Profiling of Antidiabetic Bioactive Flavonoid Compounds from an Edible Plant Kudzu (Pueraria lobata).

Pueraria lobata (Willd.) Ohwi, known as kudzu and used as a "longevity powder" in China, is an edible plant which is rich in flavonoids and believed to be useful for regulating blood sugar and treating diabetes, although the modes of action are unknown. Here, a total of 53 flavonoids including 6 novel compounds were isolated from kudzu using multidimensional preparative liquid chromatography. The flavonoid components were found to lower blood sugar levels, promote urine sugar levels in mice, and reduce the urine volume. Molecular docking and in vitro assays suggested that the antidiabetic effect of kudzu was attributed to at least three targets: sodium-dependent glucose transporter 2 (SGLT2), protein tyrosine phosphatase-1B (PTP1B), and alpha-glucosidase (AG). This study suggests a possible mechanism for the antidiabetic effect that may involve the synergistic action of multiple active compounds from kudzu.

Inhibition and disaggregation effect of flavonoid-derived carbonized polymer dots on protein amyloid aggregation.

In this research, four water-insoluble flavonoid compounds were utilized and reacted with arginine to prepare four carbonized polymer dots with good water-solubility in a hydrothermal reactor. Structural characterization demonstrated that the prepared carbonized polymer dots were classic core-shell structure. Effect of the prepared carbonized polymer dots on protein amyloid aggregation was further investigated using hen egg white lysozyme and human lysozyme as model protein in aqueous solution. All of the prepared carbonized polymer dots could retard the amyloid aggregation of hen egg white lysozyme and human lysozyme in a dose-depended manner. All measurements displayed that the inhibition ratio of luteolin-derived carbonized polymer dots (CPDs-1) was higher than that of the other three carbonized polymer dots under the same dosage. This result may be interpreted by the highest content of phenolic hydroxyl groups on the periphery. The inhibition ratio of CPDs-1 on hen egg white lysozyme and human lysozyme reached 88 % and 83 % at the concentration of 0.5 mg/mL, respectively. CPDs-1 also could disaggregate the formed mature amyloid fibrils into short aggregates.

Regulation Mechanism of Phenolic Hydroxyl Number on Self-Assembly and Interaction between Edible Dock Protein and Hydrophobic Flavonoids.

In this study, galangin (Gal), kaempferol (Kae), quercetin (Que), and myricetin (Myr) were chosen as the representative flavonoids with different phenolic hydroxyl numbers in the B-ring. The edible dock protein (EDP) was chosen as the new plant protein. Based on this, the regulation mechanism of the phenolic hydroxyl number on the self-assembly behavior and molecular interaction between EDP and flavonoid components were investigated. Results indicated that the loading capacity order of flavonoids within the EDP nanomicelles was Myr (10.92%) > Que (9.56%) > Kae (6.63%) > Gal (5.55%). Moreover, this order was consistent with the order of the hydroxyl number in the flavonoid's B ring: Myr (3) > Que (2) > Kae (1) > Gal (0). The micro morphology exhibited that four flavonoid-EDP nanomicelles had a core-shell structure. In the meantime, the EDP encapsulation remarkably improved the flavonoids' water solubility, storage stability, and sustained release characteristics. During the interaction of EDP and flavonoids, the noncovalent interactions including van der Waals forces, hydrophobic interaction, and hydrogen bonding were the main binding forces. All of the results demonstrated that the hydroxyl number of bioactive compounds is a critical factor for developing a delivery system with high loading ability and stability.

Integrative Analysis of the Metabolome and Transcriptome Provides Insights into the Mechanisms of Flavonoid Biosynthesis in Quinoa Seeds at Different Developmental Stages.

Quinoa (Chenopodium quinoa Willd.) is a crop with high nutritional and health benefits. Quinoa seeds are rich in flavonoid compounds; however, the mechanisms behind quinoa flavonoid biosynthesis remain unclear. We independently selected the high-generation quinoa strain 'Dianli-3260', and used its seeds at the filling, milk ripening, wax ripening, and mature stages for extensive targeted metabolome analysis combined with joint transcriptome analysis. The results showed that the molecular mechanism of flavonoid biosynthesis in quinoa seeds was mainly concentrated in two pathways: "flavonoid biosynthesis pathway" and "flavone and flavonol biosynthesis pathway". Totally, 154 flavonoid-related metabolites, mainly flavones and flavonols, were detected in the four development stages. Moreover, 39,738 genes were annotated with KEGG functions, and most structural genes of flavonoid biosynthesis were differentially expressed during grain development. We analyzed the differential flavonoid metabolites and transcriptome changes between the four development stages of quinoa seeds and found that 11 differential flavonoid metabolites and 22 differential genes were the key factors for the difference in flavonoid biosynthesis. This study provides important information on the mechanisms underlying quinoa flavonoid biosynthesis, the screening of potential quinoa flavonoid biosynthesis regulation target genes, and the development of quinoa products.

Intestinal Flora Mediates Antiobesity Effect of Rutin in High-Fat-Diet Mice.

SCOPE: Intestinal flora plays a critical role in the development of . Rutin is a natural flavonoid with potential prebiotic effects on regulating the intestinal flora composition that is beneficial for host health. Therefore, this study hypothesizes that rutin supplementation has beneficial effects on high-fat-diet (HFD)-induced obesity and metabolic disorder through the modulation of intestinal flora in mice. METHODS AND RESULTS: The obesity-alleviating property of rutin using 6-week-old C57BL/6J male mice fed on HFD with or without rutin supplementation for 16 weeks is investigated. Rutin supplementation effectively reduces body-weight gain, insulin resistance, and acted favorably on the intestinal barrier, thereby reducing endotoxemia and systemic inflammation. Sequencing of 16S rRNA genes from fecal samples indicate that rutin exerted modulatory effects on HFD-induced intestinal flora disorders (e.g., rutin decreased Firmicutes abundance and increased Bacteroidetes and Verrucomicrobia abundance). Antibiotic treatment and fecal microbiota transplantation further demonstrate that the salutary effects of rutin on obesity control are strongly dependent on the intestinal flora. CONCLUSION: Rutin can be considered as a prebiotic agent for improving intestinal flora disorders and obesity-associated metabolic perturbations in obese individuals.

[Determination of flavonoids in honey by solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry method].

OBJECTIVE: To establish a method for simultaneous determination of 20 flavonoid compounds from honey samples using solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS), which was applied to study the difference of flavonoid compounds in honey samples from different botanical origins. METHODS: The honey samples were extracted with ultra-water solution by ultrasound, and purified with an Oasis MAX column, and then separated on a Waters ACQUITY UPLC HSS T3(2. 1 mm×100 mm, 1. 8 µm) and eluted with the mobile phase consisted of 0. 1% formic acid in water and acetonitrile in a gradient program, and analyzed by mass spectrometry equipped with an electrospray ionization source, operating in the positive or negative ionization modes, and performed in the multiple reaction monitoring using external standards. RESULTS: Twenty flavonoid compounds showed good linearity with coefficients higher than 0. 9969; The recoveries of spiked honey samples in the range of 76. 2%-108. 6% at the concentrations of 100, 250 and 500 µg/L; The relative standard deviations were 0. 50%-4. 34% and 2. 51%-6. 71%(n=6)for inter-day and intra-day precisions, respectively. It was found that the variations of flavonoid compounds in 16 types of honey samples from different botanical origins differed largely. Among them, quercetrin content in fennel honey was the highest(165 ng/g). High contents of luteolin in red eucalyptus and manuka honey were 186 ng/g and 304 ng/g, respectively. High contents of kaempferol in buckwheat, fennel and manuka honeys were from 113 to 257 ng/g. High contents of chrysin in snow lotus honey, manuka, sunflower honey and lavender Honey were from 136 to 213 ng/g. The content of pinocembrin(473 ng/g) and pinobanksin(684 ng/g) in manuka honey were much higher than that in other honeys. CONCLUSION: The proposed method is simple for pretreatment, also sensitive, accurate and producible for quantitative of 20 flavonoid compounds in different honey samples, which provide more scientific data and application basis for quality analysis.

Subtype-selective inhibition of acid-sensing ion channel 3 by a natural flavonoid.

AIMS: Acid-sensing ion channels (ASICs) are extracellular proton-gated cation channels that have been implicated in multiple physiological and pathological processes, and peripheral ASIC3 prominently participate into the pathogenesis of chronic pain, itch, and neuroinflammation, which necessitates the need for discovery and development of novel modulators in a subtype-specific manner. METHODS: Whole-cell patch clamp recordings and behavioral assays were used to examine the effect of several natural compounds on the ASIC-mediated currents and acid-induced nocifensive behavior, respectively. RESULTS: We identified a natural flavonoid compound, (-)-epigallocatechin gallate (EGCG, compound 11), that acts as a potent inhibitor for the ASIC3 channel in an isoform-specific way. The compound 11 inhibited ASIC3 currents with an apparent half maximal inhibitory concentration of 13.2 µmol/L when measured at pH 5.0. However, at the concentration up to 100 µmol/L, the compound 11 had no significant impacts on the homomeric ASIC1a, 1b, and 2a channels. In contrast to most of the known ASIC inhibitors that usually bear either basic or carboxylic groups, the compound 11 belongs to the polyphenolic family. In compound 11, both the chirality and the 3-hydroxyl group of its pyrogallol part, in addition to the integrity of the gallate part, are crucial for the inhibitory efficacy. Finally, EGCG was found significantly to decrease the acid-induced nocifensive behavior in mice. CONCLUSION: Taken together, these results thus defined a novel backbone structure for small molecule drug design targeting ASIC3 channels to treat pain-related diseases.

Luteolin-mediated PI3K/AKT/Nrf2 signaling pathway ameliorates inorganic mercury-induced cardiac injury.

Inorganic mercury is a toxic metal of worldwide concern, and causes serious cardiac injury. However, effective treatment for cardiac injury induced by mercuric chloride (HgCl2) has not been fully identified. Luteolin (Lut) is a novel natural antioxidant. This study aimed to investigate the role of Lut on HgCl2-induced cardiac injury. Male Wistar rats were randomly assigned to 4 groups, control, Lut (80 mg/kg intragastrically), HgCl2 (80 mg/L, in drinking water), and HgCl2 + Lut groups. The results indicated that Lut significantly ameliorated cardiac histopathological damage, oxidative stress, and apoptosis induced by HgCl2 in the rat heart. Furthermore, Lut evidently increased levels of phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and nuclear factor-erythroid-2-related factor 2 (Nrf2) and its downstream proteins, and inhibited NF-κB activation in the heart of rats treated by HgCl2. Taken together, our findings suggest that activating PI3K/AKT/Nrf2 signaling pathway is involved in the protective effect of Lut against HgCl2-induced cardiac damage.

Effects and mechanism of programmed cell death of human gastric cancer cell under the treatment of flavonoid compound GL-V9 / 中国药科大学学报

@#To investigate the apoptotic effect of flavonoid compound GL-V9 on human gastric cancer cells and its potential mechanism, MGC-803 and BGC-823 cells were treated with GL-V9. MTT assay was performed to assess the growth inhibition effects on MGC-803 and BGC-823 cells under different concentrations of GL-V9. Annexin V-FITC/PI staining assay was employed to observe the apoptotic rate of GL-V9 cells with the treatment of GL-V9. DAPI staining was performed to observe the nuclear morphological changes using fluorescence microscopy. Activation of caspase-9 and caspase-3 was analyzed by Western blotting. Ca2+ concentration in gastric cancer cells was detected by Fluo-3 AM staining assay. Results showed that GL-V9 could inhibitcell viability, change the nuclear morphologyl, activate caspase-9 and caspase-3 and induce the apoptosis in gastric cancer cells. The mechanism of the induction of apoptosis in MGC-803 cells under the treatment of GL-V9 may aetivate the Ca2+ associated mitochondrial apoptosis pathway.

Optimization of extraction of antioxidants from wheat bran (Triticum spp.) using response surface methodology.

In this study, the optimal conditions for the extraction of antioxidants from hard winter wheat bran (WH711) were determined using response surface methodology (RSM). A central composite face centred design was used to investigate the effects of three independent variables, namely solvent composition (%v/v), extraction temperature (°C) and time (minutes) on the responses; free phenolic content (FPC), total flavonoid content (TFC), total antioxidant activity (TAA), ferric reducing power (FRP), hydrogen peroxide scavenging activity (HPSA). Regression analysis showed that more than 90% of the variation was explained by the models of different responses. The optimal conditions for the antioxidantss extraction were found to be methanol concentration of 85%v/v, extraction temperature of 75 °C, extraction time of 45 min, for wheat bran. The experimental values of FPC, TFC, TAA, FRP and HPSA were 0.921 mg GAE/g bran (B), 0.4588 mg CE/g B, 0.01408 mM AAE/g B, 2.532 mM AAE/g B and 3.193 mM TE/g B, respectively which agreed with those predicted, thus indicating suitability of the model employed and the suitability of RSM in optimizing the extraction conditions.