Major Flavonoid Research Articles

Flavonoids from the leaves and stems of Rhodiola ishidae (Crassulaceae)

Twenty-six flavonoids including flavonols, C-glycosylflavones, flavanone and anthocyanin were isolated from the leaves and stems of Rhodiola ishidae. Major flavonoids were flavonol glycosides based on herbacetin, gossypetin, kaempferol and quercetin, and identified by UV spectral survey, HR-MS, LC-MS, acid hydrolysis, NMR and/or HPLC and TLC comparisons with authentic samples. Of these flavonoids, three compounds, herbacetin 7-O-glucuronopyranoside-8-O-glucopyranoside, gossypetin 3-O-(2''-malonylxylopyranoside)-8-O-glucopyranoside and naringenin 7-O-sophoroside, were reported in nature for the first time. Flavonoid characters of R. ishidae were chemotaxonomically discussed.

TESTING AND EVALUATION OF BIOACTIVE COMPOUNDS IN SOYBEAN

This study was aimed to estimate the antioxidants, antibacterial, and antifungal activities of methanolic extract from soybean seeds against pathogenic microorganisms. The methanolic extract was prepared from defatted soybean flour. Total phenolics content (TPC), total flavonoid content (TFC), and the major phenolic, flavonoid, and isoflavone compounds in soybean extract were estimated by HPLC. On the other hand, biological activities such as antioxidants, antibacterial, and antifungal activities were evaluated. The value of phenolic compounds was 8.59 mg GAE/g extract, while the value of flavonoids was 0.82 mg QE/g extract. The chemicals listed below were chromatographed and identified: syringic acid, quercetin, gallic acid, benzoic acid, genistein, daidzein, p-coumaric acid, glycitein, and ferulic acid. The methanolic extract showed the antibacterial and antifungal activity against tested microorganisms. Considering the results, it is possible to employ the methanolic extract from soybean seeds, which is rich in phenolic chemicals, as an antioxidant, antibacterial, and antifungal agent. It functions well as a pure, natural product.

Narirutin exerts anti-inflammatory activity by inhibiting NLRP3 inflammasome activation in macrophages.

Citrus peel has long been used in traditional medicine in Asia to treat common cold, dyspepsia, cough, and phlegm. Narirutin-a flavanone-7-O-glycoside-is the major flavonoid in citrus peel, and has anti-oxidative, anti-allergic, and anti-inflammatory activities. However, the anti-inflammatory mechanism of narirutin has not been fully elucidated. This study is aimed to investigate the effects of narirutin on the Nod-like receptor protein 3 (NLRP3)-mediated inflammatory response in vitro and in vivo, and determine the underlying mechanism. THP-1 differentiated macrophages and bone marrow-derived macrophages (BMDMs) were used for in vitro experiments, while dextran sulfate sodium (DSS)-induced colitis and alum-induced peritonitis mouse models were constructed to test inflammation in vivo. Narirutin suppressed secretion of interleukin (IL)-1β and pyroptosis in lipopolysaccharide (LPS)/ATP-stimulated macrophages. Narirutin decreased the expression of NLRP3 and IL-1β in the LPS-priming step through inhibition of NF-κB, MAPK and PI3K /AKT signaling pathways. Narirutin inhibited NLRP3-ASC interaction to suppress NLRP3 inflammasome assembly. Furthermore, oral administration of narirutin (300 mg/kg) alleviated inflammation symptoms in mice with peritonitis and colitis. These results suggest that narirutin exerts its anti-inflammatory activity by suppressing NLRP3 inflammasome activation via inhibition of the NLRP3 inflammasome priming processes and NLRP3-ASC interaction in macrophages.

Extraction and identification of new flavonoid compounds in dandelion Taraxacum mongolicum Hand.-Mazz. with evaluation of antioxidant activities

Due to the interest in the potential pharmacological application of dandelion, the chemical constituents and activities of Taraxacum mongolicum Hand.-Mazz were studied. Box–Behnken response surface methodology was employed to optimize the protocol for extraction of flavonoid from dandelion. The molecular structures of different flavonoid compounds were acquired and analyzed by liquid chromatography-mass spectrometry (LC–MS) and nuclear magnetic resonance (NMR) spectroscopy. Several major flavonoid compounds were isolated and purified, namely, hesperetin-5′-O-β-rhamnoglucoside, hesperetin-7-glucuronide, kaempferol-3-glucoside, baicalein, hyperseroside, which were extracted for the first time from dandelion. Hesperetin-5′-O-β-rhamnoglucoside was identified as a new type of flavonoid that had never reported in the literature. This new flavonoid has outstanding antioxidant activity, as shown by its IC50 value (8.72 mg/L) for scavenging DPPH free radicals. The determination of the structure-related antioxidant activities could be interpreted based on DFT calculations. As such, we have not only illustrated the rich flavonoid contents in Taraxacum mongolicum Hand.-Mazz, but also revealed new types of flavonoid compounds in dandelion in terms of structure and antioxidant properties.

Differential distribution of phytochemicals in Scutellariae Radix and Scutellariae Amoenae Radix using microscopic mass spectrometry imaging

Scutellariae Radix, the root of Scutellaria baicalensis Georgi, is widely applied in China for the treatment of fever, ulcer, bronchitis, hepatitis and inflammatory symptoms. Sctuellariae Amoenae Radix, the root of Scutellaria amoena C.H. Wright, is often prescribed as the substitute for Scutellariae Radix. Up to now, no attempt has been made to unveil and compare the localization of phytochemicals in Scutellariae Radix and its succedaneum. This investigation succeeded to look into the differential distribution of natural compounds in Scutellariae Radix and Scutellariae Amoenae Radix using microscopic mass spectrometry imaging. Compounds presenting different distribution modes in two kinds of roots were sorted out, then a quick method for the differentiation between Scutellariae Radix and Scutellariae Amoenae Radix was established. Accumulation sites of baicalein, baicalin, wogonin and wogonoside in Scutellariae Radix were also uncovered using microscopic mass spectrometry imaging. Moreover, the application of matrix assisted laser desorption ionization-quadrupole-time of flight mass spectrometry allowed the on-tissue dissociation of major flavonoids. Overall, the utilization of microscopic mass spectrometry imaging and matrix assisted laser desorption ionization-quadrupole-time of flight mass spectrometry provided a novel perspective for the discovery of natural compounds within medicinal plants.

Probing behavior of Aphis fabae and Myzus persicae on three species of grapevines with analysis of grapevine leaf anatomy and allelochemicals

The peach-potato aphid Myzus persicae (Sulzer) and the black bean aphid Aphis fabae Scopoli are polyphagous and cosmopolitan hemipterans, therefore they can infest grapevines in all areas of cultivation. Electrical Penetration Graph (EPG) technique was applied to monitor the probing behavior of A. fabae and M. persicae on Vitis amurensis Rupr., Vitis riparia Michaux, and Vitis vinifera L. The content of major flavonoids and stilbenoids in grapevine leaves and epidermal thickness, distance between abaxial leaf surface and phloem, and the simulated shortest pathway from epidermis to phloem that might have affected aphid probing were also analyzed. Aphid probing was limited mainly to non-vascular tissues on the three studied grapevine species. Phloem phase occurred in 32%, 14%, and 6% of A. fabae and in 76%, 39%, and 74% of M. persicae on V. amurensis, V. riparia and V. vinifera, respectively. Phloem phase consisted of only salivation into sieve elements and lasted less than 2.5 minutes on average in all aphids. The time to reach the first phloem phase on grapevines was 5.0 hours in A. fabae and 2.6–3.6 hours in M. persicae. Of the analyzed flavonoids, catechin, epicatechin, and quercetin occurred in all grapevine species, while rutin – in V. amurensis and V. riparia and isorhamnetin only in V. amurensis. Of the analyzed stilbenoids, piceid occurred in all grapevines, resveratrol in V. amurensis and V. vinifera, and ε-viniferin only in V. vinifera. Aphid behavior demonstrated that V. amurensis, V. riparia and V. vinifera are not attractive host plants to A. fabae and M. persicae. It is likely that the content of flavonoids and stilbenoids contributes to the limited susceptibility of the three grapevine species to A. fabae and M. persicae, while the observed slight differences in the anatomical structure of the leaves seem not significant in this context.

Quercetin protects against iron overload-induced osteoporosis through activating the Nrf2/HO-1 pathway

AimsEucommia is the tree bark of Eucommia japonica, family Eucommiaceae. In traditional Chinese medicine, Eucommia is often used to treat osteoporosis. Quercetin (QUE), a major flavonoid extract of Eucommia japonica, has been reported to have anti-osteoporosis effects. However, there are no studies reporting the mechanism of QUE in the treatment of iron overload-induced osteoporosis. This study set out to investigate the therapeutic effects of QUE against iron overload-induced bone loss and its potential molecular mechanisms. Materials and methodsIn vitro, MC3T3-E1 cells were used to study the effects of QUE on osteogenic differentiation, anti-apoptosis and anti-oxidative stress damage in an iron overload environment (FAC 200 μM). In vivo, we constructed an iron overload mouse model by injecting iron dextrose intraperitoneally and assessed the osteoprotective effects of QUE by Micro-CT and histological analysis. Key findingsIn vitro, we found that QUE increased the ALP activity of MC3T3-E1 cells in iron overload environment, promoted the formation of bone mineralized nodules and upregulated the expression of Runx2 and Osterix. In addition, QUE was able to reduce FAC-induced apoptosis and ROS production, down-regulated the expression of Caspase3 and Bax, and up-regulated the expression of Bcl-2. In further studies, we found that QUE activated the Nrf2/HO-1 signaling pathway and attenuated FAC-induced oxidative stress damage. The results of the in vivo study showed that QUE was able to reduce iron deposition induced by iron dextrose and attenuate bone loss. SignificanceOur results suggested that QUE protects against iron overload-induced osteoporosis by activating the Nrf2/HO-1 signaling pathway.

Oroxylin A inhibited autoimmune hepatitis-induced liver injury and shifted Treg/Th17 balance to Treg differentiation.

Autoimmune hepatitis (AIH) is a kind of autoimmune disease mediated by T cells, and its incidence is gradually increasing in the world. Oroxylin A (OA) is one of the major bioactive flavonoids that has been reported to inhibit inflammatory. Here, an AIH model of mouse was induced by Concanavalin A (Con A). It found that serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were decreased in mice with the treatment of OA. Hematoxylin-eosin staining showed that the liver injury was attenuated by OA, and TUNEL staining indicated that the cells apoptosis of liver was weakened in mice with OA treatment. ELISA analysis of cytokines and chemokines suggested that OA reduced the expression of IL-6, IL-17A, chemokine ligand 2 (CCL2), C-X-C motif chemokine ligand 1 (CXCL1) and CXCL10, but promoted the expression of IL-10 and TGF-β in mice. The mRNA levels of Il-17a in liver and spleen tissues were also significantly decreased, on the contrary, the mRNA levels of Il-10 in liver and spleen tissues were increased. The proportion of Treg/Th17 detected by flow cytometry revealed that OA promoted the differentiation of Treg and inhibited the differentiation of Th17 both in the liver and spleen. The results of this study demonstrated the inhibitory effects of OA on AIH-induced liver injury and the inflammatory response of AIH, and revealed that OA affected the balance of Treg/Th17 and shifted the balance toward Treg differentiation. It provided new potential drugs for the prevention of AIH.

Hesperetin attenuates sepsis-induced intestinal barrier injury by regulating neutrophil extracellular trap formation via the ROS/autophagy signaling pathway.

Background: Hesperetin (HES), one of the major flavonoids that has various biological activities, such as anti-inflammatory and antioxidant activities, may preserve the intestinal barrier during sepsis. However, the detailed mechanism remains unclear. Our previous studies confirmed that neutrophil extracellular traps (NETs) may jeopardize the intestinal barrier via a reactive oxygen species (ROS)-dependent pathway during sepsis. Therefore, we hypothesized that HES may inhibit NET formation and protect the intestinal barrier function during sepsis. Methods: Mice were pretreated with HES (50 mg kg-1) intraperitoneally for one week, and sepsis models were then induced using lipopolysaccharides (LPS) (10 mg kg-1). The mice were randomly divided into three groups: (1) sham group; (2) LPS group; and (3) HES + LPS group. Twenty-four hours after LPS injection, the serum and terminal ileum specimens were collected for subsequent studies. To detect ROS production and NET formation in vitro, human neutrophils were collected and incubated with phorbol-12-myristate-13-acetate (PMA) and various concentrations of HES. The level of autophagy was measured by an immunofluorescence assay and western blot analysis. TUNEL staining was utilized to analyze cell apoptosis. Results: The outcomes demonstrated that HES decreased inflammatory cytokine and myeloperoxidase (MPO) levels in serum and attenuated distant organ dysfunction in LPS-induced septic mice. Meanwhile, HES treatment reversed intestinal histopathological damage in septic mice, improving intestinal permeability and enhancing tight junction expression. Moreover, we found that neutrophil infiltration and NET formation in the intestine were suppressed during sepsis after HES pretreatment. In vitro, HES treatment reduced PMA-induced ROS production and NET formation, which were reversed by hydrogen peroxide (H2O2) administration. Notably, HES also inhibited NET formation by reducing the microtubule-associated protein light chain 3 (LC3)-II/LC3-I ratio (an indicator of autophagy) in PMA-induced neutrophils, which was reversed by rapamycin. Moreover, when autophagy was suppressed by chloroquine or induced by rapamycin, apoptosis in cells will be switched with autophagy. Conclusion: Taken together, these findings suggest that HES may inhibit NET formation in a ROS/autophagy-dependent manner and switch neutrophil death from NETosis to apoptosis, which reduced NETs-related intestinal barrier damage, providing a novel protective role in intestinal barrier dysfunction during sepsis.

One stage hydrothermal treatment: A green strategy for simultaneous extraction of food hydrocolloid and co-products from sweet lime (Citrus Limetta) peels

The present study is focused on the potential of one stage hydrothermal (HT) treatment using water as a solvent for the simultaneous extraction of pectin and phenols from sweet lime (Citrus Limetta) peels. The effect of temperature (100–120 °C); time (5–25 min) and liquid to solid ratio (LSR) (10–20) were investigated for optimizing the HT process using response surface methodology. The experiments were designed using the Box-Behnken method. The optimum conditions obtained for the highest yield of pectin (23.8%) and TPC (1.18%) were at 112.2 °C, 17.1 min and LSR 14.3. Deviations between predicted and experimental values were statistically insignificant (p > 0.05). The HT process yielded higher pectin and TPC with a significant reduction in extraction time as compared to the conventional extraction process (CSE) i.e., 22.4 and 0.46% of pectin and TPC in 1.5 and 20 h respectively. The HT extracts were characterized at the optimum processing conditions. The degree of esterification (%) and molecular weight (KDa) obtained for HT extract (71.2 ± 1.0 and 330.9) was close to that of commercial citrus pectin (76.6 ± 0.6 and 423.8). The major flavonoids identified (mg/g dw) in HT extract were kaempferol (0.84), rutin (0.82), quercetin (0.71), ferulic (0.46), caffeic (0.4) and gallic (0.31) acid and found to be higher than CSE. The higher antioxidant activity of HT extract was indicated by lower IC 50 (0.62 mg/mL), higher FRAP (37.3 μM/g dw) and ABTS (119.6 μM TE/g dw) values. These results demonstrate the suitability of HT as a one-step green extraction process for simultaneous recovery of pectin and phenols. • Simultaneous extraction of pectin and phenols using hydrothermal (HT) technique. • Citrus Limetta peel was used as substrate and water as a medium of extraction. • Highest pectin (23.8%) and phenol (1.2%) obtained at 112.2 °C, 17.1min and LSR 14.3 • HT yielded high methoxy pectin with molecular weight closer to commercial pectin. • DPPH, FRAP, and ABTS values indicated higher antioxidant potential of HT extract.

Comparative metabolomics of flavonoids in twenty vegetables reveal their nutritional diversity and potential health benefits

Vegetables are rich in flavonoids and are widely consumed in our daily life. However, comprehensive information on flavonoids components in vegetable varieties and the distribution of flavonoids with health-promoting effects in different vegetables are rarely investigated. Here, we analyzed the constitution of flavonoids among 20 vegetables by widely-targeted metabolome analysis. A total of 403 flavonoids were detected and classified as flavonoid, flavonols, anthocyanins, isoflavones, flavonoid carbonoside, dihydroflavone, chalcones, flavanols, dihydroflavonol, tannin, proanthocyanidins, and other flavonoids. Interestingly, we found that the content and types of flavonoids in bean sprouts and hot pepper were relatively abundant, whereas those were lower in carrot, lettuce, and Zizania latifolia. Then, we characterized the representative flavonoids including flavonoid, flavonols, chalcones, and isoflavones, and related them to the health-promoting effects of vegetables. Finally, we examined the relevance of the flavonoids to antioxidant capacity. Both bean sprouts and hot pepper possessed higher antioxidant enzyme activity, which were responsible for their great antioxidant capacity. Our study established a database of major flavonoids components in vegetables and further provides a new hint for the selection and breeding of vegetables based on their health-promoting effects.

Integrated metabolomics and transcriptomics analysis of roots of Bupleurum chinense and B. scorzonerifolium, two sources of medicinal Chaihu

Radix Bupleuri (Chaihu in Chinese) is a traditional Chinese medicine commonly used to treat colds and fevers. The root metabolome and transcriptome of two cultivars of B. chinense (BCYC and BCZC) and one of B. scorzonerifolium (BSHC) were determined and analyzed. Compared with BSHC, 135 and 194 differential metabolites were identified in BCYC and BCZC, respectively, which were mainly fatty acyls, organooxygen metabolites. A total of 163 differential metabolites were obtained between BCYC and BCZC, including phenolic acids and lipids. Compared with BSHC, 6557 and 5621 differential expression genes (DEGs) were found in BCYC and BSHC, respectively, which were annotated into biosynthesis of unsaturated fatty acid and fatty acid metabolism. A total of 4,880 DEGs existed between the two cultivars of B. chinense. The abundance of flavonoids in B. scorzonerifolium was higher than that of B. chinense, with the latter having higher saikosaponin A and saikosaponin D than the former. Pinobanksin was the most major flavonoid which differ between the two cultivars of B. chinense. The expression of chalcone synthase gene was dramatically differential, which had a positive correlation with the biosynthesis of pinobanksin. The present study laid a foundation for further research on biosynthesis of flavonoids and terpenoids of Bupleurum L.

Characterization of the Orange Juice Powder Co-Product for Its Valorization as a Food Ingredient.

The citrus juice industry produces a large amount of fiber-rich waste and other bioactive compounds of great interest for their potential health benefits. This study focuses on the valorization of the co-product resulting from the extraction of orange juice to offer it as a versatile, healthy, high-quality, and stable natural food ingredient in powder form. To this end, the vitamin C (VC) content (ascorbic and dehydroascorbic acid, AA and DHAA), major flavonoids (hesperidin and narirutin, HES and NAT), and techno-functional properties (angle of repose, AoR; hygroscopicity and wettability; density and porosity; mean particle size, MPS; water retention capacity, WRC; oil holding capacity, ORC; emulsifying and foaming capacity, EC and FC; and emulsion and foam stability, ES and FS) have been characterized. In addition, considering that dehydrated foods with high sugar content require the incorporation of high molecular weight biopolymers for their physical stabilization, the influence of starch modified with octenyl succinic acid (OSA) and gum Arabic (GA) on these properties has been studied. The results obtained confirm the high quality of this co-product to be offered as a powdered food ingredient with nutraceutical potential. The addition of the studied biopolymers is recommended as it does not modify the flowability of the powder and favors both the encapsulation of the bioactive compounds, especially in the presence of GA, and the rehydration capacity.

Citrus nutraceutical eriocitrin and its metabolites are partial agonists of peroxisome proliferator-activated receptor gamma (PPARγ): a molecular docking and molecular dynamics study

Peroxisome proliferator-activated receptor gamma (PPARγ) agonists are potent insulin sensitizers in treating type 2 diabetes. Despite being very effective in the fight against diabetes-mediated complications, PPARγ agonists are accompanied by severe side effects leading to complicated health problems, making the discovery of novel safe ligands highly pertinent. A significant intense research effort is in progress to explore the PPARγ activating potential of a wide range of natural compounds. Lemon (Citrus limon) contains various bioactive flavonoids, and eriocitrin is the major flavonoid. It possesses substantial antioxidant and anticancer, lipid-lowering activities and prevents obesity-associated metabolic diseases. Eriocitrin is metabolized to eriodictyol in the intestine, and the absorbed eriodictyol undergoes conversion to numerous metabolites in vivo. It is unclear if eriocitrin or its metabolites are responsible for their beneficial effects. We have used molecular docking, ADMET properties, drug-likeness score and molecular dynamics simulation study to find if eriocitrin and its metabolites are potent binders for PPARγ. Docking studies revealed that eriocitrin binds to PPARγ with the highest binding energy, but ADMET properties and in vivo studies show that the bioavailability of eriocitrin is very poor. Molecular dynamics studies were carried out to validate the docking results, and multiple parameters like RMSD, RMSF, Radius of gyration, SASA, hydrogen bond analysis, interaction energy, principal component analysis, Gibbs free energy and MM-PBSA were calculated. Based on our studies, eriodictyol, eriodictyol 7-O-glucuronide, eriodictyol 3′-O-glucuronide, homoeriodictyol and homoeriodictyol 7-O-glucuronide which are metabolites of eriocitrin appear to be potent partial agonists of PPARγ under physiological conditions. Communicated by Ramaswamy H. Sarma

Xanthine oxidase inhibitory potentials of flavonoid aglycones of Tribulus terrestris: in vivo, in silico and in vitro studies

BackgroundDespite the ongoing safety-driven spate of flavonoid xanthine oxidase (XOD) inhibition investigations, there is a lack of flavonoid-based uricostatic antihyperuricemic agents in clinical medicine. The poor pharmacokinetic profiles of glycosides (the natural form of existence of most flavonoids) relative to their aglycones could be largely responsible for this paradox. This investigation was aimed at providing both functional and molecular bases for the possible discovery of XOD inhibitory (or uricostatic) anti-hyperuricemic flavonoid aglycones from the leaves of a flavonoid-rich medicinal plant, Tribulus terrestris. To this end, the flavonoid aglycone fraction of T. terrestris leaf extract (FATT) was evaluated in vivo for antihyperuricemic activity in ethanol-induced hyperuricemic mice, monitoring serum and liver uric acid levels. Molecular docking and molecular dynamics simulation studies were carried out on the three major flavonoid aglycones of T. terrestris (isorhamnetin, quercetin and kaempferol) against an inhibitor conformation XOD model. The three flavonoids were also subjected to in vitro XOD activity assay, comparing their IC50 to that of allopurinol, a standard uricostatic antihyperuricemic drug.ResultsFATT significantly lowered serum uric acid (p < 0.0001) and liver uric acid (p < 0.05) levels of the experimental animals, implying anti-hyperuricemic activity with uricostatic action mechanism allusions. Molecular docking studies revealed high binding affinity values (− 7.8, − 8.1, − 8.2 kcal/mol) for the aglycones (isorhamnetin, quercetin and kaempferol, respectively). Radius of gyration and RMSD analyses of the molecular dynamics simulation trajectories of the three aglycone–XOD complexes revealed substantial stability, the highest stability being demonstrated by the kaempferol–XOD complex. In vitro XOD activity assay showed kaempferol (IC50: 8.2 ± 0.9 μg/ml), quercetin (IC50: 20.4 ± 1.3 μg/ml) and isorhamnetin (IC50: 22.2 ± 2.1 μg/ml) to be more potent than allopurinol (IC50: 30.1 ± 3.0 μg/ml).ConclusionThis work provides a scientific basis for the use of T. terrestris in the treatment of hyperuricemia-related (e.g. kidney stone and gout) disorders. It also provides the molecular basis for a focussed screening of the flavonoid aglycones chemical space for the possible discovery of flavonoid-based uricostatic anti-hyperuricemic drugs or drug templates.

Metabolomics combined with transcriptomics analyses of mechanism regulating testa pigmentation in peanut.

Peanut testa (seed coat) contains large amounts of flavonoids that significantly influence seed color, taste, and nutritional qualities. There are various colors of peanut testa, however, their precise flavonoid components and regulatory mechanism of pigmentation remain unclear. In this study, a total of 133 flavonoids were identified and absolutely quantified in the seed coat of four peanut cultivars with different testa color using a widely targeted metabolomic approach. Black peanut skin had more types and substantial higher levels of cyanidin-based anthocyanins, which possibly contribute to its testa coloration. Procyanidins and flavan-3-ols were the major co-pigmented flavonoids in the red, spot and black peanuts, while flavanols were the most abundant constitutes in white cultivar. Although the concentrations as well as composition characteristics varied, the content ratios of procyanidins to flavan-3-ols were similar in all samples except for white peanut. Furthermore, MYB-like transcription factors, anthocyanidin reductases (ANR), and UDP-glycosyltransferases (UGT) were found to be candidate genes involved in testa pigmentation via RNA-seq and weighted gene co-expression network analysis. It is proposed that UGTs and ANR compete for the substrate cyanidin and the prevalence of UGTs activities over ANR one will determine the color pattern of peanut testa. Our results provide a comprehensive report examining the absolute abundance of flavonoid profiles in peanut seed coat, and the finding are expected to be useful for further understanding of regulation mechanisms of seed coat pigmentation in peanut and other crops.

Health Effects of Soy Isoflavones and Green Tea Catechins on Cancer and Cardiovascular Diseases Based on Urinary Biomarker Levels.

Plant polyphenols have various health effects. Genistein, which is abundant in soybeans, and epigallocatechin-3-gallate, which is abundant in green tea, are major flavonoids, a subclass group of polyphenols. Several epidemiological studies have shown that these flavonoids have beneficial effects against cancer and cardiovascular diseases. However, other studies did not show such effects. Several confounding factors, including recall bias, are related to these inconsistent findings, and the determination of metabolites in the urine may be useful in reducing the number of confounding factors. Equipment, which can be used by research participants to collect samples from a portion of voided urine within 24 h without the help of medical workers, has been developed for epidemiological investigations. Previous studies, in which flavonoid metabolites in these urine samples were measured, revealed that soy intake was correlated with a reduced risk of certain types of cancer and cardiovascular diseases worldwide. Although soybeans and green tea consumption may have protective effects against cancer and cardiovascular diseases, further clinical studies that consider different confounding factors are required to provide evidence for the actual impact of dietary flavonoids on human diseases, including cancer and cardiovascular diseases. One possible mechanism involved is discussed in relation to the downregulation of reactive oxygen species and the upregulation of 5'-adenosine monophosphate-activated protein kinase elicited by these flavonoids.

Mechanism Underlying Naringenin Hypocholesterolemic Effects: Involvement of Estrogen Receptor α Subtype

Naringenin (Nar) is one of major citrus flavonoids predominantly found in grapefruit and orange. In vivo studies have demonstrated Nar potential as a normolipidemic agent capable to reduce circulating cholesterol in hypercholesterolemic rabbits, rats, and patients, suggesting a new role for this molecule in cardiovascular disease prevention. Although Nar cholesterol-lowering effects are known, the underlying mechanisms have not yet been elucidated. Interestingly, Nar binds to the estrogen receptors (ERs), modulating both transcriptional and membrane-initiating signals. Although estrogen and ERs are deeply involved in lipid metabolism, no data are available regarding a putative role of these nuclear receptors as mediators of the hypocholesterolemic effect exerted by Nar. Thus, the aim of this work was to study the involvement of ERs in Nar-induced modulation of cholesterol metabolism. Results obtained in HepG2 cell line demonstrate that Nar can modulate the molecular network of cholesterol homeostasis. However, these effects were only partially dependent on the activity of estrogen receptor α. As a whole, our data highlight new molecular mechanisms by which Nar influences cholesterol metabolism, opening a new scenery about dietary impact on human health.

Efficient purification of flavonoids from bamboo shoot residues of Phyllostachys edulis by macroporous resin and their hypoglycemic activity.

The adsorption/desorption process of flavonoids obtained from bamboo shoots residues of Phyllostachys edulis (RPEFs) was established by resin screening, adsorption isotherms, adsorption kinetics and dynamic tests. Results indicated the Langmuir equation fairly fitted the isotherms data and the pseudo-second-order model accurately described its kinetic adsorption on HPD-500 resin. The optimal process was as follows: 2mg/mL of solution, 2.8 BV feed volume under 2 BV/h flow rate for adsorption; 5 BV volume of 70% ethanol with a flow rate of 2 BV/h for desorption. After enrichment, the flavonoids in RPEFs increased from 1.39% to 37.34%. The analysis of UPLC-TOF-MS/MS uncovered that the purified RPEFs were composed of four major flavonoids. It had potent hypoglycemic activity via PI3K/AKT pathway by upregulating the protein expression of PI3K, AKT, IRS-1, and GLUT4 in a dose-dependent manner based on HepG2-IR cells. Those results provide possible utilization of Phyllostachys edulis by-products in food additives.

UHPLC-MS/MS identification, quantification of flavonoid compounds from Areca catechu L. extracts and in vitro evaluation of antioxidant and key enzyme inhibition properties involved in hyperglycemia and hypertension

Arecanut (Areca catechu L.) is an important commercial crop extensively used in traditional and modern medicine. The studies on bioactive compounds and bioactivities of arecanut extracts are a fundamental requirement for future pharmacological research. This study focused on the flavonoid compounds of arecanut and their in vitro bioactivities, including antioxidant activities and inhibitory potential towards enzymes involved in the treatment of hyperglycemia and hypertension. Furthermore, ultra-high-performance liquid chromatography coupled with mass spectrometry (UHPLC–MS/MS) was utilized to characterize the flavonoid compositions in extracts of arecanut. The results showed that all extracts from different parts of arecanut (flower, husk, seed) had high contents of polyphenols, flavonoids and proanthocyanins. In total, seventy-two flavonoid compounds were identified and among them twenty-eight flavonoid compounds were quantitated. The dominated flavonoid compounds in three extracts were significantly different. The major flavonoids recognized in flower extract were cynaroside, luteolin and diosmetin, while the flavonoid compositions were dominated by schaftoside and diosmetin in husk extract. The flavonoids with higher contents in seed extract were catechin, procyanidin B1, procyanidin B2 and L-epicatechin. The results of scavenging activities towards DPPH·, ABTS·+, OH·−and O2·− demonstrated that all extracts from arecanut displayed good free radical scavenging abilities. All extracts also exhibited strong reducing power, especially arecanut seed extract. Additionally, arecanut seed extract were characterized by the strongest α-amylase and α-glucosidase inhibitory capacities, which were significantly superior to acarbose. Arecanut seed extract were also found to possess the highest angiotensin-converting enzyme (ACE) inhibitory properties compared to flower and husk extracts. In conclusion, arecanut is enriched in natural bioactive compounds with potent antioxidant activities and inhibitory effects on the enzyme related to hypertension and hyperglycemia. It can be a potential source for application in the relevant medicinal aspects.