Alleviatory effects of Danshen, Salvianolic acid A and Salvianolic acid B on PC12 neuronal cells and Drosophila melanogaster model of Alzheimer's disease

Role of CD36 in central nervous system diseases

CD36 is a highly glycosylated integral membrane protein that belongs to the scavenger receptor class B family and regulates the pathological progress of metabolic diseases. CD36 was recently found to be widely expressed in various cell types in the nervous system, including endothelial cells, pericytes, astrocytes, and microglia. CD36 mediates a number of regulatory processes, such as endothelial dysfunction, oxidative stress, mitochondrial dysfunction, and inflammatory responses, which are involved in many central nervous system diseases, such as stroke, Alzheimer's disease, Parkinson's disease, and spinal cord injury. CD36 antagonists can suppress CD36 expression or prevent CD36 binding to its ligand, thereby achieving inhibition of CD36-mediated pathways or functions. Here, we reviewed the mechanisms of action of CD36 antagonists, such as Salvianolic acid B, tanshinone IIA, curcumin, sulfosuccinimidyl oleate, antioxidants, and small-molecule compounds. Moreover, we predicted the structures of binding sites between CD36 and antagonists. These sites can provide targets for more efficient and safer CD36 antagonists for the treatment of central nervous system diseases.

Tanshinone IIA, the key compound in Salvia miltiorrhiza, improves cognitive impairment by upregulating Aβ-degrading enzymes in APP/PS1 mice

In Alzheimer's disease (AD), amyloid-beta (Aβ) plays a crucial role in pathogenesis. Clearing Aβ from the brain is considered as a key therapeutic strategy. Previous studies indicated that Salvia miltiorrhiza (Danshen) could protect against AD. However, the main anti-AD components in Danshen and their specific mechanisms are not clear. In this study, pharmacological network analysis indicated that Tanshinone IIA (Tan IIA) was identified as the key active compound in Danshen contributing to protect against AD. Then, APP/PS1 double transgenic mice were employed to examine the neuroprotective effect of Tan IIA. APP/PS1 mice (age, 6 months) were administered (10 and 20 mg/kg) for 8 weeks. Tan IIA improved learning and anxiety behaviors in APP/PS1 mice. Furthermore, Tan IIA reduced oxidative stress, inhibited neuronal apoptosis, improved cholinergic nervous system and decreased endoplasmic reticulum stress in the brain of APP/PS1 mice. Moreover, Tan IIA treatment reduced the level of Aβ. Molecular docking result showed that Tan IIA might block AD by upregulating Aβ-degrading enzymes. Western blot results confirmed that the expressions of insulin degrading enzymes (IDE) and neprilysin (NEP) were significantly increased after Tan IIA treatment, which demonstrated that Tan IIA improved AD by increasing Aβ-degrading enzymes.

Salvianolic acid B exerts protective effects against Aβ-induced neuroinflammation through the inhibition of NLRP3 inflammasome activation and switching of M1/M2 polarization

BACKGROUND

Salvianolic acid B (SalB) is a bioactive extract of Salvia miltiorrhiza with the ability to ameliorate amyloid beta (Aβ)-induced neuronal degeneration and neuroinflammation in Alzheimer's disease (AD). However, the underlying mechanisms of this action have not been elucidated. Herein, we aimed to investigate whether the neuroprotective effect of SalB is attributable to the modulation of microglial polarization and NLRP3 inflammasome-mediated neuroinflammation.

METHODS

Based on the TMT-labeled proteomics analysis, immunofluorescence, western blot and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were employed to investigate the effects of SalB on neuroinflammation in Aβ1-42-stimulated BV2 microglia cells.

RESULTS

At the proteomic level, a total of 6631 proteins were quantified, and of these, 104 were significantly influenced under Aβ1-42 treatment. The expression of 36 Aβ1-42-induced differentially expressed proteins were significantly recovered by SalB treatment (13 upregulated and 23 downregulated). NLRP3 was significantly recovered and was identified as one of the hub proteins. Consistent with the result of the proteomic analysis, western blot and qRT-PCR demonstrated that SalB reduced Aβ1-42-induced NLRP3 upregulation at both the protein and mRNA levels. In addition, SalB significantly blocked M1 microglia polarization, enhanced M2 microglial polarization, and inhibited the production of caspase-1 and interleukin-1β in BV2 microglia cells.

CONCLUSION

our study demonstrated, for the first time, that the anti-inflammatory effects of SalB were mediated by the regulation of NLRP3 activation and promotion of microglial M2 polarization, indicating the potential of SalB as a novel therapeutic candidate for AD.

Salvianolic acid B ameliorates retinal deficits in an early-stage Alzheimer's disease mouse model through downregulating BACE1 and Aβ generation

Alzheimer's disease (AD) is a neurodegenerative disease with subtle onset, early diagnosis remains challenging. Accumulating evidence suggests that the emergence of retinal damage in AD precedes cognitive impairment, and may serve as a critical indicator for early diagnosis and disease progression. Salvianolic acid B (Sal B), a bioactive compound isolated from the traditional Chinese medicinal herb Salvia miltiorrhiza, has been shown promise in treating neurodegenerative diseases, such as AD and Parkinson's disease. In this study we investigated the therapeutic effects of Sal B on retinopathy in early-stage AD. One-month-old transgenic mice carrying five familial AD mutations (5×FAD) were treated with Sal B (20 mg·kg-1·d-1, i.g.) for 3 months. At the end of treatment, retinal function and structure were assessed, cognitive function was evaluated in Morris water maze test. We showed that 4-month-old 5×FAD mice displayed distinct structural and functional deficits in the retinas, which were significantly ameliorated by Sal B treatment. In contrast, untreated, 4-month-old 5×FAD mice did not exhibit cognitive impairment compared to wild-type mice. In SH-SY5Y-APP751 cells, we demonstrated that Sal B (10 μM) significantly decreased BACE1 expression and sorting into the Golgi apparatus, thereby reducing Aβ generation by inhibiting the β-cleavage of APP. Moreover, we found that Sal B effectively attenuated microglial activation and the associated inflammatory cytokine release induced by Aβ plaque deposition in the retinas of 5×FAD mice. Taken together, our results demonstrate that functional impairments in the retina occur before cognitive decline, suggesting that the retina is a valuable reference for early diagnosis of AD. Sal B ameliorates retinal deficits by regulating APP processing and Aβ generation in early AD, which is a potential therapeutic intervention for early AD treatment.

3-[[(3S)-1,2,3,4-Tetrahydroisoquinoline-3-Carbonyl]Amino]Propanoic Acid (THICAPA) Is Protective Against Aβ42-Induced Toxicity In Vitro and in an Alzheimer's Disease Drosophila

Alzheimer's disease (AD) is the most prevalent type of dementia globally. The accumulation of amyloid-beta (Aβ) extracellular senile plaques in the brain is one of the hallmark mechanisms found in AD. Aβ42 is the most damaging and aggressively aggregating Aβ isomer produced in the brain. Although Aβ42 has been extensively researched as a crucial peptide connected to the development of the characteristic amyloid fibrils in AD, the specifics of its pathophysiology are still unknown. Therefore, the main objective was to identify novel compounds that could potentially mitigate the negative effects of Aβ42. 3-[[(3S)-1,2,3,4-Tetrahydroisoquinoline-3-carbonyl]amino]propanoic acid (THICAPA) was identified as a ligand for Aβ42 and for reducing fibrillary Aβ42 aggregation. THICAPA also improved cell viability when administered to PC12 neuronal cells that were exposed to Aβ42. Additionally, this compound diminished Aβ42 toxicity in the current AD Drosophila model by rescuing the rough eye phenotype, prolonging the life span, and enhancing motor functions. Through next-generation RNA-sequencing, immune response pathways were downregulated in response to THICAPA treatment. Thus, this study suggests THICAPA as a possible disease-modifying treatment for AD.

p-Coumaric acid attenuates the effects of Aβ42 in vitro and in a Drosophila Alzheimer's disease model

Alzheimer's disease (AD) is the most common neurodegenerative condition in civilizations worldwide. The distinctive occurrence of amyloid-beta (Aβ) accumulation into insoluble fibrils is part of the disease pathophysiology with Aβ42 being the most toxic and aggressive Aβ species. The polyphenol, p-Coumaric acid (pCA), has been known to boost a number of therapeutic benefits. Here, pCA's potential to counteract the negative effects of Aβ42 was investigated. First, pCA was confirmed to reduce Aβ42 fibrillation using an in vitro activity assay. The compound was next examined on Aβ42-exposed PC12 neuronal cells and was found to significantly decrease Aβ42-induced cell mortality. pCA was then examined using an AD Drosophila melanogaster model. Feeding of pCA partially reversed the rough eye phenotype, significantly lengthened AD Drosophila's lifespan, and significantly enhanced the majority of the AD Drosophila's mobility in a sex-dependent manner. The findings of this study suggest that pCA may have therapeutic benefits for AD.

Screening for Novel Inhibitors of Amyloid Beta Aggregation and Toxicity as Potential Drugs for Alzheimer's Disease

AD is the most common neurodegenerative disorder characterized by progressive memory impairment and cognitive deficits. The pathology of AD is still unclear; however, several studies have shown that the aggregation of the Aβ peptide in the CNS is an exclusively pathological process involved in AD. Currently, there is no proven medication to cure or prevent the disease progression. Nevertheless, various therapeutic approaches for AD show only relief of symptoms and mostly work on cognitive recovery. However, one of the promising approaches for therapeutic intervention is to use inhibitors for blocking the Aβ peptide aggregation process. Recently, herbal phenolic compounds have been shown to have a therapeutic property for treatment of AD due to their multifaceted action. In this study, we investigated the effectiveness of SA, Gn Rb1, and DMyr on inhibiting the aggregation and toxicity of Aβ40 and Aβ42 using different biochemical and cell-based assays. Our results showed that SA and DMyr inhibit Aβ40 and Aβ42 fibrillation, seeded aggregation, and toxicity. Gn Rb1 did not have any effect on the aggregation or toxicity induced by Aβ40 and Aβ42. Moreover, SA and DMyr were able to disaggregate the preformed fibrils. Overall, these compounds may be used alone or synergistically and could be considered as a lead for designing new compounds that could be used as effective treatment of AD and related disorders.

Behavioural Effects and RNA-seq Analysis of Aβ42-Mediated Toxicity in a Drosophila Alzheimer's Disease Model

Alzheimer's disease (AD) is the most common neurological ailment worldwide. Its process comprises the unique aggregation of extracellular senile plaques composed of amyloid-beta (Aβ) in the brain. Aβ42 is the most neurotoxic and aggressive of the Aβ42 isomers released in the brain. Despite much research on AD, the complete pathophysiology of this disease remains unknown. Technical and ethical constraints place limits on experiments utilizing human subjects. Thus, animal models were used to replicate human diseases. The Drosophila melanogaster is an excellent model for studying both physiological and behavioural aspects of human neurodegenerative illnesses. Here, the negative effects of Aβ42-expression on a Drosophila AD model were investigated through three behavioural assays followed by RNA-seq. The RNA-seq data was verified using qPCR. AD Drosophila expressing human Aβ42 exhibited degenerated eye structures, shortened lifespan, and declined mobility function compared to the wild-type Control. RNA-seq revealed 1496 genes that were differentially expressed from the Aβ42-expressing samples against the control. Among the pathways that were identified from the differentially expressed genes include carbon metabolism, oxidative phosphorylation, antimicrobial peptides, and longevity-regulating pathways. While AD is a complicated neurological condition whose aetiology is influenced by a number of factors, it is hoped that the current data will be sufficient to give a general picture of how Aβ42 influences the disease pathology. The discovery of molecular connections from the current Drosophila AD model offers fresh perspectives on the usage of this Drosophila which could aid in the discovery of new anti-AD medications.

Salvianolic Acid B Attenuates Hypertrophic Scar Formation In Vivo and In Vitro

BACKGROUND

Hypertrophic scars (HTSs) are a fibroproliferative disorder that occur following skin injuries. Salvianolic acid B (Sal-B) is an extractant from Salvia miltiorrhiza that has been reported to ameliorate fibrosis in multiple organs. However, the antifibrotic effect on HTSs remains unclear. This study aimed to determine the antifibrotic effect of Sal-B in vitro and in vivo.

METHODS

In vitro, hypertrophic scar-derived fibroblasts (HSFs) were isolated from human HTSs and cultured. HSFs were treated with (0, 10, 50, 100 μmol/L) Sal-B. Cell proliferation and migration were evaluated by EdU, wound healing, and transwell assays. The protein and mRNA levels of TGFβI, Smad2, Smad3, α-SMA, COL1, and COL3 were detected by Western blots and real-time PCR. In vivo, tension stretching devices were fixed on incisions for HTS formation. The induced scars were treated with 100 μL of Sal-B/PBS per day according to the concentration of the group and followed up for 7 or 14 days. The scar condition, collagen deposition, and α-SMA expression were analyzed by gross visual examination, H&E, Masson, picrosirius red staining, and immunofluorescence.

RESULTS

In vitro, Sal-B inhibited HSF proliferation, migration, and downregulated the expression of TGFβI, Smad2, Smad3, α-SMA, COL1, and COL3 in HSFs. In vivo, 50 and 100 μmol/L Sal-B significantly reduced scar size in gross and cross-sectional observations, with decreased α-SMA expression and collagen deposition in the tension-induced HTS model.

CONCLUSIONS

Our study demonstrated that Sal-B inhibits HSFs proliferation, migration, fibrotic marker expression and attenuates HTS formation in a tension-induced HTS model in vivo.

NO LEVEL ASSIGNED

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Protective Effect of Salvianolic Acid A against N-Methyl-N-Nitrosourea-Induced Retinal Degeneration

Objective

Retinal degeneration (RD) is a serious, irreversible, and blinding eye disease, which seriously affects the visual function and quality of life of patients. At present, there is no effective method to treat RD. The final outcome of its development is photoreceptor cell oxidation and apoptosis. Therefore, looking for safe, convenient, and effective antioxidant therapy is still the key research field of Rd. In this study, the mice model of RD was induced by N-methyl-N-nitrosourea (MNU) in vivo to explore the therapeutic effect and mechanism of salvianolic acids (Sal A) on RD. In vitro, the protective effect of Sal A on MNU injured 661 W cell line of mouse retina photoreceptor cone cells was investigated preliminarily.

Methods

Male C57BL/6 mice (7–8 weeks old) received a single intraperitoneal injection (ip) of 60 mg/kg MNU or vehicle control. Treatment groups then received Sal-A 0.5 mg/kg and 1.0 mg/kg via daily intravenous injections. On day 7, functional and morphological examinations were performed, including photopic and scotopic electroretinography (ERG) and hematological analyses to observe functional changes and damage to the outer nuclear layer (ONL). On the 3rd and 7th days, the levels of superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were determined. The expression of retinal Bax, Bcl-2, and caspase-3 was quantified by Western blot and RT-PCR assays. 661 W strain of mice retinal photoreceptor cone cells were cultured in vitro and treated with 1 µm MNU. The cells in the treatment group were given 50 μM Sal A as an intervention. The growth of 661 W cells was observed and recorded under an inverted light microscope, and the activity of cells was detected by the MTT method.

Results

Sal A treatment was effective against MNU-induced RD in mice at both 0.5 mg/kg/d and 1.0 mg/kg/d doses, and the protective effect was dose-dependent. Sal A can alleviate MNU-mediated alterations to retinal ERG activity and can support maintenance of the thickness of the ONL layer. Sal A treatment increases the expression of retinal SOD and reduces the lipid peroxidation product MDA, suggesting that its protective effect is related to the oxidation resistance. It can offset changes to the expression of apoptotic factors in the retina caused by MNU treatment. Sal A mitigates MNU-mediated damage to cultured mice photoreceptor cone cells 661 W in vitro.

Conclusion

Sal A alleviates the damage caused by MNU to retinal photoreceptor cells in vivo and in vivo, and its protective effect is related to its antioxidant and antiapoptotic activities.

Phenolic compounds that cross the blood-brain barrier exert positive health effects as central nervous system antioxidants

The blood-brain barrier (BBB) is a physical structure whose main function is to strictly regulate access to circulating compounds into the central nervous system (CNS). Vegetable-derived phenolic compounds have been widely studied, with numerous epidemiologic and interventional studies confirming their health-related bioactivities across multiple cells, organs and models. Phenolics are non-essential xenobiotics, and should theoretically be unable to cross the BBB. The present work summarizes current experimental evidence that reveals that not only are phenolic compounds able to cross the BBB and bioaccumulate in the brain, but there is some stereoselectivity, which suggests the presence of specific transporters that allow them to reach the brain. Some molecules cross the BBB intact, while others do so only after being biotransformed or metabolized elsewhere. Once inside the CNS, they prevent or counter oxidative stress, which maintains the molecular, cellular, structural and functional integrity of the brain, and subsequently, overall human health.

Protective Effects of Sal B on Oxidative Stress-Induced Aging by Regulating the Keap1/Nrf2 Signaling Pathway in Zebrafish

The models of oxidative damage-induced aging were established by adding ethanol (C2H5OH), hydrogen peroxide (H2O2) and 6-hydroxydopamine (6-OHDA) to zebrafish embryos in this research. To find effective protective drugs/foods, Salvianolic acid B (Sal B) was added after the embryos were treated by these oxidative reagents. After being treated with ethanol, H2O2 and 6-OHDA, the morphological changes were obvious and the deformities included spinal curvature, heart bleeding, liver bleeding, yolk sac deformity and pericardial edema, and the expression of oxidative stress-related genes Nrf2b, sod1 and sod2 and aging-related genes myl2a and selenbp1 were significantly up-regulated compared to the control group. While after adding 0.05 μg/mL and 0.5 μg/mL Sal B to the ethanol-treated group, death rates and MDA levels decreased, the activity of antioxidant enzyme (SOD, CAT and GSH-Px) changed and Nrf2b, sod1, sod2, myl2a, selenbp1, p53 and p21 were down-regulated compared to the ethanol-treated group. The bioinformatics analysis also showed that oxidative stress-related factors were associated with a variety of cellular functions and physiological pathways. In conclusion, Sal B can protect against aging through regulating the Keap1/Nrf2 pathway as well as antioxidative genes and enzyme activity.