The diarylheptanoid (+)-aR,11S-myricanol and two flavones from bayberry (Myrica cerifera) destabilize the microtubule-associated protein tau

Unveiling myricetin's pharmacological potency: A comprehensive exploration of the molecular pathways with special focus on PI3K/AKT and Nrf2 signaling

Myricetin can be found in the traditional Chinese medicinal plant, Myrica rubra. Myricetin is a flavonoid that is present in many vegetables, fruits, and plants and is considered to have strong antioxidant properties as well as a wide range of therapeutic applications. Growing interest has been piqued by its classification as a polyphenolic molecule because of its potential therapeutic benefits in both the prevention and management of numerous medical conditions. To clarify myricetin's traditional medical uses, modern research has investigated various pharmacological effects such as antioxidant, anticancer, anti-inflammation, antiviral, antidiabetic, immunomodulation, and antineurodegenerative effects. Myricetin shows promise as a nutritional flavonol that could be beneficial in the prevention and mitigation of prevalent health conditions like diabetes, cognitive decline, and various types of cancer in humans. The findings included in this study indicate that myricetin has a great deal of promise for application in the formulation of medicinal products and nutritional supplements since it affects several enzyme activities and alters inflammatory markers. However, comprehensive preclinical studies and research studies are necessary to lay the groundwork for assessing myricetin's possible effectiveness in treating these long-term ailments. This review summarizes both in vivo and in vitro studies investigating myricetin's possible interactions through the nuclear factor-E2-related factor 2 (Nrf2) as well as PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B) signaling pathways in an attempt to clarify the compound's possible clinical applicability across a range of disorders.

Myricanol attenuates sepsis-induced inflammatory responses by nuclear factor erythroid 2-related factor 2 signaling and nuclear factor kappa B/mitogen-activated protein kinase pathway via upregulating Sirtuin 1

Sepsis, a life-threatening condition characterized by dysregulated immune responses, remains a significant clinical challenge. Myricanol, a natural compound, plays a variety of roles in regulating lipid metabolism, anti-cancer, anti-neurodegeneration, and it could act as an Sirtuin 1 (SIRT1) activator. This study aimed to explore the therapeutic potential and underlying mechanism of myricanol in the lipopolysaccharide (LPS)-induced sepsis model. In vivo studies revealed that myricanol administration significantly improved the survival rate of LPS-treated mice, effectively mitigating LPS-induced inflammatory responses in lung tissue. Furthermore, in vitro studies demonstrated that myricanol treatment inhibited the expression of pro-inflammatory cytokines, attenuated signal pathway activation, and reduced oxidative stress in macrophages. In addition, we demonstrated that myricanol selectively enhances SIRT1 activation in LPS-stimulated macrophages, and all of the protective effect of myricanol were reversed through SIRT1 silencing. Remarkably, the beneficial effects of myricanol against LPS-induced sepsis were abolished in SIRT1 myeloid-specific knockout mice, underpinning the critical role of SIRT1 in mediating myricanol's therapeutic efficacy. In summary, this study provides significant evidence that myricanol acts as a potent SIRT1 activator, targeting inflammatory signal pathways and oxidative stress to suppress excessive inflammatory responses. Our findings highlight the potential of myricanol as a novel therapeutic agent for the treatment of LPS-induced sepsis.

Myricetin Attenuates Ethylene Glycol-Induced Nephrolithiasis in Rats via Mitigating Oxidative Stress and Inflammatory Markers

Urolithiasis or nephrolithiasis is a condition of kidney stone formation and is considered a painful disease of the urinary tract system. In this work, we planned to discover the therapeutic roles of myricetin on the ethylene glycol (EG)-induced nephrolithiasis in rats. The experimental rats were treated with 0.75% of EG through drinking water for 4 weeks to initiate the nephrolithiasis and subsequently treated with 25 and 50 mg/kg of myricetin. The body weight and urine volume were measured regularly. After the sacrification of rats, the samples were collected, and serum and urinary biomarkers such as creatinine, urea, Ca2 + ion, and BUN, OPN, oxalate, and citrate levels were determined using assay kits. These biomarkers, the MDA level and CAT, SOD, and GPx activities, were assessed in the kidney tissue homogenates. The IL-6, IL-1β, and TNF-α levels were also quantified using respective kits. The histopathological analysis was done on the kidney tissues. Myricetin treatment did not show major changes in the body weight and kidney weight in the EG-induced rats. The treatment with 25 and 50 mg/kg of myricetin considerably reduced the urea, creatinine, BUN, Ca2 + ion, and oxalate and increased the citrate content in serum and urine samples of EG-induced rats. Further, myricetin depleted the inflammatory cytokines and MDA levels and elevated the CAT, SOD, and GPx activities in the renal tissues. The activities of ALT, AST, ALP, GGT, and LDH were also reduced by the myricetin. Furthermore, the myricetin upheld the histoarchitecture of the kidneys. The outcomes of this investigation propose that myricetin is effective in EG-induced urolithiasis probably because of its antioxidant, anti-inflammatory, and renoprotective activities. In addition, further studies are still required to verify the precise therapeutic mechanism of myricetin.

Anti-amyloid potential of some phytochemicals against Aβ-peptide and α-synuclein, tau, prion, and Huntingtin protein

Some molecules self-assemble to create complex structures through molecular self-assembly. Hydrogel preparation, tissue repair, and therapeutic drug delivery are a few applications of molecular self-assembly. However, the self-assembly of amino acids, peptides, and proteins forms amyloid fibrils, resulting in various disorders, most notably neurodegenerative ailments. Examples include the self-assembly of phenylalanine, which causes phenylketonuria; Aβ, which causes Alzheimer's disease; the tau protein, which causes both Alzheimer's and Parkinson's diseases; and α-synuclein, which causes Parkinson's illness. This review provides information related to phytochemicals of great significance that can prevent the formation of, or destabilize, amino acid, peptide, and protein self-assemblies.

Binding mechanism and biological effects of flavone DYRK1A inhibitors for the design of new antidiabetics

The selective inhibition of kinases from the diabetic kinome is known to promote the regeneration of beta cells and provide an opportunity for the curative treatment of diabetes. The effect can be achieved by carefully tailoring the selectivity of inhibitor toward a particular kinase, especially DYRK1A, previously associated with Down syndrome and Alzheimer's disease. Recently DYRK1A inhibition has been shown to promote both insulin secretion and beta cells proliferation. Here, we show that commonly available flavones are effective inhibitors of DYRK1A. The observed biochemical activity of flavone compounds is confirmed by crystal structures solved at 2.06 Å and 2.32 Å resolution, deciphering the way inhibitors bind in the ATP-binding pocket of the kinase, which is driven by the arrangement of hydroxyl moieties. We also demonstrate antidiabetic properties of these biomolecules and prove that they could be further improved by therapy combined with TGF-β inhibitors. Our data will allow future structure-based optimization of the presented scaffolds toward potent, bioavailable and selective anti-diabetic drugs.

Myricetin: A Significant Emphasis on Its Anticancer Potential via the Modulation of Inflammation and Signal Transduction Pathways

Cancer is a major public health concern worldwide and main burden of the healthcare system. Regrettably, most of the currently used cancer treatment approaches such as targeted therapy, chemotherapy, radiotherapy and surgery usually cause adverse complications including hair loss, bone density loss, vomiting, anemia and other complications. However, to overcome these limitations, there is an urgent need to search for the alternative anticancer drugs with better efficacy as well as less adverse complications. Based on the scientific evidences, it is proven that naturally occurring antioxidants present in medicinal plants or their bioactive compounds might constitute a good therapeutic approach in diseases management including cancer. In this regard, myricetin, a polyhydroxy flavonol found in a several types of plants and its role in diseases management as anti-oxidant, anti-inflammatory and hepato-protective has been documented. Moreover, its role in cancer prevention has been noticed through modulation of angiogenesis, inflammation, cell cycle arrest and induction of apoptosis. Furthermore, myricetin plays a significant role in cancer prevention through the inhibition of inflammatory markers such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (Cox-2). Moreover, myricetin increases the chemotherapeutic potential of other anticancer drugs through modulation of cell signaling molecules activity. This review elaborates the information of myricetin role in cancer management through modulating of various cell-signaling molecules based on in vivo and in vitro studies. In addition, synergistic effect with currently used anticancer drugs and approaches to improve bioavailability are described. The evidences collected in this review will help different researchers to comprehend the information about its safety aspects, effective dose for different cancers and implication in clinical trials. Moreover, different challenges need to be focused on engineering different nanoformulations of myricetin to overcome the poor bioavailability, loading capacity, targeted delivery and premature release of this compound. Furthermore, some more derivatives of myricetin need to be synthesized to check their anticancer potential.

Affinity-based protein profiling-driven discovery of myricanol as a Nampt activator

Herein, we synthesized an affinity-based probe of myricanol (pMY) with a photo-affinity cross-linker to initiate a bioconjugation reaction, which was applied for target identification in live C2C12 myotubes. Pull-down of biotinylated pMY coupled with mass spectroscopy and Western blotting revealed that pMY can bind with nicotinamide phosphoribosyltransferase (Nampt), a rate-limiting enzyme in the nicotinamide adenine dinucleotide salvage pathway. Cellular thermal shift assay, drug affinity responsive target stability assay and recombinant protein labeling further validated the direct interaction between myricanol and Nampt. Myricanol did not affect the protein expression of Nampt, but enhanced its activity. Knock-down of Nampt totally abolished the promoting effect of myricanol on insulin-stimulated glucose uptake in C2C12 myotubes. Taken together, myricanol sensitizes insulin action in myotubes through binding with and activating Nampt.

Myrica esculenta Buch.-Ham. (ex D. Don): A Review on its Phytochemistry, Pharmacology and Nutritional Potential

Myrica esculenta is an important ethnomedicinal plant used in the traditional system of medicine and as an important nutraceutical. Several studies on the plant justify its use in alternative systems of medicine and establish a scientific rationale for its possible therapeutic application. The plant contains a range of biologically active classes of compounds, particularly diarylheptanoids, flavonoids, terpenes, tannins, and glycosides. The nutraceutical potential of the plant can be particularly attributed to its fruit, and several studies have demonstrated the presence of carbohydrates, proteins, fats, fiber content, and minerals like sodium, potassium, calcium, manganese, iron, copper, and zinc, in it. The current review aims to provide complete insight into the phytochemistry, pharmacological potential, and nutritional potential of the plant, which would not only serve as a comprehensive source of information but also will highlight the scope of isolation and evaluation of these molecules for various disease conditions.

Dimethylmyricacene: An In Vitro and In Silico Study of a Semisynthetic Non-Camptothecin Derivative Compound, Targeting Human DNA Topoisomerase 1B

Human topoisomerase 1B regulates the topological state of supercoiled DNA enabling all fundamental cell processes. This enzyme, which is the unique molecular target of the natural anticancer compound camptothecin, acts by nicking one DNA strand and forming a transient protein–DNA covalent complex. The interaction of human topoisomerase 1B and dimethylmyricacene, a compound prepared semisynthetically from myricanol extracted from Myrica cerifera root bark, was investigated using enzymatic activity assays and molecular docking procedures. Dimethylmyricacene was shown to inhibit both the cleavage and the religation steps of the enzymatic reaction, and cell viability of A-253, FaDu, MCF-7, HeLa and HCT-116 tumor cell lines.

Therapeutic roles of plants for 15 hypothesised causal bases of Alzheimer's disease

Alzheimer's disease (AD) is progressive and ultimately fatal, with current drugs failing to reverse and cure it. This study aimed to find plant species which may provide therapeutic bioactivities targeted to causal agents proposed to be driving AD. A novel toolkit methodology was employed, whereby clinical symptoms were translated into categories recognized in ethnomedicine. These categories were applied to find plant species with therapeutic effects, mined from ethnomedical surveys. Survey locations were mapped to assess how this data is at risk. Bioactivities were found of therapeutic relevance to 15 hypothesised causal bases for AD. 107 species with an ethnological report of memory improvement demonstrated therapeutic activity for all these 15 causal bases. The majority of the surveys were found to reside within biodiversity hotspots (centres of high biodiversity under threat), with loss of traditional knowledge the most common threat. Our findings suggest that the documented plants provide a large resource of AD therapeutic potential. In demonstrating bioactivities targeted to these causal bases, such plants may have the capacity to reduce or reverse AD, with promise as drug leads to target multiple AD hallmarks. However, there is a need to preserve ethnomedical knowledge, and the habitats on which this knowledge depends.

Suitability of Banana and Plantain Fruits in Modulating Neurodegenerative Diseases: Implicating the In Vitro and In Vivo Evidence from Neuroactive Narratives of Constituent Biomolecules

Active principles in plant-based foods, especially staple fruits, such as bananas and plantains, possess inter-related anti-inflammatory, anti-apoptotic, antioxidative, and neuromodulatory activities. Neurodegenerative diseases affect the functionality of the central and peripheral nervous system, with attendant cognitive deficits being hallmarks of these conditions. The dietary constitution of a wide range of bioactive compounds identified in this review further iterates the significance of the banana and plantain in compromising, halting, or preventing the pathological mechanisms of neurological disorders. The neuroprotective mechanisms of these biomolecules have been identified by using protein expression regulation and specific gene/pathway targeting, such as the nuclear and tumor necrosis factors, extracellular signal-regulated and mitogen-activated protein kinases, activator protein-1, and the glial fibrillary acidic protein. This review establishes the potential double-edged neuro-pharmacological fingerprints of banana and plantain fruits in their traditionally consumed pulp and less utilized peel component for human nutrition.

Myricetin (3,3',4',5,5',7-Hexahydroxyflavone) Prevents 5-Fluorouracil-Induced Cardiotoxicity

5-Fluorouracil (5-FU) is a strong anti-cancer drug used to manage numerous cancers. Cardiotoxicity, renal toxicity, and liver toxicity are some of the adverse effects which confine its clinical use to some extent. 5-FU-induced organ injuries are associated with redox imbalance, inflammation, and damage to heart functioning, particularly in the present study. Myricetin is an abundant flavonoid, commonly extracted from berries and herbs having anti-oxidative and anti-cancer activities. We planned the current work to explore the beneficial effects of myricetin against 5-FU-induced cardiac injury in Wistar rats through a biochemical and histological approach. Prophylactic myricetin treatment at two doses (25 and 50 mg/kg) was given to rats orally for 21 days against cardiac injury induced by a single injection of 5-FU (150 mg/kg b.wt.) given on the 20th day intraperitoneally. The 5-FU injection induced oxidative stress, inflammation, and extensive cardiac damage. Nevertheless, myricetin alleviated markers of inflammation, apoptosis, cardiac toxicity, oxidative stress, and upregulated anti-oxidative machinery. The histology of heart further supports our biochemical findings mitigated by the prophylactic treatment of myricetin. Henceforth, myricetin mitigates 5-FU-induced cardiac damage by modulating oxidative stress, inflammation, and cardiac-specific markers, as found in the present study.

Myricetin Disturbs the Cell Wall Integrity and Increases the Membrane Permeability of Candida albicans

The fungal cell wall and membrane are the principal targets of antifungals. Herein, we report that myricetin exerts antifungal activity against Candida albicans by damaging the cell wall integrity and notably enhancing the membrane permeability. In the presence of sorbitol, an osmotic protectant, the minimum inhibitory concentration (MIC) of myricetin against C. albicans increased from 20 to 40 and 80 μg/ml in 24 and 72 h, respectively, demonstrating that myricetin disturbs the cell wall integrity of C. albicans. Fluorescence microscopic images showed the presence of propidium iodidestained C. albicans cells, indicating the myricetin-induced initial damage of the cell membrane. The effects of myricetin on the membrane permeability of C. albicans cells were assessed using crystal violet-uptake and intracellular material-leakage assays. The percentage uptakes of crystal violet for myricetin-treated C. albicans cells at 1×, 2×, and 4× the MIC of myricetin were 36.5, 60.6, and 79.4%, respectively, while those for DMSO-treated C. albicans cells were 28.2, 28.9, and 29.7%, respectively. Additionally, myricetin-treated C. albicans cells showed notable DNA and protein leakage, compared with the DMSO-treated controls. Furthermore, treatment of C. albicans cells with 1× the MIC of myricetin showed a 17.2 and 28.0% reduction in the binding of the lipophilic probes diphenylhexatriene and Nile red, respectively, indicating that myricetin alters the lipid components or order in the C. albicans cell membrane, leading to increased membrane permeability. Therefore, these data will provide insights into the pharmacological worth of myricetin as a prospective antifungal for treating C. albicans infections.

Antioxidant Potential and Inhibition of Mitochondrial Permeability Transition Pore by Myricetin Reduces Aluminium Phosphide-Induced Cytotoxicity and Mitochondrial Impairments

Oxidative stress and mitochondrial dysfunction are involved in the mechanisms of cardiac toxicity induced by aluminum phosphide (AlP). AlP-induced cardiotoxicity leads to cardiomyocyte death, cardiomyopathy, cardiac dysfunction, and eventually severe heart failure and death. Importantly, protecting cardiomyocytes from death resulting from AlP is vital for improving survival. It has been reported that flavonoids such as myricetin (Myr) act as modifiers of mitochondrial function and prevent mitochondrial damage resulting from many insults and subsequent cell dysfunction. In this study, the ameliorative effect of Myr, as an important antioxidant and mitochondrial protective agent, was investigated in cardiomyocytes and mitochondria isolated from rat heart against AlP-induced toxicity, oxidative stress, and mitochondrial dysfunction. Treatment of AlP (20 μg/ml) significantly increased cytotoxicity; reduced glutathione (GSH) depletion, cellular reactive oxygen species (ROS) formation, malondialdehyde (MDA) level, ATP depletion, caspase-3 activation, mitochondrial membrane potential (ΔΨm) collapse, and lysosomal dysfunction; and decreased the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in intact cardiomyocytes. Also, treatment of AlP (20 μg/ml) significantly increased mitochondrial dysfunction and swelling in isolated mitochondria. Myr (80 µM) appeared to ameliorate AlP-induced cytotoxicity in isolated cardiomyocytes; significantly lessened the AlP-stimulated intracellular ROS and MDA production and depletion of GSH; and increased the activities of SOD, CAT, and GSH-Px. Furthermore, Myr (40 and 80 µM) lowered AlP-induced lysosomal/mitochondrial dysfunction, ATP depletion, and caspase-3 activation. In the light of these findings, we concluded that Myr through antioxidant potential and inhibition of mitochondrial permeability transition (MPT) pore exerted an ameliorative role in AlP-induced toxicity in isolated cardiomyocytes and mitochondria, and it would be valuable to examine its in vivo effects.

Alzheimer's Disease and other Tauopathies: Exploring Efficacy of Medicinal Plant-Derived Compounds in Alleviating Tau-Mediated Neurodegeneration

Alzheimer's disease (AD), a major form of dementia, has been reported to affect more than 50 million people worldwide. It is characterized by the presence of amyloid-β (Aβ) plaques and hyperphosphorylated Tau-associated neurofibrillary tangles in the brain. Apart from AD, microtubule (MT)-associated protein Tau is also involved in other neurodegenerative diseases called tauopathies, including Pick's disease, frontotemporal lobar degeneration, progressive supranuclear palsy, and corticobasal degeneration. The recently unsuccessful phase III clinical trials related to Aβ-targeted therapeutic drugs indicated that alternative targets, such as Tau, should be studied to discover more effective and safer drugs. Recent drug discovery approaches to reduce AD-related Tau pathologies are primarily based on blocking Tau aggregation, inhibiting Tau phosphorylation, compensating impaired Tau function with MT-stabilizing agents, and targeting the degradation pathways in neuronal cells to degrade Tau protein aggregates. Owing to several limitations of the currently-available Tau-directed drugs, further studies are required to generate further effective and safer Tau-based disease-modifying drugs. Here, we review the studies that focused on medicinal plant-derived compounds capable of modulating the Tau protein, which is significantly elevated and hyperphosphorylated in AD and other tauopathies. We mainly considered the studies that focused on Tau protein as a therapeutic target. We reviewed several pertinent papers retrieved from PubMed and ScienceDirect using relevant keywords, with a primary focus on the Tau-targeting compounds from medicinal plants. These compounds include indolines, phenolics, flavonoids, coumarins, alkaloids, and iridoids, which have been scientifically proven to be Tau-targeting candidates for the treatment of AD.

Natural Anti-Inflammatory Compounds as Drug Candidates for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) represents chronic recurrent intestinal inflammation resulting from various factors. Crohn’s disease (CD) and ulcerative colitis (UC) have been identified as the two major types of IBD. Currently, most of the drugs for IBD used commonly in the clinic have adverse reactions, and only a few drugs present long-lasting treatment effects. Moreover, issues of drug resistance and disease recurrence are frequent and difficult to resolve. Together, these issues cause difficulties in treating patients with IBD. Therefore, the development of novel therapeutic agents for the prevention and treatment of IBD is of significance. In this context, research on natural compounds exhibiting anti-inflammatory activity could be a novel approach to developing effective therapeutic strategies for IBD. Phytochemicals such as astragalus polysaccharide (APS), quercetin, limonin, ginsenoside Rd, luteolin, kaempferol, and icariin are reported to be effective in IBD treatment. In brief, natural compounds with anti-inflammatory activities are considered important candidate drugs for IBD treatment. The present review discusses the potential of certain natural compounds and their synthetic derivatives in the prevention and treatment of IBD.

Phytochemicals with Added Value from Morella and Myrica Species

Terrestrial plants, due to their sessile nature, are highly exposed to environmental pressure and therefore need to produce very effective molecules that enable them to survive all the threats. Myrica and Morella (Myricaceae) are taxonomically close genera, which include species of trees or shrubs with edible fruits that exhibit relevant uses in traditional medicine. For instance, in Chinese or Japanese folk medicine, they are used to treat diarrhea, digestive problems, headache, burns, and skin diseases. A wide array of compounds isolated from different parts of Myrica and/or Morella species possess several biological activities, like anticancer, antidiabetic, anti-obesity, and cardio-/neuro-/hepatoprotective activities, both in vitro and in vivo, with myricanol, myricitrin, quercitrin, and betulin being the most promising. There are still many other compounds isolated from both genera whose biological activities have not been evaluated, which represents an excellent opportunity to discover new applications for those compounds and valorize Morella/Myrica species.

Myricanol 5-fluorobenzyloxy ether regulation of survivin pathway inhibits human lung adenocarcinoma A549 cells growth in vitro

Background

This study aimed to explore the growth inhibitory effect of myricanol 5-fluorobenzyloxy ether (5FEM) and its underlying mechanisms in human lung adenocarcinoma A549 cells in vitro.

Methods

5FEM was obtained by the chemical modification of myricanol with fluorobenzyloxy ether at the OH(5) position. The cytotoxicity, cell apoptosis, cell cycle, mitochondrial membrane potential (ΔΨm), scratch test, colony formation, and the expression levels of the key survivin pathway-related genes in A549 were evaluated.

Results

5FEM could significantly inhibit A549 cell growth; induce cell apoptosis; increase G0/G1 population; reduce ΔΨm; inhibit cell migration and colony formation; upregulate caspase-9, P21, and Bax expression levels; and downregulate PARP, survivin, and Bcl-2 expression level.

Conclusion

These results enhanced our understanding of 5FEM and aid the discovery of novel myricanol derivatives as potential antitumor agents.

Myricetin bioactive effects: moving from preclinical evidence to potential clinical applications

Several flavonoids have been recognized as nutraceuticals, and myricetin is a good example. Myricetin is commonly found in plants and their antimicrobial and antioxidant activities is well demonstrated. One of its beneficial biological effects is the neuroprotective activity, showing preclinical activities on Alzheimer, Parkinson, and Huntington diseases, and even in amyotrophic lateral sclerosis. Also, myricetin has revealed other biological activities, among them as antidiabetic, anticancer, immunomodulatory, cardiovascular, analgesic and antihypertensive. However, few clinical trials have been performed using myricetin as nutraceutical. Thus, this review provides new insights on myricetin preclinical pharmacological activities, and role in selected clinical trials.

The Protective Effects of Myricetin against Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of death globally, except Africa, and poses a severe health burden worldwide. Both in vitro and in vivo studies have demonstrated the protective effects of myricetin for preventing CVD. For this review, we have assessed the literature from 2009 to 2019 at home and abroad to uncover the protective roles of myricetin for preventing CVD. Myricetin exhibits cardioprotective, anti-hypertensive, anti-atherosclerotic, anti-hyperglycemic, and anti-hyperlipidemic effects. In addition, myricetin may alleviate some of the complications caused by adult-onset diabetes. The combined functions of myricetin allow for the prevention of CVD. This review describes the possible therapeutic benefits of myricetin, along with its potential mechanisms of action, to support the clinical use of the myricetin for the prevention of CVD.

Oxidative stress mediated cytotoxicity in leukemia cells induced by active phyto-constituents isolated from traditional herbal drugs of West Bengal

ETHNOPHARMACOLOGICAL RELEVANCE

In search of safe and effective therapeutic agents as alternative to synthetic chemotherapeutics for the treatment of leukemia, the herbal drugs (Leaf of Madhuca longifolia, leaf of Prosopis cineraria and bark of Flacourtia indica) with long traditional use in West Bengal have received our attention.

AIM OF THE STUDY

Present work was conducted to isolate and identify the active compounds of the selected herbal drugs using bio-assay guided fractionation and also to investigate their anticancer mechanism in leukemia cell lines.

MATERIALS AND METHODS

Bio-assay guided fractionation was used for the isolation of active constituents such as myricitrin, vitexin and vanillin from the aqueous extracts of M. longifolia, P. cineraria and F. indica, respectively using liquid partitioning and column chromatography and the compounds were characterized by HPLC, MS and NMR. Dose and time-dependent cytotoxicity of isolated compounds were studied against leukemia cells and their anticancer mechanism such as cell wall damage, nuclear damage, ROS and NO generation, SOD level, LDH release and lipid peroxidation were investigated.

RESULTS

Aqueous extract of M. longifolia, P. cineraria and F. indica exhibited maximum anti-proliferative activity against HL-60 (Acute myeloid leukemia, AML, 72.06%), K-562 (Chronic myeloid leukemia, CML, 42.14%) and Jurkat (Acute lymphoblastic leukemia, ALL, 51.71%) cells. Myricitrin, vitexin and vanillin exhibited dose-dependent (IC-50 values 164.4, 147 & 29.22 μg/ml) and time-dependent activity with maximum cytotoxicity at 48 h. All these three compounds caused apoptosis in leukemia cells by inducing free radicals such as ROS (1.33-2.65 Arbitrary units) and NO (11.17-18.53 μM), cell membrane damage and nuclear condensation which were evidenced by increased release of LDH (1326-1439 U/L), improved lipid peroxidation (10.19-14.41 nM/mg protein) and reduced SOD level (6.2-9.21 U/mg protein) in leukemia cells.

CONCLUSIONS

Based on anti-proliferative activity, the isolated phyto-compounds myrcitrin, vitexin and vanillin from M. longifolia, P. cineraria and F. indica could be developed as natural drugs for treating AML, CML and ALL leukemia types, respectively.

Chromium-Salen Catalyzed Cross-Coupling of Phenols: Mechanism and Origin of the Selectivity

A highly chemoselective phenol cross-coupling reaction catalyzed by a Cr-salen catalyst was developed. Kinetic studies showed that the oxidation of Cr(III) to Cr(V) is the rate-determining step of the reaction. In addition, experimental stoichiometric analysis showed that a high valent Cr(V) species is the active catalyst for this process. The selectivity of the reaction was found to be determined by the cross-coupling carbon-carbon bond forming reaction, rather than any precoordination species. It appears that the lowest energy cross-coupling pathway requires a lesser degree of electronic reorganization in its transition state vs the lowest energy homocoupling pathway. This result was supported by stoichiometric Cr(V) kinetics, ¹³C kinetic isotope effects, and density functional theory (DFT) calculations. The understanding of the full landscape of this reaction allowed us to develop a general analysis to predict the regioselectivity of the cross-coupling reaction.

Myrica esculenta Buch.-Ham. ex D. Don: A Natural Source for Health Promotion and Disease Prevention

Myrica esculenta (Myricaceae) is a popular medicinal plant most commonly found in the sub-tropical Himalayas. It is widely used in folk medicine to treat several ailments such as asthma, cough, chronic bronchitis, ulcers, inflammation, anemia, fever, diarrhea, and ear, nose, and throat disorders. Due to its multidimensional pharmacological and therapeutic effects, it is well recognized in the ayurvedic pharmacopeia. However, the recent upsurge in M. esculenta use and demand has led to illicit harvesting by the horticultural trade and habitat loss, pushing the plant to the brink of extinction. Thus, the present review aims to provide updated information on M. esculenta botany, ethnomedicinal uses, phytochemistry, pharmacological effects, toxicity, and conservation methods, as well as also highlight prospective for future research. Particular emphasis is also given to its antioxidant potential in health promotion. In-depth literature was probed by searching several sources via online databases, texts, websites, and thesis. About 57 compounds were isolated and identified from M. esculenta, and the available reports on physicochemical parameters, nutritional and high-performance thin-layer chromatography analysis of bioactive plant parts are portrayed in a comparative manner. Friendly holistic conservation approaches offered by plant biotechnology applications, such as micropropagation, germplasm preservation, synthetic seed production, and hairy root technologies are also discussed. Nonetheless, further studies are needed to propose the mechanistic role of crude extracts and other bioactives, and even to explore the structure–function relationship of active components.

Myricanol rescues dexamethasone-induced muscle dysfunction via a sirtuin 1-dependent mechanism

BACKGROUND

Muscle atrophy and weakness are adverse effects of high dose or the sustained usage of glucocorticoids. Loss of mitochondria and degradation of protein are highly correlated with muscle dysfunction. The deacetylase sirtuin 1 (SIRT1) plays a vital role in muscle remodelling. The current study was designed to identify myricanol as a SIRT1 activator, which could protect skeletal muscle against dexamethasone-induced wasting.

METHODS

The dexamethasone-induced atrophy in C2C12 myotubes was evaluated by expression of myosin heavy chain, muscle atrophy F-box (atrogin-1), and muscle ring finger 1 (MuRF1), using western blots. The mitochondrial content and oxygen consumption were assessed by MitoTracker staining and extracellular flux analysis, respectively. Muscle dysfunction was established in male C57BL/6 mice (8-10 weeks old, n = 6) treated with a relatively high dose of dexamethasone (25 mg/kg body weight, i.p., 10 days). Body weight, grip strength, forced swimming capacity, muscle weight, and muscle histology were assessed. The expression of proteolysis-related, autophagy-related, apoptosis-related, and mitochondria-related proteins was analysed by western blots or immunoprecipitation.

RESULTS

Myricanol (10 μM) was found to rescue dexamethasone-induced muscle atrophy and dysfunction in C2C12 myotubes, indicated by increased expression of myosin heavy chain (0.33 ± 0.14 vs. 0.89 ± 0.21, *P < 0.05), decreased expression of atrogin-1 (2.31 ± 0.67 vs. 1.53 ± 0.25, *P < 0.05) and MuRF1 (1.55 ± 0.08 vs. 0.99 ± 0.12, **P < 0.01), and elevated ATP production (3.83 ± 0.46 vs. 5.84 ± 0.79 nM/mg protein, **P < 0.01), mitochondrial content (68.12 ± 10.07% vs. 116.38 ± 5.12%, *P < 0.05), and mitochondrial oxygen consumption (166.59 ± 22.89 vs. 223.77 ± 22.59 pmol/min, **P < 0.01). Myricanol directly binds and activates SIRT1, with binding energy of -5.87 kcal/mol. Through activating SIRT1 deacetylation, myricanol inhibits forkhead box O 3a transcriptional activity to reduce protein degradation, induces autophagy to enhance degraded protein clearance, and increases peroxisome proliferator-activated receptor γ coactivator-1α activity to promote mitochondrial biogenesis. In dexamethasone-induced muscle wasting C57BL/6 mice, 5 mg/kg myricanol treatment reduces the loss of muscle mass; the percentages of quadriceps and gastrocnemius muscle in myricanol-treated mice are 1.36 ± 0.02% and 0.87 ± 0.08%, respectively (cf. 1.18 ± 0.06% and 0.78 ± 0.05% in dexamethasone-treated mice, respectively). Myricanol also rescues dexamethasone-induced muscle weakness, indicated by improved grip strength (70.90 ± 4.59 vs. 120.58 ± 7.93 g, **P < 0.01) and prolonged swimming exhaustive time (48.80 ± 11.43 vs. 83.75 ± 15.19 s, **P < 0.01). Myricanol prevents dexamethasone-induced muscle atrophy and weakness by activating SIRT1, to reduce muscle protein degradation, enhance autophagy, and promote mitochondrial biogenesis and function in mice.

CONCLUSIONS

Myricanol ameliorates dexamethasone-induced skeletal muscle wasting by activating SIRT1, which might be developed as a therapeutic agent for treatment of muscle atrophy and weakness.

Recent Studies on Cyclic 1,7-Diarylheptanoids: Their Isolation, Structures, Biological Activities, and Chemical Synthesis

Diarylheptanoids are a family of plant secondary metabolites with a 7 carbon skeleton possessing two phenyl rings at the 1- and 7-positions. They can be subdivided into acyclic and cyclic diarylheptanoids where the latter are further divided into meta,meta-bridged biphenyls ([7.0]metacyclophanes) and meta,para-bridged diphenyl ether heptanoids (oxa[7.1]metapara-cyclophanes). Since the isolation of curcumin from the rhizomes of turmeric (Curcuma longa) in 1815 which was named curcumin, a variety of diarylheptanoids have been isolated from a number of plant families such as Aceraceae, Actinidiaceae, Betulaceae, Burseraceae, Casuarinaceae, Juglandaceae, Leguminosae, Myricaceae, and Zingiberaceae. Earlier studies on these diarylheptanoids have been summarized on several occasions, of which the main themes only focus on isolation, structure elucidation, and the biological properties of linear types. Only a few have covered cyclic diarylheptanoids and their chemical synthesis has been covered lastly by Zhu et al. in 2000. The present paper has, therefore, covered recent progress in cyclic diarylheptanoids focusing on the isolation, structural and biological features, and chemical synthesis.

Current Screening Methodologies in Drug Discovery for Selected Human Diseases

The increase of many deadly diseases like infections by multidrug-resistant bacteria implies re-inventing the wheel on drug discovery. A better comprehension of the metabolisms and regulation of diseases, the increase in knowledge based on the study of disease-born microorganisms’ genomes, the development of more representative disease models and improvement of techniques, technologies, and computation applied to biology are advances that will foster drug discovery in upcoming years. In this paper, several aspects of current methodologies for drug discovery of antibacterial and antifungals, anti-tropical diseases, antibiofilm and antiquorum sensing, anticancer and neuroprotectors are considered. For drug discovery, two different complementary approaches can be applied: classical pharmacology, also known as phenotypic drug discovery, which is the historical basis of drug discovery, and reverse pharmacology, also designated target-based drug discovery. Screening methods based on phenotypic drug discovery have been used to discover new natural products mainly from terrestrial origin. Examples of the discovery of marine natural products are provided. A section on future trends provides a comprehensive overview on recent advances that will foster the pharmaceutical industry.

Convergent total synthesis of (±) myricanol, a cyclic natural diarylheptanoid

Third total synthesis of the meta, meta-bridged diarylheptanoid: myricanol with remarkable anti-tau properties.

Diarylheptanoid Glycosides of Morella salicifolia Bark

A methanolic extract of Morella salicifolia bark was fractionated by various chromatographic techniques yielding six previously unknown cyclic diarylheptanoids, namely, 7-hydroxymyricanol 5-O-β-d-glucopyranoside (1), juglanin B 3-O-β-d-glucopyranoside (2), 16-hydroxyjuglanin B 17-O-β-d-glucopyranoside (3), myricanone 5-O-β-d-gluco-pranosyl-(1→6)-β-d-glucopyranoside (4), neomyricanone 5-O-β-d-glucopranosyl-(1→6)-β-d-glucopyranoside (5), and myricanone 17-O-α-l-arabino-furanosyl-(1→6)-β-d-glucopyranoside (6), respectively, together with 10 known cyclic diarylheptanoids. The structural diversity of the diarylheptanoid pattern in M. salicifolia resulted from varying glycosidation at C-3, C-5, and C-17 as well as from substitution at C-11 with hydroxy, carbonyl or sulfate groups, respectively. Structure elucidation of the isolated compounds was achieved on the basis of one- and two-dimensional nuclear magnetic resonance (NMR) as well as high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) analyses. The absolute configuration of the glycosides was confirmed after hydrolysis and synthesis of O-(S)-methyl butyrated (SMB) sugar derivatives by comparison of their ¹H-NMR data with those of reference sugars. Additionally, absolute configuration of diarylheptanoid aglycones at C-11 was determined by electronic circular dichroism (ECD) spectra simulation and comparison with experimental CD spectra after hydrolysis.

Cinnamon, a promising prospect towards Alzheimer's disease

Over the last decades, an exponential increase of efforts concerning the treatment of Alzheimer's disease (AD) has been practiced. Phytochemicals preparations have a millenary background to combat various pathological conditions. Various cinnamon species and their biologically active ingredients have renewed the interest towards the treatment of patients with mild-to-moderate AD through the inhibition of tau protein aggregation and prevention of the formation and accumulation of amyloid-β peptides into the neurotoxic oligomeric inclusions, both of which are considered to be the AD trademarks. In this review, we presented comprehensive data on the interactions of a number of cinnamon polyphenols (PPs) with oxidative stress and pro-inflammatory signaling pathways in the brain. In addition, we discussed the potential association between AD and diabetes mellitus (DM), vis-à-vis the effluence of cinnamon PPs. Further, an upcoming prospect of AD epigenetic pathophysiological conditions and cinnamon has been sighted. Data was retrieved from the scientific databases such as PubMed database of the National Library of Medicine, Scopus and Google Scholar without any time limitation. The extract of cinnamon efficiently inhibits tau accumulations, Aβ aggregation and toxicity in vivo and in vitro models. Indeed, cinnamon possesses neuroprotective effects interfering multiple oxidative stress and pro-inflammatory pathways. Besides, cinnamon modulates endothelial functions and attenuates the vascular cell adhesion molecules. Cinnamon PPs may induce AD epigenetic modifications. Cinnamon and in particular, cinnamaldehyde seem to be effective and safe approaches for treatment and prevention of AD onset and/or progression. However, further molecular and translational research studies as well as prolonged clinical trials are required to establish the therapeutic safety and efficacy in different cinnamon spp.

Biological Activities of Triterpenoids and Phenolic Compounds from Myrica cerifera Bark

Seven triterpenoids, 1 - 7, two diarylheptanoids, 8 and 9, four phenolic compounds, 10 - 13, and three other compounds, 14 - 16, were isolated from the hexane and MeOH extracts of the bark of Myrica cerifera L. (Myricaceae). Among these compounds, betulin (1), ursolic acid (3), and myricanol (8) exhibited cytotoxic activities against HL60 (leukemia), A549 (lung), and SK-BR-3 (breast) human cancer cell lines (IC₅₀ 3.1 - 24.2 μm). Compound 8 induced apoptotic cell death in HL60 cells (IC₅₀ 5.3 μm) upon evaluation of the apoptosis-inducing activity by flow cytometric analysis and by Hoechst 33342 staining method. Western blot analysis on HL60 cells revealed that 8 activated caspases-3, -8, and -9 suggesting that 8 induced apoptosis via both mitochondrial and death receptor pathways in HL60. Upon evaluation of the melanogenesis-inhibitory activity in B16 melanoma cells induced with α-melanocyte-stimulating hormone (α-MSH), erythrodiol (7), 4-hydroxy-2-methoxyphenyl β-d-glucopyranoside (13), and butyl quinate (15) exhibited inhibitory effects (65.4 - 86.0% melanin content) with no, or almost no, toxicity to the cells (85.9 - 107.4% cell viability) at 100 μm concentration. In addition, 8, myricanone (9), myricitrin (10), protocatechuic acid (11), and gallic acid (12) revealed potent DPPH radical-scavenging activities (IC₅₀ 6.9 - 20.5 μm).

Inhibition of Both Hsp70 Activity and Tau Aggregation in Vitro Best Predicts Tau Lowering Activity of Small Molecules

Three scaffolds with inhibitory activity against the heat shock protein 70 (Hsp70) family of chaperones have been found to enhance the degradation of the microtubule associated protein tau in cells, neurons, and brain tissue. This is important because tau accumulation is linked to neurodegenerative diseases including Alzheimer's disease (AD) and chronic traumatic encephalopathy (CTE). Here, we expanded upon this study to investigate the anti-tau efficacy of additional scaffolds with Hsp70 inhibitory activity. Five of the nine scaffolds tested lowered tau levels, with the rhodacyanine and phenothiazine scaffolds exhibiting the highest potency as previously described. Because phenothiazines also inhibit tau aggregation in vitro, we suspected that this activity might be a more accurate predictor of tau lowering. Interestingly, the rhodacyanines did inhibit in vitro tau aggregation to a similar degree as phenothiazines, correlating well with tau-lowering efficacy in cells and ex vivo slices. Moreover, other Hsp70 inhibitor scaffolds with weaker tau-lowering activity in cells inhibited tau aggregation in vitro, albeit at lower potencies. When we tested six well-characterized tau aggregation inhibitors, we determined that this mechanism of action was not a better predictor of tau-lowering than Hsp70 inhibition. Instead, we found that compounds possessing both activities were the most effective at promoting tau clearance. Moreover, cytotoxicity and PAINS activity are critical factors that can lead to false-positive lead identification. Strategies designed around these principles will likely yield more efficacious tau-lowering compounds.

Identification of Novel Tau Interactions with Endoplasmic Reticulum Proteins in Alzheimer's Disease Brain

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is pathologically characterized by the formation of extracellular amyloid plaques and intraneuronal tau tangles. We recently identified that tau associates with proteins known to participate in endoplasmic reticulum (ER)-associated degradation (ERAD); consequently, ERAD becomes dysfunctional and causes neurotoxicity. We hypothesized that tau associates with other ER proteins, and that this association could also lead to cellular dysfunction in AD. Portions of human AD and non-demented age matched control brains were fractionated to obtain microsomes, from which tau was co-immunoprecipitated. Samples from both conditions containing tau and its associated proteins were analyzed by mass spectrometry. In total, we identified 91 ER proteins that co-immunoprecipitated with tau; 15.4% were common between AD and control brains, and 42.9% only in the AD samples. The remainder, 41.8% of the proteins, was only seen in the control brain samples. We identified a variety of previously unreported interactions between tau and ER proteins. These proteins participate in over sixteen functional categories, the most abundant being involved in RNA translation. We then determined that association of tau with these ER proteins was different between the AD and control samples. We found that tau associated equally with the ribosomal protein L28 but more robustly with the ribosomal protein P0. These data suggest that the differential association between tau and ER proteins in disease could reveal the pathogenic processes by which tau induces cellular dysfunction.

Pathological Tau Promotes Neuronal Damage by Impairing Ribosomal Function and Decreasing Protein Synthesis

One of the most common symptoms of Alzheimer's disease (AD) and related tauopathies is memory loss. The exact mechanisms leading to memory loss in tauopathies are not yet known; however, decreased translation due to ribosomal dysfunction has been implicated as a part of this process. Here we use a proteomics approach that incorporates subcellular fractionation and coimmunoprecipitation of tau from human AD and non-demented control brains to identify novel interactions between tau and the endoplasmic reticulum (ER). We show that ribosomes associate more closely with tau in AD than with tau in control brains, and that this abnormal association leads to a decrease in RNA translation. The aberrant tau-ribosome association also impaired synthesis of the synaptic protein PSD-95, suggesting that this phenomenon contributes to synaptic dysfunction. These findings provide novel information about tau-protein interactions in human brains, and they describe, for the first time, a dysfunctional consequence of tau-ribosome associations that directly alters protein synthesis. Significance statement: Despite the identification of abnormal tau-ribosomal interactions in tauopathies >25 years ago, the consequences of this association remained elusive until now. Here, we show that pathological tau associates closely with ribosomes in AD brains, and that this interaction impairs protein synthesis. The overall result is a stark reduction of nascent proteins, including those that participate in synaptic plasticity, which is crucial for learning and memory. These data mechanistically link a common pathologic sign, such as the appearance of pathological tau inside brain cells, with cognitive impairments evident in virtually all tauopathies.

Myricetin: A Dietary Molecule with Diverse Biological Activities

Myricetin is a common plant-derived flavonoid and is well recognised for its nutraceuticals value. It is one of the key ingredients of various foods and beverages. The compound exhibits a wide range of activities that include strong anti-oxidant, anticancer, antidiabetic and anti-inflammatory activities. It displays several activities that are related to the central nervous system and numerous studies have suggested that the compound may be beneficial to protect against diseases such as Parkinson's and Alzheimer's. The use of myricetin as a preserving agent to extend the shelf life of foods containing oils and fats is attributed to the compound's ability to protect lipids against oxidation. A detailed search of existing literature revealed that there is currently no comprehensive review available on this important molecule. Hence, the present work includes the history, synthesis, pharmaceutical applications and toxicity studies of myricetin. This report also highlights structure-activity relationships and mechanisms of action for various biological activities.

Recent Breakthroughs in the Antioxidant and Anti-Inflammatory Effects of Morella and Myrica Species

Oxidative stress is one of the risk factors for the development of several chronic diseases, such as diabetes, cancer, cardiovascular and neurodegenerative diseases. Antioxidants are therefore highly sought and can be seen as a type of preventive medicine against several diseases. Myrica and Morella genus (Myricaceae) are taxonomically very close and their species are trees or shrubs with edible fruits that exhibit relevant uses in traditional medicine, for instance in Chinese or Japanese folk medicine they are used to treat diarrhea, digestive problems, headache, burns and skin diseases. Nearly 36 compounds were isolated from different morphological parts of Myrica and/or Morella species and their antioxidant and anti-inflammatory activities evaluated. Thirteen of these compounds exhibit greater effects than the positive controls used. Adenodimerin A was the most active compound reported (in a 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay EC50= 7.9 ± 0.3 µM). These results are just one aspect of the antioxidant and anti-inflammatory evaluations reported regarding Myrica and Morella species, so a comprehensive overview on the current status, highlighting the antioxidant health promoting effect of these species, their key antioxidant compounds as well as the compounds with protective effects against oxidative stress related diseases such as inflammation, is relevant.

Synthesis, stereochemical analysis, and derivatization of myricanol provide new probes that promote autophagic tau clearance

We previously discovered that one specific scalemic preparation of myricanol (1), a constituent of Myrica cerifera (bayberry/southern wax myrtle) root bark, could lower the levels of the microtubule-associated protein tau (MAPT). The significance is that tau accumulates in a number of neurodegenerative diseases, the most common being Alzheimer's disease (AD). Herein, a new synthetic route to prepare myricanol using a suitable boronic acid pinacol ester intermediate is reported. An X-ray crystal structure of the isolated myricanol (1) was obtained and showed a co-crystal consisting of (+)-aR,11S-myricanol (2) and (-)-aS,11R-myricanol (3) coformers. Surprisingly, 3, obtained from chiral separation from 1, reduced tau levels in both cultured cells and ex vivo brain slices from a mouse model of tauopathy at reasonable mid-to-low micromolar potency, whereas 2 did not. SILAC proteomics and cell assays revealed that 3 promoted tau degradation through an autophagic mechanism, which was in contrast to that of other tau-lowering compounds previously identified by our group. During the course of structure-activity relationship (SAR) development, we prepared compound 13 by acid-catalyzed dehydration of 1. 13 had undergone an unexpected structural rearrangement through the isomyricanol substitution pattern (e.g., 16), as verified by X-ray structural analysis. Compound 13 displayed robust tau-lowering activity, and, importantly, its enantiomers reduced tau levels similarly. Therefore, the semisynthetic analogue 13 provides a foundation for further development as a tau-lowering agent without its SAR being based on chirality.

Myricanol induces apoptotic cell death and anti-tumor activity in non-small cell lung carcinoma in vivo

This study explored the inhibiting effect and mechanism of myricanol on lung adenocarcinoma A549 xenografts in nude mice. Forty nude mice with subcutaneous A549 xenografts were randomly divided into five groups: high-dose myricanol (40 mg/kg body weight) group; middle-dose myricanol (20 mg/kg body weight) group; low-dose myricanol (10 mg/kg body weight) group; polyethylene glycol 400 vehicle group (1 mL/kg); and tumor model group. Nude mice were sacrificed after 14 days of treatment and the tumor inhibition rate (TIR, %) was then calculated. The relative mRNA expression levels of Bax, Bcl-2, VEGF, HIF-1α, and survivin in the tumor tissues were determined by real-time PCR. TUNEL assay was applied to determine cellular apoptosis, while IHC test was performed to detect the protein expression levels of Bax, Bcl-2, VEGF, HIF-1α, and survivin. The TIR of the three myricanol-treated groups ranged from 14.9% to 38.5%. The IHC results showed that the protein expression of Bcl-2, VEGF, HIF-1α, and survivin were consistently downregulated, whereas that of Bax was upregulated after myricanol treatment. Myricanol also significantly upregulated the mRNA expression of Bax and downregulated that of Bcl-2, VEGF, HIF-1α, and survivin in a dose-dependent manner (p < 0.05 to 0.001). These results are consistent with those of IHC. The TUNEL assay results indicated that apoptotic-positive cells significantly increased in the myricanol-treated tumor tissues compared with the cells of the vehicle control group (p < 0.01 to 0.001). These data suggest that myricanol could significantly decelerate tumor growth in vivo by inducing apoptosis.

A twist of nature – the significance of atropisomers in biological systems

This review encompasses the synthesis and identification of recently detected natural atropisomers with potential therapeutic activity.

Natural antitubulin agents: importance of 3,4,5-trimethoxyphenyl fragment

Microtubules are polar cytoskeletal filaments assembled from head-to-tail and comprised of lateral associations of α/β-tubulin heterodimers that play key role in various cellular processes. Because of their vital role in mitosis and various other cellular processes, microtubules have been attractive targets for several disease conditions and especially for cancer. Antitubulin is the most successful class of antimitotic agents in cancer chemotherapeutics. The target recognition of antimitotic agents as a ligand is not much explored so far. However, 3,4,5-trimethoxyphenyl fragment has been much highlighted and discussed in such type of interactions. In this review, some of the most important naturally occurring antimitotic agents and their interactions with microtubules are discussed with a special emphasis on the role of 3,4,5-trimethoxyphenyl unit. At last, some emerging naturally occurring antimitotic agents have also been tabulated.

Growth-inhibiting and apoptosis-inducing activities of Myricanol from the bark of Myrica rubra in human lung adenocarcinoma A549 cells

Myrica rubra (Lour.) Sieb. Et Zucc. is a myricaceae Myrica plant. It is a subtropical fruit tree in China and other Asian countries. The bark of M. rubra is used in Chinese folk medicine because of its antibacterial, antioxidant, anti-inflammatory, and anticancer activities. However, the mechanisms underlying such activities remain unclear. This study investigated whether or not Myricanol extracted from M. rubra bark elicits anti-cancer effects on human lung adenocarcinoma A549 cells by inducing apoptosis in vivo. Myricanol was extracted from M. rubra bark through system solvent extraction and silica gel layer column separation. The results of tritiated thymidine assay, colony formation assay, and flow cytometry indicated that Myricanol inhibited the growth of A549 cells. The effects of Myricanol on the expression of key apoptosis-related genes in A549 cells were evaluated by quantitative PCR and Western blot analyses. Myricanol significantly inhibited the growth of A549 cells in a dose-dependent manner, with a half maximal inhibitory concentration of 4.85 μg/ml. Myricanol significantly decreased colony formation and induced A549 cell apoptosis. Myricanol upregulated the expression of Caspase-3, Caspase-9, Bax, and p21 and downregulated the expression of Bcl-2 at the mRNA and protein levels. These changes were associated with apoptosis. Based on these results, we propose that Myricanol elicits growth inhibitory and cytotoxic effects on lung cancer cells. Therefore, Myricanol may be a clinical candidate for the prevention and treatment of lung cancer.

Phenotypic screens targeting neurodegenerative diseases

Neurodegenerative diseases affect millions of people worldwide, and the incidences increase as the population ages. Disease-modifying therapy that prevents or slows disease progression is still lacking, making neurodegenerative diseases an area of high unmet medical need. Target-based drug discovery for disease-modifying agents has been ongoing for many years, without much success due to incomplete understanding of the molecular mechanisms underlying neurodegeneration. Phenotypic screening, starting with a disease-relevant phenotype to screen for compounds that change the outcome of biological pathways rather than activities at certain specific targets, offers an alternative approach to find small molecules or targets that modulate the key characteristics of neurodegeneration. Phenotypic screens that focus on amelioration of disease-specific toxins, protection of neurons from degeneration, or promotion of neuroregeneration could be potential fertile grounds for discovering therapeutic agents for neurodegenerative diseases. In this review, we will summarize the progress of compound screening using these phenotypic-based strategies for this area, with a highlight on unique considerations for disease models, assays, and screening methodologies. We will further provide our perspectives on how best to use phenotypic screening to develop drug leads for neurodegenerative diseases.

Natural products as a rich source of tau-targeting drugs for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder and the most common form of dementia, affecting more than 5.4 million people in the USA. Although the cause of AD is not well understood, the cholinergic, amyloid and tau hypotheses were proposed to explain its development. Drug discovery for AD based on the cholinergic and amyloid theories have not been effective. In this article we summarize tau-based natural products as AD therapeutics from a variety of biological sources, including the anti-amyloid agent curcumin, isolated from turmeric, the microtubule stabilizer paclitaxel, from the Pacific Yew Taxus brevifolia, and the Streptomyces-derived Hsp90 inhibitor, geldanamycin. The overlooked approach of clearing tau aggregation will most likely be the next objective for AD drug discovery.

Chaperone-dependent Neurodegeneration: A Molecular Perspective on Therapeutic Intervention

Maintenance of cellular homeostasis is regulated by the molecular chaperones. Under pathogenic conditions, aberrant proteins are triaged by the chaperone network. These aberrant proteins, known as "clients," have major roles in the pathogenesis of numerous neurological disorders, including tau in Alzheimer's disease, α-synuclein and LRRK2 in Parkinson's disease, SOD-1, TDP-43 and FUS in amyotrophic lateral sclerosis, and polyQ-expanded proteins such as huntingtin in Huntington's disease. Recent work has demonstrated that the use of chemical compounds which inhibit the activity of molecular chaperones subsequently alter the fate of aberrant clients. Inhibition of Hsp90 and Hsc70, two major molecular chaperones, has led to a greater understanding of how chaperone triage decisions are made and how perturbing the chaperone system can promote clearance of these pathogenic clients. Described here are major pathways and components of several prominent neurological disorders. Also discussed is how treatment with chaperone inhibitors, predominately Hsp90 inhibitors which are selective for a diseased state, can relieve the burden of aberrant client signaling in these neurological disorders.

Cognition-enhancing and neuroprotective activities of the standardized extract of Betula platyphylla bark and its major diarylheptanoids

Diarylheptanoids have been the center of the intensive research efforts for Alzheimer's disease and other neurodegenerative diseases. The present study aimed to determine the effect of the standardized extract of B. platyphylla bark and its major diarylheptanoids in scopolamine-induced amnesic mice through cyclic AMP response element-binding protein (CREB) activation. Oral administration of the standardized extract of B. platyphylla bark (100mg/kg body weight), aceroside VIII (1mg/kg body weight) and platyphylloside (1 or 2mg/kg body weight) significantly ameliorated scopolamine-induced amnesia in passive avoidance test. CREB phosphorylation and brain-derived neurotrophic factor (BDNF) expression in the cortex and hippocampus of the scopolamine-treated mice were markedly increased by the treatment of the standardized extract of B. platyphylla bark and platyphylloside. The standardized extract of B. platyphylla bark and its major diarylheptanoids also significantly protected HT22 cells against neurotoxicity induced by glutamate insult. The standardized extract of B. platyphylla bark and platyphylloside may ameliorate memory deficits by activating the CREB-BDNF pathway and prevent a neurodegeneration by inhibiting neuronal cell death.