventions are known to interfere with these mechanisms, focusing on nutritional approaches and physical activity but also the beneficial effects of cognition-oriented treatments with a focus on language and communication. Interestingly, recent findings also suggest a causal link between oral conditions, such as periodontitis or edentulism, and Alzheimer's disease, raising the question of whether dental intervention in Alzheimer's patients can be beneficial as well. Unfortunately, all previous single-domain interventions have been shown to have limited benefit to patients. However, the latest studies indicate that combining these efforts into multidomain approaches may have increased preventive or therapeutic potential. Therefore, as another emphasis in this review, we provide an overview of current literature dealing with studies combining the above-mentioned approaches and discuss potential advantages compared to monotherapies. Considering current literature and intervention options, we also propose a multidomain interdisciplinary approach for the treatment of Alzheimer's disease patients that synergistically links the individual approaches. In conclusion, this review highlights the need to combine different approaches in an interdisciplinary manner, to address the future challenges of Alzheimer's disease.

Protective Effects of Flavonoids against Alzheimer's Disease: Pathological Hypothesis, Potential Targets, and Structure-Activity Relationship

Alzheimer’s disease (AD) is a neurodegenerative disease with high morbidity and mortality, for which there is no available cure. Currently, it is generally believed that AD is a disease caused by multiple factors, such as amyloid-beta accumulation, tau protein hyperphosphorylation, oxidative stress, and inflammation. Multitarget prevention and treatment strategies for AD are recommended. Interestingly, naturally occurring dietary flavonoids, a class of polyphenols, have been reported to have multiple biological activities and anti-AD effects in several AD models owing to their antioxidative, anti-inflammatory, and anti-amyloidogenic properties. In this review, we summarize and discuss the existing multiple pathogenic factors of AD. Moreover, we further elaborate on the biological activities of natural flavonoids and their potential mode of action and targets in managing AD by presenting a wide range of experimental evidence. The gathered data indicate that flavonoids can be regarded as prophylactics to slow the advancement of AD or avert its onset. Different flavonoids have different activities and varying levels of activity. Further, this review summarizes the structure–activity relationship of flavonoids based on the existing literature and can provide guidance on the design and selection of flavonoids as anti-AD drugs.

Dioscorea nipponica Makino Rhizome Extract and Its Active Compound Dioscin Protect against Neuroinflammation and Scopolamine-Induced Memory Deficits

Activation of microglial cells by intrinsic or extrinsic insult causes neuroinflammation, a common phenomenon in neurodegenerative diseases. Prevention of neuroinflammation may ameliorate many neurodegenerative disease progressions. Dioscorea nipponica Makino (DN) extract can alleviate muscular atrophy and inflammatory diseases; however, the efficacy and mechanism of action in microglial cells remain unknown. The current study investigates the possible anti-inflammatory effects and mechanisms of Dioscorea nipponica Makino ethanol extract and its steroidal saponin dioscin. Our in vitro study shows that Dioscorea nipponica rhizome ethanol extract (DNRE) and dioscin protect against lipopolysaccharide (LPS)-activated inflammatory responses in BV-2 microglial cells by inhibiting phosphorylation and the nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), resulting in the downregulation of pro-inflammatory cytokines and enzymes. Consistent with our previous report of dioscin-mediated enhancement of neurotrophic factors in dopaminergic cells, here we found that dioscin upregulates brain-derived neurotrophic factor (BDNF) and cAMP-response element binding protein (CREB) phosphorylation (pCREB) in the cerebral cortex and hippocampus regions of the mouse brain. Scopolamine treatment increased pro-inflammatory enzyme levels and reduced the expression of BDNF and pCREB in the hippocampus and cortex regions, which led to impaired learning and referencing memory in mice. Pre-treatment of dioscin for 7 days substantially enhanced mice performances in maze studies, indicating amelioration in cognitive deficits. In conclusion, DNRE and its active compound dioscin protect against neurotoxicity most likely by suppressing NF-κB phosphorylation and upregulating neurotrophic factor BDNF.

Effects of Different Lipopolysaccharide Doses on Short- and Long-Term Spatial Memory and Hippocampus Morphology in an Experimental Alzheimer’s Disease Model

Background: Alzheimer’s disease (AD) is a progressive neurodegenerative disease and the most common cause of dementia. Various animal models are widely used to investigate its underlying mechanisms, including lipopolysaccharide (LPS)-induced neuroinflammation models. Aim: In this study, we aimed to investigate the effect of different doses (0.25, 0.5, and 0.75 mg/kg) of LPS on short- and long-term spatial memory and hippocampal morphology in an experimental AD mouse model. Materials and methods: Twenty-four adult male Swiss mice (SWR/J) weighing 18–25 g were divided into four groups: control, 0.25 mg/kg LPS, 0.50 mg/kg LPS, and 0.75 mg/kg LPS. All groups were treated with LPS or vehicle for 7 days. Behavioral tests were started (Morris water maze for 6 days and Y maze for 1 day) on the last 2 days of injections. After the behavioral procedures, tissues were collected for further histological investigations. Result: All LPS doses induced significant short- and long-term spatial memory impairment in both the Y maze and Morris water maze compared with the control group. Furthermore, histological examination of the hippocampus indicated degenerating neurons in both the 0.50 mg/kg and 0.75 mg/kg LPS groups, while the 0.25 mg/kg LPS group showed less degeneration. Conclusion: our results showed that 0.75 mg/kg LPS had a greater impact on early-stage spatial learning memory and short-term memory than other doses. Our behavioral and histological findings suggest 0.75 mg/kg LPS as a promising dose for LPS-induced AD models.

Inosine Pretreatment Attenuates LPS-Induced Lung Injury through Regulating the TLR4/MyD88/NF-κB Signaling Pathway In Vivo

Inosine is a type of purine nucleoside, which is considered to a physiological energy source, and exerts a widely range of anti-inflammatory efficacy. The TLR4/MyD88/NF-κB signaling pathway is essential for preventing host oxidative stresses and inflammation, and represents a promising target for host-directed strategies to improve some forms of disease-related inflammation. In the present study, the results showed that inosine pre-intervention significantly suppressed the pulmonary elevation of pro-inflammatory cytokines (including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β)), malondialdehyde (MDA), nitric oxide (NO), and reactive oxygen species (ROS) levels, and restored the pulmonary catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and myeloperoxidase (MPO) activities (p < 0.05) in lipopolysaccharide (LPS)-treated mice. Simultaneously, inosine pre-intervention shifted the composition of the intestinal microbiota by decreasing the ratio of Firmicutes/Bacteroidetes, elevating the relative abundance of Tenericutes and Deferribacteres. Moreover, inosine pretreatment affected the TLR4/MyD88/NF-κB signaling pathway in the pulmonary inflammatory response, and then regulated the expression of pulmonary iNOS, COX2, Nrf2, HO-1, TNF-α, IL-1β, and IL-6 levels. These findings suggest that oral administration of inosine pretreatment attenuates LPS-induced pulmonary inflammatory response by regulating the TLR4/MyD88/NF-κB signaling pathway, and ameliorates intestinal microbiota disorder.

Discovery of novel MIF inhibitors that attenuate microglial inflammatory activation by structures-based virtual screening and in vitro bioassays

Macrophage migration inhibitory factor (MIF) is a pluripotent pro-inflammatory cytokine and is related to acute and chronic inflammatory responses, immune disorders, tumors, and other diseases. In this study, an integrated virtual screening strategy and bioassays were used to search for potent MIF inhibitors. Twelve compounds with better bioactivity than the prototypical MIF-inhibitor ISO-1 (IC₅₀ = 14.41 μM) were identified by an in vitro enzymatic activity assay. Structural analysis revealed that these inhibitors have novel structural scaffolds. Compound 11 was then chosen for further characterization in vitro, and it exhibited marked anti-inflammatory efficacy in LPS-activated BV-2 microglial cells by suppressing the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs). Our findings suggest that MIF may be involved in the regulation of microglial inflammatory activation and that small-molecule MIF inhibitors may serve as promising therapeutic agents for neuroinflammatory diseases.

Chlorogenic Acid Alleviates the Inflammatory Stress of LPS-Induced BV2 Cell via Interacting with TLR4-Mediated Downstream Pathway

Background

Neuroinflammation is related with the inflammatory stress of brain tissue induced by the activation of microglial in the central nervous system (CNS), which is still an intractable disease for modern clinical system. Chlorogenic acid has multiple biological activities such as antivirus and anti-inflammation, while few researches have revealed its therapeutic functions in neuroinflammation.

Methods

BV2 cells were treated with lipopolysaccharide (LPS) to establish neuroinflammation cell models, and the effects and mechanism of chlorogenic acid in improving the inflammatory progression were investigated. In brief, the toxicity of chlorogenic acid on BV2 cells was detected with MTT assay. The levels of the inflammatory factors including TNF-α, IL-6, IL-1β, and IFN-α were measured with ELISA, and the abundances of TLR4, MyD88, TRIF, and NF-κB were observed by qRT-PCR and western blot.

Results

Chlorogenic acid did not exhibit obvious toxic and side effects on BV2 cells. The levels of TNF-α, IL-6, IL-1β, and IFN-α were observably upregulated in BV2 cells after treating with LPS. Chlorogenic acid significantly reduced the levels of TNF-α, IL-6, IL-1β, and IFN-α. Moreover, the abundances of TLR4, MyD88, TRIF, and NF-κB were increased in LPS-induced BV2 cells, while chlorogenic acid could obviously reduce their expressions.

Conclusion

This study suggests that chlorogenic acid can improve the inflammatory stress of LPS-induced BV2 cell via interacting with the TLR4-mediated downstream pathway, which is a potential drug for neuroinflammation treatment.

Antidepressant-like Effects of Renin Inhibitor Aliskiren in an Inflammatory Mouse Model of Depression

Depression is considered a neuropsychic disease that has global prevalence and is associated with disability. The pathophysiology of depression is not well understood; however, emerging evidence has indicated that neuroinflammation could contribute to developing depression symptoms. One of the factors that have a role in the development of neuroinflammation is the renin–angiotensin system. Therefore, the goal of the current study is to determine the antidepressant-like effects of Aliskiren, a renin inhibitor, against lipopolysaccharide (LPS)-induced depressive-like behavior in mice, glial cell activation, and the upregulation of proinflammatory cytokines in the prefrontal cortex. For behavioral studies, the open field test (OFT), tail suspension test (TST), forced swim test (FST), and sucrose preference test (SPT) were used. Inflammatory markers were assessed using real-time polymerase chain reaction (RT-PCR). LPS administration (0.5 mg/kg, intraperitoneal injection (i.p.)) sufficiently reduced the number of crossings in OFT, whereas Aliskiren pretreatment (10 mg/kg, i.p.) attenuated the LPS effect for two hours after LPS injection. The treatments did not show effects on locomotor activity in OFT 24 h after LPS administration. LPS increased the immobility time in TST and FST or reduced sucrose consumption in SPT after 24 h. Aliskiren reversed the effects induced by LPS in TST, FST, and SPT. CD11 b mRNA, a microglial marker, GFAP mRNA, an astroglial marker, and proinflammatory cytokines genes (TNF-α, IL-1β, and IL-6) were upregulated in the prefrontal cortex in LPS exposed animals. However, Aliskiren reduced LPS-induced inflammatory genes in the prefrontal cortex. Hence, the outcomes conclude that Aliskiren prevents depressive illness associated with neuroinflammation in humans.

Eriodictyol and Homoeriodictyol Improve Memory Impairment in Aβ25-35-Induced Mice by Inhibiting the NLRP3 Inflammasome

(1) Alzheimer's disease (AD) is a neurodegenerative disorder, and it is now widely accepted that neuroinflammation plays a key role in its pathogenesis. Eriodictyol (Eri) and homoeriodictyol (Hom), dihydroflavonoids extracted from a variety of plants, have been confirmed to display a relationship with neuroprotection. (2) Methods: An AD mouse model was constructed by intracerebroventricular (ICV) injection of the Aβ25-35 peptide, and Eri and Hom were administered orally for 4 weeks. UPLC-MS/MS was used to determine whether Eri and Hom cross the blood-brain barrier to exert their therapeutic effects. Histological changes in the brain and levels of Aβ were evaluated, and Y-maze and new object recognition experiments were conducted to assess the effects of Eri and Hom on Aβ25-35-induced memory impairment in mice. The levels of oxidative stress and apoptosis in peripheral immune cells and progenitor cells in the hippocampal region were analyzed by flow cytometry and in vitro assays. Western blotting and enzyme-linked immunosorbent assays (ELISA) were used to measure the expression levels of NLRP3 inflammasome-related proteins and inflammatory factors in the brain. The effect of nigericin (an agonist of the NLRP3 inflammasome) on Eri and Hom intervention in LPS-induced N9 microglia was examined using a High Content Screening System. (3) Results: Eri and Hom reduced neuronal damage in mouse brain tissue, decreased Aβ levels in the brain, downregulated oxidative stress and apoptosis levels, and improved learning and memory capacity by crossing the blood-brain barrier to exert its effects. Moreover, Eri and Hom inhibited NLRP3 inflammasome activation and ameliorated immune cell disorder. Furthermore, the effect of Eri and Hom on LPS-induced N9 microglia disappeared after the addition of nigericin to agonize NLRP3 receptors. (4) Conclusions: Eri and Hom improved Aβ25-35-induced memory impairment in mice by inhibiting the NLRP3 inflammasome.

Potential of flavonoids as anti-Alzheimer's agents: bench to bedside

Developing therapies for neurodegenerative diseases are challenging because of the presence of blood-brain barrier and Alzheimer being one of the commonest and uprising neurodegenerative disorders possess the need for developing novel therapies. Alzheimer's is attributed to be the sixth leading cause of death in the USA and the number of cases is estimated to be increased from 58 million in 2021 to 88 million by 2050. Natural drugs have benefits of being cost-effective, widely available, fewer side effects, and immuno-booster can be useful in managing Alzheimer. Flavonoids can slow the neuronal degeneration as they have shown activity in central nervous system and are able to cross the blood-brain barrier. These can be easily extracted from fruits, vegetable, and plants. In Alzheimer disease, flavonoids scavenges the reactive oxygen species and reduces the production of amyloid beta protein. Agents from sub-classes of flavonoids such as flavanones, flavanols, flavones, flavonols, anthocyanins, and isoflavones having pharmacological action in treating Alzheimer disease are discussed in this review.

Marein Prevented LPS-Induced Osteoclastogenesis by Regulating the NF-κB Pathway In Vitro

Many bone diseases such as osteolysis, osteomyelitis, and septic arthritis are caused by gram-negative bacterial infection, and lipopolysaccharide (LPS), a bacterial product, plays an essential role in this process. Drugs that inhibit LPS-induced osteoclastogenesis are urgently needed to prevent bone destruction in infective bone diseases. Marein, a major bioactive compound of Coreopsis tinctoria, possesses anti-oxidative, anti-inflammatory, anti-hypertensive, anti-hyperlipidemic, and anti-diabetic effects. In this study, we measured the effect of marein on RAW264.7 cells by CCK-8 assay and used TRAP staining to determine osteoclastogenesis. The levels of osteoclast-related genes and NF-κB-related proteins were then analyzed by western blot, and the levels of pro-inflammatory cytokines were quantified by ELISA. Our results showed that marein inhibited LPS-induced osteoclast formation by osteoclast precursor RAW264.7 cells. The effect of marein was related to its inhibitory function on expressions of pro-inflammatory cytokines and osteoclast-related genes containing RANK, TRAF6, MMP-9, CK, and CAII. Additionally, marein leads to markedly inhibited NF-κB signaling pathway activation in LPS-induced RAW264.7 cells. Concurrently, when the NF-κB signaling pathway was inhibited, osteoclast formation and pro-inflammatory cytokine expression were decreased. Collectively, marein could inhibit LPS-induced osteoclast formation in RAW264.7 cells via regulating the NF-κB signaling pathway. Our data demonstrate that marein might be a potential drug for bacteria-induced bone destruction disease. Our findings provide new insights into LPS-induced bone disease.

Natural Products as Novel Neuroprotective Agents; Computational Predictions of the Molecular Targets, ADME Properties, and Safety Profile

Neurodegenerative diseases (NDs) are one of the most challenging public health issues. Despite tremendous advances in our understanding of NDs, little progress has been made in establishing effective treatments. Natural products may have enormous potential in preventing and treating NDs by targeting microglia; yet, there have been several clinical concerns about their usage, primarily due to a lack of scientific evidence for their efficacy, molecular targets, physicochemical properties, and safety. To solve this problem, the secondary bioactive metabolites derived from neuroprotective medicinal plants were identified and selected for computational predictions for anti-inflammatory activity, possible molecular targets, physicochemical properties, and safety evaluation using PASS online, Molinspiration, SwissADME, and ProTox-II, respectively. Most of the phytochemicals were active as anti-inflammatory agents as predicted using the PASS online webserver. Moreover, the molecular target predictions for some phytochemicals were similar to the reported experimental targets. Moreover, the phytochemicals that did not violate important physicochemical properties, including blood-brain barrier penetration, GI absorption, molecular weight, and lipophilicity, were selected for further safety evaluation. After screening 54 neuroprotective phytochemicals, our findings suggest that Aromatic-turmerone, Apocynin, and Matrine are the most promising compounds that could be considered when designing novel neuroprotective agents to treat neurodegenerative diseases via modulating microglial polarization.

Eriodictyol ameliorates cognitive dysfunction in APP/PS1 mice by inhibiting ferroptosis via vitamin D receptor-mediated Nrf2 activation

Background

Alzheimer’s disease (AD) is the most common type of neurodegenerative disease in the contemporary era, and it is still clinically incurable. Eriodictyol, a natural flavonoid compound that is mainly present in citrus fruits and some Chinese herbal medicines, has been reported to exert anti-inflammatory, antioxidant, anticancer and neuroprotective effects. However, few studies have examined the anti-AD effect and molecular mechanism of eriodictyol.

Methods

APP/PS1 mice were treated with eriodictyol and the cognitive function of mice was assessed using behavioral tests. The level of amyloid-β (Aβ) aggregation and hyperphosphorylation of Tau in the mouse brain were detected by preforming a histological analysis and Western blotting. HT-22 cells induced by amyloid-β peptide (1–42) (Aβ_1–42) oligomers were treated with eriodictyol, after which cell viability was determined and the production of p-Tau was tested using Western blotting. Then, the characteristics of ferroptosis, including iron aggregation, lipid peroxidation and the expression of glutathione peroxidase type 4 (GPX4), were determined both in vivo and in vitro using Fe straining, Western blotting and qPCR assays. Additionally, the expression level of vitamin D receptor (VDR) and the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway were tested using Western blotting and qPCR assays. Afterward, HT-22 cells with VDR knockout were used to explore the potential mechanisms, and the relationship between VDR and Nrf2 was further assessed by performing a coimmunoprecipitation assay and bioinformatics analysis.

Results

Eriodictyol obviously ameliorated cognitive deficits in APP/PS1 mice, and suppressed Aβ aggregation and Tau phosphorylation in the brains of APP/PS1 mice. Moreover, eriodictyol inhibited Tau hyperphosphorylation and neurotoxicity in HT-22 cells induced by Aβ_1–42 oligomer. Furthermore, eriodictyol exerted an antiferroptosis effect both in vivo and in vitro, and its mechanism may be associated with the activation of the Nrf2/HO-1 signaling pathway. Additionally, further experiments explained that the activation of Nrf2/HO-1 signaling pathway by eriodictyol treatment mediated by VDR.

Conclusions

Eriodictyol alleviated memory impairment and AD-like pathological changes by activating the Nrf2/HO-1 signaling pathway through a mechanism mediated by VDR, which provides a new possibility for the treatment of AD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00442-3.

Hydroxylation decoration patterns of flavonoids in horticultural crops: chemistry, bioactivity and biosynthesis

Flavonoids are the most widespread polyphenolic compounds and are important dietary constituents present in horticultural crops such as fruits, vegetables, and tea. Natural flavonoids are responsible for important quality traits, such as food colors and beneficial dietary antioxidants and numerous investigations have shown that intake of flavonoids can reduce the incidence of various non-communicable diseases (NCDs). Analysis of the thousands of flavonoids reported so far has shown that different hydroxylation modifications affect their chemical properties and nutritional values. These diverse flavonoids can be classified based on different hydroxylation patterns in the B, C, A rings and multiple structure-activity analyses have shown that hydroxylation decoration at specific positions markedly enhances their bioactivities. This review focuses on current knowledge concerning hydroxylation of flavonoids catalyzed by several different types of hydroxylase enzymes. Flavonoid 3'-hydroxylase (F3'H) and flavonoid 3'5'-hydroxylase (F3'5'H) are important enzymes for the hydroxylation of the B ring of flavonoids. Flavanone 3-hydroxylase (F3H) is key for the hydroxylation of the C ring, while flavone 6-hydroxylase (F6H) and flavone 8-hydroxylase (F8H) are key enzymes for hydroxylation of the A ring. These key hydroxylases in the flavonoid biosynthesis pathway are promising targets for the future bioengineering of plants and mass production of flavonoids with designated hydroxylation patterns of high nutritional importance. In addition, hydroxylation in key places on the ring may help render flavonoids ready for degradation, the catabolic turnover of which may open the door for new lines of inquiry.