Effect of Aspergillus oryzae-challenged germination on soybean isoflavone content and antioxidant 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.

ROS Scavenging Effect of Selected Isoflavones in Provoked Oxidative Stress Conditions in Human Skin Fibroblasts and Keratinocytes

Isoflavones, belonging to polyphenolic compounds, show structural similarity to natural estrogens, and in this context, they have been extensively studied. Some of them are also applied as cosmetic additives; however, little is known regarding their effects on skin cells. In this investigation, common isoflavones, including genistein, daidzein, glycitein, formononetin, and biochanin A, as well as coumestrol, were evaluated for antioxidant activity and their impact on human skin fibroblasts and keratinocytes. Antioxidant effects were assessed using DPPH, ABTS, and FRAP tests, and the ability to scavenge reactive oxygen species (ROS) was tested in cells with H2O2-provoked oxidative stress. The impact on the activity of antioxidant enzymes (SOD, CAT, GSH) and lipid peroxidation (MDA) was also explored. As shown by Alamar Blue and neutral red uptake assays, the compounds were not toxic within the tested concentration range, and formononetin and coumestrol even demonstrated a stimulatory effect on cells. Coumestrol and biochanin A demonstrated significant antioxidative potential, leading to a significant decrease in ROS in the cells stimulated by H2O2. Furthermore, they influenced enzyme activity, preventing depletion during induced oxidative stress, and also reduced MDA levels, demonstrating protection against lipid peroxidation. In turn, genistein, daidzein, and glycitein exhibited low antioxidant capacity.

Ingestion of Soybean Sprouts Containing a HASPIN Inhibitor Improves Condition in a Mouse Model of Alzheimer's Disease

The MATP/tau protein is hyperphosphorylated in Alzheimer's patients. Therefore, research into the regulation of tau protein phosphorylation is important for understanding Alzheimer's disease. HASPIN is a serine/threonine kinase that is expressed in various cells. To examine whether HASPIN is involved in the onset of Alzheimer's disease through tau protein phosphorylation, we investigated the effects of a diet including soybean sprouts rich in the HASPIN inhibitor coumestrol in a mouse model of Alzheimer's disease (5xFAD). The results showed that HASPIN was expressed in the hippocampus and phosphorylated tau protein, while the ingestion of soybean sprouts containing coumestrol suppressed the development of spatial cognitive dysfunction in 5xFAD. These results indicate that HASPIN may be one of the target molecules for the repression of tau phosphorylation in the treatment of Alzheimer's disease.

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.

Occurrence of isoflavones in soybean sprouts and strategies to enhance their content: A review

Sprouting is a common strategy to enhance the nutritional value of seeds. Here, all the reports regarding the occurrence of isoflavones in soybean sprouts have been covered for the first time. Isoflavones were detected with concentrations ranging from 1 × 10-2 to 1 × 101  g/kg in soybean sprouts. Isoflavone concentration depends on the cultivar, germination time, part of the sprout, light, and temperature. Aglycon isoflavones increased during germination, especially in the hypocotyl, while 6″-O-malonyl-7-O-β-glucoside isoflavones decreased in the hypocotyl and increased in the cotyledon and root. Cooking reduced total isoflavone content. Regarding the strategies to enhance isoflavone contents, fermentation with Aspergillus sojae and external irradiation with UV-A or far-infrared were the methods that caused the greatest increases in aglycon, 7-O-β-glucoside, and total isoflavones. However, the largest increases in 6″-O-malonyl-7-O-β-glucoside and 6″-O-acetyl-7-O-β-glucosides isoflavones were detected after treatment with chitohexaose and calcium chloride, respectively. PRACTICAL APPLICATION: Soybean sprouts are widely consumed and provide essential proteins, antioxidants, and minerals. They are rich in isoflavones, which exhibit numerous health benefits, and have been studied as alternative therapies for a range of hormone-dependent conditions, such as cancer, menopausal symptoms, cardiovascular disease, and osteoporosis. Despite numerous reports being published to date regarding the occurrence of isoflavones in soybean sprouts, the publications in this field are highly dispersed, and a review has not yet been published. This review aims to (1) highlight the particular isoflavones that have been detected in soybean sprouts and their concentrations, (2) compared the effects of temperature, light, cooking and soybean cultivar affect the isoflavone levels on the different parts of the sprout, and (3) discuss the efficacy of the methods to enhance isoflavone contents. This review will provide a better understanding of the current state of this field of research by comparing the general trends and the different treatments for soybean sprouts.

Dietary Phytoestrogens and Their Metabolites as Epigenetic Modulators with Impact on Human Health

The impact of dietary phytoestrogens on human health has been a topic of continuous debate since their discovery. Nowadays, based on their presumptive beneficial effects, the amount of phytoestrogens consumed in the daily diet has increased considerably worldwide. Thus, there is a growing need for scientific data regarding their mode of action in the human body. Recently, new insights of phytoestrogens’ bioavailability and metabolism have demonstrated an inter-and intra-population heterogeneity of final metabolites’ production. In addition, the phytoestrogens may have the ability to modulate epigenetic mechanisms that control gene expression. This review highlights the complexity and particularity of the metabolism of each class of phytoestrogens, pointing out the diversity of their bioactive gut metabolites. Futhermore, it presents emerging scientific data which suggest that, among well-known genistein and resveratrol, other phytoestrogens and their gut metabolites can act as epigenetic modulators with a possible impact on human health. The interconnection of dietary phytoestrogens’ consumption with gut microbiota composition, epigenome and related preventive mechanisms is discussed. The current challenges and future perspectives in designing relevant research directions to explore the potential health benefits of dietary phytoestrogens are also explored.

Coumestrol mitigates retinal cell inflammation, apoptosis, and oxidative stress in a rat model of diabetic retinopathy via activation of SIRT1

Diabetes-induced oxidative stress is vital in initiating neuronal damage in the diabetic retina, leading to diabetic retinopathy (DR). This study investigates the possible effects of coumestrol (CMS) on streptozotocin (STZ)-induced DR. First, we established a rat model of DR by STZ injection and a cell model involving high-glucose (HG) exposure of human retinal microvascular endothelial cells (hRMECs). We characterized the expression patterns of oxidative stress indicators, pro-inflammatory cytokines, and pro-apoptotic proteins in hRMECs. Polymerase chain reaction showed sirtuin 1 (SIRT1) to be poorly expressed in the retinal tissues of STZ-treated rats and HG-exposed hRMECs, but its expression was upregulated upon treatment with CMS treatment. Furthermore, CMS treatment attenuated the STZ-induced pathologies such as oxidative stress, inflammation, and cell apoptosis. Consistent with the in vivo results, CMS activated the expression of SIRT1, thereby inhibiting oxidative stress, inflammation, and apoptosis of HG-treated hRMECs. From these findings, we concluded that CMS ameliorated DR by inhibiting inflammation, apoptosis and oxidative stress through activation of SIRT1.

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.

Small-Seeded Legumes as a Novel Food Source. Variation of Nutritional, Mineral and Phytochemical Profiles in the Chain: Raw Seeds-Sprouted Seeds-Microgreens

Growing public concerns about health haves prompted the search for novel food sources. The study is focused on the seeds, sprouted seeds and microgreens of Trifolium pratense, T. medium, Medicago sativa, M. lupulina, Onobrychis viciifolia, Astragalus glycyphyllos and A. cicer species as a potential source of value-added food ingredientsr. The samples were analysed for nutritional (wet chemistry, standard methods) and mineral (atomic absorption spectroscopy, UV-Vis spectrophotometry) profiles, isoflavones (ultra-performance liquid with diode array detector ⁻UPLC-DAD), coumestrol (UPLC-DAD), condensed tannins (CT) (vanillin-H₂SO₄ assay) and triterpene saponins (UPLC with triple-stage quadrupole MS). In our study, each species displayed high, but species-dependent nutritional, mineral and phytochemical value. All counterparts of legumes were mineral and protein rich. A. glycyphyllos samples, especially seeds, were abundant in iron. Trifolium spp. were found to be important sources of isoflavones, Medicago spp. of coumestrol and saponins, and O. viciifolia of CT. The protein and phytochemical contents increased and total carbohydrates decreased from seeds to microgreens.Our findings proved for the first time that seeds, sprouted seeds, and especially microgreens of small-seeded legumes are promising new sources of ingredients for fortification of staple foods with bioactive compounds, minerals and nutrients.

Coumestrol Confers Partial Resistance in Soybean Plants Against Cercospora Leaf Blight

Although previous research showed that the purple symptom of Cercospora leaf blight (CLB) is associated with lower biomass of Cercospora cf. flagellaris and lower concentrations of cercosporin, a reactive oxygen species producer, as compared with blighted leaves, the hypothesis that the purple symptom is a plant reaction to the pathogen has never been tested. In this study, we demonstrated that high levels of coumestrol (COU) were associated with purple symptoms of CLB and that COU has strong antioxidant activity. Additionally, we found that COU is restricted to the pigmented areas of purple leaves, and the pigmentation is restricted to the adaxial surfaces, suggesting that COU may be acting as a sunscreen. Even though COU is associated with the purple leaf symptom, this coumestan is not the direct cause of discoloration in that COU is colorless. Quantification of chlorophyll a and b and total carotenoids suggested that blighted but not purple or asymptomatic leaves were undergoing photooxidative stress. Because the purple symptom is associated with high COU concentrations, lower biomass of C. cf. flagellaris, and lower cercosporin concentrations, we conclude that the purple symptom is a disease resistance reaction, mediated in part by COU, which provides a high level of antioxidant activity and, hence, partial resistance.

Comparative Evaluation of the Antioxidant and Anti-Alzheimer's Disease Potential of Coumestrol and Puerarol Isolated from Pueraria lobata Using Molecular Modeling Studies

The current study assesses the antioxidant effects of two similar isoflavonoids isolated from Pueraria lobata, coumestrol and puerarol, along with the cholinergic and amyloid-cascade pathways to mitigate Alzheimer’s disease (AD). Antioxidant activity was evaluated via 1,1-diphenyl-2-picryhydrazyl (DPPH) and peroxynitrite (ONOO⁻) scavenging ability further screened via ONOO⁻-mediated nitrotyrosine. Similarly, acetyl- and butyrylcholinesterase (AChE/BChE) and β-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitory activities were assessed together with docking and kinetic studies. Considering DPPH and ONOO⁻ scavenging activity, coumestrol (EC₅₀ values of 53.98 and 1.17 µM) was found to be more potent than puerarol (EC₅₀ values of 82.55 and 6.99 µM) followed by dose dependent inhibition of ONOO⁻-mediated nitrotyrosine. Coumestrol showed pronounced AChE and BChE activity with IC₅₀ values of 42.33 and 24.64 µM, respectively, acting as a dual cholinesterase (ChE) inhibitor. Despite having weak ChE inhibitory activity, puerarol showed potent BACE1 inhibition (28.17 µM). Kinetic studies of coumestrol showed AChE and BChE inhibition in a competitive and mixed fashion, whereas puerarol showed mixed inhibition for BACE1. In addition, docking simulations demonstrated high affinity and tight binding capacity towards the active site of the enzymes. In summary, we undertook a comparative study of two similar isoflavonoids differing only by a single aliphatic side chain and demonstrated that antioxidant agents coumestrol and puerarol are promising, potentially complementary therapeutics for AD.

Metabolite changes in nine different soybean varieties grown under field and greenhouse conditions

Global food security remains a worldwide concern due to changing climate, increasing population, and reduced agriculture acreages. Greenhouse cultivation increases productivity by extending growing seasons, reducing pest infestations and providing protection against short term drastic weather fluctuations like frost, heat, rain, and wind. In the present study, we examined and compared the metabolic responses of nine soybean varieties grown under field and greenhouse conditions. Extracts were assayed by GC-FID, GC-MS, and LC-MS for the identification of 10 primary (amino acids, organic acids, and sugars) and 10 secondary (isoflavones, fatty acid methyl esters) metabolites. Sugar molecules (glucose, sucrose, and pinitol) and isoflavone aglycons were increased but the isoflavones glucoside content decreased in the greenhouse cultivated soybeans. The amino acids and organic acids varied between the varieties. The results show that clustering (PCA and PLS-DA) patterns of soybean metabolites were significantly influenced by the genetic variation and growing conditions.

Aspergillus oryzae fermented germinated soybean extract alleviates perimenopausal symptoms in ovariectomised rats

BACKGROUND

Soybeans have been widely used to alleviate climacteric symptoms. In this study, we investigated the oestrogenic activities of isoflavones extracted from Aspergillus oryzae-challenged germinated soybeans (AO-GS). Eight-week-old virgin Sprague-Dawley female rats were ovariectomised (OVX). The rats were orally administered 0.1 mg kg(-1) 17α-ethinyl oestradiol or three different doses of AO-GS (0.5, 1.0 2.0 g kg(-1) day(-1)) in distilled water for 6 weeks, while control rats were administered vehicle alone. Uterine weights and levels of oestradiol and testosterone in serum were measured. In addition to serum parameters, bone parameters were also acquired by using micro-computed tomography scanning.

RESULTS

Treatments of OVX rats with AO-GS changed the secretory profile of serum oestradiol and testosterone. Serum oestradiol levels were significantly increased in OVX rats treated with and AO-GS (0.5, 1.0, 2.0 g kg(-1) day(-1)), while serum testosterone levels were not significantly increased in OVX rats treated with 1.0 g kg(-1) day(-1) of AO-GS. Furthermore, AO-GS (2.0 g kg(-1) day(-1)) significantly attenuated bone loss, increased trabecular bone volume fraction and trabecular thickness, and significantly decreased trabecular pattern factor.

CONCLUSION

AO-GS treatments caused moderate oestrogenic activity in OVX rats compared to those treated with oestradiol, suggesting the potential for the use of AO-GS in the treatment of menopausal symptoms and in osteoporosis caused by oestrogen deficiency.

Protective effects of germinated and fermented soybean extract against tert-butyl hydroperoxide-induced hepatotoxicity in HepG2 cells and in rats

The aim of the current study is to investigate the antioxidant and hepatoprotective effects of germinated and fermented soybean extract (GFSE) on tert-butyl hydroperoxide (t-BHP)-induced oxidative stress in HepG2 cells and in the rat liver. High performance liquid chromatography (HPLC) analysis showed that genistin (3.40 ± 0.14 μg mg(-1)) was the most abundant isoflavone in the GFSE. Coumestrol (1.00 ± 0.04 μg mg(-1)), daidzin (0.78 ± 0.14 μg mg(-1)), genistein (0.68 ± 0.05 μg mg(-1)), glycitin (0.54 ± 0.02 μg mg(-1)), glycitein (0.41 ± 0.02 μg mg(-1)), and daidzein (0.02 ± 0.0 g mg(-1)) are also contained in decreasing order of content. GFSE significantly inhibited t-BHP-induced reactive oxygen species (ROS) production in HepG2 cells. This GFSE-induced ROS reduction was associated with the down-regulation of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4), a pro-oxidant enzyme, and the up-regulation of the mRNA levels of antioxidant enzymes, including catalase, superoxide dismutase (SOD), glutathione reductase (GR), and glutathione peroxidase (Gpx) in the rat liver. In addition, increased levels of antioxidant enzyme mRNAs correlated with the enhanced enzymatic activities of SOD, catalase, and glutathione-S-transferase (GST). The antioxidant effect of GFSE was supported by the reduction in the levels of malondialdehyde (MDA), a hydroperoxide, and the serum levels of lactate dehydrogenase (LDH), a biomarker of cell damage, were also lowered by GFSE. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST), which are clinical biomarkers of liver function, were shown to be improved with GFSE administration. The effects of GFSE were attributable to an improvement in liver tissue morphology. Taken together, GFSE protected the liver from t-BHP-induced oxidative stress by regulating ROS-related enzymes. Our results suggest that GFSE might be a hepatoprotective source against oxidative stress.

Flt3 is a target of coumestrol in protecting against UVB-induced skin photoaging

While skin aging is a naturally occurring process by senescence, exposure to ultraviolet (UV) radiation accelerates wrinkle formation and sagging of skin. UV induces skin aging by degrading collagen via activating matrix metalloproteinases (MMPs). In this study, we show that coumestrol, a metabolite of the soybean isoflavone daidzein, has a preventive effect on skin photoaging in three-dimensional human skin equivalent model. Coumestrol inhibited UVB-induced MMP-1 expression and activity. Whole human kinase profiling assay identified FLT3 kinase as a novel target protein of coumestrol in UVB-induced signaling pathway in skin. Coumestrol suppresses FLT3 kinase activity, and subsequently, Ras/MEK/ERK and Akt/p70 ribosomal S6 kinase pathway. This suppresses AP-1 activity and in turn, diminishes MMP-1 gene transcription. Using X-ray crystallography, the binding of coumestrol to FLT3 was defined and implied ATP-competitive inhibition. Residues Lys644 and Phe830 showed local changes to accommodate coumestrol in the ATP-binding pocket. 4-APIA, a pharmacological inhibitor of FLT3, inhibited MMP-1 expression and induced signal transduction changes similar to coumestrol. Taken together, coumestrol inhibits UVB-induced MMP-1 expression by suppressing FLT3 kinase activity. These findings suggest that coumestrol is a novel dietary compound with potential application in preventing and improving UVB-associated skin aging.

A metabolic profiling strategy for the dissection of plant defense against fungal pathogens

Here we present a metabolic profiling strategy employing direct infusion Orbitrap mass spectrometry (MS) and gas chromatography-mass spectrometry (GC/MS) for the monitoring of soybean's (Glycine max L.) global metabolism regulation in response to Rhizoctonia solani infection in a time-course. Key elements in the approach are the construction of a comprehensive metabolite library for soybean, which accelerates the steps of metabolite identification and biological interpretation of results, and bioinformatics tools for the visualization and analysis of its metabolome. The study of metabolic networks revealed that infection results in the mobilization of carbohydrates, disturbance of the amino acid pool, and activation of isoflavonoid, α-linolenate, and phenylpropanoid biosynthetic pathways of the plant. Components of these pathways include phytoalexins, coumarins, flavonoids, signaling molecules, and hormones, many of which exhibit antioxidant properties and bioactivity helping the plant to counterattack the pathogen's invasion. Unraveling the biochemical mechanism operating during soybean-Rhizoctonia interaction, in addition to its significance towards the understanding of the plant's metabolism regulation under biotic stress, provides valuable insights with potential for applications in biotechnology, crop breeding, and agrochemical and food industries.

Spectroscopic determination of metabolic and mineral changes of soya-chunk mediated by Aspergillus sojae

Time dependent changes of primary (GC-MS), isoflavones (LC-MS) and minerals (ICP-OES) content of fermented soya-chunk were compared with un-fermented (0H) soya-chunk and presented. Results revealed that the amino acid content increased gradually based on the fermentation time; whereas the maltose, sucrose and fructose contents were reduced due to the fungal growth. The glucosides changed extensively during the initial fermentation time resulting in augmentation of aglycones and phytoalexins. This affects the antioxidant potential whereas the DPPH and ABTS of 0H showed lowest activity (18.15% and 54.92%) and increased quite high with fungal fermentation (45.81% and 93.47%). The calcium (0.55%), magnesium (0.47 mg/kg), nickel (5.17 mg/kg l(-1)), and copper (8.33 mg/kg l(-1)) content were increased during the fermentation and in a decrease of iron and aluminium contents. Findings suggest that the soya-chunk prepared by fungal fermentation will improve the antioxidant and mineral content and hence their nutritional property will be enhanced for humans.

Coumestrol induces mitochondrial biogenesis by activating Sirt1 in cultured skeletal muscle cells

The mitochondrion is a central organelle in cellular energy homeostasis; thus, reduced mitochondrial activity has been associated with aging and metabolic disorders. This paper provides biological evidence that coumestrol, which is a natural isoflavone, activates mitochondrial biogenesis. In cultured myocytes, coumestrol activated the silent information regulator two ortholog 1 (Sirt1) through the elevation of the intracellular NAD(+)/NADH ratio. Coumestrol also increased the mitochondrial contents and induced the expression of key proteins in the mitochondrial electron transfer chain in cultured myocytes. A Sirt1 inhibitor and Sirt1-targeting siRNAs abolished the effect of coumestrol on mitochondrial biogenesis. Similar to an increase in mitochondrial content, coumestrol improved myocyte function with increased ATP concentration. Taken together, the data suggest that coumestrol is a novel inducer of mitochondrial biogenesis through the activation of Sirt1.

Targeted metabolomics for Aspergillus oryzae-mediated biotransformation of soybean isoflavones, showing variations in primary metabolites

This study aimed to investigate the biotransformation of soybean isoflavones to hydroxyisoflavones, and the primary and secondary metabolite change during Aspergillus oryzae KACC40247-mediated fermentation by gas chromatography-time of flight-mass spectrometry and LC-MS with multivariate analysis. The mass spectrometric analysis revealed that acetylglycosides and glycosides decreased during the first 12 h of fermentation, while the aglycones increased up to that time point. This was followed by a decrease in aglycone levels due to the formation of hydroxyisoflavones. The hydroxyflavones, 8-hydroxydaidzein, hydroxygenistein, and hydroxyglycitein, resulting from the biotransformation of the corresponding aglycones, increased up to 24 h, and then subsequently decreased. During fermentation, the levels of monosaccharides, aspartic acid, pyroglutamic acid, gamma-aminobutyric acid, and organic acids gradually decreased, whereas the levels of threonine, serine, and glycine increased. Hydroxyisoflavone was more strongly correlated with antioxidant activity than the other metabolites. Our results suggest that biotransformation has the potential to improve the nutritional properties of soy-based food.