The most abundant polyphenol of soy leaves, coumestrol, displays potent α-glucosidase inhibitory activity

Dietary Polyphenols: Review on Chemistry/Sources, Bioavailability/Metabolism, Antioxidant Effects, and Their Role in Disease Management

Polyphenols, as secondary metabolites ubiquitous in plant sources, have emerged as pivotal bioactive compounds with far-reaching implications for human health. Plant polyphenols exhibit direct or indirect associations with biomolecules capable of modulating diverse physiological pathways. Due to their inherent abundance and structural diversity, polyphenols have garnered substantial attention from both the scientific and clinical communities. The review begins by providing an in-depth analysis of the chemical intricacies of polyphenols, shedding light on their structural diversity and the implications of such diversity on their biological activities. Subsequently, an exploration of the dietary origins of polyphenols elucidates the natural plant-based sources that contribute to their global availability. The discussion extends to the bioavailability and metabolism of polyphenols within the human body, unraveling the complex journey from ingestion to systemic effects. A central focus of the review is dedicated to unravelling the antioxidant effects of polyphenols, highlighting their role in combating oxidative stress and associated health conditions. The comprehensive analysis encompasses their impact on diverse health concerns such as hypertension, allergies, aging, and chronic diseases like heart stroke and diabetes. Insights into the global beneficial effects of polyphenols further underscore their potential as preventive and therapeutic agents. This review article critically examines the multifaceted aspects of dietary polyphenols, encompassing their chemistry, dietary origins, bioavailability/metabolism dynamics, and profound antioxidant effects. The synthesis of information presented herein aims to provide a valuable resource for researchers, clinicians, and health enthusiasts, fostering a deeper understanding of the intricate relationship between polyphenols and human health.

Eco-friendly and efficient extraction of polyphenols from Ligustrum robustum by deep eutectic solvent assisted ultrasound

An eco-friendly and efficient extraction method using deep eutectic solvents assisted ultrasound extraction (DESs-UAE) for the polyphenols from Ligustrum robustum was developed. Among the 34 kinds of DESs prepared, tetraethyl ammonium bromide: 1,2,4-butanol (Teab: 1,2,4-But) was proved to be a suitable extraction solvent based on the extraction efficiency. The extraction parameters including temperature, water content, liquid-solid ratio were optimized with response surface methodology (RSM). Under the optimal conditions, the total phenolic content (TPC) and total flavonoid content (TFC) were 101.46 ± 2.96 mg GAE/g DW and 264.17 ± 5.39 mg RE/g DW, respectively. Furthermore, the extraction mechanism of DESs-UAE was investigated by extraction kinetics, molecular dynamic simulation and theory calculations of interaction. In particular, 9 kinds of polyphenols compounds from Ligustrum robustum were firstly identified by UPLC-Q-TOF-MS. Moreover, the recovered polyphenols exhibited significant antioxidant, α-glucosidase inhibition, acetylcholinesterase inhibition and anticancer activity.

Common pregnancy complications and polyphenols intake: an overview

During pregnancy, the body undergoes a great amount of changes in order to support a healthy developing fetus. In this context, maternal dietary supplementation is widely encouraged to provide adequate nutrition for the newborn. In the past few years, studies have emerged highlighting the benefits of polyphenols intake during pregnancy. Indeed, despite differences among reports, such as experimental model, polyphenol employed, dosage and regimen of administration, there is no doubt that the ingestion of these molecules has a protective effect in relation to three pregnancy-associated diseases or conditions: preeclampsia, gestational diabetes and fetal growth restriction. In this review, we describe the effects of different polyphenols and polyphenol-rich extracts or juices on the main outcomes of these common pregnancy-associated complications, obtained in human, animal and in vitro studies. Therefore, this work provides a critical analysis of the literature, and a summary of evidences, from which future research using polyphenols can be designed and evaluated.

Experimental and theoretical investigation of mild steel corrosion control in acidic solution by Ranunculus arvensis and Glycine max extracts as novel green inhibitors

In the present research, the ability of Ranunculus arvensis (RA) and Glycine max (GM) extracts as green corrosion inhibitors of mild steel (MS) in 1 M HCl was investigated. The inhibiting potential of RA and GM was analysed employing electrochemical impedance spectroscopy (EIS), polarization curves, potentiometry, and theoretical investigations. An enhancement in the inhibition efficiency (I.E) with increasing inhibitors concentrations indicated by EIS data and polarization curves. According to obtained results both extracts indicated inhibitory effect, with their effectiveness following the order of RA > GM. In addition, the interactions between the inhibitors on the MS surface were assessed using B3LYP/6-311g(d,p) theory level in liquid water phase. The interaction energies for three orientations of RA and GM depicted that inhibitors have located parallel to the alloy surface. The preferred complex orientation is one in which the maximum number of inhibitor donor atoms interacted with the alloy surface. Finally, experimental and theoretical results were in accordance which confirmed the inhibition effect of RA and GM extracts.

Comprehensive characterization of flavonoid derivatives in young leaves of core-collected soybean (Glycine max L.) cultivars based on high-resolution mass spectrometry

Most previous studies have been focused on isoflavone profile with biological activities from soybean seed and its related products. However, in the present study, eighty-three flavonoid derivatives (55 flavonols, 9 flavones and 19 isoflavones) were comprehensively identified and quantified from young leaves of 21 core-collected soybean cultivars based on ultra-performance liquid chromatography-diode array detector with quadrupole time of flight/mass spectrometry (UPLC-DAD-QToF/MS). Among total flavonoids from soybean leaves (SLs), the abundant flavonols (83.6%) were primarily composed of di- and tri- glycosides combined to the aglycones (K, kaempferol; Q, quercetin; I, isorhamnetin). Particularly, K-rich SLs (yellow coated seed), Nongrim 51 (breeding line) and YJ208-1 (landrace) contained mainly kaempferol 3-O-(2″-O-glucosyl-6″-O-rhamnosyl)galactoside and 3-O-(2″,6″-di-O-rhamnosyl)galactoside, and were expected to be superior cultivars by their higher flavonoids. Besides, the new tri-I-glycosides (soyanins I–V) were presented as predominant components in Junyeorikong (landrace, black). Thus, this study suggest that the SLs can be considered as valuable edible resources due to their rich flavonoids. Also, these detailed profiles will support breeding of superior varieties with excellent biological activities as well as relationship with seed anthocyanins production, and contribute to perform metabolomics approach to investigate the changes of SLs flavonols during the leaf growth and fermentation in further research.

Genome wide association study to detect genetic regions related to isoflavone content in a mutant soybean population derived from radiation breeding

Isoflavones are major secondary metabolites that are exclusively produced by legumes, including soybean. Soy isoflavones play important roles in human health as well as in the plant defense system. The isoflavone content is influenced by minor-effect quantitative trait loci, which interact with polygenetic and environmental factors. It has been difficult to clarify the regulation of isoflavone biosynthesis because of its complex heritability and the influence of external factors. Here, using a genotype-by-sequencing-based genome-wide association mapping study, 189 mutant soybean genotypes (the mutant diversity pool, MDP) were genotyped on the basis of 25,646 high-quality single nucleotide polymorphisms (SNPs) with minor allele frequency of >0.01 except for missing data. All the accessions were phenotyped by determining the contents of 12 isoflavones in the soybean seeds in two consecutive years (2020 and 2021). Then, quantitative trait nucleotides (QTNs) related to isoflavone contents were identified and validated using multi-locus GWAS models. A total of 112 and 46 QTNs related to isoflavone contents were detected by multiple MLM-based models in 2020 and 2021, respectively. Of these, 12 and 5 QTNs were related to more than two types of isoflavones in 2020 and 2021, respectively. Forty-four QTNs were detected within the 441-Kb physical interval surrounding Gm05:38940662. Of them, four QTNs (Gm05:38936166, Gm05:38936167, Gm05:38940662, and Gm05:38940717) were located at Glyma.05g206900 and Glyma.05g207000, which encode glutathione S-transferase THETA 1 (GmGSTT1), as determined from previous quantitative trait loci annotations and the literature. We detected substantial differences in the transcript levels of GmGSTT1 and two other core genes (IFS1 and IFS2) in the isoflavone biosynthetic pathway between the original cultivar and its mutant. The results of this study provide new information about the factors affecting isoflavone contents in soybean seeds and will be useful for breeding soybean lines with high and stable concentrations of isoflavones.

Chemical Constituents of the Flowers of Pueraria lobata and Their Cytotoxic Properties

The flower of Pueraria lobata (Puerariae Flos) is a reddish-purple to violet-purple flower that blooms between July and September. In our preliminary study, Puerariae Flos extract exhibited significant activity against a human ovarian cancer cell line. This research aims to identify the active compounds in Pueraria Flos. By repeated chromatography, one new tryptophan derivative (1), two new flavanones (4 and 5), and 19 known compounds, including tryptophan derivatives (2 and 3), flavonoids (6–9), isoflavonoids (10–20), a flavonolignan (21), and a phenolic compound (22), were isolated from a methanol extract of Puerariae Flos. The structures of new compounds were elucidated as 13-N-benzoyl-l-tryptophan-1-N-β-d-glucopyranoside (1), 2-hydroxy-5-methoxy-naringenin (4), and 2-hydroxy-5-methoxy-naringenin 7-O-β-d-glucopyranoside (5). Among the isolates, afromosin (17), tectorigenin (11), apigenin (8), glycitein (16), (-)-hydnocarpin (21), irilin D (12), irisolidone 7-O-glucoside (14), and genistein (10) showed cytotoxicity against human ovarian cancer cell line A2780. Apigenin (8) and (-)-hydnocarpin (21) were the most active (IC₅₀ values of 9.99 and 7.36 μM, respectively).

Mass Biosynthesis of Coumestrol Derivatives and Their Isomers via Soybean Adventitious Root Cultivation in Bioreactors

Coumestrol (CMS) derivatives are unique compounds, which function as phytoalexins; they are derived from soybean roots, following abiotic and biotic stresses. As a phytoalexin, CMS forms a defense system that enables plants to maintain their viability. However, it is still challenging to achieve the mass production of phytoalexins, which exhibit pharmacological values, via plant breeding. Here, the synthesis of CMS derivatives from the seedling, plant, and adventitious root (AR) of Glycine max were investigated under artificial light, as well as via a chemical elicitor treatment. In the presence of constant light, as well as under treatment with methyl jasmonate, the CMS monoglucoside (coumestrin; CMSN) and malonyl CMSN (M-CMSN) contents of the AR culture (4 weeks) increased drastically. The two CMS derivatives, CMSN and M-CMSN, were obtained as a mixture of isomers, which were identified via nuclear magnetic resonance analysis. These derivatives were also observed in a soybean plant that was grown on artificial soil (AS; 5 weeks) and a Petri dish (9 days) although in considerably lesser quantities than those observed in the AR culture. Compared with the two other media (AS and the Petri dish), the AR culture achieved the superior synthesis of CMSN and M-CMSN within a relatively short cultivation period (<1 month) in laboratory-scale (3 L) and pilot-scale (1,000 L) bioreactors. The isoflavone content of AR under the constant light conditions was three-fold that under dark conditions. Significant quantities of malonyl daidzin and malonyl genistin were produced in the root of AS and the seedling of Petri dish, respectively. Flavonol glycosides were not produced in the AR culture under the dark and light conditions, as well as in AS under the dark condition. However, significant contents of kaempferol glycosides were produced in the leaves of AS and seedling of Petri dish, following the light treatment. Thus, we proposed that the established soybean AR-cultivation approach represented a better method for biosynthesizing phytoalexins, such as the CMS derivatives, as plant-derived functional materials.

A Narrative Review of Human Clinical Trials on the Impact of Phenolic-Rich Plant Extracts on Prediabetes and Its Subgroups

Phenolic-rich plant extracts have been demonstrated to improve glycemic control in individuals with prediabetes. However, there is increasing evidence that people with prediabetes are not a homogeneous group but exhibit different glycemic profiles leading to the existence of prediabetes subgroups. Prediabetes subgroups have been identified as: isolated impaired fasting glucose (IFG), isolated impaired glucose tolerance (IGT), and combined impaired fasting glucose and glucose intolerance (IFG/IGT). The present review investigates human clinical trials examining the hypoglycemic potential of phenolic-rich plant extracts in prediabetes and prediabetes subgroups. Artemisia princeps Pampanini, soy (Glycine max (L.) Merrill) leaf and Citrus junos Tanaka peel have been demonstrated to improve fasting glycemia and thus may be more useful for individuals with IFG with increasing hepatic insulin resistance. In contrast, white mulberry (Morus alba Linn.) leaf, persimmon (Diospyros kaki) leaf and Acacia. Mearnsii bark were shown to improve postprandial glycemia and hence may be preferably beneficial for individuals with IGT with increasing muscle insulin resistance. Elaeis guineensis leaf was observed to improve both fasting and postprandial glycemic measures depending on the dose. Current evidence remains scarce regarding the impact of the plant extracts on glycemic control in prediabetes subgroups and therefore warrants further study.

A new prenylated coumestan from the roots of Campylotropis hirtella

A new prenylated coumestan, campylohirtin A (1), along with fifteen phenolic known compounds (2‒16) and four other known compounds (17‒20), was obtained from the 95% ethanol extract of roots of Campylotropis hirtella. Their structures were elucidated based on extensive spectroscopic analysis (1 D and 2 D-NMR, MS, UV and IR). In vitro antimalarial activities of compounds 1-3, 5-14 and 16 were evaluated by β-hematin formation inhibition assay. Compared with the positive control chloroquine diphosphate, compounds 8, 11 and 16 exhibited strong antimalarial activity with the IC₅₀ values of 69.9, 33.2 and 75.4 µM, respectively. Compounds 1-3, 5-7 and 12 showed moderate antimalarial activities with IC₅₀ values ranging from 134.6 µM to 578.6 µM.[Formula: see text].

Vegetable soybean (Glycine max (L.) Merr.) leaf extracts: Functional components and antioxidant and anti-inflammatory activities

To investigate ways to extract greater dietary value from the leaves of the vegetable soybean (Glycine max (L.) Merr.) cultivar 'Kaohsiung No. 9'. Our results indicate that phenolic content and flavonoid content are highest in extracts prepared with 70% methanol and 70% ethanol. The 70% ethanol extracts also had the highest quercetin (135 ± 1.62 µg/g) and kaempferol (450 ± 1.35 µg/g) contents. These results show that flavonoids are a dominant class of compounds in these vegetable soybean leaf extracts and serve as their main source of antioxidants. At an extract concentration of 5 mg/ml, the 70% methanol extracts achieved good antioxidant effects, with a DPPH radical scavenging rate of 80%, and a reducing power of 88%. In assays of anti-inflammatory capacity using lipopolysaccharide-stimulated RAW 264.7 macrophages. The 70% methanol extracts displayed the most significant inhibition of nitric oxide (NO) synthesis, achieving up to 86% inhibition. As a similar trend was observed in expression levels of inducible nitric oxide synthase (iNOS), we deduced that vegetable soybean leaves may regulate NO synthesis through inhibiting iNOS. We also observed a significant decrease in cyclooxygenase (COX)-2 gene expression. Analysis of proinflammatory cytokine synthesis revealed that the 70% methanol and 70% ethanol extracts significantly reduced TNF-α, IL-6, and IL-1β synthesis, and increased the intracellular reduced glutathione/oxidized glutathione (GSH/GSSG) ratio from 8 to 12.8. These results indicate that vegetable soybean leaves possess antioxidant activities and exert inhibitory effects on inflammatory mediators, suggesting their potential for use as dietary supplements.

Antidiabetic and antimicrobial flavonoids from the twigs and roots of Erythrina subumbrans (Hassk.) Merr

The phytochemical investigation of the twig and root extracts of Erythrina subumbrans (Hassk.) Merr. (Fabaceae) resulted in the isolation and identification of a new pterocarpan, erythrinocarpan (1), along with 27 known compounds (2-28). All isolated compounds were evaluated for their antidiabetic, antimicrobial, and anti-inflammatory properties. Compounds 3, 8, 9, and 22 had α-glucosidase inhibitory activity with IC50 values of 13.4 ± 0.05, 24.5 ± 0.13, 29.0 ± 0.05, and 12.8 ± 0.14 μM, respectively, while compound 2 inhibited α-amylase activity with an IC50 value of 67.6 ± 1.12 μM. Compounds 22 and 24 inhibited glycation activity with the IC50 values of 36.9 ± 0.62 and 40.5 ± 0.37 μM, respectively. From cell-based assays, compound 27 showed the highest ability to induce glucose consumption (IC50 29.1 ± 0.86 μM) and glucose uptake (2.8-fold), and to inhibit nitric oxide (NO) production (IC50 52.5 ± 0.56 μM) without cell toxicity. Furthermore, compound 9 showed antimicrobial activities against Gram-positive bacteria and fungi with MIC values ranging from 2-4 μg/mL.

Effects of isoflavone-rich red clover extract on blood glucose level: A randomized, double-blind, placebo-controlled trial

High blood glucose is associated with increased risk of various diseases. Red clover (RC; Trifolium pratense L.) is an edible legume whose sprout is rich in isoflavones such as formononetin and biochanin A. We examined the effects of RC extract on postprandial and fasting blood glucose level, using a randomized, double-blind, placebo-controlled trial with 36 participants, aged 25 to 64 years, who were randomly assigned to receive either 1.91 g of RC extract (containing 8 mg formononetin and 1.8 mg biochanin A) or placebo. Each participant ingested the assigned test food daily for 8 weeks, and at the oral maltose tolerance test (OMTT). Initially, the two groups did not significantly differ in OMTT results. However, fasting insulin levels at 8 weeks were significantly lower in the RC group (4.76 μIU/ml at Week 0 to 4.01 μIU/ml at Week 8) with a significant interaction (P = 0.046). Subgroup analysis showed that change in blood glucose level (blood glucose ΔC) tended to decrease late in the trial period during OMTT in the ≤50-year-old RC group, as did fasting blood glucose and insulin levels at 8 weeks; hemoglobin A1c was also significantly reduced in this subgroup (5.36% at Week 0 to 5.28% at Week 8) with a significant interaction (P = 0.040). These results suggest that the daily intake of RC could reduce blood glucose, particularly for those ≤50 years old. Formononetin-an α-glucosidase inhibitor-is considered to be the major functional molecule for these effects. Therefore, intake of RC that contains formononetin might help blood glucose control.

Optimization of Two Eco-Friendly Extractions of Black Medick (Medicago lupulina L.) Phenols and Their Antioxidant, Cosmeceutical, α-Glucosidase and α-Amylase Inhibitory Properties

Medicago lupulina is an ancient edible plant from the Fabaceae family. In this work, two eco-friendly methods for extraction of bioactive phenolics from M. lupulina were developed using mixtures of water with two non-toxic, skin- and environmentally-friendly polyol solvents: glycerol and polypropylene glycol. Ultrasound-assisted extractions were optimized using a Box–Behnken design. The independent variables were the concentration of organic solvent in water (X₁), extraction temperature (X₂) and time (X₃), while the response was phenolic content. The optimum conditions for extraction of polyphenols were (X₁, X₂, X₃): (45%, 70 °C, 60 min) and (10%, 80 °C, 60 min) for glycerol and polypropylene glycol extraction, respectively. The extracts prepared at optimum conditions were rich in phenolic compounds, mainly derivatives of apigenin, kaempferol, luteolin, quercetin, caffeic and ferulic acid, as well as coumestrol. Their cosmeceutical and antidiabetic activity was tested. Both extracts demonstrated notable antioxidant, anti-lipoxygenase and anti-α-amylase activity. In addition to those activities, the glycerol extract efficiently inhibited protein coagulation, elastase and α-glucosidase activity. Glycerol present in the extract displayed enzyme-inhibiting activity in several assays and supported the action of the bioactive constituents. Thus, the optimized glycerol extract is a desirable candidate for direct incorporation in antidiabetic food supplements and cosmeceutical products.

A Significant Change in Free Amino Acids of Soybean (Glycine max L. Merr) through Ethylene Application

In this study, the changes in free amino acids of soybean leaves after ethylene application were characterized based on quantitative and metabolomic analyses. All essential and nonessential amino acids in soybean leaves were enhanced by fivefold (250 to 1284 mg/100 g) and sixfold (544 to 3478 mg/100 g), respectively, via ethylene application. In particular, it was found that asparagine is the main component, comprising approximately 41% of the total amino acids with a twenty-five fold increase (78 to 1971 mg/100 g). Moreover, arginine and branched chain amino acids (Val, Leu, and Ile) increased by about 14 and 2-5 times, respectively. The increase in free amino acid in stem was also similar to the leaves. The metabolites in treated and untreated soybean leaves were systematically identified by gas chromatography-mass spectrometry (GC-MS), and partial variance discriminant analysis (PLS-DA) scores and heat map analysis were given to understand the changes of each metabolite. The application of ethylene may provide good nutrient potential for soybean leaves.

A Review of Plant Extracts and Plant-Derived Natural Compounds in the Prevention/Treatment of Neonatal Hypoxic-Ischemic Brain Injury

Neonatal hypoxic-ischemic (HI) brain injury is one of the major drawbacks of mortality and causes significant short/long-term neurological dysfunction in newborn infants worldwide. To date, due to multifunctional complex mechanisms of brain injury, there is no well-established effective strategy to completely provide neuroprotection. Although therapeutic hypothermia is the proven treatment for hypoxic-ischemic encephalopathy (HIE), it does not completely chang outcomes in severe forms of HIE. Therefore, there is a critical need for reviewing the effective therapeutic strategies to explore the protective agents and methods. In recent years, it is widely believed that there are neuroprotective possibilities of natural compounds extracted from plants against HIE. These natural agents with the anti-inflammatory, anti-oxidative, anti-apoptotic, and neurofunctional regulatory properties exhibit preventive or therapeutic effects against experimental neonatal HI brain damage. In this study, it was aimed to review the literature in scientific databases that investigate the neuroprotective effects of plant extracts/plant-derived compounds in experimental animal models of neonatal HI brain damage and their possible underlying molecular mechanisms of action.

A Potential Role of Coumestrol in Soybean Leaf Senescence and Its Interaction With Phytohormones

Coumestrol is a natural organic compound synthesized in soy leaves and functions as a phytoalexin. The coumestrol levels in plants are reported to increase upon insect attack. This study investigates the correlation between coumestrol, senescence, and the effect of phytohormones on the coumestrol levels in soybean leaves. Our analysis involving high-performance liquid chromatography and 2-D gel electrophoresis indicated a significant difference in the biochemical composition of soybean leaves at various young and mature growth stages. Eight chemical compounds were specifically detected in young leaves (V1) only, whereas three different coumestans isotrifoliol, coumestrol, and phaseol were detected only in mature, yellow leaves of the R6 and R7 growth stage. MALDI-TOF-MS analysis was used to identify two proteins 3,9 -dihydroxypterocarpan 6A-monooxygenase (CYP93A1) and isoflavone reductase homolog 2 (IFR2) only in mature leaves, which are key components of the coumestrol biosynthetic pathway. This indicates that senescence in soybean is linked to the accumulation of coumestrol. Following the external application of coumestrol, the detached V1-stage young leaves turned yellow and showed an interesting development of roots at the base of the midrib. Additionally, the application of phytohormones, including SA, methyl jasmonate (MeJA), and ethephon alone and in various combinations induced yellowing within 5 days of the application with a concomitant significant increase in endogenous coumestrol accumulation. This was also accompanied by a significant increase in the expression of genes CYP81E28 (Gm08G089500), CYP81E22 (Gm16G149300), GmIFS1, and GmIFS2. These results indicate that various coumestans, especially coumestrol, accumulate during leaf maturity, or senescence in soybean.

Insight into interaction mechanism between theaflavin-3-gallate and α-glucosidase using spectroscopy and molecular docking analysis

To elucidate the α-glucosidase (α-GC) inhibitory mechanism of theaflavin-3-gallate (TF-3-G), their interaction mechanism was investigated using spectroscopy and molecular docking analysis. The inhibition ratio of TF-3-G against α-GC was determined to be 92.3%. Steady fluorescence spectroscopy showed that TF-3-G effectively quenched the intrinsic fluorescence of α-GC through static quenching, forming a stable complex through hydrophobic interactions. Formation of the TF-3-G/α-GC complex was also confirmed by resonance light scattering spectroscopy. Synchronous fluorescence spectroscopy and circular dichroism spectroscopy indicated that the secondary structure of α-GC was changed by TF-3-G. Molecular docking was used to simulate TF-3-G/α-GC complex formation, showing that TF-3-G might be inserted into the hydrophobic region around the active site of ɑ-GC, and bind with the catalytic Asp215 and Asp352 residues. The ɑ-GC inhibitory mechanism of TF-3-G was mainly attributed to the change in ɑ-GC secondary structure caused by the complex formation. PRACTICAL APPLICATIONS: α-Glucosidase (α-GC) can hydrolyze the glycosidic bonds of starch and oligosaccharides in food and release glucose. Therefore, the inhibition of α-GC activity has been used to treat postprandial hyperglycemia and type 2 diabetes mellitus. Theaflavin-3-gallate (TF-3-G), a flavonoid found in the fermentation products of black tea, exhibits strong inhibition of α-GC activity. However, the α-GC inhibitory mechanism of TF-3-G is unclear. This study aids understanding of this mechanism, and proposed a possibly basic theory for improving the medicinal value of TF-3-G in diabetes therapy.

Induction of promising antibacterial prenylated isoflavonoids from different subclasses by sequential elicitation of soybean

Elicited soybean (Glycine max (L.) Merrill, Leguminosae) seedlings can produce prenylated isoflavonoids from different subclasses, namely pterocarpans (glyceollins), isoflavones and coumestans. These prenylated isoflavonoids serve as defence compounds and can possess antimicrobial activity. Recently, we showed that priming with reactive oxygen species (ROS) specifically stimulated the production of glyceollins in Rhizopus spp.-elicited soybean seedlings (ROS + R). In this study, we achieved diversification of the inducible subclasses of prenylated isoflavonoids in soybean, by additional stimulation of two prenylated isoflavones and one prenylated coumestan. This was achieved by using a combination of the relatively long-lived ROS representative, H2O2, with AgNO3 prior to microbial elicitation. Microbial elicitation was performed with a live preparation of either a phytopathogenic fungus, Rhizopus spp. or a symbiotic bacterium, Bacillus subtilis. B. subtilis induced 30% more prenylated isoflavones than Rhizopus spp. in (H2O2 + AgNO3)-treated seedlings, without significantly compromising the total levels of glyceollins, compared to (ROS + R)-treated seedlings. The most abundant prenylated isoflavone induced was 6-prenyl daidzein, which constituted 60% of the total isoflavones. The prenylated coumestan, phaseol, was also induced in the (H2O2 + AgNO3)-treated and microbially elicited seedlings. Based on previously developed quantitative structure-activity relationship (QSAR) models, 6-prenyl daidzein and phaseol were predicted to be promising antibacterials. Overall, we show that treatment with H2O2 and AgNO3 prior to microbial elicitation leads to the production of promising antibacterial isoflavonoids from different subclasses. Extracts rich in prenylated isoflavonoids may potentially be applied as natural antimicrobial agents.

Phytochemical properties of black tea (Camellia sinensis) and rooibos tea (Aspalathus linearis); and their modulatory effects on key hyperglycaemic processes and oxidative stress

The comparative phytochemicals, antioxidative and antidiabetic activities of Camellia sinensis (black tea) and Aspalathus linearis (rooibos tea) were studied in vitro and ex vivo. Concentrated infusions of the teas showed significant free radical scavenging activities in vitro. They significantly increased the glutathione level, superoxide dismutase and catalase enzyme activities in oxidative hepatic injury, while concomitantly depleting malondialdehyde level. The teas significantly inhibited intestinal glucose absorption and α-amylase activities, and elevated muscle glucose uptake. LCMS phytochemical profiling revealed the presence of hydroxycaffeic acid, l-threonate, caffeine, vanillic acid, n-acetylvaline, and spinacetin 3-glucoside in C. sinensis. While quinolinic acid, coumestrol, phloroglucinol, 8-hydroxyquercetagetin, umbelliferone, and ajoene were identified in A. linearis. These results portray the antioxidant and antidiabetic potencies of both teas, with A. linearis showed better activity compared to C. sinensis. These teas may thus be used as functional foods in the management of diabetes and other oxidative stress related metabolic disorders.

Isolation and Identification of Antiarthritic Constituents from Glycine tabacina and Network Pharmacology-Based Prediction of Their Protective Mechanisms against Rheumatoid Arthritis

Glycine tabacina (Labill.) Benth is an edible medicinal herb for rheumatoid arthritis (RA) treatment in folk medicine. Current phytochemical research on this dried herb led to the isolation of eight new coumestans, named glytabastan A-H (1-8), and twenty-three known compounds 9-31. Their structures were elucidated using spectroscopic methods. The antiarthritic activities of all isolates were evaluated, and the results showed that coumestans 1-6 and 8-10 could inhibit arthritic inflammation in vitro, while coumestans 1, 2, 9, and 10 significantly blocked the osteoclastogenesis induced by receptor activator of nuclear factor (NF) κB ligand (RANKL). Moreover, network pharmacological analysis revealed that the anti-RA effect of G. tabacina involved multitargets, multipathways such as PI3K/Akt and MAPK signaling pathways, and various biological processes such as inflammatory response and cytokine-mediated signaling pathways. These results suggested that this species and its novel coumestans could serve as potential antiarthritic agents for functional food or medicinal use.

A neutral polysaccharide from green tea: Structure, effect on α-amylase activity and hydrolysis property

A neutral tea polysaccharide (TPSN) was isolated from green tea. Gas chromatography analysis showed that TPSN was composed of d-glucose, l-arabinose and d-galactose residues at a molar ratio of 90.0: 9.1: 0.9. The weight-averaged molecular weight of TPSN was determined as about 2.0 × 10⁵ g mol^-1 using static light scattering analysis. The result of nuclear magnetic resonance (NMR) spectroscopy indicated that TPSN and water-soluble starch had similar structures. TPSN exhibited inhibitory activity towards α-amylase through the noncompetitive inhibition mechanism, but the tertiary structure of α-amylase related to enzymatic activity, analyzed using circular dichroism spectroscopy, was not affected by TPSN. Meanwhile, TPSN exhibited hydrolysis properties catalyzed by α-amylase. Molecular docking analysis revealed that the various behaviors of TPSN to α-amylase could be attributed to that the different chain segments of TPSN combined with different amino acid residues of α-amylase.

Comparative analysis of isoflavone aglycones using microwave-assisted acid hydrolysis from soybean organs at different growth times and screening for their digestive enzyme inhibition and antioxidant properties

The objectives of this research were to demonstrate the changes in isoflavone-aglycones, total phenolics, and biological properties (digestive enzyme inhibition; antioxidant) from six organs including leaves, leafstalks, roots, stems, seeds, and pods at different growth times of soybean plant. Three isoflavone-aglycones in microwave-assisted acid hydrolysis extracts were elucidated using UHPLC-ESI-Q-TOF-MS/MS and their contents exhibited remarkable differences in leaves (245.93-2239.33 μg/g), roots (854.96-4425.34 μg/g), and seeds (ND-2339.62 μg/g). Specifically, the collected samples on 15-Oct (leaves: 2239.33; seeds: 2339.62 μg/g) and 31-Aug (roots: 4425.34 μg/g) showed the highest isoflavone-aglycones, and daidzein was observed the most abundant component, comprising approximately 70%. Moreover, the inhibitions against α-glucosidase and α-amylase displayed the predominant effects in roots (89;91%) and leaves (81;85%) of samples on 31-Aug and 15-Oct at 300 μg/ml. The antioxidant activities on ABTS, DPPH, and hydroxyl radicals increased considerably with the increases of growth times in leaves and seeds, especially, ABTS showed the highest scavenging abilities: leaves (15-Oct;83%) > roots (31-Aug;75%) > seeds (15-Oct;68%). Therefore, our results suggest that soybean leaves, roots and seeds may be considered as excellent natural sources for nutraceuticals.

Isolation, structural elucidation and in vitro hepatoprotective activity of flavonoids from Glycyrrhiza uralensis

Two new flavonoid glycosides, 2',4'-dihydroxydihydrochalcone-4-O-β-D-glucopyranoside (1) and medicarpin-3-O-β-D-apiofuranosyl (1 → 2)-β-D-glucopyranoside (2), together with 34 known flavonoids were isolated from the 75% EtOH extract of the dried roots of Glycyrrhiza uralensis Fisch. Their structures were elucidated on the basis of spectroscopic analyses. The flavonoids were classified into ten sub-types, namely, dihydrochalcone (1), pterocarpans (2-4), flavones (5-6), flavanones (7-11), chalcones (12-15), retro-chalcones (16-18), isoflavans (19-21), isoflavones (22-28), 3-arylcoumarins (29-30), and coumestans (31-36). The isolated flavonoids were evaluated for in vitro hepatoprotective activity against D-galactosamine-induced toxicity in human hepatoma HepG2 cells.

Phytoestrogen coumestrol: Antioxidant capacity and its loading in albumin nanoparticles

Coumestrol is a polyphenol with promising therapeutic applications as phytoestrogen, antioxidant and potential cancer chemoprevention agent. The presence of two hydroxyl groups on its chemical structure, with orientation analogous to estradiol, is responsible of both, its antioxidant capacity and its estrogenic activity. However, several studies show that the interaction of polyphenols with food and plasma proteins reduces their antioxidant efficacy. We studied the interaction of coumestrol with bovine serum albumin protein (BSA) by fluorescence spectroscopy and circular dichroism techniques, and the effect of this interaction on its antioxidant activity as a hydroxyl radical scavenger. In addition, coumestrol antioxidant capacity profile using different assays (DPPH, ORAC-FL and ORAC-EPR) was studied. To explain its reactivity we used several methodologies, including DFT calculations, to define its antioxidant mechanism. Coumestrol antioxidant activity unveiled interesting antioxidant properties. BSA interaction with coumestrol reduces significantly photolytic degradation in several media thus preserving its antioxidant properties. Results suggest no significant changes in BSA structure and activity when interacting with coumestrol. Furthermore, this interaction is stronger than for other phytoestrogens such as daidzein and genistein. Considering our promising results, we reported for the first time the fabrication and characterization of coumestrol-loaded albumin nanoparticles. The resulting spherical and homogeneous nanoparticles showed a diameter close to 96 nm. The coumestrol incorporation efficiency in BSA NPs was 22.4%, which is equivalent to 3 molecules of coumestrol for every 10 molecules of BSA.

Comprehensive RNA sequencing and co-expression network analysis to complete the biosynthetic pathway of coumestrol, a phytoestrogen

Coumestrol (CMS), a coumestan isoflavone, plays key roles in nodulation through communication with rhizobia, and has been used as phytoestrogens for hormone replacement therapy in humans. Because CMS content is controlled by multiple genetic factors, the genetic basis of CMS biosynthesis has remained unclear. We identified soybean genotypes with consistently high (Daewonkong) or low (SS0903-2B-21-1-2) CMS content over 2 years. We performed RNA sequencing of leaf samples from both genotypes at developmental stage R7, when CMS levels are highest. Within the phenylpropanoid biosynthetic pathway, 41 genes were tightly connected in a functional co-expression gene network; seven of these genes were differentially expressed between two genotypes. We identified 14 candidate genes involved in CMS biosynthesis. Among them, seven were annotated as encoding oxidoreductases that may catalyze the transfer of electrons from daidzein, a precursor of CMS. Two of the other genes, annotated as encoding a MYB domain protein and a MLP-like protein, may increase CMS accumulation in response to stress conditions. Our results will help to complete our understanding of the CMS biosynthetic pathway, and should facilitate development of soybean cultivars with high CMS content that could be used to promote the fitness of plants and human beings.

Suppression of Hyperglycemia and Hepatic Steatosis by Black-Soybean-Leaf Extract via Enhanced Adiponectin-Receptor Signaling and AMPK Activation

Yellow-soybean-leaf extract includes kaempferol glycosides and pheophorbides that reduce obesity and plasma glucose levels. This study researched the molecular mechanisms underlying the glucose-lowering effect of the extract of black-soybean leaves (EBL), which mainly contains quercetin glycosides and isorhamnetin glycosides, in mice with high-fat-diet (HFD)-induced obesity and diabetes and in HepG2 cells. Twelve weeks of EBL supplementation decreased body weight and fasting glucose, glycated hemoglobin, insulin, triglyceride, and nonesterified fatty acid levels. Histological analyses manifested that EBL suppressed hepatic steatosis. Interestingly, EBL significantly improved plasma adiponectin levels and increased adiponectin-receptor-gene ( AdipoR1 and AdipoR2) expression in the liver. EBL restored the effects of HFD on hepatic AMP-activated protein kinase (AMPK) and on the family of peroxisome proliferator-activated receptors (PPARα, PPARδ, and PPARγ), which are associated with fatty acid metabolism and are downstream of the adiponectin receptors. Hence, EBL effectively diminished hyperglycemia and hepatic steatosis through enhancing adiponectin-induced signaling and AMPK activation in the liver.

Transcriptomic Plasticity in the Arthropod Generalist Tetranychus urticae Upon Long-Term Acclimation to Different Host Plants

The two-spotted spider mite Tetranychus urticae is an important pest with an exceptionally broad host plant range. This generalist rapidly acclimatizes and adapts to a new host, hereby overcoming nutritional challenges and a novel pallet of constitutive and induced plant defenses. Although recent studies reveal that a broad transcriptomic response upon host plant transfer is associated with a generalist life style in arthropod herbivores, it remains uncertain to what extent these transcriptional changes are general stress responses or host-specific. In the present study, we analyzed and compared the transcriptomic changes that occur in a single T. urticae population upon long-term transfer from Phaseolus vulgaris to a similar, but chemically defended, host (cyanogenic Phaseolus lunatus) and to multiple economically important crops (Glycine max, Gossypium hirsutum, Solanum lycopersicum and Zea mays). These long-term host plant transfers were associated with distinct transcriptomic responses with only a limited overlap in both specificity and directionality, suggestive of a fine-tuned transcriptional plasticity. Nonetheless, analysis at the gene family level uncovered overlapping functional processes, recruiting genes from both well-known and newly discovered detoxification families. Of note, our analyses highlighted a possible detoxification role for Tetranychus-specific short-chain dehydrogenases and single PLAT domain proteins, and manual genome annotation showed that both families are expanded in T. urticae Our results shed new light on the molecular mechanisms underlying the remarkable adaptive potential for host plant use of generalist arthropods and set the stage for functional validation of important players in T. urticae detoxification of plant secondary metabolites.

Collective Syntheses of 2-(3-Methylbenzofuran-2-yl)phenol-Derived Natural Products by a Cascade [3,3]-Sigmatropic Rearrangement/Aromatization Strategy

A cascade [3,3]-sigmatropic rearrangement/aromatization strategy to the synthesis of 2-(3-methylbenzofuran-2-yl)phenol derivatives was developed and applied to the collective syntheses of seven 2-arylbenzofuran-containing natural products, namely glycybenzofuran, glycyuralin E, lespedezol A₁, puerariafuran, 7,2',4'-trihydroxy-3-benzofurancarboxylic acid, coumestrol, and 4'-O-methylcoumestrol. Among them, the total syntheses of glycybenzofuran, glycyuralin E, puerariafuran, 7,2',4'-trihydroxy-3-benzofurancarboxylic acid, and 4'-O-methylcoumestrol were reported for the first time. The practicality of this novel strategy in preparation of the key intermediates was demonstrated by performing the reaction on gram scale and by synthesizing a series of natural products with 2-(3-methylbenzofuran-2-yl)phenol scaffolds in a common strategy.

Isotrifoliol inhibits pro-inflammatory mediators by suppression of TLR/NF-κB and TLR/MAPK signaling in LPS-induced RAW264.7 cells

Soybeans, produced by Glycine max (L.) Merr., contain high levels of isoflavones, such as genistein and daidzein. However, soy leaves contain more diverse and abundant flavonol glycosides and coumestans, as compared to the soybean. This study investigated the anti-inflammatory effects of the major coumestans present in soy leaf (coumestrol, isotrifoliol, and phaseol) in lipopolysaccharide (LPS)-induced RAW264.7 cells. Coumestans significantly reduced LPS-induced nitric oxide (NO), prostaglandin E2 (PGE2), and reactive oxygen species (ROS) production; isotrifoliol had the most potent anti-inflammatory activity. Isotrifoliol reduced LPS-mediated induction of mRNA expression of inducible nitric-oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin (IL)-1β, IL-6, tumor necrosis factor alpha (TNFα), and chemokines, such as chemokine (C-C motif) ligand (CCL) 2, CCL3, and CCL4. Isotrifoliol prevented NF-κB p65 subunit activation by reducing the phosphorylation and degradation of the inhibitor of NF-κB. And isotrifoliol significantly suppressed phosphorylation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). Furthermore, isotrifoliol suppressed LPS-induced Toll-like Receptor (TLR) signaling pathway, including mRNA expression of TNF receptor associated factor 6, transforming growth factor beta-activated kinase 1 (TAK1), TAK1 binding protein 2 (TAB2), and TAB3. These results demonstrate that isotrifoliol exerts an anti-inflammatory effect by suppressing the expression of inflammatory mediators via inhibition of TLR/NF-κB and TLR/MAPK signaling in LPS-induced RAW264.7 macrophages. Therefore, isotrifoliol can be used as an anti-inflammatory agent, and coumestan-rich soy leaf extracts may provide a useful dietary supplement.

Soy-Leaf Extract Exerts Atheroprotective Effects via Modulation of Krüppel-Like Factor 2 and Adhesion Molecules

Soy-leaf extracts exert their cardioprotective effects by inducing endothelium-dependent vasodilation in the arteries, and they favorably modulate the serum lipid profile. In this study, we investigated the atheroprotective effects of an ethanol extract of soy leaf (ESL) in human umbilical vein endothelial cells (HUVECs) and high-cholesterol diet (HCD)-fed low-density lipoprotein receptor deficient (LDLR-/-) mice. ESL induced the expression of Krüppel-like factor 2 (KLF2), an endothelial transcription factor, and endothelial nitric oxide synthase (eNOS), and suppressed the expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) through moderate inflammatory signal activation, not only in tumor necrosis factor-α (TNF-α)-stimulated HUVECs but also in 7-ketocholesterol (7-KC)-stimulated HUVECs. ESL supplementation reduced aortic lesion formation in Western diet-fed LDLR-/- mice by 46% (p < 0.01) compared to the HCD group. ESL also markedly decreased the aortic expression levels of VCAM-1, ICAM-1, monocyte chemotactic protein-1 (MCP-1), TNF-α, IL-6, IL-1β, matrix metallopeptidase 9 (MMP-9), and fractalkine, while the expression of KLF2 was significantly increased. These results suggest that ESL supplementation has potential for preventing HCD-induced atherosclerosis effectively.

Antibacterial and Cytotoxic Phenolic Metabolites from the Fruits of Amorpha fruticosa

Fourteen new natural products, namely, 2-[(Z)-styryl]-5-geranylresorcin-1-carboxylic acid (1), amorfrutin D (2), 4-O-demethylamorfrutin D (3), 8-geranyl-3,5,7-trihydroxyflavanone (4), 8-geranyl-5,7,3'-trihydroxy-4'-methoxyisoflavone (5), 6-geranyl-5,7,3'-trihydroxy-4'-methoxyisoflavone (6), 8-geranyl-7,3'-dihydroxy-4'-methoxyisoflavone (7), 3-O-demethyldalbinol (8), 6a,12a-dehydro-3-O-demethylamorphigenin (9), (6aR,12aR,5'R)-amorphigenin (10), amorphispironones B and C (11 and 12), resokaempferol 3-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside-7-O-α-l-rhamnopyranoside (13), and daidzein 7-O-β-d-glucopyranosyl-(1→2)-β-d-glucopyranoside (14), together with 40 known compounds, were isolated from the fruits of Amorpha fruticosa. The structures of the new compounds were elucidated by 1D and 2D NMR spectroscopic analysis as well as from the mass spectrometry data. ECD calculations were performed to determine the absolute configurations of 11 and 15. Compounds 1, 4-6, and 16-23 showed potent to moderate antibacterial activities against several Gram-positive bacteria with MIC values ranging from 3.1 to 100 μM. In addition, compounds 11 and 24-33 were significantly cytotoxic against the L5178Y mouse lymphoma cell line and exhibited IC₅₀ values from 0.2 to 10.2 μM.

Trypanocidal Activity of 2,5-Diphenyloxazoles Isolated from the Roots of Oxytropis lanata

Eleven 2,5-diphenyloxazole derivatives (1-11), together with six known isoflavonoid derivatives, were isolated from the roots of Oxytropis lanata. The 2,5-diphenyloxazole (1) obtained proved to be identical to a standard sample used as a scintillator and liquid laser dye. The other oxazole derivatives isolated were found to have one to four hydroxy and/or O-methyl groups in their phenyl rings. Seven of the oxazole derivatives obtained are new (3-9). The inhibitory activity of the isolated compounds was evaluated against Trypanosoma congolense, the causative agent of African trypanosomosis in animals. Oxazoles with di- and trihydroxy groups showed trypanocidal activity, and 2-(2',3'-dihydroxyphenyl)-5-(2″-hydroxyphenyl)oxazole (4) exhibited the most potent inhibitory activity (IC₅₀ 1.0 μM).

Beneficial Effects of Pterocarpan-High Soybean Leaf Extract on Metabolic Syndrome in Overweight and Obese Korean Subjects: Randomized Controlled Trial

Pterocarpans are known to have antifungal and anti-inflammatory properties. However, little is known about the changes in transcriptional profiles in response to a pterocarpan-high soybean leaf extract (PT). Therefore, this study investigated the effects of PT on blood glucose and lipid levels, as well as on the inflammation-related gene expression based on a peripheral blood mononuclear cells (PBMCs) mRNA sequencing analysis in Korean overweight and obese subjects with mild metabolic syndrome. The participants were randomly assigned to two groups and were administered either placebo (starch, 3 g/day) or PT (2 g/day) for 12 weeks. The PT intervention did not change body weight, body fat percentage and body mass index (BMI). However, PT significantly decreased the glycosylated hemoglobin (HbA1c), plasma glucose, free fatty acid, total cholesterol, and non-HDL cholesterol levels after 12 weeks. Furthermore, PT supplementation significantly lowered the homeostatic index of insulin resistance, as well as the plasma levels of inflammatory markers. Finally, the mRNA sequencing analysis revealed that PT downregulated genes related to immune responses. PT supplementation is beneficial for the improvement of metabolic syndrome by altering the fasting blood and plasma glucose, HbA1c, plasma lipid levels and inflammation-related gene expression in PBMCs.

Analysis of isoflavones and coumestrol in soybean sprouts

High-performance liquid chromatography analysis is used to examine the distribution of isoflavones in different parts of soybean sprouts. Between the seed leaf and hypocotyl, the ratio of isoflavones differs depending on the aglycone type. Glycitein exists predominantly in the hypocotyl. Three compounds isolated from 4-day-old seed coats were identified as coumestrol and its glycosides.

Synthesis of Coumestrol and Aureol

A total synthesis of coumestrol (1) and aureol (2) is described. The Perkin condensation of 2-bromo-4-hydroxylphenylacetic acid (6) and o-hydroxybenzaldehydes (7) gave the corresponding 2'-bromo-3-arylcoumarins (9). A copper-catalyzed consecutive hydroxylation and aerobic oxidative coupling of 9 under microwave conditions facilitated the total synthesis of 1 and 2, respectively, with spectroscopic data highly similar to those of natural products.

Ethylene Induced a High Accumulation of Dietary Isoflavones and Expression of Isoflavonoid Biosynthetic Genes in Soybean (Glycine max) Leaves

Dietary isoflavones, daidzein and genistein are of huge interest in the nutraceutical field due to their practical application to postmenopause complications. This study is the first report an efficient method to prepare isoflavone rich soybean leaves (soyleaves) which is an edible food stuff in Asian countries. The preharvest treatment of ethylene highly stimulated the level of isoflavone in soyleaves. Annotation and quantification of metabolites were determined by UPLC-Q-TOF-MS and HPLC. Phenolic metabolites of soyleaves are mostly kaempferol glycosides, but not dietary isoflavones. The accumulated isoflavones by ethylene treatment were determined to be daidzin 1, genistin 2, malonyldaidzin 3 and malonylgenistin 4, which were easily hydrolyzed to daidzein and genistein by β-glucosidase. Total content of dietary isoflavones was increased up to 13854 μg/g. The most suitable condition was estimated to be 250 μg/g ethylene or 200 μg/g ethephon (ethylene donor) treatment at the R3 growth stage. The ratio of daidzein and genistein glycosides was approximately 5 to 3. The accumulated isoflavonoid biosynthesis pathway genes were identified within the transcriptome of soyleaves tissues at 1 day after treatment of ethephon. The quantitative RT-PCR analysis of these genes indicated significantly higher expression of CHS, CHI, IFS, HID, IF7GT, and IF7MaT compared to control leaves. These findings suggest that ethylene activates a set of structural genes involved in isoflavonoid biosynthesis, thereby leading to enhanced production of isoflavones in soybean plants.

Distinctive Metabolism of Flavonoid between Cultivated and Semiwild Soybean Unveiled through Metabolomics Approach

Soybeans are an important crop for agriculture and food, resulting in an increase in the range of its application. Recently, soybean leaves have been used not only for food products but also in the beauty industry. To provide useful and global metabolite information on the development of soy-based products, we investigated the metabolic evolution and cultivar-dependent metabolite variation in the leaves of cultivated (Glycine max) and semiwild (G. gracilis) soybean, through a (1)H NMR-based metabolomics approach, as they grew from V (vegetative) 1 to R (reproductive) 7 growth stages. The levels of primary metabolites, such as sucrose, amino acids, organic acids, and fatty acids, were decreased both in the G. gracilis and G. max leaves. However, the secondary metabolites, such as pinitol, rutin, and polyphenols, were increased while synthesis of glucose was elevated as the leaves grew. When metabolite variations between G. gracilis and G. max are compared, it was noteworthy that rutin and its precursor, quercetin-3-O-glucoside, were found only in G. gracilis but not in G. max. Furthermore, levels of pinitol, proline, β-alanine, and acetic acid, a metabolite related to adaptation toward environmental stress, were different between the two soybean cultivars. These results highlight their distinct metabolism for adaptation to environmental conditions and their intrinsic metabolic phenotype. This study therefore provides important information on the cultivar-dependent metabolites of soybean leaves for better understanding of plant physiology toward the development of soy-based products.

Glyceollins and dehydroglyceollins isolated from soybean act as SERMs and ER subtype-selective phytoestrogens

Seven prenylated 6a-hydroxy-pterocapans and five prenylated 6a,11a-pterocarpenes with different kinds of prenylation were purified from an ethanolic extract of fungus-treated soybean sprouts. The activity of these compounds toward both human estrogen receptors (hERα and hERβ) was determined in a yeast bioassay and the activity toward hERα was additionally tested in an U2-OS based hERα CALUX bioassay. In the yeast bioassay, compounds with chain prenylation showed in general an agonistic mode of action toward hERα, whereas furan and pyran prenylation led to an antagonistic mode of action. Five of these antagonistic compounds had an agonistic mode of action in the U2-OS based hERα CALUX bioassay, implying that these compounds can act as SERMs. The yeast bioassay also identified 8 ER subtype-selective compounds, with either an antagonistic mode of action or no response toward hERα and an agonistic mode of action toward hERβ. The ER subtype-selective compounds were characterized by 6a-hydroxy-pterocarpan or 6a,11a-pterocarpene backbone structure. It is suggested that either the extra D-ring or the increase in length to 12-13.5Å of these compounds is responsible for an agonistic mode of action toward hERβ and, thereby, inducing ER subtype-selective behavior.

Inhibition of α-glucosidase by vitamin D3 and the effect of vitamins B1 and B2

Vitamin D₃ occupies the active site of α-glucosidase to avoid the entry of the substrate and causes the inhibition of α-glucosidase.

Re-exploring promising α-glucosidase inhibitors for potential development into oral anti-diabetic drugs: Finding needle in the haystack

Treatment of diabetes mellitus by oral α-glucosidase inhibitors is currently confined to acarbose, miglitol and voglibose marred by efficacy problems and unwanted side effects. Since the discovery of the drugs more than three decades ago, no significant progress has been made in the drug development area of anti-diabetic α-glucosidase inhibitors. Despite existence of a wide chemical diversity of α-glucosidase inhibitors identified to date, majority of them are simply piled up in publications and reports thus creating a haystack destined to be forgotten in the scientific literature without given consideration for further development into drugs. This review finds those "needles" in that haystack and lays groundwork for highlighting promising α-glucosidase inhibitors from the literature that may potentially become suitable candidates for pre-clinical or clinical trials while drawing attention of the drug development community to consider and take already-identified promising α-glucosidase inhibitors into the next stage of drug development.

Soy Leaf Extract Containing Kaempferol Glycosides and Pheophorbides Improves Glucose Homeostasis by Enhancing Pancreatic β-Cell Function and Suppressing Hepatic Lipid Accumulation in db/db Mice

This study investigated the molecular mechanisms underlying the antidiabetic effect of an ethanol extract of soy leaves (ESL) in db/db mice. Control groups (db/+ and db/db) were fed a normal diet (ND), whereas the db/db-ESL group was fed ND with 1% ESL for 8 weeks. Dietary ESL improved glucose tolerance and lowered plasma glucose, glycated hemoglobin, HOMA-IR, and triglyceride levels. The pancreatic insulin content of the db/db-ESL group was significantly greater than that of the db/db group. ESL supplementation altered pancreatic IRS1, IRS2, Pdx1, Ngn3, Pax4, Ins1, Ins2, and FoxO1 expression. Furthermore, ESL suppressed lipid accumulation and increased glucokinase activity in the liver. ESL primarily contained kaempferol glycosides and pheophorbides. Kaempferol, an aglycone of kaempferol glycosides, improved β-cell proliferation through IRS2-related FoxO1 signaling, whereas pheophorbide a, a product of chlorophyll breakdown, improved insulin secretion and β-cell proliferation through IRS1-related signaling with protein kinase A in MIN6 cells. ESL effectively regulates glucose homeostasis by enhancing IRS-mediated β-cell insulin signaling and suppressing SREBP-1-mediated hepatic lipid accumulation in db/db mice.