Isoflavone Levels Research Articles

Association of equol producing status with aortic calcification in middle-aged Japanese men: The ERA JUMP study

BackgroundEquol, an isoflavone (ISF)-derived metabolite by the gut microbiome in certain individuals termed as equol-producers, might be the key anti-atherogenic component of ISFs. Our objective was to determine the association between equol-producing status and aortic atherosclerosis assessed as aortic calcification (AC). MethodsThis population-based study of 302 Japanese men aged 40–49, free of cardiovascular disease, examined serum levels of equol and ISFs, AC in the entire aorta by electron-beam computed tomography with Agatston method, and cardiovascular risk factors. We defined equol-producers as individuals with serum levels of equol ≥20 nM and prevalent AC as an AC score ≥ 10. We analyzed the association between equol-producing status and AC using Tobit and logistic regressions. We performed age-stratified analyses since age was a significant effect-modifier. ResultsThe 70th to 90th percentile AC scores were 4 to 243 in equol-producers and 15 to 444 in non-producers, respectively. Overall, equol-producers (41% of the sample) had lower AC scores (−209, [95% confidence interval (CI): −455, 36]) and odds of AC (odds ratio (OR): 0.7 [95% CI: 0.4, 1.3]), although not statistically significant, compared to non-producers after controlling for cardiovascular risk factors. Among men aged 46–49, equol-producers had significantly lower AC scores (−428 [95% CI: −827, −29]). Furthermore, there were null associations between serum levels of ISFs and both AC score and the odds of AC. ConclusionIn middle-aged Japanese men, equol-producers had a non-significantly lower burden of aortic atherosclerosis than non-producers whereas ISFs had a null association. Studies with larger sample sizes in both sexes are warranted.

Long-term exposure to genistein inhibits the proliferation of gallbladder cancer by downregulating the MCM complex

Soy isoflavones are natural tyrosine kinase inhibitors closely associated with decreased morbidity and mortality of various tumors. The activation of tyrosine kinases such as ERBB2 is the mechanism by which cholecystitis transforms into gallbladder cancer (GBC), therefore, it is important to investigate the relationship between long-term exposure to soy isoflavones and the occurrence and progression of GBC. This case-control study (n = 85 pairs) found that the high level of plasma soy isoflavone—genistein (GEN) was associated with a lower risk of gallbladder cancer (≥326.00 ng/mL compared to ≤19.30 ng/mL, crude odds ratio 0.15, 95% CI 0.04–0.59; P for trend = 0.016), and that the level of GEN exposure negatively correlated with Ki67 expression in GBC tissue (n = 85). Consistent with these results, the proliferation of GBC cells was inhibited in the long-term exposure models of GEN in vitro and in vivo. The long-term exposure to GEN reduced the tyrosine kinase activity of ERBB2 and impaired the function of the PTK6-AKT-GSK3β axis, leading to downregulation of the MCM complex in GBC cells. In summary, long-term exposure to GEN associated with soy products intake might play a certain role in preventing GBC and even inhibiting the proliferation of GBC cells.

Identification of Pueraria spp. through DNA barcoding and comparative transcriptomics

BackgroundKudzu is a term used generically to describe members of the genus Pueraria. Kudzu roots have been used for centuries in traditional Chinese medicine in view of their high levels of beneficial isoflavones including the unique 8-C-glycoside of daidzein, puerarin. In the US, kudzu is seen as a noxious weed causing ecological and economic damage. However, not all kudzu species make puerarin or are equally invasive. Kudzu remains difficult to identify due to its diverse morphology and inconsistent nomenclature.ResultsWe have generated sequences for the internal transcribed spacer 2 (ITS2) and maturase K (matK) regions of Pueraria montana lobata, P. montana montana, and P. phaseoloides, and identified two accessions previously used for differential analysis of puerarin biosynthesis as P. lobata and P. phaseoloides. Additionally, we have generated root transcriptomes for the puerarin-producing P. m. lobata and the non-puerarin producing P. phaseoloides. Within the transcriptomes, microsatellites were identified to aid in species identification as well as population diversity.ConclusionsThe barcode sequences generated will aid in fast and efficient identification of the three kudzu species. Additionally, the microsatellites identified from the transcriptomes will aid in genetic analysis. The root transcriptomes also provide a molecular toolkit for comparative gene expression analysis towards elucidation of the biosynthesis of kudzu phytochemicals.

Characterization of the Probiotic Potential of Lactic Acid Bacteria Isolated from Kimchi, Yogurt, and Baby Feces in Hong Kong and Their Performance in Soymilk Fermentation.

Background: There are several potential healthy or nutritional benefits from the use of lactic acid bacteria (LAB) in foods. This study aimed to characterize the LAB isolates from kimchi, yogurt, and baby feces in the Hong Kong area and evaluate their performance in fermented soymilk, which allowed us to assess their potential use in future experiments. Methods: General characteristics including tolerance to acid, NaCl, bile salts and phenol, antimicrobial activity to various pathogens, and adhesive ability to Caco-2 cells were evaluated using 18 LAB in this study. To further demonstrate the influence of such isolates in soymilk fermentation, we measured viability by plating and noting changes in pH, amino acid content, aglyconic isoflavones content and antioxidant capacities in vitro, such as scavenging ability, and iron chelating ability. Results: In this study, various LAB isolates belonging to Lactobacillus rhamnosus, Lactobacillus sakei, Lactiplantibacillus plantarum, and Leuconostoc mesenteroides isolated in Hong Kong were evaluated. L. plantarum isolates R7, AC12, and AC14.1, and L. rhamnosus AC1 showed higher tolerance to acid, NaCl, bile salts, and phenol as compared to the other isolates tested. L. plantarum isolates AC12, AC13 and AC14.1, and L. rhamnosus AC1 harbored strong antimicrobial activity. L. plantarum isolates R7, AC12, AC13 and AC14.1, and L. paracasei isolates R6 and R8 showed higher adhesive ability than the other tested isolates. In soymilk, the viable numbers of L. paracasei R5, L. plantarum R7, L. rhamnosus AC1, L. sakei AC2, and Leu. mesenteroides AC5 were much higher than the other tested isolates after 48 h of fermentation. The pH value measuring the lactic acid level in soymilk fermented by L. plantarum AC14.1 was the lowest in comparison to those in soymilk fermented by other isolates. In addition, the levels of free amino acids and isoflavones in the aglycone forms of L. rhamnosus AC1-fermented soymilk were the highest. L. rhamnosus AC1-fermented soymilk also showed the highest antioxidant potential, including DPPH scavenging ability and iron chelating ability. Conclusions: In general, L. plantarum isolates R7 and AC14.1 and L. rhamnosus AC1 exhibited higher tolerance to challenging conditions as compared to the other isolates. Moreover, L. rhamnosus AC1 exhibited superior performance in soymilk fermentation and potential as a starter and probiotic culture.

Soy isoflavones supplementation improves reproductive performance and serum antioxidant status of sows and the growth performance of their offspring.

A total of 60sows (Landrace×Yorkshire, average parity was 1.39) were used to evaluate the effects of soy isoflavones (ISO) supplementation on reproductive performance, serum antioxidant enzyme parameters, and milk compositions of sows, and the growth performance of offspring. Sows were randomly assigned to 4groups based on the parity. There were 15 replicates per treatment. Dietary treatments were based on a corn-soybean meal-based basal diet and supplemented with 0, 10, 20, or 40mg/kg ISO. With the increase of the ISO dosage, average daily feed intake of sows increased linearly; oestrus interval decreased linearly and quadratically. In addition, on day 10 of lactation, linear increases in serum superoxide dismutase levels, linear and quadratic increases in serum total antioxidant capacity, and linear decreases in serum malondialdehyde levels were observed in increasing ISO dosage in the diet of sows. The body weight on day 10 and 21 and the average daily gain during days 3-10 and 3-21 of offspring increased linearly at graduated doses of ISO increased. Therefore, feeding sows with graded levels of ISO containing diet during late-gestation and lactation periods improved the reproductive performance of sows and the growth performance of their offspring in a dose-dependent manner.

Nutritional Quality and Preliminary Investigation of Processing Characteristics for Main Soybean Cultivars

In order to investigate nutritional quality and processing characteristics for soybeans in China, eightmain soybean cultivars were collected by measuring their nutritional components, active compounds and protein composition. The results showed that these cultivars of soybean with widely processed application were higher in contents of protein and fat, but lower in total carbohydrate with higher content of dietary fiber than other soybean cultivars in China. Jikexiandou, jikeyuzhong08, 690 belonged to high protein soybean and Jikexiandou, Jikemidou, Heinong51, Dongsheng7, Nongken9 were the highest content oil soybean. The samples in the test exhibited high content of vitamin E, iron, calcium, ranged from 11.0~21.8 mg/100 g, 560.0~1270.0 mg/kg, 66.20~83.40 mg/kg respectively. The content of vitamin B2 had little difference among varieties, while the level of soybean isoflavones in the tested samples had great differences. The 7S and 11S protein contents and the coefficient of variation of protein aggregates’ particle size in eight samples were all above 30%, which speculated that there were great differences in soybean processing characteristics among different varieties.

Metabolic Engineering of Isoflavones: An Updated Overview

Isoflavones are ecophysiologically active secondary metabolites derived from the phenylpropanoid pathway. They were mostly found in leguminous plants, especially in the pea family. Isoflavones play a key role in plant–environment interactions and act as phytoalexins also having an array of health benefits to the humans. According to epidemiological studies, a high intake of isoflavones-rich diets linked to a lower risk of hormone-related cancers, osteoporosis, menopausal symptoms, and cardiovascular diseases. These characteristics lead to the significant advancement in the studies on genetic and metabolic engineering of isoflavones in plants. As a result, a number of structural and regulatory genes involved in isoflavone biosynthesis in plants have been identified and characterized. Subsequently, they were engineered in various crop plants for the increased production of isoflavones. Furthermore, with the advent of high-throughput technologies, the regulation of isoflavone biosynthesis gains attention to increase or decrease the level of isoflavones in the crop plants. In the review, we begin with the role of isoflavones in plants, environment, and its benefits in human health. Besides, the main theme is to discuss the updated research progress in metabolic engineering of isoflavones in other plants species and regulation of production of isoflavones in soybeans.

Effects of Obesity and Low and High Isoflavones in Soy Protein Concentrate Diet on Liver Steatosis

Abstract Objectives To examine the role of isoflavones levels in soy protein diets on protection against Non-Alcoholic Fatty Liver Disease (NAFLD) in obese rat model (8 weeks of feeding). Methods 42 six-week old lean (n = 21) and obese (n = 21) Zucker rats were randomly assigned to one of 3 dietary groups: casein diet (C = control), soy protein with low isoflavones (LIF), or soy protein with high isoflavones (HIF) for 8 weeks (n = 7 rats/group). Rats were weighed twice weekly. After 8 weeks, all rats were sacrificed and livers taken for histopathological analysis. Results Obese rats gained significantly more weight (P < 0.0001) than lean rats for all three diet groups, with no significant difference between obese (O) LIF vs. OHIF groups (P = 0.19). Body weight was higher in OHIF (717 g) than in OLIF and OC (694 and 620, respectively). No significant difference between LC, LLIF and LHIF (P between 0.3 and 0.6) was found. Liver steatosis scores were significantly higher in obese rats compared to lean rats (P < 0.001). In addition, differences in the steatosis scores between OC vs. OHIF (P < 0.0001) were more significant than differences between OC vs. OLIF (P = 0.01), and OLIF vs. OHIF (P = 0.01) groups, showing the protective effect against liver steatosis exerted by soy protein concentrate with higher isoflavones. Conclusions We found that soy protein concentrate protects against liver steatosis and protection is more significant with higher concentration of isoflavones. Funding Sources USDA.

265 BERBERINE AMELIORATES OVARIECTOMY-INDUCED ANXIETY-LIKE BEHAVIORS BY ENRICHMENT IN EQUOL GENERATING GUT MICROBIOTA

Background Decline in circulating ovarian hormone levels is associated with increment in anxiety and alteration in intestinal microbiota. As a kind of gut microbiota modulator, berberine (BBR) has shown efficacy in treating diseases such as menopausal osteoporosis and type 2 diabetes through regulating bacteria. However, the effects of BBR on ovariectomy-induced anxiety are still unclear and whether or not gut microbiota modifies the possible effect of BBR remain to be fully elucidated. Aim To demonstrate that BBR is able to alleviate anxiety through modulating intestinal microbiota under estrogen-deficient conditions. Methods Female specific pathogen-free (SPF) SD rats were ovariectomized (OVX) or shamoperated (sham). BBR (100mg/kg) or control vehicle was administered via oral gavage every day for four weeks. Open field test (OFT) and elevated plus maze test (EPM) were used to detect the anxiety-like behaviors. Moreover, the 16S rRNA sequencing and liquid chromatography/mass spectrometry (LC/MS) analysis were utilized to validate the changes in intestinal microbes and microbiota isoflavone metabolites, respectively. The concentration of serum estradiol (E2) was measured using ELISA. Further, female germ-free (GF) SD rats were operated and treated with BBR or vehicle under sterile conditions. Fecal microbiota transplantation (FMT) was conducted using fecal samples from SPF rats to colonize GF-OVX rats. Results Compared with SPF-sham rats, OFT and EPM showed increased anxiety in SPFOVX rats, and BBR treatment significantly ameliorated anxiety-like behaviors compared with SPF-OVX rats. The serum level of isoflavone metabolite equol and the ratio of equol to daidzein were decreased by ovariectomy and elevated by BBR treatment. Furthermore, BBR treatment altered the microbiota diversity and taxa richness of the gut microbiome. The alpha diversity revealed a significant reduction in richness and diversity after BBR administration compared with SPF-OVX group. The beta diversity showed dissimilarity in composition among each group. At the genus level, BBR-treated rats harbored a higher abundance of beneficial gut microbes, such as Bacteroides, Bifidobacterium, Lactobacillus, and Akkermansia, among which many species are involved in isoflavone bioconversion (Fig.1). Notably, estrogen deficiency in GF rats also resulted in anxiety-like behaviors, however gavage feeding of BBR to GF-OVX rats had no significant effects on behavior improvement and equol metabolism. FMT of SPF-BBR rats to GF-OVX rats improved anxiety-like behaviors and increased the serum concentration of isoflavone metabolite equol (Fig.2). Conclusions Gut microbiota is critical in BBR treatment of ovariectomy-aggravated anxiety, indicating a promising therapeutic strategy for postmenopausal anxiety. Download : Download high-res image (316KB) Download : Download full-size image Fig. 1 . BBR ameliorates the anxiety-like behaviors and gut dysbiosis of SPF-OVX rats. (A) Elevated plus-maze test results. (B) Open field test results. (C) Ovarian hormone levels. (D) Isoflavone levels. (E) α-diversity indices. (F) β-diversity measured by PCoA. (G) LEfSe analysis from phylum to genus. Data are expressed as the mean ± SEM. *P Download : Download high-res image (217KB) Download : Download full-size image Fig. 2 . GF condition eliminates the anti-anxiety effects of BBR, while fecal microbes from SPF-BBR rats ameliorates anxiety of GF-OVX rats. (A) Elevated plus-maze test results of GF rats. (B) Open field test results of GF rats. (C) Ovarian hormone levels of GF rats. (D) Isoflavone levels of GF rats. (E) Elevated plus-maze test results of FMT rats. (F) Open field test results of FMT rats. (G) Ovarian hormone levels of FMT rats. (H) Isoflavone levels of FMT rats. Data are expressed as the mean ± SEM. *P

The Synergistic role of serotonin and melatonin during temperature stress in promoting cell division, ethylene and isoflavones biosynthesis in Glycine max

Serotonin (SER) and melatonin (MEL) are signalling molecules involved in signalling in various stress response mechanisms in plants. However, their role and molecular mechanism in the accumulation of isoflavones and biomass under temperature stress are not clearly defined. To explicate their function, SER and MEL at different ratios were applied to the in vitro cultures of soybean at 16, 24, and 32 °C and were analyzed for the accumulation of bioactive compounds, isoflavones content, and culture biomass followed by transcript levels of cell division, isoflavones, and ethylene biosynthesis genes. An increase in biomass, total phenolics, total flavonoids, and different forms of isoflavones content was evident in the treatments. The expression level of critical genes of isoflavone (chalcone synthase, chalcone reductase, chalcone isomerase, and isoflavone synthase), ethylene (s-adenosyl methionine and 1-aminocyclopropane-1-carboxylic acid oxidase), cell division (cyclin and cyclin-dependent kinase), and MEL biosynthesis genes (acetyl serotonin O-methyltransferase and serotonin N-acetyltransferase) and transcription factors (melatonin 2 hydroxylase, myeloblastosis like protein) were co-expressed during temperature stress in the presence of SER and MEL. At 32 °C, the SER and MEL application showed maximum biomass and isoflavones content and was substantiated with the corresponding gene expression. We hypothesize that the SER and MEL ratio may play a role in increasing the biomass and isoflavones content under temperature stress in soybean cell culture.

Comparison of Phenolic and Flavonoid Compound Profiles and Antioxidant and α-Glucosidase Inhibition Properties of Cultivated Soybean (Glycine max) and Wild Soybean (Glycine soja).

Wild soybean (Glycine soja Sieb.et Zucc; WS) has been used as a traditional food in China for many years and contains significantly higher levels of isoflavones than cultivated soybean (Glycine max; CS), but the secondary metabolites, including flavonoids and the phenolic composition differences between them, remain unclear. The results showed that WS possessed significantly higher total phenolic and flavonoid content and exhibited better antioxidant and α-glucosidase inhibition activities as well as excellent protective effects against H2O2-induced oxidative injury in a human endothelial cell line. Through metabolomic analysis, 642 metabolites were identified, and 238 showed differential expression, with 151 upregulated and 87 downregulated. A total of 79 flavonoid compounds were identified, 42 of which were upregulated in WS. 2′-Hydroxygenistein, garbanzol, protocatechuic aldehyde, ligustilide, and resveratrol were the most discriminated compounds in WS. The metabolic pathway analysis of differential metabolites related to the biosynthesis of flavonoids and phenolic acids were the biosynthesis of phenylpropanoids, flavonoids, isoflavonoids, flavones, and flavonols. This study substantially elucidated differences in the content of flavonoids and biological activities between WS and CS, which is useful information for the effective utilization of these two black soybean species in food processing.

Characteristic and Isoflavone Level of Soymilk Fermented by Single and Mixed Culture of <i>Lactobacillus plantarum </i>and Yoghurt Starter

Fermented soymilk has better health benefits compared to unfermented soymilk. The health benefits of fermented soymilk are improving blood lipid profile, antioxidants and anti-inflammatory. Fermentation of lactic acid bacteria can increase the content of aglycon isoflavones, namely genistein and daidzein. The purpose of this study was to analyze the characteristics of soymilk and isoflavone level fermented with a single culture of Lactobacillus plantarum and mixed culture of Lactobacillus plantarum and yogurt starter. This research consisted of 4 treatments, namely unfermented, fermentation using L. plantarum, fermentation using S. thermophilus and L.bulgaricus, and fermentation using L. plantarum, S. thermophillus, L. bulgaricus. Samples analyzed proximate, titratable acid , pH, total lactic acid bacteria, total daidzein, genistein and sensory quality. The results showed that the total acid, pH, and total lactic acid bacteria for fermentation with mixed cultures were higher compared to L. plantarum single culture. Total daidzein and genistein for single culture and mixed culture were not significantly different between the two groups. Sensory analysis shows that soymilk with a single culture have the highest value for the parameters of taste, aroma and color.

Berberine ameliorates ovariectomy-induced anxiety-like behaviors by enrichment in equol generating gut microbiota

The gut microbiota is recognized as a promising therapeutic target for anxiety. Berberine (BBR) has shown efficacy in the treatment of diseases such as postmenopausal osteoporosis, obesity, and type 2 diabetes through regulating the gut microbiota. However, the effects of BBR on postmenopausal anxiety are still unclear. The purpose of the study is to test whether BBR ameliorates anxiety by modulating intestinal microbiota under estrogen-deficient conditions. Experimental anxiety was established in specific pathogen-free (SPF) ovariectomized (OVX) rats, which were then treated with BBR for 4 weeks before undergoing behavioral tests. Open field and elevated plus maze tests demonstrated that BBR treatment significantly ameliorated anxiety-like behaviors of OVX rats compared with vehicle-treated counterparts. Moreover, as demonstrated by 16S rRNA sequencing and liquid chromatography/mass spectrometry (LC/MS) analysis, BBR-treated OVX rats harbored a higher abundance of beneficial gut microbes, such as Bacteroides, Bifidobacterium, Lactobacillus, and Akkermansia, and exhibited increased equol generation. Notably, gavage feeding of BBR had no significant anti-anxiety effects on germ-free (GF) rats that underwent ovariectomy, whereas GF rats transplanted with fecal microbiota from SPF rats substantially phenocopied the donor rats in terms of anxiety-like symptoms and isoflavone levels. This study indicates that the gut microbiota is critical in the treatment of ovariectomy-aggravated anxiety, and that BBR modulation of the gut microbiota is a promising therapeutic strategy for treating postmenopausal symptoms of anxiety.

Serum isoflavones and lignans and odds of breast cancer in pre- and postmenopausal Chinese women.

Isoflavones and lignans are phytoestrogens present in plant-based foods, which have a potential preventive effect on breast carcinogenesis. The effects of phytoestrogens on breast cancer may differ according to the hormonal environment. This case-control study aimed to investigate the association between serum phytoestrogens and odds of breast cancer among Chinese pre- and postmenopausal women. A total of 792 cases and 813 age-matched controls were included. Serum isoflavone (daidzein, genistein, glycitein, equol, and formononetin) and lignan (enterodiol and enterolactone) concentrations were measured using a liquid chromatography-tandem mass spectrometry method. Significant inverse associations were found between serum total soy isoflavone precursors, daidzein, genistein, formononetin, total lignans, enterodiol, enterolactone, and the odds of breast cancer in premenopausal but not postmenopausal women. For premenopausal women, the adjusted odds ratios (95% confidence intervals) for the highest versus the lowest serum concentration groups were 0.60 (0.41-0.87) for total soy isoflavones precursors, 0.64 (0.44-0.93) for daidzein, 0.62 (0.43-0.90) for genistein, 0.49 (0.35-0.68) for formononetin, 0.38 (0.25-0.57) for total lignans, 0.49 (0.33-0.73) for enterodiol, and 0.49 (0.33-0.74) for enterolactone. However, the interaction between serum phytoestrogens and menopausal status on odds of breast cancer was statistically significant only for daidzein. No significant association was found between serum equol or gycitein and the odds of breast cancer among either pre- or postmenopausal women. Higher levels of certain serum isoflavones and lignans were associated with reduced odds of breast cancer in premenopausal women, but the interaction was statistically significant only for daidzein.

Isoflavone levels, nodulation and gene expression profiles of a CRISPR/Cas9 deletion mutant in the isoflavone synthase gene of red clover.

Isoflavones are not involved in rhizobial signaling in red clover, but likely play a role in defense in the rhizosphere. Red clover (Trifolium pratense) is a high-quality forage legume, well suited for grazing and hay production in the temperate regions of the world. Like many legumes, red clover produces a number of phenylpropanoid compounds including anthocyanidins, flavan-3-ols, flavanols, flavanones, flavones, and isoflavones. The study of isoflavone biosynthesis and accumulation in legumes has come into the forefront of biomedical and agricultural research due to potential for medicinal, antimicrobial, and environmental implications. CRISPR/Cas9 was used to knock out the function of a key enzyme in the biosynthesis of isoflavones, isoflavone synthase (IFS1). A hemizygous plant carrying a 9-bp deletion in the IFS1 gene was recovered and was intercrossed to obtain homozygous mutant plants. Levels of the isoflavones formononetin, biochanin A and genistein were significantly reduced in the mutant plants. Wild-type and mutant plants were inoculated with rhizobia to test the effect of the mutation on nodulation, but no significant differences were observed, suggesting that these isoflavones do not play important roles in nodulation. Gene expression profiling revealed an increase in expression of the upstream genes producing the precursors for IFS1, namely, phenylalanine ammonium lyase and chalcone synthase, but there were no significant differences in IFS1 gene expression or in the downstream genes in the production of specific isoflavones. Higher expression in genes involved in ethylene response was observed in the mutant plants. This response is normally associated with biotic stress, suggesting that the plants may have been responding to cues in the surrounding rhizosphere due to lower levels of isoflavones.

Yellow- and green-cotyledon seeds of black soybean: Phytochemical and bioactive differences determine edibility and medical applications

Black soybean seed (BSS) is a traditional edible and medical food. The cotyledons of BSS are either yellow or green, but that difference's effect on functional and bioactivities are not clear. In the present study, the concentrations of the main functional components, including anthocyanins, isoflavones, fatty acids, protein, and polysaccharides, and in vitro antioxidant activities of yellow-cotyledon and green-cotyledon BSS (YBS and GBS, respectively) were compared. The anti-fatigue activities of the ethanol extract of BSS (EEB) were evaluated using mouse swimming endurance tests. Additionally, a metabolomics comparison between YBS and GBS was done using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF MS) on high doses of EEB-treated mouse plasma. The results indicated that YBS showed significantly higher contents of anthocyanin and protein, and stronger antioxidant activity and anti-fatigue activity than GBS; while GBS showed higher levels of isoflavone, stearic acid, and polysaccharide. By infusing the feed with EEB, the swimming time of mice increased in a dose-dependent manner. The metabolomics results suggested that the anti-fatigue effect of EEB correlated well with serotonin and melatonin biosynthesis in vivo. All of the above results showed that BSS has anti-fatigue potential and might be used as a potential source of functional food ingredients.

Varietal differences in flavonoid and antioxidant activity in Japanese soybean accessions.

Soybean seeds contain many antioxidants, including flavonoids and other phytochemicals. Isoflavone is a phytoestrogen that mimics estrogenic effects on target tissues and also exerts antioxidant activity by sequestering free radicals. Despite many cultivars developed to date, varietal differences in flavonoid content and antioxidant activity in Japanese soybean accessions remain less well characterized. Here, we evaluated the seed content of isoflavones, total flavonoids, and total phenolics in 26 soybean accessions. Next, the antioxidant activity of each accession was examined using antioxidant responsive element (ARE) linked to a luciferase reporter in human HepG2 stable cells. The relative ARE luciferase activity rate of all soybean accessions varied up to 4-fold which ranged from 1.00 to 4.02; and 22 accessions exhibited significant antioxidant activities. Correlation analysis indicated that the level of total isoflavone moderately correlated with antioxidant activity.

The fermentation properties and microbial diversity of soy sauce fermented by germinated soybean.

The quality of commercial soy sauce is variable at present. Technical work is needed to improve the quality and flavor of soy sauce, especially in China. Material is a factor for influencing soy sauce characters in fermentation. Germinated soybean sauce (fermented by germinated soybean) had a gamma aminobutyric acid (GABA) concentration of 6.83 μg mL-1 , whereas a control (a soy sauce fermented by soybean) had a GABA concentration of less than 2.42 μg mL-1 . Germinated soybean sauce also contained significantly higher levels of isoflavones, total polyphenol, and amino acid nitrogen than the control soy sauce. Microbial diversity results showed that Bacillus was the dominant bacteria in germinated soy sauce compared with the control. Aldehydes, alcohols, esters, and phenols were the major flavor components of germinated soybean sauce. A soy sauce with high levels of GABA, isoflavones, and total polyphenol was developed using germinated soybean. Stenotrophomonas, the typical pathogen found in the control, was reduced dramatically and replaced by Bacillus during fermentation with the germinated soybean. The germinated soybean sauce exhibited a better aroma and taste than the control. Soy sauce fermented by soybeans that germinated for 48 h exhibited greater advantages than soy sauce that germinated for 24 and 72 h. © 2020 Society of Chemical Industry.

Characterization of chlorophyll-deficient soybean [Glycine max (L.) Merr.] mutants obtained by ion-beam irradiation reveals concomitant reduction in isoflavone levels

Ion-beam irradiation serves as a powerful tool of mutagenesis for engineering novel traits in a wide range of plants. A previous study indicated that coincidental changes in multiple traits are frequently induced by ion-beam irradiation in soybean [Glycine max (L.) Merr.], a paleopolyploid plant whose genome comprises a large number of duplicated genes. Here we analyzed the levels of isoflavones, major secondary compounds in soybean seeds, in a population of mutants with various degrees of chlorophyll deficiency induced by the mutagenesis. The isoflavones daidzin, genistin, and their respective malonylglucosides were significantly reduced in 4–9 plant lines among 28 lines analyzed. The average levels of chlorophyll in the leaf tissues were correlated with the level of each isoflavone in seeds from multiple lines. In selected mutant lines, the levels of isoflavones were lower than in the wild-type plants throughout seed development. Gene expression profiles indicated that the mRNA levels of multiple genes involved in the isoflavone synthetic pathway were also reduced during seed development in these mutants, consistent with the reduced levels of the compounds. These data suggest that ion-beam irradiation caused changes in multiple pathways of metabolism directly or indirectly and can provide useful plant resources for dissecting isoflavone synthesis and/or accumulation in soybean.

Isoflavone malonyl-CoA acyltransferase GmMaT2 is involved in nodulation of soybean by modifying synthesis and secretion of isoflavones.

Malonyl-CoA:flavonoid acyltransferases (MaTs) modify isoflavones, but only a few have been characterized for activity and assigned to specific physiological processes. Legume roots exude isoflavone malonates into the rhizosphere, where they are hydrolyzed into isoflavone aglycones. Soybean GmMaT2 was highly expressed in seeds, root hairs, and nodules. GmMaT2 and GmMaT4 recombinant enzymes used isoflavone 7-O-glucosides as acceptors and malonyl-CoA as an acyl donor to generate isoflavone glucoside malonates. GmMaT2 had higher activity towards isoflavone glucosides than GmMaT4. Overexpression in hairy roots of GmMaT2 and GmMaT4 produced more malonyldaidzin, malonylgenistin, and malonylglycitin, and resulted in more nodules than control. However, only GmMaT2 knockdown (KD) hairy roots showed reduced levels of malonyldaidzin, malonylgenistin, and malonylglycitin, and, likewise, reduced nodule numbers. These were consistent with the up-regulation of only GmMaT2 by rhizobial infection, and higher expression levels of early nodulation genes in GmMaT2- and GmMaT4-overexpressing roots, but lower only in GmMaT2-KD roots compared with control roots. Higher malonyl isoflavonoid levels in transgenic hairy roots were associated with higher levels of isoflavones in root exudates and more nodules, and vice versa. We suggest that GmMaT2 participates in soybean nodulation by catalyzing isoflavone malonylation and affecting malonyl isoflavone secretion for activation of Nod factor and nodulation.