Novel Flavonol Alkaloids in Green Tea: Synthesis, Detection, and Anti-Alzheimer's Disease Effect in a Transgenic Caenorhabditis elegans CL4176 Model.

Novel N-ethy-2-pyrrolidinone-substituted flavonols, myricetin alkaloids A-C (1-3), quercetin alkaloids A-C (4a, 4b, and 5), and kaempferol alkaloids A and B (6 and 7), were prepared from thermal reaction products of myricetin, quercetin, kaempferol─l-theanine, respectively. We used HPLC-ESI-HRMS/MS to detect 1-7 in 14 cultivars of green tea and found that they were all present in "Shuchazao," "Longjing 43", "Fudingdabai", and "Zhongcha 108" green teas. The structures of 1-4 and 6 were determined by extensive 1D and 2D NMR spectroscopies. These flavonol alkaloids along with their skeletal flavonols were assessed for anti-Alzheimer's disease effect based on molecular docking, acetylcholinesterase inhibition, and the transgenic Caenorhabditis elegans CL4176 model. Compound 7 strongly binds to the protein amyloid ß (Aß1-42) through hydrogen bonds (BE: -9.5 kcal/mol, Ki: 114.3 nM). Compound 3 (100 µM) is the strongest one in significantly extending the mean lifespan (13.4 ± 0.5 d, 43.0% promotion), delaying the Aß1-42-induced paralysis (PT50: 40.7 ± 1.9 h, 17.1% promotion), enhancing the locomotion (140.0% promotion at 48 h), and alleviating glutamic acid (Glu)-induced neurotoxicity (153.5% promotion at 48 h) of CL4176 worms (p < 0.0001).

GABase and glutaminase inhibitory activities of herbal extracts and acylated flavonol monoglycosides isolated from the leaves of Laurus nobilis L.

This study was to compare GABase [a mixture of γ-aminobutyric acid (GABA) aminotransferase and succinic semialdehyde dehydrogenase] and glutaminase inhibitory activities of 20 herbal extracts and investigate the isolation, structural elucidation and those inhibitory activities of three acylated flavonol monoglycosides from the selected extract of Laurus nobilis L. (laurel). On the basis of the NMR spectroscopic data and the ESI MS spectra together with the comparison with the literature values, three compounds were identified as kaempferol-3-O-(4″-E-p-coumaroyl)-α-l-rhamnopyranoside (1), kaempferol-3-O-(3″,4″-di-E-p-coumaroyl)-α-l-rhamnopyranoside (2) and kaempferol-3-O-(2″,4″-di-E-p-coumaroyl)-α-l-rhamnopyranoside (3), respectively. The IC50 values of GABase inhibitory activity of 1-3 and p-hydroxybenzaldehyde (HBA) as control were 0.24 mM, 0.14 mM, 0.12 mM and 0.43 mM, respectively. Additionally, the IC50 values of glutaminase inhibitory activity of 1-3 and 6-diazo-5-oxo-l-norleucine (DON) as control were 0.34 mM, 0.13 mM, 0.14 mM and 0.33 mM, respectively. The results suggest that the extract from laurel shows the strongest biological activities among 20 herbal extracts and three acylated flavonol monoglycosides may serve as potential lead compounds for the prevention and treatment of neurodegenerative and lifestyle-related diseases by targeting GABase and glutaminase. This is the first report on GABase and glutaminase inhibitory activities of 1-3.

An efficient cocrystallization strategy for separation of dihydromyricetin from vine tea and enhanced its antibacterial activity for food preserving application.

The objective of this study was to optimize the separation and purification of dihydromyricetin (DMY) from vine tea to obtain high purity, antibacterial and antioxidant crystal forms. We developed a cocrystallization approach for separation of DMY from vine tea with easy operation and high efficiency. The type and concentration of co-formers as well as solvent for separation have been investigated in detail. Under the optimal conditions, DMY with a purity of 92.41% and its two co-crystal forms (purity >97%) can be obtained. Three DMY crystal forms had consistent and good antioxidant activities according to DPPH radical scavenging results. DMY had effective antibacterial activity against the two kinds of drug-resistant bacteria including CRAB and MRSA, and DMY co-crystals had a greater advantage than DMY itself on CRAB. This work implies that cocrystallization can be used for the DMY separation and enhanced its anti-drug-resistant bacteria activity in food preservation.

Myricetin possesses the potency against SARS-CoV-2 infection through blocking viral-entry facilitators and suppressing inflammation in rats and mice.

BACKGROUND: Myricetin (3,5,7-trihydroxy-2-(3,4,5-tri hydroxyphenyl)-4-benzopyrone) is a common flavonol extracted from many natural plants and Chinese herb medicines and has been demonstrated to have multiple pharmacological activities, such as anti-microbial, anti-thrombotic, neuroprotective, and anti-inflammatory effects. Previously, myricetin was reported to target Mpro and 3CL-Pro-enzymatic activity to SARS-CoV-2. However, the protective value of myricetin on SARS-Cov-2 infection through viral-entry facilitators has not yet been comprehensively understood. PURPOSE: The aim of the current study was to evaluate the pharmacological efficacy and the mechanisms of action of myricetin against SARS-CoV-2 infection both in vitro and in vivo. METHODS: The inhibitory effects of myricetin on SARS-CoV-2 infection and replication were assessed on Vero E6 cells. Molecular docking analysis and bilayer interferometry (BLI) assays, immunocytochemistry (ICC), and pseudoviruses assays were performed to evaluate the roles of myricetin in the intermolecular interaction between the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein and angiotensin-converting enzyme 2 (ACE2). The anti-inflammatory potency and mechanisms of myricetin were examined in THP1 macrophages in vitro, as well as in carrageenan-induced paw edema, delayed-type hypersensitivity (DTH) induced auricle edema, and LPS-induced acute lung injury (ALI) animal models. RESULTS: The results showed that myricetin was able to inhibit binding between the RBD of the SARS-CoV-2 S protein and ACE2 through molecular docking analysis and BLI assay, demonstrating its potential as a viral-entry facilitator blocker. Myricetin could also significantly inhibit SASR-CoV-2 infection and replication in Vero E6 cells (EC50 55.18 µM), which was further validated with pseudoviruses containing the RBD (wild-type, N501Y, N439K, Y453F) and an S1 glycoprotein mutant (S-D614G). Moreover, myricetin exhibited a marked suppressive action on the receptor-interacting serine/threonine protein kinase 1 (RIPK1)-driven inflammation and NF-kappa B signaling in THP1 macrophages. In animal model studies, myricetin notably ameliorated carrageenan-induced paw edema in rats, DTH induced auricle edema in mice, and LPS-induced ALI in mice. CONCLUSION: Our findings showed that myricetin inhibited HCoV-229E and SARS-CoV-2 replication in vitro, blocked SARS-CoV-2 virus entry facilitators and relieved inflammation through the RIPK1/NF-κB pathway, suggesting that this flavonol has the potential to be developed as a therapeutic agent against COVID-19.

Network pharmacology identifies fisetin as a treatment for osteoporosis that activates the Wnt/ß-catenin signaling pathway in BMSCs.

BACKGROUND: Although fisetin may exist widely in many natural herbs, its anti-OP mechanism is still unclear. The aim of this study is to explore the molecular anti-osteoporosis (OP) mechanism of fisetin based on network pharmacology and cell experiments. METHODS: The target of fisetin was extracted by the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP). The targets of OP were obtained by DisGeNET, GeneCards and the Comparative Toxicogenomics Database, and the targets of fisetin in OP were screened by cross-analysis. The protein-protein interaction (PPI) network was constructed by STRING, and the core targets were obtained. We performed gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses on common targets via the Database for Annotation, Visualization and Integrated Discovery. Finally, an in vitro cell experiment was used to verify the anti-OP effect and mechanism of fisetin. RESULTS: There are 44 targets of fisetin related to the treatment of OP. The PPI results suggest that CTNNB1, CCND1, TP53, JUN, and AKT1 are the core targets. A total of 259 biological process, 57 molecular function and 26 cell component terms were obtained from GO enrichment analysis. The results of KEGG pathway enrichment analysis suggested that fisetin treatment of OP may be related to the Wnt signaling pathway, estrogen signaling pathway, PI3K-Akt signaling pathway and other signaling pathways. In vitro cell experiments showed that fisetin significantly increased the expression levels of ALP, collagen I, osteopontin and RUNX2 in bone marrow mesenchymal stem cells (BMSCs) (p < 0.05). Fisetin also increased the gene expression levels of Wnt3 and ß-catenin (CTNNB1) in BMSCs, which indicates that fisetin can regulate the Wnt/ß-catenin signaling pathway and promote the osteogenic differentiation of BMSCs. CONCLUSIONS: Fisetin acts on multiple targets and pathways in the treatment of OP; mechanistically, it regulates the Wnt/ß-catenin signaling pathway, which promotes the osteogenic differentiation of BMSCs and maintains bone homeostasis. The results of this study provide a theoretical basis for further study on the complex anti-OP mechanism of fisetin.

Dysosmaflavonoid A-F, new flavonols with potent DPPH radical scavenging activity from Dysosma versipellis.

Six new flavonols, including four glucosylated flavonols (dysosmaflavonoid A-D), one phenylpropanoid-substituted flavonol (dysosmaflavonoid E), and one phenyl-substituted flavonol (dysosmaflavonoid F), together with five known analogues, were isolated from the roots and rhizomes of Dysosma versipellis. Their structures were elucidated by comprehensive analysis of their NMR, IR, UV, HRESIMS, and HPLC data. The antioxidant activities of all isolated compounds were examined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. Compounds 2, 3, 5-8, and 12 exhibited significant DPPH scavenging capacity with IC50 values of 33.95, 39.02, 31.17, 32.79, 31.85, 30.48, and 23.75 µM, respectively, in comparison with Trolox (IC50, 15.80 µM). Compound 12 displayed more potent DPPH radical scavenging activity than prenylated and (or) glucosided derivatives (2-4, or 10). The preliminary structure-activity relationship showed that the catechol structure in flavonol is essential for DPPH radical scavenging effect.

Cocoa Flavanol Supplementation and the Effect on Insulin Resistance in Females Who Are Overweight or Obese: A Randomized, Placebo-Controlled Trial.

There is interest in the impact that dietary interventions can have on preventing the transition from insulin resistance to type 2 diabetes, including a suggestion that the bioactive components of cocoa may enhance fasting insulin sensitivity. However, a role for cocoa flavanols (CF) in reducing insulin resistance in the insulin-stimulated state, an important risk factor for cardiovascular disease, is unresolved. This study investigated whether CF consumption improved whole-body insulin-mediated glucose uptake ('M') in females with overweight/obesity, using a randomized, double-blinded, placebo-controlled, parallel-group design. Thirty-two premenopausal females (19-49 years; 27-35 kg·m-2) with elevated HOMA-IR (HOMA-IR >1.5) supplemented their habitual diet with two servings/day of a high-flavanol cocoa drink (HFC; 609 mg CF/serving; n = 16) or low-flavanol cocoa drink (LFC; 13 mg CF/serving; n = 16) for 4 weeks. Assessment of HOMA-IR and 'M' during a 3-h, 60 mIU insulin·m-2·min-1 euglycemic clamp was performed before and after the intervention. Data are the mean (SD). Changes to HOMA-IR (HFC -0.003 (0.57); LFC -0.0402 (0.86)) and 'M' (HFC 0.99 (7.62); LFC -1.32 (4.88) µmol·kg-1·min-1) after the intervention were not different between groups. Four weeks' consumption of ~1.2 g CF/day did not improve indices of fasting insulin sensitivity or insulin-mediated glucose uptake. A recommendation for dietary supplementation with cocoa flavanols to improve glycemic control is therefore not established.

Constituents of Pulicaria inuloides and Cytotoxic Activities of Two Methoxylated Flavonols.

Plants of the genus Pulicaria are known for providing traditional medicines, spices, herbal teas, and insect deterrents. Pulicaria inuloides (Poir.). DC. is one of the less chemically studied species within the genus. Hydroalcoholic extracts from roots and aerial parts of P. inuloides were analyzed using the UHPLC-PAD-MSn technique and revealed the presence of six caffeoylquinic and eleven caffeoylhexaric conjugates together with hydroxykaempferol dimethyl ether and quercetagetin trimethyl ether. Moreover, constituents of chloroform extract from the whole P. inuloides plants were isolated and identified by spectroscopic methods. One new and four known caryophyllene derivatives, three thymol derivatives, and four polymethoxylated flavonols were found in the analyzed extract. The structure of the new compound was established by spectroscopic methods (HRESIMS, 1H NMR, 13C NMR, COSY, HSQC, HMBC, NOESY). The cytotoxicity of 6-Hydroxykaempferol 3,7-dimethyl ether and quercetagetin 3,7,3'-trimethyl ether (chrysosplenol C), which are major flavonols isolated from the plant, were tested on prostate epithelial cells (PNT2), prostate cancer cells (DU145 and PC3), human keratinocytes (HaCaT), and melanoma cells (HTB140 and A375). Both flavonols demonstrated moderate cytotoxic activity against PC3 cells (IC50 = 59.5 µM and 46.6 µM, respectively). The remaining cell lines were less affected (IC50 > 150 µM).

Medicinal Importance, Pharmacological Activities, and Analytical Aspects of Engeletin in Medicine: Therapeutic Benefit Through Scientific Data Analysis.

BACKGROUND: Phytochemicals belonging to the class of flavonoids have been used in medicine for the treatment of different kinds of human health complications. Flavonoids have beneficial health aspects in medicine mainly due to their anti-microbial, anti-diabetic, anti-inflammatory, anticancer, and anti-carcinogenic activities. They have been scientifically investigated for their health benefit and pharmacological activities in medicine. Engeletin is a pure flavanonol class phytocompound present in the skin of white grapes and white wine. Engeletin has numerous pharmacological activities in medicine. METHODS: In order to know the beneficial health aspects of engeletin in medicine, scientific data on engeletin have been collected from different literature sources and analyzed in the present work. The present work summarized the important findings of engeletin with respect to its medicinal uses, pharmacological activities, and analytical aspects in medicine. All the scientific data were collected from PubMed, Google, Scopus, Science Direct and Google Scholar and analyzed in the present work. RESULTS: Scientific data analysis of research works revealed the biological importance and therapeutic benefit of engeletin in medicine. Engeletin has attracted scientific attention mainly due to its antiinflammatory and anti-tumor potential. Engeletin could inhibit the occurrence of cervical cancer and delay the development of liver damage and lung cancer in mice. Engeletin was found to inhibit lipopolysaccharides- induced endometritis in mice by inhibiting the inflammatory response. Pharmacological data analysis revealed the therapeutic importance of engeletin against acute lung injury, inflammatory diseases, liver injury, pulmonary fibrogenesis, Alzheimer's disease, endometritis, cervical carcinogenesis, lung cancer, and osteoarthritis. Analytical data signified the importance of modern analytical tools for separating, isolating, and identifying engeletin. CONCLUSION: Scientific data analysis revealed the biological importance and therapeutic benefit of engeletin in medicine and other allied health sectors.

The effect of flavonols in Anacardium occidentale L. leaf extracts on skin pathogenic microorganisms.

Cashew (Anacardium occidentale L.) leaf is traditionally used to treat skin infections. Although many flavonols have been identified from its leaf extract, their inhibitory effects on skin pathogens are not yet determined. The aims of this study were to determine the antimicrobial (against skin pathogenic microbes) and antioxidant activities of four flavonol glycosides from the crude extract and three flavonol aglycones from the hydrolyzed extract. The hydrolyzed extract was found to show higher activities than the crude extract. Myricetin showed the highest activity against all the tested bacteria and yeast with the lowest Minimum Inhibition Concentration (MIC) of 7.81 µg/mL on Corynebacterium minutissimum ATCC23348. Myricetin also exhibited good primary antioxidant activities with the effective concentration with 50% of activity (EC50) values ranged between 2.23 µg/mL and 6.40 µg/mL. The highest secondary antioxidant activity was indicated by myricetin-3-O-rhamnoside. Thus, myricetin can be considered as a bioactive compound of the hydrolyzed extract.

Flavones, Flavonols, Lignans, and Caffeic Acid Derivatives from Dracocephalum moldavica and Their In Vitro Effects on Multiple Myeloma and Acute Myeloid Leukemia.

Phenolic plant constituents are well known for their health-promoting and cancer chemopreventive properties, and products containing such constituents are therefore readily consumed. In the present work, we isolated 13 phenolic constituents of four different compound classes from the aerial parts of the Moldavian dragonhead, an aromatic and medicinal plant with a high diversity on secondary metabolites. All compounds were tested for their apoptotic effect on myeloma (KMS-12-PE) and AML (Molm-13) cells, with the highest activity observed for the flavone and flavonol derivatives. While diosmetin (6) exhibited the most pronounced effects on the myeloma cell line, two polymethylated flavones, namely cirsimaritin (1) and xanthomicrol (3), were particularly active against AML cells and therefore subsequently investigated for their antiproliferative effects at lower concentrations. At a concentration of 2.5 µM, cirsimaritin (1) reduced proliferation of Molm-13 cells by 72% while xanthomicrol (3) even inhibited proliferation to the extent of 84% of control. In addition, both compounds were identified as potent FLT3 inhibitors and thus display promising lead structures for further drug development. Moreover, our results confirmed the chemopreventive properties of flavonoids in general, and in particular of polymethylated flavones, which have been intensively investigated especially over the last decade.

Molecular mechanisms and promising role of dihydromyricetin in cardiovascular diseases.

Vine tea, a Chinese herbal medicine, is widely used in traditional Asian medicine to treat common health problems. Dihydromyricetin (DMY) is the main functional flavonoid compound extracted from vine tea. In recent years, preclinical studies have focused on the potential beneficial effects of dihydromyricetin, including glucose metabolism regulation, lipid metabolism regulation, neuroprotection, and anti-tumor effects. In addition, DMY may play a role in cardiovascular disease by resisting oxidative stress and participating in the regulation of inflammation. This review is the first review that summaries the applications of dihydromyricetin in cardiovascular diseases, including atherosclerosis, myocardial infarction, myocardial hypertrophy, and diabetic cardiomyopathy. We also clarified the underlying mechanisms and signaling pathways involved in the above process. The aim of this review is to provide a better understanding and quick overview for future researches of dihydromyricetin in the field of cardiovascular diseases, and more detailed and robust researches are needed for evaluation and reference.

Flavonols and Flavones as Potential anti-Inflammatory, Antioxidant, and Antibacterial Compounds.

Plant preparations have been used to treat various diseases and discussed for centuries. Research has advanced to discover and identify the plant components with beneficial effects and reveal their underlying mechanisms. Flavonoids are phytoconstituents with anti-inflammatory, antimutagenic, anticarcinogenic, and antimicrobial properties. Herein, we listed and contextualized various aspects of the protective effects of the flavonols quercetin, isoquercetin, kaempferol, and myricetin and the flavones luteolin, apigenin, 3',4'-dihydroxyflavone, baicalein, scutellarein, lucenin-2, vicenin-2, diosmetin, nobiletin, tangeretin, and 5-O-methyl-scutellarein. We presented their structural characteristics and subclasses, importance, occurrence, and food sources. The bioactive compounds present in our diet, such as fruits and vegetables, may affect the health and disease state. Therefore, we discussed the role of these compounds in inflammation, oxidative mechanisms, and bacterial metabolism; moreover, we discussed their synergism with antibiotics for better disease outcomes. Indiscriminate use of antibiotics allows the emergence of multidrug-resistant bacterial strains; thus, bioactive compounds may be used for adjuvant treatment of infectious diseases caused by resistant and opportunistic bacteria via direct and indirect mechanisms. We also focused on the reported mechanisms and intracellular targets of flavonols and flavones, which support their therapeutic role in inflammatory and infectious diseases.

Fisetin, a Potent Anticancer Flavonol Exhibiting Cytotoxic Activity against Neoplastic Malignant Cells and Cancerous Conditions: A Scoping, Comprehensive Review.

Diet plays a crucial role in homeostasis maintenance. Plants and spices containing flavonoids have been widely used in traditional medicine for thousands of years. Flavonols present in our diet may prevent cancer initiation, promotion and progression by modulating important enzymes and receptors in signal transduction pathways related to proliferation, differentiation, apoptosis, inflammation, angiogenesis, metastasis and reversal of multidrug resistance. The anticancer activity of fisetin has been widely documented in numerous in vitro and in vivo studies. This review summarizes the worldwide, evidence-based research on the activity of fisetin toward various types of cancerous conditions, while describing the chemopreventive and therapeutic effects, molecular targets and mechanisms that contribute to the observed anticancer activity of fisetin. In addition, this review synthesized the results from preclinical studies on the use of fisetin as an anticancer agent. Based on the available literature, it might be suggested that fisetin has a bioactive potential to become a complementary drug in the prevention and treatment of cancerous conditions. However, more in-depth research is required to validate current data, so that this compound or its derivatives can enter the clinical trial phase.

Undescribed glucosylceramide, flavonol triglycoside, and oleanane saponin from the halophyte Agathophora alopecuroides: Promising candidates for stimulating ceramide synthesis.

The phytochemical study of Agathophora alopecuroides (Chenopodiaceae) led to the isolation of previously undescribed glucosylceramide, flavonol triglycoside, and triterpene oleanane saponin, together with eight known compounds. Their structures were elucidated using NMR analysis and HR-MS as (2'R, 12E) N-[(2S, 3S, 4R)-1-(ß-D-glucopyranosyloxy)-3,4-dihydroxy-octadec-2-yl]-2-hydroxytetracos-12-enamide, namely Agathophamide A; isorhamnetin-3-O-[ß-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→6)]-ß-D-galactopyranoside, namely Agathophoroside A; and 3-O-[4'-(ß-D-xylopyranosyl)-ß-D-glucuronopyranosyl]-28-O-ß-D-glucopyranosyl-olean-12-en-3ß-ol-28-oic acid, namely Solysaponin A. We evaluated the effect of extract and isolates on ceramide levels via the up-regulated expression of the enzyme for ceramide synthesis in HaCaT keratinocytes. Interestingly, the study results revealed that the methanol extract of A. alopecuroides, together with some isolated compounds significantly up-regulated the mRNA expression of ceramide synthase-3 by 1.2- to 4.3-fold compared with the control in HaCaT cells. These findings indicate that the halophyte A. alopecuroides is a promising source of candidate compounds that can contribute to ceramide synthesis via the up-regulated expression levels of ceramide synthase-3 in the ceramide synthesis pathway.

Effects of dietary dihydromyricetin supplementation on intestinal barrier and humoral immunity in growing-finishing pigs.

In this study, we investigated the effect of dietary dihydromyricetin (DHM) supplementation on intestinal barrier and humoral immunity in growing-finishing pigs. The data showed that dietary DHM supplementation improved jejunal barrier function by upregulating the protein expressions of Occludin and Claudin-1 and the mRNA levels of MUC1 and MUC2. Dietary DHM supplementation increased the amylase, lipase, sucrase and maltase activities and the mRNA expression of nutrient transporter (SGLT1, GLUT2, PepT1) in the jejunum mucosa. Dietary DHM supplementation significantly reduced the E. coli population in the cecum and colon and increased the Lactobacillus population in the cecum. In addition, dietary DHM supplementation increased the contents of butyric acid and valeric acid in cecum and colon. In serum, dietary DHM supplementation reduced interleukin-1ß (IL-1ß) content and increased interleukin-10 (IL-10), Immunoglobulin M (IgM) and Immunoglobulin A (IgA) contents (p < 0.05). In addition, compared with the control group, dietary DHM supplementation improved secretory immunoglobulin A (sIgA) and interleukin-10 (IL-10) contents and down-regulated TNF-α protein expression in jejunum mucosa (p < 0.05). Together, this study demonstrated that dietary DHM supplementation improved intestinal barrier function, digestion and absorption capacity and immune function in growing-finishing pigs.

O-methylated flavonol as a multi-kinase inhibitor of leukemogenic kinases exhibits a potential treatment for acute myeloid leukemia.

BACKGROUND: Acute myeloid leukemia (AML) is a heterogeneous disease with poor overall survival characterized by various genetic changes. The continuous activation of oncogenic pathways leads to the development of drug resistance and limits current therapeutic efficacy. Therefore, a multi-targeting inhibitor may overcome drug resistance observed in AML treatment. Recently, groups of flavonoids, such as flavones and flavonols, have been shown to inhibit a variety of kinase activities, which provides potential opportunities for further anticancer applications. PURPOSE: In this study, we evaluated the anticancer effects of flavonoid compounds collected from our in-house library and investigated their potential anticancer mechanisms by targeting multiple kinases for inhibition in AML cells. METHODS: The cytotoxic effect of the compounds was detected by cell viability assays. The kinase inhibitory activity of the selected compound was detected by kinase-based and cell-based assays. The binding conformation and interactions were investigated by molecular docking analysis. Flow cytometry was used to evaluate the cell cycle distribution and cell apoptosis. The protein and gene expression were estimated by western blotting and qPCR, respectively. RESULTS: In this study, an O-methylated flavonol (compound 11) was found to possess remarkable cytotoxic activity against AML cells compared to treatment in other cancer cell lines. The compound was demonstrated to act against multiple kinases, which play critical roles in survival signaling in AML, including FLT3, MNK2, RSK, DYRK2 and JAK2 with IC50 values of 1 - 2 µM. Compared to our previous flavonoid compounds, which only showed inhibitions against MNKs or FLT3, compound 11 exhibited multiple kinase inhibitory abilities. Moreover, compound 11 showed effectiveness in inhibiting internal tandem duplications of FLT3 (FLT3-ITDs), which accounts for 25% of AML cases. The interactions between compound 11 and targeted kinases were investigated by molecular docking analysis. Mechanically, compound 11 caused dose-dependent accumulation of leukemic cells at the G0/G1 phase and followed by the cells undergoing apoptosis. CONCLUSION: O-methylated flavonol, compound 11, can target multiple kinases, which may provide potential opportunities for the development of novel therapeutics for drug-resistant AMLs. This work provides a good starting point for further compound optimization.

Targeting Cardiovascular Diseases by Flavonols: An Update.

Flavonols are one of the most plentiful flavonoid subclasses found in natural products and are extensively used as dietary supplements. Numerous in vitro and in vivo studies have shown the cardioprotective properties of flavonols, especially quercetin. This group of substances exerts positive impacts primarily due to their antiatherogenic, antithrombotic, and antioxidant activities. The potential of flavonols to promote vasodilation and regulation of apoptotic processes in the endothelium are other beneficial effects on the cardiovascular system. Despite promising experimental findings, randomized controlled trials and meta-analyses have yielded inconsistent results on the influence of these substances on human cardiovascular parameters. Thus, this review aims to summarize the most recent clinical data on the intake of these substances and their effects on the cardiovascular system. The present study will help clinicians and other healthcare workers understand the value of flavonol supplementation in both subjects at risk for cardiovascular disease and patients with cardiovascular diseases.

Anti-osteoporosis Effect of Fisetin against Ovariectomy Induced Osteoporosis in Rats: In silico, in vitro and in vivo Activity.

Osteoporosis is a bone related disease that is characterised by bone loss that further increases the susceptibility to bone fractures and bone frailty due to disturbances in the micro-architecture of bone tissue. Fisetin (flavonoids) exhibited anti-inflammatory and antioxidative stress effects against various diseases. In this protocol, we make an effort to comfort the anti-osteoporosis effect of fisetin against ovariectomy (OVX) induced osteoporosis. A docking study of fisetin and alendronate on the estrogen (α and ß) and vitamin D receptors was carried out. SaOS-2 (osteoblast like human) cells were used for the estimation of cell proliferation. The OVX induced OVX model was used and three doses of fisetin and alendronate was given to rats till 16 weeks. The hormone levels, bone turnover markers and biochemical parameters were estimated. Fisetin was docked into estrogen (α and ß) and vitamin D receptors, resulting in stable complexes with lower binding scores. Fisetin significantly (p < 0.001) exhibited the induction of cell proliferation against the SaOS-2 cells. OVX induced osteoporosis rats exhibited a suppression of body weight and uterus index, after the Fisetin treatment. Fisetin treatment significantly (p < 0.001) improved the level of bone mineral content (BMC), bone mineral density (BMD) and biochemical parameters such as energy, maximum load, stiffness, young modules, maximum stress and reduced the level of 1,25(OH) 2 D3 and E 2 . Fisetin treatment significantly (p < 0.001) declined the level of phosphorus (P), calcium (Ca) and boosted the level of VitD. Fisetin treatment significantly (p < 0.001) reduced the malonaldehyde (MDA) level and enhanced the glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) level in the bone, intestine and hepatic tissue. Fisetin treatment suppressed the cytokines, RANKL/OPG ratio, receptor activator of nuclear factor-κB ligand (RANKL) and improved the level of osteoprotegerin (OPG). The findings suggest that fisetin could be a beneficial phytoconstituent for the treatment and prevention of postmenopausal osteoporotic complications.

Rhamnazin suppresses melanosome transport by promoting the ubiquitin-mediated proteasomal degradation of melanophilin.

BACKGROUND: Melanosomes are intracellularly transported from the perinuclear region to the cell periphery and then to neighboring keratinocytes. We recently reported that the flavonoid rhamnazin suppresses melanosomal transport within pigment cells, yet the action mechanism remained unclear. OBJECTIVE: Our aim was to elucidate how rhamnazin influences the intracellular transport of melanosomes. METHODS: A melanosome distribution assay and immunostaining were performed using B16F10 mouse melanoma cells and normal human epidermal melanocytes, respectively. Expression levels of melanosome transport-related proteins, including melanophilin (MLPH), RAB27A, and myosin VA (MYO5A), were analyzed by immunoblotting. Ubiquitinated MLPH was detected using a commercial ubiquitin detection kit. To investigate the interaction between rhamnazin and MLPH, we prepared rhamnazin conjugated with magnetic FG beads. RESULTS: Immunoblotting analysis revealed that rhamnazin specifically reduces the expression of MLPH but not RAB27A or MYO5A proteins. The ubiquitin detection assay, which made use of a proteasome inhibitor, showed that MLPH accumulated as a polyubiquitinated protein after treatment with rhamnazin. We speculated that the affinity of rhamnazin for the components of the melanosome transport-related tripartite complex may alter the stability of the formation of the tripartite assembly. By using affinity-based techniques with B16F10 whole cell lysates or recombinant MLPH and RAB27A proteins, we revealed the interaction of rhamnazin with the components of the tripartite complex. CONCLUSION: We found that rhamnazin inhibits intracellular transport of melanosomes through proteasomal degradation of MLPH. Our results suggest that topical application of rhamnazin may provide a new approach for treating skin pigmentation disorders.