Synergistic Action of Flavonoids, Baicalein, and Daidzein in Estrogenic and Neuroprotective Effects: A Development of Potential Health Products and Therapeutic Drugs against Alzheimer's Disease

Unveiling the neuroprotective properties of isoflavones: current evidence, molecular mechanisms and future perspectives

Neurodegenerative diseases encompass a wide range of debilitating and incurable brain disorders characterized by the progressive deterioration of the nervous system's structure and function. Isoflavones, which are naturally occurring polyphenolic phytochemicals, have been found to regulate various cellular signaling pathways associated with the nervous system. The main objective of this comprehensive review is to explore the neuroprotective effects of isoflavones, elucidate the underlying mechanisms, and assess their potential for treating neurodegenerative disorders. Relevant data regarding isoflavones and their impact on neurodegenerative diseases were gathered from multiple library databases and electronic sources, including PubMed, Google Scholar, Web of Science, and Science Direct. Numerous isoflavones, including genistein, daidzein, biochanin A, and formononetin, have exhibited potent neuroprotective properties against various neurodegenerative diseases. These compounds have been found to modulate neurotransmitters, which in turn contributes to their ability to protect against neurodegeneration. Both in vitro and in vivo experimental studies have provided evidence of their neuroprotection mechanisms, which involve interactions with estrogenic receptors, antioxidant effects, anti-inflammatory properties, anti-apoptotic activity, and modulation of neural plasticity. This review aims to provide current insights into the neuroprotective characteristics of isoflavones and shed light on their potential therapeutic applications in future clinical scenarios.

Design, synthesis, and evaluation of dual-target inhibitors for the treatment of Alzheimer's disease

Aβ1-42 and acetylcholinesterase (AChE) are two key therapeutic targets for Alzheimer's disease (AD). The purpose of this study is to develop a dual-target inhibitor that inhibits both of these targets by fusing the chemical structure of baicalein and donepezil. Among them, we modified the structure of baicalein to arylcoumarin, synthesized three kinds of structural compounds, and evaluated their biological activities. The results showed that compound 3b had the strongest inhibitory effect on AChE (IC50 = 0.05 ± 0.02 µM), which was better than those of donepezil and baicalein. In addition, compound 3b has a strong ability to inhibit the aggregation of Aβ1-42 and protect nerve cells, and it can also penetrate the blood-brain barrier well. Using a zebrafish behavioral analyzer test, it was found that compound 3b can alleviate the behavioral effects of AlCl3-induced zebrafish larval movement retardation, which has a certain guiding significance for simulating the movement disorders of AD patients. In summary, compound 3b is expected to become a multifunctional agent for treating and alleviating the symptoms of AD patients.

Sonic hedgehog signalling pathway contributes in age-related disorders and Alzheimer's disease

Alzheimer's disease (AD) is caused by the aging process and manifested by cognitive deficits and progressive memory loss. During aging, several conditions, including hypertension, diabetes, and cholesterol, have been identified as potential causes of AD by affecting Sonic hedgehog (Shh) signalling. In addition to being essential for cell differentiation and proliferation, Shh signalling is involved in tissue repair and the prevention of neurodegeneration. Neurogenesis is dependent on Shh signalling; inhibition of this pathway results in neurodegeneration. Several protein-protein interactions that are involved in Shh signalling are implicated in the pathophysiology of AD like overexpression of the protein nexin-1 inhibits the Shh pathway in AD. A protein called Growth Arrest Specific-1 works with another protein called cysteine dioxygenase (CDO) to boost Shh signalling. CDO is involved in the development of the central nervous system (CNS). Shh signalling strengthened the blood brain barrier and therefore prevent the entry of amyloid beta and other toxins to the brain from periphery. Further, several traditional remedies used for AD and dementia, including Epigallocatechin gallate, yokukansan, Lycium barbarum polysaccharides, salvianolic acid, and baicalin, are known to stimulate the Shh pathway. In this review, we elaborated that the Shh signalling exerts a substantial influence on the pathogenesis of AD. In this article, we have tried to explore the various possible connections between the Shh signalling and various known pathologies of AD.

Update on new trends and progress of natural active ingredients in the intervention of Alzheimer's disease, based on understanding of traditional Chinese and Western relevant theories: A review

Alzheimer's disease (AD) is one of the major neurological disorders causing death in the elderly worldwide. As a neurodegenerative disease that is difficult to prevent and cure, the pathogenesis of AD is complex and there is no effective cure. A variety of natural products derived from plants have been reported to have promising anti-AD activities, including flavonoids, terpenes, phenolic acids and alkaloids, which can effectively relieve the symptoms of AD in a variety of ways. This paper mainly reviews the pharmacological activity and mechanisms of natural products against AD. Although the clinical efficacy of these plants still needs to be determined by further high-quality studies, it may also provide a basis for future researchers to study anti-AD in depth.

Synergistic Inhibiting Effect of Phytochemicals in Rheum palmatum on Tyrosinase Based on Metabolomics and Isobologram Analyses

Tyrosinase (TYR) plays a key role in the enzymatic reaction that is responsible for a range of unwanted discoloration effects, such as food browning and skin hyperpigmentation. TYR inhibitors could, therefore, be candidates for skin care products that aim to repair pigmentation problems. In this study, we used a metabolomics approach combined with the isobologram analysis to identify anti-TYR compounds within natural resources, and evaluate their possible synergism with each other. Rheum palmatum was determined to be a model plant for observing the effect, of which seven extracts with diverse phytochemicals were prepared by way of pressurized solvent extraction. Each Rheum palmatum extract (RPE) was profiled using nuclear magnetic resonance spectroscopy and its activity of tyrosinase inhibition was evaluated. According to the orthogonal partial least square analysis used to correlate phytochemicals in RPE with the corresponding activity, the goodness of fit of the model (R₂ = 0.838) and its predictive ability (Q₂ = 0.711) were high. Gallic acid and catechin were identified as the active compounds most relevant to the anti-TYR effect of RPE. Subsequently, the activity of gallic acid and catechin were evaluated individually, and when combined in various ratios by using isobologram analysis. The results showed that gallic acid and catechin in the molar ratios of 9:5 and 9:1 exhibited a synergistic inhibition on TYR, with a combination index lower than 0.77, suggesting that certain combinations of these compounds may prove effective for use in cosmetic, pharmaceutical, and food industries.

Exploring the Inhibition of Quercetin on Acetylcholinesterase by Multispectroscopic and In Silico Approaches and Evaluation of Its Neuroprotective Effects on PC12 Cells

This study investigated the inhibitory mechanism of quercetin in acetylcholinesterase (AChE) and its neuroprotective effects on β-amyloid_25-35-induced oxidative stress injury in PC12 cells. Quercetin inhibited AChE in a reversible mixed manner with an IC₅₀ of 4.59 ± 0.27 µM. The binding constant of quercetin with AChE at 25 °C was (5.52 ± 0.05) × 10⁴ L mol^-1. Hydrogen bonding and van der Waals forces were the main interactions in forming the stable quercetin-AChE complex. Computational docking revealed that quercetin was dominant at the peripheral aromatic site in AChE and induced enzymatic allosterism; meanwhile, it extended deep into the active center of AChE and destabilized the hydrogen bond network, which caused the constriction of the gorge entrance and prevented the substrate from entering the enzyme, thus resulting in the inhibition of AChE. Molecular dynamics (MD) simulation emphasized the stability of the quercetin-AChE complex and corroborated the previous findings. Interestingly, a combination of galantamine hydrobromide and quercetin exhibited the synergistic inhibition effect by binding to different active sites of AChE. In a β-amyloid_25-35-induced oxidative stress injury model in PC12 cells, quercetin exerted neuroprotective effects by increasing the glutathione level and reducing the malondialdehyde content and reactive oxygen species levels. These findings may provide novel insights into the development and application of quercetin in the dietary treatment of Alzheimer's disease.

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.

Flavonoids extract from the seeds of Psoralea corylifolia L. (PFE) alleviates atherosclerosis in high-fat diet-induced LDLR-/- mice

BACKGROUND

The seeds of Psoralea corylifolia L., a traditional medicine popular used in China and India, have been recommended in the treatment of leucoderma, psoriasis, osteoporosis, and gynecological bleeding. Our previous studies have found that flavonoid extract from the seeds of Psoralea corylifolia L. could activate fat browning and correct the disorder of glucose and lipid metabolism in obese mice.

PURPOSE

The present study aimed to investigate the anti-atherosclerosis of flavonoids extract from the seeds of Psoralea corylifolia L.

METHODS

Leukocyte adhesion assay, RT-PCR, Western blot analysis, and immunofluorescent assay were carried out in ox-LDL induced endothelium injury and foam cells formation in vitro. Flavonoids from the seeds of P. corylifolia L. (PFE) was administrated 150 and 300 mg/kg/day in HFD-induced LDLR-/- mice for 12 weeks.

RESULTS

Flavonoids from the seeds of P. corylifolia L. (PFE) could prevent leukocyte adhesion to the endothelium by inhibiting mRNA and protein expression of these adhesion molecules (VCAM-1, ICAM-1, and E-selectin). PFE could also prevent ox-LDL stimulated inflammation in HUVECs by inhibiting the NF-κB pathway. In addition, PFE significantly ameliorated ox-LDL induced macrophages-oriented foam cells formation through inducing cholesterol efflux via PPARγ-ABCA1/ABCG1. In HFD-induced LDLR-/- mice, PFE reversed the serum profile and circulated inflammation level. Meanwhile, PFE could remarkably alleviate atherosclerotic lesion sizes and intraplaque macrophage infiltration in aortic roots.

CONCLUSION

Flavonoids from the seeds of P. corylifolia L. could alleviate atherosclerosis by preventing endothelium injury, attenuating vascular inflammation, and alleviating the formation of foam cells.

Synergistic Neuroprotective Effects of a Natural Product Mixture against AD Hallmarks and Cognitive Decline in Caenorhabditis elegans and an SAMP8 Mice Model

The study of different natural products can provide a wealth of bioactive compounds, and more interestingly, their combination can exert a new strategy for several neurodegenerative diseases with major public health importance, such as Alzheimer’s disease (AD). Here, we investigated the synergistic neuroprotective effects of a mixed extract composed of docosahexaenoic acid, Ginkgo biloba, D-pinitol, and ursolic acid in several transgenic Caenorhabditis elegans (C. elegans) and a senescence-accelerated prone mice 8 (SAMP8) model. First, we found a significantly higher survival percentage in the C. elegans group treated with the natural product mixture compared to the single extract-treated groups. Likewise, we found a significantly increased lifespan in group of C. elegans treated with the natural product mixture compared to the other groups, suggesting synergistic effects. Remarkably, we determined a significant reduction in Aβ plaque accumulation in the group of C. elegans treated with the natural product mixture compared to the other groups, confirming synergy. Finally, we demonstrated better cognitive performance in the group treated with the natural product mixture in both AD models (neuronal Aβ C. elegans strain CL2355 and the SAMP8 mice model), confirming the molecular results and unraveling the synergist effects of this combination. Therefore, our results proved the potential of this new natural product mixture for AD therapeutic strategies.

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.

A mechanistic insight of phytoestrogens used for Rheumatoid arthritis: An evidence-based review

Assessment of the potential therapeutic benefits offered by naturally occurring phytoestrogens necessitate inspection of their potency and sites of action in impeding the chronic, systemic, autoimmune, joint destructing disorder Rheumatoid arthritis (RA). Possessing structural and functional similarity with human estrogen, phytoestrogen promisingly replaces the use of hormone therapy in eradicating RA symptoms with their anti-inflammatory, anti-oxidative, anti-proliferative, anti-angiogenesis, immunomodulatory, joint protection properties abolishing the harmful side effects of synthetic drugs. Scientific evidences revealed that use of phytoestrogens from different chemical categories including flavonoids, alkaloids, stilbenoids derived from different plant species manifest beneficial effects on RA through various cellular mechanisms including suppression of pro-inflammatory cytokines in particular tumor necrosis factor (TNF-α), interleukin(IL-6) and nuclear factor kappa B (NF-κB) and destructive metalloproteinases, inhibition of oxidative stress, suppressing inflammatory signalling pathways, attenuating osteoclastogenesis ameliorating cartilage degradation and bone erosion. This review summarizes the evidences of different phytoestrogen treatment and their pharmacological mechanisms in both in vitro and in vivo studies along with discussing clinical evaluations in RA patients showing phytoestrogen as a promising agent for RA therapy. Further investigations and more clinical trials are mandatory to clarify the utility of these plant derived compounds in RA prevention and in managing oestrogen deficient diseases in patients.

Total flavonoids of alleviates cognitive impairment in mice

Cognitive impairment (CI) refers to dysfunctional cognition, which encompasses a spectrum of disorders, ranging from mild cognitive impairment to dementia. Any factor that results in cortical damage may cause CI. Total flavonoids of Selaginella pulvinata (TFSP), have shown promising antioxidant and protective effects in animal models. In the present study, mice were intraperitoneally treated with scopolamine, sodium nitrite or 45% ethanol to induce memory impairment, and the effects were assessed using a step-down test. After performing the behavioural test, hippocampal sections were collected for anatomical analysis, and the brain and serum levels of memory-related molecules were evaluated. The results showed that TFSP improved memory in a mouse model of CI significantly. Serum data were consistent with the behavioural results: TFSP increased blood acetylcholine levels through modulation of the acetylcholinesterase and choline acetyltransferase levels. It also ameliorated oxidative stress in neurons, increasing superoxide dismutase, glutathione peroxidase and inhibiting nitric oxide synthase levels in the brain. These results suggest that TFSP may exhibit potential as a clinical treatment for neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease, and senile dementia.

Allium cepa fraction attenuates STZ-induced dementia via cholinesterase inhibition and amelioration of oxidative stress in mice

Background An earlier study demonstrated significant antioxidant and anticholinesterase activities of hydromethanol extract (HME) of Allium cepa. The aim of the study was to investigate the component responsible for these activities followed by an in vivo study. Methods In vitro antioxidant and anticholinesterase activities of standardized ethylacetate fraction (EAF) of HME were assessed. Bioactivity-guided fractionation showed that, as compared with its subfractions, EAF had most significant activity in 2,2-diphenyl-1-picrylhydrazyl and Ellman assays. Thus, EAF was further examined using a streptozotocin (STZ)-induced model of Alzheimer's disease in mice. STZ was injected intracerebroventricularly on days 1 and 3 (3 mg/kg) in mice. EAF was thereafter administered (42, 84, and 168 mg/kg b.w./day p.o.) from days 9 to 22. The Morris water maze test was used to evaluate learning and memory in mice. Acetylcholinesterase (AChE) activity and oxidative stress markers were assessed in the brain homogenates of mice. Additionally, histopathological studies were performed to observe effects in the brain at the cellular level. EAF was standardized based on quercetin and quercetin 4'-O-glucoside content using a validated thin layer chromatography densitometric method. Results STZ produced significant (p < 0.05) memory impairment along with oxidative stress and a cholinergic deficit in mice. EAF treatment ameliorated STZ-induced behavioral deficits and biochemical alterations in mice in a significant and dose-dependent manner. Conclusions Our results show that EAF is efficacious in improving memory and learning via AChE inhibition and antioxidant activity in the mice brain. Thus, AC could be explored further to find out a lead candidate for Alzheimer's disease.

Pueraria lobata and Daidzein Reduce Cytotoxicity by Enhancing Ubiquitin-Proteasome System Function in SCA3-iPSC-Derived Neurons

Spinocerebellar ataxia type 3 (SCA3) is an autosomal dominant neurodegenerative disorder caused by a CAG repeat expansion within the ATXN3/MJD1 gene. The expanded CAG repeats encode a polyglutamine (polyQ) tract at the C-terminus of the ATXN3 protein. ATXN3 containing expanded polyQ forms aggregates, leading to subsequent cellular dysfunctions including an impaired ubiquitin-proteasome system (UPS). To investigate the pathogenesis of SCA3 and develop potential therapeutic strategies, we established induced pluripotent stem cell (iPSC) lines from SCA3 patients (SCA3-iPSC). Neurons derived from SCA3-iPSCs formed aggregates that are positive to the polyQ marker 1C2. Treatment with the proteasome inhibitor, MG132, on SCA3-iPSC-derived neurons downregulated proteasome activity, increased production of radical oxygen species (ROS), and upregulated the cleaved caspase 3 level and caspase 3 activity. This increased susceptibility to the proteasome inhibitor can be rescued by a Chinese herbal medicine (CHM) extract NH037 (from Pueraria lobata) and its constituent daidzein via upregulating proteasome activity and reducing protein ubiquitination, oxidative stress, cleaved caspase 3 level, and caspase 3 activity. Our results successfully recapitulate the key phenotypes of the neurons derived from SCA3 patients, as well as indicate the potential of NH037 and daidzein in the treatment for SCA3 patients.

Targeting Ubiquitin Proteasome Pathway with Traditional Chinese Medicine for Treatment of Spinocerebellar Ataxia Type 3

Nine autosomal dominant spinocerebellar ataxias (SCAs) are caused by an abnormal expansion of CAG trinucleotide repeats that encodes a polyglutamine (polyQ) tract within different genes. Accumulation of aggregated mutant proteins is a common feature of polyQ diseases, leading to progressive neuronal dysfunction and degeneration. SCA type 3 (SCA3), the most common form of SCA worldwide, is characterized by a CAG triplet expansion in chromosome 14q32.1 ATXN3 gene. As accumulation of the mutated polyQ protein is a possible initial event in the pathogenic cascade, clearance of aggregated protein by ubiquitin proteasome system (UPS) has been proposed to inhibit downstream detrimental events and suppress neuronal cell death. In this study, Chinese herbal medicine (CHM) extracts were studied for their proteasome-activating, polyQ aggregation-inhibitory and neuroprotective effects in GFP^u and ATXN3/Q 75 -GFP 293/SH-SY5Y cells. Among the 14 tested extracts, 8 displayed increased proteasome activity, which was confirmed by 20S proteasome activity assay and analysis of ubiquitinated and fused GFP proteins in GFP^u cells. All the eight extracts displayed good aggregation-inhibitory potential when tested in ATXN3/Q 75 -GFP 293 cells. Among them, neuroprotective effects of five selected extracts were shown by analyses of polyQ aggregation, neurite outgrowth, caspase 3 and proteasome activities, and ATXN3-GFP, ubiquitin, BCL2 and BAX protein levels in neuronal differentiated ATXN3/Q 75 -GFP SH-SY5Y cells. Finally, enhanced proteasome function, anti-oxidative activity and neuroprotection of catalpol, puerarin and daidzein (active constituents of Rehmannia glutinosa and Pueraria lobata) were demonstrated in GFP^u and/or ATXN3/Q 75 -GFP 293/SH-SY5Y cells. This study may have therapeutic implication in polyQ-mediated disorders.

Computer-Aided Multi-Target Management of Emergent Alzheimer's Disease

Alzheimer's disease (AD) represents an enormous global health burden in terms of human suffering and economic cost. AD management requires a shift from the prevailing paradigm targeting pathogenesis to design and develop effective drugs with adequate success in clinical trials. Therefore, it is of interest to report a review on amyloid beta (Aβ) effects and other multi-targets including cholinesterase, NFTs, tau protein and TNF associated with brain cell death to be neuro-protective from AD. It should be noted that these molecules have been generated either by target-based or phenotypic methods. Hence, the use of recent advancements in nanomedicine and other natural compounds screening tools as a feasible alternative for circumventing specific liabilities is realized. We review recent developments in the design and identification of neuro-degenerative compounds against AD generated using current advancements in computational multi-target modeling algorithms reflected by theragnosis (combination of diagnostic tests and therapy) concern.

Role of Plant-Derived Flavonoids and Their Mechanism in Attenuation of Alzheimer's and Parkinson's Diseases: An Update of Recent Data

Neurodegeneration is a progressive loss of neuronal cells in certain regions of the brain. Most of the neurodegenerative disorders (NDDs) share the communal characteristic such as damage or reduction of various cell types typically including astrocytes and microglial activity. Several compounds are being trialed to treat NDDs but they possess solitary symptomatic advantages along with copious side effects. The finding of more enthralling and captivating compounds to suspend and standstill the pathology of NDDs will be considered as a hallmark of present times. Phytochemicals possess the potential to alternate the synthetic line of therapy against NDDs. The present review explores the potential efficacy of plant-derived flavonoids against most common NDDs including Alzheimer's disease (AD) and Parkinson's disease (PD). Flavonoids are biologically active phytochemicals which possess potential pharmacological effects, including antiviral, anti-allergic, antiplatelet, anti-inflammatory, anti-tumor, anti-apoptotic and anti-oxidant effects and are able to attenuate the pathology of various NDDs through down-regulating the nitric oxide (NO) production, by reducing the tumor necrosis factor-α (TNF-α), by reducing the excitotoxicity of superoxide as well as acting as tyrosine kinase (TK) and monoamine oxidase (MAO) inhibiting enzyme.

Rapid Screening and Identification of Daidzein Metabolites in Rats Based on UHPLC-LTQ-Orbitrap Mass Spectrometry Coupled with Data-Mining Technologies

Daidzein, the main bioactive soy isoflavone in Nature, has been found to possess many biological functions. It has been investigated in particular as a phytoestrogen owing to the similarity of its structure with that of the human hormone estrogen. Due to the lack of comprehensive studies on daidzein metabolism, further research is still required to clarify its in vivo metabolic fate and intermediate processes. In this study, an efficient strategy was established using UHPLC-LTQ-Orbitrap mass spectrometry to profile the metabolism of daidzein in rats. Meanwhile, multiple data-mining methods including high-resolution extracted ion chromatogram (HREIC), multiple mass defect filtering (MMDF), neutral loss fragment (NLF), and diagnostic product ion (DPI) were utilized to investigate daidzein metabolites from the HR-ESI-MS¹ to ESI-MSⁿ stage in both positive and negative ion modes. Consequently, 59 metabolites, including prototype compounds, were positively or tentatively elucidated based on reference standards, accurate mass measurements, mass fragmentation behaviors, chromatographic retention times, and corresponding calculated ClogP values. As a result, dehydration, hydrogenation, methylation, dimethylation, glucuronidation, glucosylation, sulfonation, ring-cleavage, and their composite reactions were ascertained to interpret its in vivo biotransformation. Overall, our results not only revealed the potential pharmacodynamics forms of daidzein, but also aid in establishing a practical strategy for rapid screening and identifying metabolites of natural compounds.

Baicalein as a potent neuroprotective agent: A review

In recent times, neurodegenerative diseases are the most challenging global health problems. Neuronal cell death or damage is a key factor for many neurodegenerative disorders. Therefore, there has been a growing interest in the development of effective neuroprotective agents, especially from natural sources. In particular, phytochemicals have shown high efficacy with low side effects in various in vitro and in vivo studies. In the various phytoconstituents, flavonoids are important bioactive products and mainly found in various vegetables and fruits. Among them, baicalein is one of the important flavones, which is mainly found in the root of Scutellaria baicalensis Georgi. A number of studies have reported that baicalein has potent neuroprotective properties under in vitro as well as in vivo systems. Hence, the purpose of this paper is to provide a review of the existing literature in connection with the neuroprotective effects of baicalein and its molecular mechanisms of action. The current review highlights could be useful to identify novel therapeutic agents in relation to the treatment of neurotoxicity-mediated diseases.

A benign alternative process for efficient separation of pure commercially important flavonoid nutraceuticals from edible plants

The present study signifies the development of a unique, optimized procedure for both selective determination and separation of different flavonoid nutraceuticals from edible plants. Totally ten different flavonoids were determined (HPLC-DAD) and isolated from five different plants using the developed process with a remarkable purity of 91-98% and recovery of 88-95%. Box-Behnken experimental design model yielded a optimized amount of 40.36 mg/g of AI extract (Pinostrobin) and 28.95 mg/g of AI extract (Baicalein) with a high correlation coefficient (0.98-0.99), indicating a good fit between the second order regression model and the experimental observations. The final purity of compounds through optimized process is 97.1% (Pinostrobin) and 93.5% (Baicalein) respectively. The optimized yields depicted a total recovery of 92% for pinostrobin, and 89% for Baicalein respectively. Thus, the developed process worked as a potential alternative which when statistically optimized results in a remarkable recovery of flavonoids from various plants. Being an environmentally friendly protocol the process could be useful in industrial separation of commercially important flavonoids widely applied in food industry.

Xanthone and Flavone Derivatives as Dual Agents with Acetylcholinesterase Inhibition and Antioxidant Activity as Potential Anti-Alzheimer Agents

Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder that is associated with the elderly. The current therapy that is used to treat AD is based mainly on the administration of acetylcholinesterase (AChE) inhibitors. Due to their low efficacy there is a considerable need for other therapeutic strategies. Considering that the malfunctions of different, but interconnected, biochemical complex pathways play an important role in the pathogenesis of this disease, a promising therapy may consist in administration of drugs that act on more than a target on biochemical scenery of AD. In this work, the synthesis and evaluation of xanthone and flavone derivatives as antioxidants with AChE inhibitory activity were accomplished. Among the obtained compounds, Mannich bases3and14showed capacity to inhibit AChE and antioxidant property, exerting dual activity. Moreover, for the most promising AChE inhibitors, docking studies on the target have been performed aiming to predict the binding mechanism. The results presented here may help to identify new xanthone and flavone derivatives as dual anti-Alzheimer agents with AChE inhibitory and antioxidant activities.

Natural products against Alzheimer's disease: Pharmaco-therapeutics and biotechnological interventions

Alzheimer's disease (AD) is a severe, chronic and progressive neurodegenerative disease associated with memory and cognition impairment ultimately leading to death. It is the commonest reason of dementia in elderly populations mostly affecting beyond the age of 65. The pathogenesis is indicated by accumulation of the amyloid-beta (Aβ) plaques and neurofibrillary tangles (NFT) in brain tissues and hyperphosphorylation of tau protein in neurons. The main cause is considered to be the formation of reactive oxygen species (ROS) due to oxidative stress. The current treatment provides only symptomatic relief by offering temporary palliative therapy which declines the rate of cognitive impairment associated with AD. Inhibition of the enzyme acetylcholinesterase (AChE) is considered as one of the major therapeutic strategies offering only symptomatic relief and moderate disease-modifying effect. Other non-cholinergic therapeutic approaches include antioxidant and vitamin therapy, stem cell therapy, hormonal therapy, use of antihypertensive or lipid-lowering medications and selective phosphodiesterase (PDE) inhibitors, inhibition of β-secretase and γ-secretase and Aβ aggregation, inhibition of tau hyperphosphorylation and intracellular NFT, use of nonsteroidal anti-inflammatory drugs (NSAIDs), transition metal chelators, insulin resistance drugs, etanercept, brain-derived neurotrophic factor (BDNF) etc. Medicinal plants have been reported for possible anti-AD activity in a number of preclinical and clinical trials. Ethnobotany, being popular in China and in the Far East and possibly less emphasized in Europe, plays a substantial role in the discovery of anti-AD agents from botanicals. Chinese Material Medica (CMM) involving Chinese medicinal plants has been used traditionally in China in the treatment of AD. Ayurveda has already provided numerous lead compounds in drug discovery and many of these are also undergoing clinical investigations. A number of medicinal plants either in their crude forms or as isolated compounds have exhibited to reduce the pathological features associated with AD. In this present review, an attempt has been made to elucidate the molecular mode of action of various plant extracts, phytochemicals and traditional herbal formulations investigated against AD as reported in various preclinical and clinical tests. Herbal synergism often found in polyherbal formulations were found effective to combat disease heterogeneity as found in complex pathogenesis of AD. Finally a note has been added to describe biotechnological improvement, genetic and genomic resources and mathematical and statistical techniques for empirical model building associated with anti-AD plant secondary metabolites and their source botanicals.

Protective effects of fractions from Artemisia biennis hydro-ethanolic extract against doxorubicin-induced oxidative stress and apoptosis in PC12 cells

OBJECTIVES

This study was designed to indicate whether different fractions from Artemisia biennis hydroethanolic extract could provide cytoprotection against oxidative stress and apoptosis induced by doxorubicin (DOX) in rat pheochromocytoma cell line (PC12).

MATERIAL AND METHODS

Cell viability was determined by MTT assay. Also, activation of caspase-3 and superoxide dismutase were evaluated by spectrophotometry. Detection of reactive oxygen species (ROS) and measurement of mitochondrial membrane potential (MMP) were performed by flowcytometry.

RESULTS

Treatment of PC12 cells with DOX reduced viability dose dependently. For evaluation of the effect of fractions (A-G) on DOX-induced cytotoxicity, PC12 cells were pretreated for 24 hr with the A. biennis fractions and then cells were treated with DOX. The fractions C and D increased PC12 cells viability significantly compared to DOX treated cells. Moreover, pretreatment with fractions C and D for 24 hr attenuated DOX-mediated apoptosis and the anti-apoptotic action of A. biennis fractions was partially dependent on inhibition of caspase 3 activity and also increasing the mitochondrial membrane potential (MMP). Selected A. biennis fractions also suppressed the generation of ROS and increased superoxide dismutase (SOD) activity.

CONCLUSION

Taken together our observation indicated that subtoxic concentration of aforementioned fractions of A. biennis hydroetanolic extract has protective effect against apoptosis induced by DOX in PC12 cell. The results highlighted that fractions C and D may exert cytoprotective effects through their antioxidant actions.

Estrogenic endocrine disruptors: Molecular mechanisms of action

A comprehensive summary of more than 450 estrogenic chemicals including estrogenic endocrine disruptors is provided here to understand the complex and profound impact of estrogen action. First, estrogenic chemicals are categorized by structure as well as their applications, usage and effects. Second, estrogenic signaling is examined by the molecular mechanism based on the receptors, signaling pathways, crosstalk/bypassing and autocrine/paracrine/homeostatic networks involved in the signaling. Third, evaluation of estrogen action is discussed by focusing on the technologies and protocols of the assays for assessing estrogenicity. Understanding the molecular mechanisms of estrogen action is important to assess the action of endocrine disruptors and will be used for risk management based on pathway-based toxicity testing.

Optimizing the compatibility of paired-herb in an ancient Chinese herbal decoction Kai-Xin-San in activating neurofilament expression in cultured PC12 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Kai-Xin-San (KXS), a well-known traditional Chinese herbal decoction, has been widely used to treat mental depression and memory loss in China. It has a combination of four herbs: Ginseng Radix et Rhizoma (GR; root and rhizome of Panax ginseng C. A. Mey.), Polygalae Radix (PR; root of Polygala tenuifolia Wild.), Acori Tatarinowii Rhizoma (ATR; rhizome of Acorus tatarinowii Schott), and Poria (PO; sclerotium of Poriacocos (Schw.) Wolf), from which a pairing of two herbs was considered as paired-herb, such as the pairing of GR-PR and ATR-PO. The depression-induced neural cell loss is one of the major pathogenesis in depression. Here, an optimized KXS by changing the ratio of paired-herbs in KXS was demonstrated aiming at promoting neural cell differentiation.

MATERIALS AND METHODS

Quantitative assessment of chemical markers in each herbal extract was determined by LC-MS. Promoters of neurofilaments, NF68 and NF200, linked with luciferase reporter gene (pNF68-Luc and pNF200-Luc) were applied in cultured pheochromocytoma (PC12) cells to study the transcriptional activation of each herbal extract. The effect of GR-PR and ATR-PO in improving NF promoter activity was analyzed by Compusyn software. The activation of PKA was indicated.

RESULTS

In PC12 cells, an optimized KXS named KXS1:5 having 1:5 of GR-PR:ATR-PO had greater capability in promoting the expression of neurofilament. The synergistic effect of GR-PR and ATR-PO on the improved efficiency was further determined. Moreover, the treatment of H89, a PKA inhibitor, significantly inhibited the induced NF promoter activity.

CONCLUSION

These results indicated an optimized KXS by optimizing the compatibility of paired-herb and this compatibility was proven to exert synergistic effect. Moreover, the underlying mechanism was mediated by a PKA signaling pathway.

Therapeutic approaches against common structural features of toxic oligomers shared by multiple amyloidogenic proteins

Impaired proteostasis is one of the main features of all amyloid diseases, which are associated with the formation of insoluble aggregates from amyloidogenic proteins. The aggregation process can be caused by overproduction or poor clearance of these proteins. However, numerous reports suggest that amyloid oligomers are the most toxic species, rather than insoluble fibrillar material, in Alzheimer's, Parkinson's, and Prion diseases, among others. Although the exact protein that aggregates varies between amyloid disorders, they all share common structural features that can be used as therapeutic targets. In this review, we focus on therapeutic approaches against shared features of toxic oligomeric structures and future directions.