Isoflavones of the soybean components and the effect of germination time in the cotyledons and embryonic axis

Flavonoid localization in soybean seeds: Comparative analysis of wild (Glycine soja) and cultivated (Glycine max) varieties

Wild soybean (Glycine soja) is known for its high flavonoid contents, yet the distribution of flavonoids in the seeds is not well understood. Herein, we utilized matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) and metabolomics methods to systematically investigate flavonoid differences in the seed coats and embryos of G. soja and G. max. The results of flavonoid profiles and total flavonoid content analyses revealed that flavonoid diversity and abundance in G. soja seed coats were significantly higher than those in G. max whereas the levels were similar in embryos. Specifically, 23 unique flavonoids were identified in the seed coats of G. soja, including procyanidins, epicatechin derivatives, and isoflavones. Using MALDI-MSI, we further delineated the distribution of the important flavonoids in the cotyledons, hypocotyls, and radicles of the two species. These findings imply that G. soja holds considerable breeding potential to enhance the nutritional and stress resistance traits of G. max.

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.

Comparative Analysis of Phenolic Compound Profiles, Antioxidant Capacities, and Expressions of Phenolic Biosynthesis-Related Genes in Soybean Microgreens Grown under Different Light Spectra

Light-emitting diode (LED) based light sources, which can selectively and quantitatively provide different spectra, have been frequently applied to manipulate plant growth and development. In this study, the effects of different LED light spectra on the growth, phenolic compounds profile, antioxidant capacity, and transcriptional changes in genes regulating phenolic biosynthesis in soybean microgreens were investigated. The results showed that light illumination decreased the seedling length and yield but increased phenolic compound content. Blue light and ultraviolet-A (UV-A) induced significant increases in total phenolic and total flavonoid content, as compared with the white light control. Sixty-six phenolic compounds were identified in the soybean samples, of which isoflavone, phenolic acid, and flavonol were the main components. Ten phenolic compounds obtained from the orthogonal partial least-squares discriminant analysis (OPLS-DA) were reflecting the effect of light spectra. The antioxidant capacity was consistent with the phenolic metabolite levels, which showed higher levels under blue light and UV-A compared with the control. The highest transcript levels of phenolic biosynthesis-related genes were observed under blue light and UV-A. The transcript levels of GmCHI, GmFLS, and GmIOMT were also upregulated under far-red and red light. Taken together, our findings suggested that the application of LED light could pave a green and effective way to produce phenolic compound-enriched soybean microgreens with high nutritional quality, which could stimulate further investigations for improving plant nutritional value and should have a wide impact on maintaining human health.

Improvement of Soybean Products Through the Response Mechanism Analysis Using Proteomic Technique

Soybean is rich in protein/vegetable oil and contains several phytochemicals such as isoflavones and phenolic compounds. Because of the predominated nutritional values, soybean is considered as traditional health benefit food. Soybean is a widely cultivated crop; however, its growth and yield are markedly affected by adverse environmental conditions. Proteomic techniques make it feasible to map protein profiles both during soybean growth and under unfavorable conditions. The stress-responsive mechanisms during soybean growth have been uncovered with the help of proteomic studies. In this review, the history of soybean as food and the morphology/physiology of soybean are described. The utilization of proteomics during soybean germination and development is summarized. In addition, the stress-responsive mechanisms explored using proteomic techniques are reviewed in soybean.

Brotos de linhagens genéticas de soja: avaliação das propriedades físico-químicas

Resumo Brotos de soja são vegetais de consumo direto, obtidos de grãos germinados, que são utilizados há séculos nos países orientais. Suas características nutritivas e a facilidade de produção têm chamado a atenção de consumidores do Ocidente. Sementes pequenas com alto poder germinativo e vigor são qualidades inerentes para produção de brotos. Na Embrapa, essas características têm sido contempladas no programa de melhoramento genético para obtenção de cultivares de soja especiais para o consumo humano. O objetivo deste trabalho foi produzir e caracterizar a qualidade de brotos de soja obtidos a partir das linhagens BRM09-10505, BRM10-60599 e PF133002, em comparação com a cultivar BRS 216, desenvolvida para ser utilizada como brotos ou natto. Os brotos foram produzidos em bandejas dispostas em câmara de germinação (25°C e 99% de umidade relativa). Sementes e brotos foram avaliados nos seguintes aspectos: teor de proteínas, lipídios, cinzas, isoflavonas, inibidor de tripsina Kunitz, ácido fítico, comprimento e peso dos brotos. As sementes da BRM09-10505 apresentaram 95% de poder germinativo, seguida pela BRS 216 (93%) e pelas outras linhagens (88%, em média). A germinação pela mobilização dos compostos químicos aumentou os teores de proteínas (8,96%) e de isoflavonas (56,00%) e reduziu os teores de inibidor de tripsina Kunitz (26,91%) e de ácido fítico (13,78%). A cultivar BRS 216 apresentou o maior teor de proteína nas sementes (41,96 g.100 g-1) e nos brotos (47,70 g.100 g-1). A linhagem BRM09-10505 apresentou maior teor de inibidor de tripsina nas sementes (27,56 mg IT g-1) e nos brotos (19,62 mg. IT g-1); maior concentração de isoflavonas totais nas sementes (340,10 mg.100 g-1) e nos brotos (406,38 mg.100 g-1), e menor teor de ácido fítico nos brotos (1,13 g.100 g-1). Após quatro dias de germinação, destacaram-se, quanto ao comprimento e ao peso, a linhagem BRM09-10505 (8,03 cm e 214,36 g) e a cultivar BRS 216 (7,31 cm e 140,93 g). Entre as linhagens testadas, a linhagem BRM09-10505 apresentou bom potencial para produção de brotos.

Metabolite Profiling of Soybean Seed Extracts from Near-Isogenic Low and Normal Phytate Lines Using Orthogonal Separation Strategies

Untargeted metabolomic profiling using liquid chromatography-mass spectrometry (LC-MS) was applied to lipid-depleted methanolic extracts of soybean seeds utilizing orthogonal chromatographic separations (reversed-phase and hydrophilic interaction) in both positive and negative ionization modes. Four near-isogenic lines (NILs) differing in mutations for two genes encoding highly homologous multidrug resistant proteins (MRPs) were evaluated. The double mutant exhibited a low phytate phenotype, whereas the other three NILs, the two single mutants and the wild type, did not. Principal component analysis (PCA) of the four LC-MS data sets fully separated the low phytate line from the other three. While the levels of neutral oligosaccharides were the same for all lines, there were significant metabolite differences residing in the levels of malonyl isoflavones, soyasaponins, and arginine. Two methanol-soluble polypeptides were also found as differing in abundance levels, one of which was identified as the allergen Gly m 1.