Anti-dementia Activity of Nobiletin, a Citrus Flavonoid: A Review of Animal Studies

Multi-target-directed therapeutic strategies for Alzheimer's disease: controlling amyloid-β aggregation, metal ion homeostasis, and enzyme inhibition

Alzheimer's disease (AD) is the most prevalent neurodegenerative dementia, marked by progressive cognitive decline and memory impairment. Despite advances in therapeutic research, single-target-directed treatments often fall short in addressing the complex, multifactorial nature of AD. This arises from various pathological features, including amyloid-β (Aβ) aggregate deposition, metal ion dysregulation, oxidative stress, impaired neurotransmission, neuroinflammation, mitochondrial dysfunction, and neuronal cell death. This review illustrates their interrelationships, with a particular emphasis on the interplay among Aβ, metal ions, and AD-related enzymes, such as β-site amyloid precursor protein cleaving enzyme 1 (BACE1), matrix metalloproteinase 9 (MMP9), lysyl oxidase-like 2 (LOXL2), acetylcholinesterase (AChE), and monoamine oxidase B (MAOB). We further underscore the potential of therapeutic strategies that simultaneously inhibit Aβ aggregation and address other pathogenic mechanisms. These approaches offer a more comprehensive and effective method for combating AD, overcoming the limitations of conventional therapies.

Dynamic changes in the metabolome and microbiome during Citrus depressa Hayata liquid fermentation

Citri Reticulatae Pericarpium (CRP) is a common traditional Chinese herbal medicine, valued for its multi-bioactivity. However, its processing time, environment, and microorganisms all affect its quality and bioactivity. To address this, the study replaced solid-state fermentation with liquid fermentation using microorganisms and isolated Bacillus amyloliquefaciens, respectively. This aimed to discover a more stable processing method and examine metabolite-micobiota correlations. Non-targeted metabolomics identified 70 differential metabolites, focusing on amino acids, polymethoxyflavones (PMFs), and carbohydrates. Long-read sequencing showed a shift in dominant bacterial genera from Lactobacillus to Pediococcus, then to Clostridium. Spearman analysis revealed a positive correlation between specific Clostridium species and PMFs production. B. amyloliquefaciens fermentation notably increased PMFs content without reducing hesperidin levels, suggesting its potential as an alternative processing method. This study offers valuable insights into metabolome-microbiome interactions for future biotransformation research.

Anti-Inflammatory and Neurotrophic Factor Production Effects of 3,5,6,7,8,3',4'-Heptamethoxyflavone in the Hippocampus of Lipopolysaccharide-Induced Inflammation Model Mice

Citrus fruits contain several bioactive components. Among them, one of the major components is 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF), which has previously shown protective effects in the brain in some disease models; moreover, HMF has been shown to penetrate the brain. In recent years, inflammation has been identified as a defense response in the body; however, a chronic inflammatory response may trigger several diseases. Inflammation in the peripheral tissues spreads to the brain and is suggested to be closely associated with diseases of the central nervous system. HMF has shown anti-inflammatory effects in the hippocampus following global cerebral ischemia; however, its effects on acute and chronic inflammation in the brain remain unclear. Therefore, in the present study, we examined the effects of HMF in a mouse model of systemic inflammation induced by lipopolysaccharide (LPS) administration. In this study, HMF suppressed LPS-induced microglial activation in the brains of acute inflammation model mice two days after LPS administration. In addition, 24 days after the administration of LPS in a chronic inflammation model, HMF promoted BDNF production and neurogenesis in the brain, which also tended to suppress tau protein phosphorylation at Ser396. These results suggest that HMF has anti-inflammatory and neurotrophic effects in the brains of model mice with lipopolysaccharide-induced systemic inflammation.

In Vitro and In Vivo Investigations of Chromone Derivatives as Potential Multitarget-Directed Ligands: Cognitive Amelioration Utilizing a Scopolamine-Induced Zebrafish Model

Alzheimer's disease is a complex neurological disorder linked with multiple pathological hallmarks. The interrelation of therapeutic targets assists in the enhancement of cognitive decline through interference with overall neuronal transmission. We have synthesized and screened various chromone derivatives as potential multitarget-directed ligands for the effective treatment of Alzheimer's disease. The synthesized compounds exhibited multipotent activity against AChE, BuChE, MAO-B, and amyloid β aggregation. Three potent compounds, i.e., VN-3, VN-14, and VN-19 were identified that displayed remarkable activities against different targets. These compounds displayed IC50 values of 80 nM, 2.52 μM, and 140 nM against the AChE enzyme, respectively, and IC50 values of 2.07 μM, 70 nM, and 450 nM against the MAO-B isoform, respectively. VN-3 displayed potent activity against self-induced Aβ1-42 aggregation with inhibition of 58.3%. In the ROS inhibition studies, the most potent compounds reduced the intracellular ROS levels up to 80% in SH-SY5Y cells at 25 μM concentration. The compounds were found to be neuroprotective and noncytotoxic even at a concentration of 25 μM against SH-SY5Y cells. In silico studies showed that the compounds were nicely accommodated in the active sites of the receptors along with thermodynamically stable orientations. Compound VN-19 exhibited a balanced multitargeting profile against AChE, BuChE, MAO-B, and Aβ1-42 enzymes and was further evaluated for in vivo activities on the scopolamine-induced zebrafish model. VN-19 was found to ameliorate the cognitive decline in zebrafish brains by protecting them against scopolamine-induced neurodegeneration. Thus, VN-3, VN-14, and VN-19 were identified as potent multitarget-directed ligands with a balanced activity profile against different targets and can be developed as therapeutics for AD.

Role of BDNF Signaling in the Neuroprotective and Memory-enhancing Effects of Flavonoids in Alzheimer's Disease

BACKGROUND

Foods rich in flavonoids are associated with a reduced risk of various chronic diseases, including Alzheimer's disease (AD). In fact, growing evidence suggests that consuming flavonoid- rich foods can beneficially affect normal cognitive function. Animal models have shown that many flavonoids prevent the development of AD-like pathology and improve cognitive deficits.

OBJECTIVE

Identifying the molecular causes underlying the memory-enhancing effect of flavonoid-rich foods makes it possible to provide the best diet to prevent cognitive decline associated with aging and Alzheimer's disease. Based on the most recent scientific literature, this review article critically examines the therapeutic role of dietary flavonoids in ameliorating and preventing the progression of AD and enhancement of memory with a focus on the role of the BDNF signaling pathway.

METHODS

The databases of PubMed, Web of Science, Google Scholar, and Scopus were searched up to March 2023 and limited to English language. Search strategies were using the following keywords in titles and abstracts: (Flavonoid-rich foods OR Flavonoids OR Polyphenols); AND (Brain-Derived Neurotrophic Factor OR BDNF OR CREB OR) AND (Alzheimer's disease OR memory OR cognition OR).

RESULTS

Flavonoid-rich foods including green tea, berries, curcumin and pomegranate exert their beneficial effects on memory decline associated with aging and Alzheimer's disease mostly through the direct interaction with BDNF signaling pathway.

CONCLUSION

The neuroprotective effects of flavonoid-rich foods through the CREB-BDNF mechanism have the potential to prevent or limit memory decline due to aging and Alzheimer's disease, so their consumption throughout life may prevent age-related cognitive impairment.

The citrus flavonoid "Nobiletin" impedes STZ-induced Alzheimer's disease in a mouse model through regulating autophagy mastered by SIRT1/FoxO3a mechanism

The prominence of autophagy in the modulation of neurodegenerative disorders has sparked interest to investigate its stimulation in Alzheimer's disease (AD). Nobiletin possesses several bioactivities such as anti-inflammation, antioxidation, and neuroprotection. Consequently, the study's aim was to inspect the possible neurotherapeutic impact of Nobiletin in damping AD through autophagy regulation. Mice were randomly assigned into: Group I which received DMSO, Groups II, III, and IV obtained STZ (3 mg/kg) intracerebroventricularly once with Nobiletin (50 mg/kg/day; i.p.) in Group III and Nobiletin with EX-527 (2 mg/kg, i.p.) in Group IV. Interestingly, Nobiletin ameliorated STZ-induced AD through enhancing the motor performance and repressing memory defects. Moreover, Nobiletin de-escalated hippocampal acetylcholinesterase (AChE) activity and enhanced acetylcholine level while halting BACE1 and amyloid-β levels. Meanwhile, Nobiletin stimulated the autophagy process through activating the SIRT1/FoxO3a, LC3B-II, and ATG7 pathway. Additionally, Nobiletin inhibited Akt pathway and controlled the level of NF-κB and TNF-α. Nobiletin amended the oxidative stress through enhancing GSH and cutting down MDA levels. However, EX527, SIRT1 inhibitor, counteracted the neurotherapeutic effects of Nobiletin. Therefore, the present study provides a strong verification for the therapeutic influence of Nobiletin in AD. This outcome may be assigned to autophagy stimulation through SIRT1/FoxO3a, inhibiting AChE activity, reducing neuroinflammation and oxidative stress.

Neuroprotection of Multitargeted Phytochemicals against Alzheimer: A Desperate Need from Nature

Background:

Alzheimer’s disease (AD) is an incurable neurodegenerative disorder associated with dementia which leads to the alteration in the psychological and physiological functioning of the individual. From antiquity, medicinal plants serve as important sources of bioactive phytochemicals representing tremendous therapeutic potential. The unavoidable adverse effects associated with synthetic compounds trigger the exploration of new and safer substitutes for the treatment and management of disease conditions. Herbal medication proves to be an emerging and most promising alternative, which is expected to be a revolutionary approach in modern medicine for disease treatment.

Objective:

Several phytochemicals like resveratrol, curcumin, apigenin, docosahexaenoic acid, epigallocatechin gallate, and α-lipoic acid exhibit great potential in the prevention and management of AD. Their use might be a possible remedy and lead to a safe strategy to delay the onset of AD and slow the progression of this pervasive disorder. To determine the potential of these natural components as anti- AD, this review focuses on the updates on clinical studies and research.

Methods:

Extensive literature survey was carried out on natural multitargeted bioactive phytochemicals from various scientific databases like PubMed, Science Direct, Scopus, Clinicaltrails.gov, and many reputed foundations. Current prose emphasizes the identified bioactive compounds as anti-AD, which were reviewed with particular emphasis on their scientific impact and novelty.

Results:

These compounds diminish the pathophysiological aspects of AD; still, further studies are required to prove the safety and efficacy of these compounds in humans.

Conclusion:

This present review might help the researchers, academicians and industrialists in drug development as a new paradigm of drug discovery.

Effects of Citrus kawachiensis Peel in Frailty-like Model Mice Induced by Low Protein Nutrition Disorders

"Frailty" caused by a decline in physiological reserve capacity, chronic inflammation, and oxidative stress in the elderly has recently become a major social issue. The present study examined the effects of the peel of Citrus kawachiensis (CK), which exhibits anti-inflammatory, antioxidant, and pro-neurogenesis activities in frailty-like model mice. Male C57BL/6 mice (15 weeks old) were fed an 18% protein diet (CON), a 2.5% protein diet (PM), and PM mixed with 1% dried CK peel powder for approximately 1 month. Mice were euthanized 2 or 8 days after a single intraperitoneal administration of lipopolysaccharide (LPS) and tissues were dissected. Among peripheral tissues, muscle weight, liver weight, and blood glucose levels were significantly higher in the PM-LPS-CK group than in the PM-LPS group. In the behavioral analysis, locomotive activity was significantly lower in the PM-LPS group than in the PM group. The reduction in locomotive activity in the PM-LPS-CK group was significantly smaller than that in the PM-LPS group. The quantification of microglia in the hippocampal stratum lacunosum-moleculare revealed that increases in the PM-LPS group were significantly suppressed by the dried CK peel powder. Furthermore, the quantification of synaptic vesicle membrane proteins in the hippocampal CA3 region showed down-regulated expression in the PM-LPS group, which was significantly ameliorated by the administration of the dried CK peel powder. Collectively, these results suggest that CK inhibits inflammation and oxidative stress induced by PM and LPS in the central nervous system and peripheral tissue. Therefore, C. kawachiensis is highly effective against "frailty".

A simple array integrating machine learning for identification of flavonoids in red wines

Bioactive flavonoids, the major ingredients of red wines, have been proven to prevent atherosclerosis and cardiovascular disease due to their anti-inflammatory and anti-oxidant activity. However, flavonoids have proven challenging to identify, even when multiple approaches are combined. Hereby, a simple array was constructed to detect flavonoids by employing phenylboronic acid modified perylene diimide derivatives (PDIs). Through multiple non-specific interactions (hydrophilic, hydrophobic, charged, aromatic, hydrogen-bonded and reversible covalent interactions) with flavonoids, the fluorescence of PDIs can be modulated, and variations in intensity can be used to create fingerprints of flavonoids. This array successfully discriminated 14 flavonoids of diverse structures and concentrations with 100% accuracy, based on patterns in fluorescence intensity modulation, via optimized machine learning algorithms. As a result, this array demonstrated the parallel detection of 8 different types and origins of red wines with a high accuracy, revealing the excellent potential of the sensor array in food mixtures detection.

Virtual screening reveals liquiritigenin as a broad-spectrum inhibitor of SARS-CoV-2 variants of concern: an in silico study

The SARS-CoV-2 has severely impacted the lives of people worldwide. Global concern is on the rise due to a large number of unexpected mutations in the viral genome, resulting in new variants. Nature-based bioactive phytochemicals hold great promise as inhibitors against pathogenic viruses. The current study was aimed at evaluating some bioactive antiviral phytochemicals against SARS-CoV-2 variants of concern. A total of 46 phytochemicals were screened against the pathogenic spike protein of Alpha, Beta, Delta, Gamma, and Omicron variants. In addition to molecular docking, screening for favorable pharmacokinetic and pharmacodynamic properties such as absorption, distribution, metabolism, excretion, and toxicity was undertaken. For each of the aforementioned five SARS-CoV-2 variants of concern, a 100 ns molecular dynamics simulation was run to assess the stability of the complexes between their respective spike protein receptor-binding domain and the best-selected compound. From our current investigation, the natural compound liquiritigenin turned out to be the most promising potential lead compound against almost all the variants. These findings could pave the way for the development of effective medications against SARS-CoV-2 variants. However, in vivo trials in future studies are necessary for further validation of our results.Communicated by Ramaswamy H. Sarma.

Nobiletin prevents amyloid β1-40-induced cognitive impairment via inhibition of neuroinflammation and oxidative/nitrosative stress

Alzheimer's disease (AD) is presented as an age-related neurodegenerative disease with multiple cognitive deficits and amyloid β (Aβ) accumulation is the most important involved factor in its development. Nobiletin is a bioflavonoid isolated from citrus fruits peels with anti-inflammatory and anti-oxidative activity as well as anti-dementia property that has shown potency to ameliorate intracellular and extracellular Ab. The aim of the present study was to assess protective effect of nobiletin against Aβ_1-40-induced cognitive impairment as a consistent model of AD. After bilateral intrahippocampal (CA1 subfield) injection of Aβ_1-40, rats were treated with nobiletin (10 mg/kg/day; p.o.) from stereotaxic surgery day (day 0) till day + 7. Cognition function was evaluated in a battery of behavioral tasks at week 3 with final assessment of hippocampal oxidative stress and inflammation besides Nissl staining and 3-nitrotyrosine (3-NT) immunohistochemistry. Analysis of behavioral data showed notable and significant improvement of alternation in Y maze test, discrimination ratio in novel object recognition task, and step through latency in passive avoidance test in nobiletin-treated Aβ group. Additionally, nobiletin treatment was associated with lower hippocampal levels of MDA and ROS and partial reversal of SOD activity and also improvement of Nrf2 with no significant effect on GSH and catalase. Furthermore, nobiletin attenuated hippocampal neuroinflammation in Aβ group as shown by lower tissue levels of TLR4, NF-kB, and TNFa. Histochemical findings showed that nobiletin prevents CA1 neuronal loss in Nissl staining in addition to its alleviation of 3-nitrotyrosine (3-NT) immunoreactivity as a marker of nitrosative stress. Collectively, these findings indicated neuroprotective and anti-dementia potential of nobiletin that is partly attributed to its anti-oxidative, anti-nitrosative, and anti-inflammatory property associated with proper modulation of TLR4/NF-kB/Nrf2 pathways.

Circadian clocks, cognition, and Alzheimer's disease: synaptic mechanisms, signaling effectors, and chronotherapeutics

Modulation of basic biochemical and physiological processes by the circadian timing system is now recognized as a fundamental feature of all mammalian organ systems. Within the central nervous system, these clock-modulating effects are reflected in some of the most complex behavioral states including learning, memory, and mood. How the clock shapes these behavioral processes is only now beginning to be realized. In this review we describe recent findings regarding the complex set of cellular signaling events, including kinase pathways, gene networks, and synaptic circuits that are under the influence of the clock timing system and how this, in turn, shapes cognitive capacity over the circadian cycle. Further, we discuss the functional roles of the master circadian clock located in the suprachiasmatic nucleus, and peripheral oscillator populations within cortical and limbic circuits, in the gating of synaptic plasticity and memory over the circadian cycle. These findings are then used as the basis to discuss the connection between clock dysregulation and cognitive impairments resulting from Alzheimer's disease (AD). In addition, we discuss the conceptually novel idea that in AD, there is a selective disruption of circadian timing within cortical and limbic circuits, and that it is the disruption/desynchronization of these regions from the phase-entraining effects of the SCN that underlies aspects of the early- and mid-stage cognitive deficits in AD. Further, we discuss the prospect that the disruption of circadian timing in AD could produce a self-reinforcing feedback loop, where disruption of timing accelerates AD pathogenesis (e.g., amyloid deposition, oxidative stress and cell death) that in turn leads to a further disruption of the circadian timing system. Lastly, we address potential therapeutic approaches that could be used to strengthen cellular timing networks and, in turn, how these approaches could be used to improve cognitive capacity in Alzheimer's patients.

Potential of nobiletin against Alzheimer's disease through inhibiting neuroinflammation

OBJECTIVE

This study aimed to explore the mechanism of Nobiletin attenuating Alzheimer's disease (AD) by inhibiting neuroinflammation.

METHODS

The expression of inflammatory cytokines and HMGB-1 in serum of AD patients were examined. Microglia (MGs) were treated with different doses of Nobiletin before LPS and Nigericin induction. Cell viability and apoptosis were determined by CCK-8 and TUNEL assays, respectively. APP/PS1 mice were gavaged with Nobiletin, and Morris water maze (MWM) was established to record swimming speed, escape latency, the number of platform crossings, and time spent in the platform quadrant. MGs activation in brain tissues was evaluated by immunofluorescence. The expression of pyroptosis-related proteins, inflammatory cytokines, and HMGB-1 was determined in the hippocampus and MGs.

RESULTS

The levels of inflammatory cytokines and HMGB-1 were high in serum of AD patients. Treatment with different concentrations of Nobiletin prominently enhanced cell viability and reduced apoptosis and the expression of inflammatory cytokine and pyroptosis-related proteins in LPS + Nigericin-induced MGs. Gavage of different doses of Nobiletin into APP/PS1 mice shortened the escape latency in mice, diminished MGs activation in brain tissues, and remarkably elevated the number of platform crossings and the time spent in the platform quadrant without obvious change in swimming speed, suggesting that Nobiletin improved the spatial learning and memory abilities in APP/PS1 mice. The expression of pyroptosis-related proteins, HMGB-1, and inflammatory cytokines was decreased dramatically by Nobiletin in the hippocampus of APP/PS1 mice.

CONCLUSIONS

Nobiletin can inhibit neuroinflammation by inhibiting HMGB-1, pyroptosis-related proteins, and inflammatory cytokines, thus mitigating AD.

Characterization of a Caffeic Acid 8-O-Methyltransferase from Citrus and Its Function in Nobiletin Biosynthesis

Nobiletin (3',4',5,6,7,8-hexamethoxyflavone) is a polymethoxylated flavonoid specifically accumulated in citrus fruit with numerous beneficial effects to human health. In this study, a novel O-methyltransferase (CitOMT2) was isolated from three citrus varieties, Ponkan mandarin (Citrus reticulata Blanco), Nou 6 ("King mandarin" × "Mukaku-kishu"), and Satsuma mandarin (Citrus unshiu Marc.), and its functions were characterized in vitro. The gene expression results showed that CitOMT2 was highly expressed in the two nobiletin abundant varieties of Ponkan mandarin and Nou 6. However, the expression level of CitOMT2 was low in the flavedo of Satsuma mandarin, in which only a small amount of nobiletin was accumulated. Functional analysis suggested that CitOMT2 was a caffeic acid 8-O-methyltransferase, and it catalyzed the O-methylation of 7,8-dihydroxyflavone at 8-OH. As the methylation of flavone at 8-OH was required for nobiletin biosynthesis, the results presented in this study suggested that CitOMT2 was a key gene regulating nobiletin accumulation in citrus fruit.

Pharmacokinetics and Metabolites of 12 Bioactive Polymethoxyflavones in Rat Plasma

Polymethoxyflavones (PMFs) are a subgroup of flavonoids possessing various health benefits. 3,5,7,4'-Tetramethoxyflavone (1), 5,6,7,4'-tetramethylflavone (2), 3,7,3',4'-tetramethoxyflavone (3), 5,7,3',4'-tetramethoxyflavone (4), 5-hydroxy-3,7,2',4'-tetramethoxyflavone (5), 3,5,7,2',4'-pentamethoxyflavone (6), 5-hydroxy-3,7,3',4'-tetramethoxyflavone (7), 3-hydroxy-5,7,3',4'-tetramethylflavone (8), 3,5,7,3',4'-pentamethoxyflavone (9), 5-hydroxy-3,7,3',4',5'-pentamethoxyflavone (10), 3-hydroxy-5,7,3',4',5'-pentamethoxyflavone (11), and 3,5,7,3',4',5'-hexamethoxylflavone (12) were 12 bioactive and available PMFs. The aim of this study was to investigate the pharmacokinetic, metabolite, and antitumor activities as well as the structure-pharmacokinetic-antitumor activity relationships of these 12 PMFs to facilitate further studies of their medicinal potentials. The cytotoxicity of PMFs with a hydroxy group toward HeLa, A549, HepG2, and HCT116 cancer cell lines was generally significantly more potent than that of PMFs without a hydroxy group. Compounds 5, 7, 8, 10, and 11 were all undetectable in rat plasma, while compounds 1-4, 6, 9, and 12 were detectable. Both the number and position of hydroxy and methoxy groups played an important role in modulating PMF pharmacokinetics and metabolites.

A novel in vitro assay model developed to measure both extracellular and intracellular acetylcholine levels for screening cholinergic agents

Background

Cholinergic neurons utilize choline (Ch) to synthetize acetylcholine (ACh) and contain a high-affinity Ch transporter, Ch acetyltransferase (ChAT), ACh receptors, and acetylcholinesterase (AChE). As the depletion or malfunction of each component of the cholinergic system has been reported in patients with dementia, many studies have sought to evaluate whether treatment candidates affect each of the cholinergic components. The associated changes in the cholinergic components may be reflected by intra- or extra-cellular ACh levels, with an increase in extracellular ACh levels occurring following AChE inhibition. We hypothesized that increases in intracellular ACh levels can be more sensitively detected than those in extracellular ACh levels, thereby capturing subtle effects in the cholinergic components other than AChE. The objective of this study was to test this hypothesis.

Methods

We developed an in vitro model to measure both extracellular and intracellular ACh levels using the human cholinergic neuroblastoma cell line, LA-N-2, which have been reported to express Ch transporter, ChAT, muscarinic ACh receptor (mAChR), and AChE. With this model, we evaluated several drug compounds and food constituents reported to improve cholinergic function through various mechanisms. In addition, we conducted western blotting to identify the subtype of mAChR that is expressed on the cell line.

Results

Our cell-based assay system was capable of detecting increases in extracellular ACh levels induced by an AChE inhibitor at relatively high doses, as well as increases in intracellular ACh levels following the administration of lower AChE-inhibitor doses and an mAChR agonist. Moreover, increases in intracellular ACh levels were observed even after treatment with food constituents that have different mechanisms of action, such as Ch provision and ChAT activation. In addition, we revealed that LA-N-2 cells expressed mAChR M2.

Conclusion

The findings support our hypothesis and indicate that the developed assay model can broadly screen compounds from drugs to food ingredients, with varying strengths and mechanisms of action, to develop treatments for ACh-relevant phenomena, including dementia and aging-related cognitive decline.

Identification and Quantification of Polymethoxylated Flavonoids in Different Citrus Species Using UPLC-QTOF-MS/MS and HPLC-DAD

Many species from the genus Citrus are used in traditional medicine and contain polymethoxylated flavonoids. These compounds show anti-inflammatory and chemopreventive activities, among others, and therefore have a big potential to be developed as therapeutic agents or dietary supplements. Citrus species are different in their profile and yield of polymethoxylated flavonoids. Therefore, polymethoxylated flavonoids were identified and quantified in seven different Citrus species, including wild-type and commercially available species. All species were profiled using UPLC-QTOF-MS/MS analysis combined with mass spectral molecular networking. A total of 38 polymethoxylated flavonoids were detected and 8 of them were present in every species. As the yield of polymethoxylated flavonoids was different for each species, a generally applicable HPLC-diode array detection method was developed and validated according to the ICH guidelines to quantify the amount of nobiletin and the total amount of polymethoxylated flavonoids expressed as nobiletin. Analysis of the seven samples showed evidence that wild-type Citrus species (e.g., Citrus depressa) contain higher yields of polymethoxylated flavonoids compared to commercially available species (e.g., Citrus limon). Qualitative analysis revealed the broadest variety of different PMFs in C. depressa, Citrus reticulata, and Citrus reticulata × Citrus sinensis, which makes them interesting sources of polymethoxylated flavonoids for future development as therapeutic agents or dietary supplements.

The Application of Citrus folium in Breast Cancer and the Mechanism of Its Main Component Nobiletin: A Systematic Review

Citrus folium and its main ingredient nobiletin (NOB) have received widespread attention in recent years due to their antitumor effects. The antitumor effect of Citrus folium is related to the traditional use, mainly in its Chinese medicinal properties of soothing the liver and promoting qi, resolving phlegm, and dispelling stagnation. Some studies have proved that Citrus folium and NOB are more effective for triple-negative breast cancer (TNBC), which is related to the syndrome of stagnation of liver qi. From the perspective of modern biomedical research, NOB has anticancer effects. Its potential molecular mechanisms include inhibition of the cell cycle, induction of apoptosis, and inhibition of angiogenesis, invasion, and migration. Citrus folium and NOB can also reduce the side effects of chemotherapy drugs and reverse multidrug resistance (MDR). However, more research studies are needed to clarify the underlying mechanisms. The modern evidence of Citrus folium and NOB in breast cancer treatment has a strong connection with the traditional concepts and laws of applying Citrus folium in Chinese medicine (CM). As a low-toxic anticancer drug candidate, NOB and its structural changes, Citrus folium, and compound prescriptions will attract scientists to use advanced technologies such as genomics, proteomics, and metabolomics to study its potential anticancer effects and mechanisms. On the contrary, there are relatively few studies on the anticancer effects of Citrus folium and NOB in vivo. The clinical application of Citrus folium and NOB as new cancer treatment drugs requires in vivo verification and further anticancer mechanism research. This review aims to provide reference for the treatment of breast cancer by Chinese medicine.

Nobiletin: Targeting the Circadian Network to Promote Bioenergetics and Healthy Aging

The circadian clock is the biological mastermind governing orderly execution of bodily processes throughout the day. In recent years, an emerging topic of broad interest is clock-modulatory agents, including small molecules both of synthetic and natural origins, and their potential applications in disease models. Nobiletin is a naturally occurring flavonoid with the greatest abundance found in citrus peels. Extensive research has shown that Nobiletin is endowed with a wide range of biological activities, yet its mechanism of action remains unclear. We recently found through unbiased chemical screening that Nobiletin impinges on the clock machinery to activate temporal control of downstream processes within the cell and throughout the body. Using animal models of diseases and aging, we and others illustrate potent beneficial effects of Nobiletin on cellular energetics in both periphery and brain to promote healthy aging. Given its excellent safety profile, Nobiletin may represent a promising candidate molecule for development of nutraceutical and chronotherapeutic agents against chronic and age-related neurodegenerative diseases.

Role of natural plant products against Alzheimer's disease

Alzheimer's disease (AD) is one of the major neurodegenerative disorder. Deposition of amyloid fibrils and tau protein are associated with various pathological symptoms. Currently limited medication is available for AD treatment. Most of the drugs are basically cholinesterase inhibitors and associated with various side effects. Natural plant products have shown potential as a therapeutic agent for the treatment of AD symptoms. Variety of secondary metabolites like flavonoids, tannins, terpenoids, alkaloids and phenols are used to reduce the progression of the disease. Plant products have less or no side effect and are easily available. The present review gives a detailed account of the potential of natural plant products against the AD symptoms.

Molecular regulation of brain metabolism underlying circadian epilepsy

Extensive study has demonstrated that epilepsy occurs with greater frequency at certain times in the 24-h cycle. Although these findings implicate an overlap between the circadian rhythm and epilepsy, the molecular and cellular mechanisms underlying this circadian regulation are poorly understood. Because the 24-h rhythm is generated by the circadian molecular system, it is not surprising that this system comprised of many circadian genes is implicated in epilepsy. We summarized evidence in the literature implicating various circadian genes such as Clock, Bmal1, Per1, Rev-erb⍺, and Ror⍺ in epilepsy. In various animal models of epilepsy, the circadian oscillation and the steady-state level of these genes are disrupted. The downstream pathway of these genes involves a large number of metabolic pathways associated with epilepsy. These pathways include pyridoxal metabolism, the mammalian target of rapamycin pathway, and the regulation of redox state. We propose that disruption of these metabolic pathways could mediate the circadian regulation of epilepsy. A greater understanding of the cellular and molecular mechanism of circadian regulation of epilepsy would enable us to precisely target the circadian disruption in epilepsy for a novel therapeutic approach.

Preventive Effects of Continuous Betaine Intake on Cognitive Impairment and Aberrant Gene Expression in Hippocampus of 3xTg Mouse Model of Alzheimer's Disease

BACKGROUND

The deposition of amyloid-β (Aβ) and hyperphosphorylation of tau are well-known as the pathophysiological features of Alzheimer's disease (AD), leading to oxidative stress and synaptic deficits followed by cognitive symptoms. We already demonstrated that betaine (glycine betaine) prevented cognitive impairment and hippocampal oxidative stress in mice intracerebroventricularly injected with an active fragment of Aβ, whereas the effect of betaine in chronic models of AD remains unknown.

OBJECTIVE

Our objective was to investigate the effects of chronic betaine intake on cognitive impairment and aberrant expression of genes involved in synapse and antioxidant activity in the hippocampus of a genetic AD model.

METHODS

We performed cognitive tests and RT-PCR in the hippocampus in 3xTg mice, a genetic AD model.

RESULTS

Cognitive impairment in the Y-maze and novel object recognition tests became evident in 3xTg mice at 9 months old, and not earlier, indicating that cognitive impairment in 3xTg mice developed age-dependently. To examine the preventive effect of betaine on such cognitive impairment, 3xTg mice were fed betaine-containing water for 3 months from 6 to 9 months old, and subsequently subjected to behavioral tests, in which betaine intake prevented the development of cognitive impairment in 3xTg mice. Additionally, the expression levels of genes involved in synapse and antioxidant activity were downregulated in hippocampus of 3xTg mice at 9 months old compared with age-matched wild-type mice, which were suppressed by betaine intake.

CONCLUSION

Betaine may be applicable as an agent preventing the progression of AD by improving the synaptic structure/function and/or antioxidant activity.

Important Flavonoids and Their Role as a Therapeutic Agent

Flavonoids are phytochemical compounds present in many plants, fruits, vegetables, and leaves, with potential applications in medicinal chemistry. Flavonoids possess a number of medicinal benefits, including anticancer, antioxidant, anti-inflammatory, and antiviral properties. They also have neuroprotective and cardio-protective effects. These biological activities depend upon the type of flavonoid, its (possible) mode of action, and its bioavailability. These cost-effective medicinal components have significant biological activities, and their effectiveness has been proved for a variety of diseases. The most recent work is focused on their isolation, synthesis of their analogs, and their effects on human health using a variety of techniques and animal models. Thousands of flavonoids have been successfully isolated, and this number increases steadily. We have therefore made an effort to summarize the isolated flavonoids with useful activities in order to gain a better understanding of their effects on human health.

Chromone and donepezil hybrids as new multipotent cholinesterase and monoamine oxidase inhibitors for the potential treatment of Alzheimer's disease

A series of chromone and donepezil hybrids were designed, synthesized, and evaluated as multipotent cholinesterase (ChE) and monoamine oxidase (MAO) inhibitors for the potential therapy of Alzheimer's disease (AD). In vitro studies showed that the great majority of these compounds exhibited potent inhibitory activity toward BuChE and AChE and clearly selective inhibition for hMAO-B. In particular, compound 5c presented the most balanced potential for ChE inhibition (BuChE: IC₅₀ = 5.24 μM; AChE: IC₅₀ = 0.37 μM) and hMAO-B selectivity (IC₅₀ = 0.272 μM, SI = 247). Molecular modeling and kinetic studies suggested that 5c was a mixed-type inhibitor, binding simultaneously to peripheral and active sites of AChE. It was also a competitive inhibitor, which occupied the substrate and entrance cavities of MAO-B. Moreover, compound 5c could penetrate the blood-brain barrier (BBB) and showed low toxicity to rat pheochromocytoma (PC12) cells. Altogether, these results indicated that compound 5c might be a hopeful multitarget drug candidate with possible impact on Alzheimer's disease therapy.

Nobiletin Delays Aging and Enhances Stress Resistance of Caenorhabditis elegans

Nobiletin (NOB), one of polymethoxyflavone existing in citrus fruits, has been reported to exhibit a multitude of biological properties, including anti-inflammation, anti-oxidation, anti-atherosclerosis, neuroprotection, and anti-tumor activity. However, little is known about the anti-aging effect of NOB. The objective of this study was to determine the effects of NOB on lifespan, stress resistance, and its associated gene expression. Using Caenorhabditis elegans, an in vivo nematode model, we found that NOB remarkably extended the lifespan; slowed aging-related functional declines; and increased the resistance against various stressors, including heat shock and ultraviolet radiation. Also, NOB reduced the effects of paraquat stressor on nematodes and scavenged reactive oxygen species (ROS). Furthermore, gene expression revealed that NOB upregulated the expression of sod-3, hsp-16.2, gst-4, skn-1, sek-1, and sir-2.1, which was suggested that anti-aging activity of NOB was mediated most likely by activation of the target genes of the transcription factors including dauer formation (DAF)-16, heat-shock transcription factor (HSF)-1, and skinhead (SKN)-1. In summary, NOB has potential application in extension of lifespan, and its associated healthspan and stress resistances.

Ameliorating effect of Citrus aurantium extracts and nobiletin on β‑amyloid (1‑42)‑induced memory impairment in mice

The aim of the present study was to evaluate the neuroprotective effect of Citrus aurantium extract (CAE) and nobiletin against amyloid β 1‑42 (Aβ 1‑42)‑induced spatial learning and memory impairment in mice. After injecting Aβ 1‑42 (5 µl/2.5 min, intracerebroventricular injection), amnesic mice were orally administered CAE and nobiletin for 28 days. Memory, spatial and cognitive ability were measured using passive avoidance and a Morris water maze task. Acetylcholinesterase (AchE) activity was investigated in the hippocampus and cortex using commercial kits and the analysis of Bax, Bcl‑2, and cleaved caspase‑3 protein expression by western blot assays was used to confirm the anti‑apoptotic mechanism of CAE and nobiletin. The present study confirmed impairments in learning and memory in the Aβ‑induced neurodegenerative mice with increased AchE activity in the brain. However, the daily administration of CAE and nobiletin reduced the spatial learning deficits and increased the AchE activity in the cortex and hippocampus. Furthermore, CAE and nobiletin significantly downregulated the Bax and cleaved caspase‑3 protein expression and upregulated the Bcl‑2 and Bcl‑2/Bax expression in the cortex and hippocampus of Aβ‑treated mice. These results suggest that CAE and nobiletin exert a neuroprotective effect by regulating anti‑apoptotic mechanisms, including reduced AchE activity in the cortex and hippocampus of the cognitive deficit mouse model.

Inhibitory effects of nobiletin and its major metabolites on lung tumorigenesis

The present study demonstrated that the oral administration of nobiletin significantly inhibited lung carcinogenesis in mice, and these chemopreventive effects could be attributed to its metabolites that showed potent anti-cancer effects.

Effect of Nobiletin on Experimental Model of Epilepsy

Background

The effects of nobiletin, a plant-derived flavonoid was examined against pentylenetetrazole (PTZ)-induced seizures. The study also aimed to assess whether nobiletin potentiated the effects of antiepileptic drug clonazepam (CZP).

Methods

PTZ (92 mg/kg, subcutaneous) was used to induce seizures in mice. Treatment groups (n = 18/group) received nobiletin (12.5, 25, or 50 mg/kg) via oral gavage for 6 consecutive days and 45 min prior to PTZ injection. CZP (0.015-2.0 mg/kg) was administered 15 min prior to PTZ. Skeletal muscle strength was assessed by measuring grip strength and Chimney test was performed to study the motor performance in animals. TUNEL assay was done to study neuro-apoptosis. RT-PCR and Western blot analysis were performed for assessment of mRNA and protein expressions.

Results

Nobiletin and CZP improved muscle strength and motor coordination and reduced seizure severity significantly. The administration of nobiletin and CZP, individually or in combination, downregulated seizure-induced increases in apoptotic cell count and apoptotic protein expression, modulated the expression of gamma-aminobutyric acid (GABA)A and glutamate decarboxylase 65 and restored the glutamate/GABA balance. Nobiletin and CZP administration significantly upregulated phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling.

Conclusion

Nobiletin exerted protective effect against seizures by regulating signaling pathways associated with epileptogenesis and potentiated the effects of CZP.

Alzheimer Disease: Clues from traditional and complementary medicine

Despite modern medicine's incredible innovation and resulting accumulation of valuable knowledge, many of the world's most problematic diseases such as Alzheimer Disease (AD) still lack effective cures and treatments. Western medicine has revealed many genetic, cellular, and molecular processes that characterize AD such as protein aggregation and inflammation. As the need for novel and effective treatments increases, researchers have turned towards traditional medicine as a resource. Modern, evidence based research examining traditional and complementary remedies for AD has generated promising results within the last decade. Animal based products inhibiting cellular toxicity, anti-inflammatory nutraceuticals such as omega-3 fatty acids, and plant based compounds derived from herbal medicine demonstrate viability as neuroprotective treatments and possible application in developing pharmaceuticals. Analysis of antioxidant, anti-inflammatory, and neuroprotective phytochemicals used in various traditional medicines around the world reveal potential to ameliorate and prevent the devastating neurodegeneration observed in AD.

Polymethoxyflavones: Novel β-Secretase (BACE1) Inhibitors from Citrus Peels

Beta-site amyloid precursor protein (APP) cleaving enzyme1 (BACE1) catalyzes the rate-limiting step of amyloid-β protein (Aβ) generation, and is considered as a prime target for Alzheimer’s disease (AD). In search of a candidate for AD prevention, our efforts exploring the natural BACE1 inhibitor have led to the finding of nobiletin, tangeretin, and sinensetin—representative compounds of polymethoxyflavones (PMFs). Tangeretin exhibited the strongest BACE1 inhibition (IC₅₀, 4.9 × 10⁻⁵ M), followed by nobiletin and sinensetin with IC₅₀ values of 5.9 × 10⁻⁵ M and 6.3 × 10⁻⁵ M, respectively. In addition, all compounds reacted in a non-competitive manner with the substrate. Docking analysis results for complexes with BACE1 indicated that SER10 and THR232 residues of BACE1 hydrogen bonded with two oxygen atoms of tangeretin, while three additional BACE1 residues (ALA157, VAL336 and THR232) interacted with three oxygen atoms of nobiletin. Furthermore, sinensetin formed four hydrogen bonds through nitrogen atoms of TYR71, LYS75, and TRP76, and an oxygen atom of TYR198. Furthermore, the lowest-energy conformations of the most proposed complexes of sinensetin, nobiletin, and tangeretin with BACE1 were −7.2, −7.0, and −6.8 kcal/mol, respectively. Taken together, our results suggest that these polymethoxyflavones (PMFs) might be considered as promising BACE1 inhibitory agents that could lower Aβ production in AD.

Extraction of nobiletin from Citrus Unshiu peels by supercritical fluid and its CRE-mediated transcriptional activity

BACKGROUND

Polymethoxyflavone (PMF) is one of bioactive compounds in Citrus Unshiu and included mainly in the peels rather than the fruits, seeds and leaves.

HYPOTHESIS/PURPOSE

Supercritical CO₂ extraction is one candidate for selective extraction of polymethoxyflavone and in this study, supercritical CO₂ extraction with/without ethanol entrainer from Citrus Unshiu peels was examined at a temperature of 333K and a pressure of 30MPa.

METHODS

CRE (cyclic AMP response element)-mediated transcriptional assay was examined by using the extracts from supercritical fluid extraction.

RESULTS

The results showed that extracts including nobiletin increased with increasing ethanol concentration in supercritical CO₂ and the elapsed extraction time. Extracts at ethanol concentration of 5 mol% showed high CRE-mediated transcription activity. This can be caused by activity of the extract including nobiletin in addition to the other methoxylated flavonoid species such as tangeretin. Extracts at ethanol concentration of 50% showed the highest CRE-mediated transcription activity, which can be attributed to flavonoid glycoside such as hesperidin. From our investigations, flavonoid glycoside can be one of promoters of CRE-mediated transcription activity.

Novel multitarget-directed tacrine derivatives as potential candidates for the treatment of Alzheimer's disease

Alzheimer’s disease (AD) is a neurodegenerative disorder, which is complex and progressive; it has not only threatened the health of elderly people, but also burdened the whole social medical and health system. The available therapy for AD is limited and the efficacy remains unsatisfactory. In view of the prevalence and expected increase in the incidence of AD, the design and development of efficacious and safe anti-AD agents has become a hotspot in the field of pharmaceutical research. Due to the multifactorial etiology of AD, the multitarget-directed ligands (MTDLs) approach is promising in search for new drugs for AD. Tacrine, which is the first acetylcholinesterase (AChE) inhibitor, has been selected as the ideal active fragment because of its simple structure, clear activity, and its superiority in the structural modification, thus it could be introduced into the overall molecular skeletons of the multi-target-directed anti-AD agents. In this review, we have summarized the recent advances (2012 to the present) in the chemical modification of tacrine, which could provide the reference for the further study of novel multi-target-directed tacrine derivatives to treat AD.

Mitochondrial Target of Nobiletin's Action

Nobiletin is an O-methylated flavonoid found in citrus peels that have anticancer, antiviral, neuroprotective, anti-inflammatory activities and depending on the cell types exhibits both pro- or anti-apoptotic properties. We have found that nobiletin decreases oxygen consumption by bovine brain isolated mitochondria in the presence of glutamate and malate and increases in the presence of succinate. In parallel, nobiletin increases NADH oxidation, a-ketoglutarate dehydrogenase activities and through matrix substrate-level phosphorylation elevates the a-ketoglutarate-dependent production of ATP. In addition, nobiletin reduces the production of peroxides in the presence of complex I substrates and slightly enhances succinate-driven H2O2 formation. Besides, nobiletin induces transient elevation of membrane potential followed by mild depolarization. Affinity purified nobiletin binding proteins revealed one major anti-NDUFV1 positive protein with 52kD and NADH: ubiquinone oxidoreductase activity. This fraction can produce peroxide that is inhibited by nobiletin. We propose that nobiletin may act as a mild “uncoupler”, which through activation of a-ketoglutarate dehydrogenase (a-KGDH)-complex and acceleration of matrix substrate-level phosphorylation maintains membrane potential at an abnormal level. This switch in mitochondrial metabolism could elevate succinate-driven oxygen consumption that may underlay in both pro- and anti-apoptotic effects of nobiletin.

Nobiletin ameliorates isoflurane-induced cognitive impairment via antioxidant, anti-inflammatory and anti-apoptotic effects in aging rats

A recent study reported that nobiletin is an active ingredient in Fructus Aurantii immaturus and Pericarpium Citri Reticulatae, which may be capable of preventing ischemic stroke. Therefore, the present study aimed to determine the neuroprotective effects of nobiletin, and to evaluate whether it could ameliorate isoflurane‑induced cognitive impairment via antioxidant, anti‑inflammatory and anti‑apoptotic effects in aging rats. Male Sprague‑Dawley rats (age, 18 months) were used to analyze the neuroprotective effects of nobiletin. Morris water maze test was used to determine cognitive competence. Enzyme‑linked immunosorbent assay and western blot analysis were also used to quantify nuclear factor‑κB, tumor necrosis factor (TNF)‑α, IL‑1β, IL‑6, glutathione, (GSH), GSH‑peroxidase, superoxide dismutase and malondialdehyde concentration and relevant protein expression levels Cognitive competence was increased in isoflurane-treated rats following treatment with nobiletin. In addition, as expected, nobiletin exerted antioxidant, anti-inflammatory and anti‑apoptotic effects on isoflurane‑induced cognitive impairment in aging rats. Treatment with nobiletin induced the activation of phosphorylated (p)‑Akt, p‑cAMP response element binding protein (CREB) and brain‑derived neurotrophic factor (BDNF) protein expression and reduced the levels of B‑cell lymphoma 2‑associated X protein (Bax) in isoflurane‑induced rats. In conclusion, the present study demonstrated that nobiletin may ameliorate isoflurane-induced cognitive impairment through antioxidant, anti‑inflammatory and anti‑apoptotic effects via modulation of Akt, Bax, p‑CREB and BDNF in aging rats. These findings provide support for the molecular mechanisms underlying the effects of nobiletin treatment on isoflurane-induced damage.

The Multifunctional Effects of Nobiletin and Its Metabolites In Vivo and In Vitro

Nobiletin (NOB) chemically known as 5,6,7,8,3′,4′-hexamethoxyflavone is a dietary polymethoxylated flavonoid found in Citrus fruits. Recent evidences show that NOB is a multifunctional pharmaceutical agent. The various pharmacological activities of NOB include neuroprotection, cardiovascular protection, antimetabolic disorder, anticancer, anti-inflammation, and antioxidation. These events may be underpinned by modulation of signaling cascades, including PKA/ERK/MEK/CREB, NF-κB, MAPK, Ca²⁺/CaMKII, PI3K/Akt1/2, HIF-1α, and TGFβ signaling pathways. The metabolites may exhibit stronger beneficial effects than NOB on diseases pathogenesis. The biological activities of NOB have been clarified on many systems. This review aims to discuss the pharmacological effects of NOB with specific mechanisms of actions. NOB may become a promising candidate for potential drug development. However, further investigations of NOB on specific intracellular targets and clinical trials are still needed, especially for in vivo medical applications.

[A new strategy for preventive and functional therapeutic methods for dementia--approach using natural products]

Alzheimer's disease (AD) has become a serious social problem in Japan. However, effective preventive and fundamental therapeutic methods for AD have not yet been developed. Using a new strategy in the course of our survey of numerous natural resouces having neurotrophic activity, we isolated a variety of active constituents and proved their pharmacological properties. As a result, we successfully found nobiletin, a compound with anti-dementia activity that comes from citrus peels. Also, we have demonstrated that nobiletin ameliorates cognitive impairment in several dementia model animals such as chronically amyloid β(Aβ) infused rats, amyloid precursor protein transgenic (APPTg) mice, olfactory-bulbectomized (OBX) mice, N-methyl-D-aspartate (NMDA) receptor antagonist (MK-801)-treated mice, senescence-accelated mice and bilaterial common carotid arteries occlusion mice. In a APPTg mouse of AD, nobiletin greatly improved memory impairment, and this was accompanied by a marked decrease in Aβ deposition. Also, in OBX mice memory impairment was markedly recoverd by nobiletin, accompanied by improvement of a decrease indensity of cholinergic neurons. Interestingly, nobiletin improves age-related congnitive impairment and decreased hyperphosphorylation of tau as well as oxidative stress in senescence-accelerated mice. In cultured cells, nobiletin reversed the Aβ-induced inhibition of glutamate-induced increases in cAMP response element binding protein (CREB) phosphorylation and modulated gen expression of thioredoxin-interacting protein and NMDA resceptor subunits. These results suggest that nobiletin prevents memory impairment and exhibits a protecting action against neurodgeneration in AD model animals. Nobiletin and citrus peels thus have potential as functional foods for prevention of dementia.

Immune effects and antiacetylcholinesterase activity of Polygonum hydropiper L

To determine the potential utility of Polygonum hydropiper (tade) as an anti-dementia functional food, the present study assessed the acetylcholinesterase inhibitory and anti-inflammatory activities of tade crude extracts in human cells. Crude extracts of tade were obtained by homogenizing tade in distilled water and then heating the resulting crude extracts. The hot aqueous extracts were purified by centrifugation and freeze-dried. The inhibition of acetylcholinesterase (AChE) by tade was investigated quantitatively by Ellman’s method. Furthermore, the in vitro effects on human leukocytes (phagocytic activity, phagosome-lysosome fusion, and superoxide anion release) of coating inactive Staphylococcus aureus cells with tade crude extracts were studied. The tade crude extracts inhibited AChE activity. Furthermore, they increased phagocytic activity and phagosome-lysosome fusion in human neutrophils and monocytes in a nominally dose-dependent manner. However, the tade crude extracts did not alter superoxide anion release (O₂⁻) from neutrophils. Our results confirmed that crude extracts of P. hydropiper exhibit antiacetylcholinesterase and immunostimulation activities in vitro. P. hydropiper thus is a candidate functional food for the prevention of dementia.

Dietary Habits Are Associated With School Performance in Adolescents

Several studies suggest that dietary habits are associated with poor academic performance. However, few studies have evaluated these relations after adjusting for numerous confounding factors. This study evaluated the frequency of various diet items (fruit, soft drinks, fast foods, instant noodles, confections, vegetables, and milk) and the regularity of meal times (breakfast, lunch, and dinner) all at once.A total of 359,264 participants aged from 12 to 18 years old were pooled from the Korea Youth Risk Behavior Web-based Survey (KYRBWS) for the 2009 to 2013 period. Dietary habits over the last 7 days were surveyed, including the regularity of consuming breakfast, lunch and dinner and the frequency of eating fruits, soft drinks, fast foods, instant noodles, confections, vegetables, and milk. Physical activity, obesity, region of residence, subjective assessment of health, stress level, economic level, and parental education level were collected from all of the study participants. School performance was classified into 5 levels. The adjusted odds ratios (AORs) of dietary habits for school performance were analyzed using multinomial logistic regression analyses with complex sampling. Structural equation modeling was used to analyze the effects of diet factors on school performance while considering the effects of other variables on both diet factors and school performance.Frequent intakes of breakfast (AOR = 2.34, 95% confidence interval [CI] = 2.20-2.48), fruits (AOR = 1.73, 95% CI = 1.62-1.86), vegetables (AOR = 1.48, 95% CI = 1.37-1.61), and milk (AOR = 1.35, 95% CI = 1.28-1.43) were related to high levels of school performance (each with P < 0.001). In contrast, soft drinks (AOR = 0.42, 95% CI = 0.38-0.46), instant noodles (AOR = 0.62, 95% CI = 0.55-0.70), fast food (AOR = 0.83, 95% CI = 0.72-0.96), and confectionary (AOR = 0.86, 95% CI = 0.80-0.93) were negatively associated with school performance (each with P < 0.001).This study confirms previous studies of school performance and dietary habits that find a positive association with eating breakfast and consuming fruits and milk and a negative relation with soft drinks, instant noodles, fast foods, and confections.

Nerve growth factor enhances the CRE-dependent transcriptional activity activated by nobiletin in PC12 cells

Prevention and treatment of Alzheimer disease are urgent problems for elderly people in developed countries. We previously reported that nobiletin, a poly-methoxylated flavone from the citrus peel, improved the symptoms in various types of animal models of memory loss and activated the cAMP responsive element (CRE)-dependent transcription in PC12 cells. Nobiletin activated the cAMP/PKA/MEK/Erk/MAPK signaling pathway without using the TrkA signaling activated by nerve growth factor (NGF). Here, we examined the effect of combination of nobiletin and NGF on the CRE-dependent transcription in PC12 cells. Although NGF alone had little effect on the CRE-dependent transcription, NGF markedly enhanced the CRE-dependent transcription induced by nobiletin. The NGF-induced enhancement was neutralized by a TrkA antagonist, K252a. This effect of NGF was effective on the early signaling event elicited by nobiletin. These results suggested that there was crosstalk between NGF and nobiletin signaling in activating the CRE-dependent transcription in PC12 cells.

Polymethoxyflavones Isolated from the Peel of Miaray Mandarin (Citrus miaray) Have Biofilm Inhibitory Activity in Vibrio harveyi

Citrus fruits are a good source of bioactive compounds with numerous beneficial biological activities. In the present study, fruits of the unexplored Miaray mandarin were used for the isolation of 10 bioactive compounds. Dried peels were sequentially extracted with hexane and chloroform in a Soxhlet-type apparatus for 8 h. The extracts were concentrated under vacuum and separated by flash chromatography to obtain nine polymethoxyflavones and a limonoid. The purity of each compound was analyzed by high-performance liquid chromatography (HPLC), and the compounds were identified by spectral analysis using MALDI-TOF-MS and NMR. The isolated compounds were identified as 5-hydroxy-3,7,3',4'-tetramethoxyflavone, 5,6,7,8,4'-pentamethoxyflavone (tangeretin), 3,5,6,7,8,3',4'-heptamethoxyflavone, 5,6,7,8,3',4'-hexamethoxyflavone (nobiletin), 3,5,7,8,3',4'-hexamethoxyflavone, 3,5,7,3',4'-pentamethoxyflavone (pentamethylquercetin), 5,7,4'-trimethoxyflavone, 5,7,8,4'-tetramethoxyflavone, 5,7,8,3',4'-pentamethoxyflavone, and limonin. These compounds were further tested for their ability to inhibit cell-cell signaling and biofilm formation in Vibrio harveyi. Among the evaluated polymethoxyflavones, 3,5,6,7,8,3',4'-heptamethoxyflavone and 3,5,7,8,3',4'-hexamethoxyflavone inhibited autoinducer-mediated cell-cell signaling and biofilm formation. These results suggest that Miaray mandarin fruits are a good source of polymethoxyflavones. This is the first report on the isolation of bioactive compounds from Miaray mandarin and evaluation of their biofilm inhibitory activity as well as isolation of pentamethylquercetin from the Citrus genus.

Design, synthesis and evaluation of novel 5,6,7-trimethoxyflavone-6-chlorotacrine hybrids as potential multifunctional agents for the treatment of Alzheimer's disease

A series of 5,6,7-trimethoxyflavone-6-chlorotacrine hybrids were designed, synthesized and evaluated as multifunctional agents for the treatment of Alzheimer's disease (AD). The results showed that the target compounds exhibited good acetylcholinesterase (AChE) inhibitory potencies, high selectivity toward AChE over butyrylcholinesterase (BuChE), potential antioxidant activities and significant inhibitory potencies of self-induced beta-amyloid peptide (Aβ) aggregation. In particular, compound 14c had the strongest AChE inhibitory activity with IC50 value of 12.8 nM, potent inhibition of self-induced Aβ1-42 aggregation with inhibition ratio of 33.8% at 25 μM. Moreover, compound 14c acted as an antioxidant, as well as a neuroprotectant. Furthermore, 14c could cross the blood-brain barrier (BBB) in vitro. The results showed that compound 14c might be a potential multifunctional candidate for the treatment of AD.