Effects of Light Orientation and Mechanical Damage to Leaves on Isoflavone Accumulation in Soybean Seeds

Soybean is largely cultivated worldwide providing high amounts of proteins and oil for food and feed, and isoflavones for nutraceutical uses. The increasing interest in agroforestry practices for improving carbon sequestration and mitigating climate changes suggests the need to assess soybean response to variations of light availability and direction. A two-year pot trial was carried out at Legnaro (NE Italy) in order to mimic the response of the soybean var. Sponsor to contrasting light orientation (east or west) by artificial shading, associated or not with mechanical leaf damage, in terms of protein accumulation, total cotyledon isoflavone concentration (TCIC) and isoflavone profile. Here, we demonstrate that a different intensity of the isoflavone metabolism exists in response to lighting conditions, with higher TCIC and slightly increased seed crude proteins in plants lighted from the east (morning time) and after mechanical leaf damage. The isoflavone profile was not changed, but low temperatures and high rainfall during seed filling (1st year) were associated with increased accumulation of medium-high molecular weight (MW) forms (i.e., glycosyls and malonyls), while high temperatures and low rainfall (2nd year) with increased accumulation of medium-low MW forms (i.e., glycosyls and aglycones). It is concluded that within agroforestry systems, there is possibly a large scope for maximizing isoflavone accumulation by selecting the harvesting area in the neighboring of the east side of the tree alleys, with further improvements if a mild shoot stripping is applied before flowering.

Potential Impacts of Soil Tillage System on Isoflavone Concentration of Soybean as Functional Food Ingredients

Soybean is an important natural source of isoflavones, but their concentration is likely to be influenced by external factors, such as climatic conditions and soil tillage systems. However, there is minimal information about the effects of such external factors on the isoflavone concentration in soybeans grown in Europe. Therefore, in this study, field experiments were established in Romania to investigate the potential impacts of three different soil tillage systems—conventional, minimum tillage and no-tillage—on crop yields and the isoflavone concentration of soybeans for three experimental years, 2014–2016. Our experimental results indicated that the soil tillage systems had little impact on the soybean yields each year. However, the 2016 yield was found to be higher than the 2014 and 2015 yields under all three soil systems. For every experimental year, the higher yield was recorded by the conventional system, followed by the minimum tillage system and no-tillage system under first weed control (weed control two (wct2): S-metolaclor 960 g/L, imazamox 40 g/L and propaquizafop 100 g/L). Likewise, the soil tillage system did not have a significant influence on the total isoflavone concentrations. Nevertheless, we noticed some variations in the individual isoflavone concentration (daidzin, genistin, glycitin, daidzein, genistein) in each year. Altogether, the minimum tillage and no-tillage systems may be employed as a suitable soil tillage system in soybean farming without an impact on the total isoflavone.

Mineral and Phytochemical Profiles and Antioxidant Activity of Herbal Material from Two TemperateAstragalusSpecies

Only a few species of the largeAstragalusgenus, widely used for medicinal purposes, have been thoroughly studied for phytochemical composition. The aim of our research was to investigate the rarely studied speciesA. glycyphyllosL. andA. cicerL. for the distribution of mineral elements and phytochemicals in whole plants at two growth stages and in morphological fractions. We also investigated the capacity of the plant extracts to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and to chelate ferrous ions. Chemical composition and antioxidant properties depended on species, maturity, and plant part. Herbal material ofA. glycyphylloswas richer in Fe, total phenolics, and flavonoids, whereas extracts ofA. cicershowed a higher antioxidant activity. Young plants had more isoflavones, showed greater quenching of DPPH radicals, and exhibited better mineral profiles than flowering plants. Among plant parts, leaves were the most valuable plant material according to most characteristics investigated. Isoflavone concentration in flowers was lower than in leaves and stems. None of theAstragalussamples contained detectable amounts of the alkaloid swainsonine. The study demonstrates the potential of plant material from twoAstragalusspecies as a valuable source of iron, phenolic substances including isoflavones, free-radical scavengers, and Fe2+chelators for pharmaceutical use.

Abstract P426: Association of Serum Soy Isoflavones with Metabolic Markers in Japanese Men and Women

Objectives: Soy isoflavones may have beneficial roles as antioxidants and phytoestrogens. Dietary intake varies widely across populations: very high in Japan but low in North America. We measured the concentrations of daidzein and genistein in the serum of Japanese men and women and evaluated their associations with metabolic markers. Methods: Serum samples were obtained from a population based sample of 94 Japanese men (mean age 45.3), and 142 Japanese women (mean age 66.6; 97% were post-menopausal). Isoflavones were analyzed after extraction and derivatization using GC-MS. Concentrations of daidzein and genistein were summed to obtain total isoflavone concentrations. Results: Isoflavone concentrations were very high among the Japanese. Median values (nM) for men: 558, 452 and 86 and for women 660, 494 and 150 (total isoflavones, genistein and daidzein, respectively). Spearman correlation coefficients for the isoflavones with multiple outcomes among Japanese men and women are shown in the table. No significant (p<0.05) associations were observed among the men but borderline negative associations were observed for total isoflavones (p=0.063) and genistein (p=0.063) with LDLc. Among women there was a significant association between total isoflavones (p=0.041) and daidzein (p=0.006) with HDLc. Borderline significant associations were also observed for total isoflavones (p=0.068) and genistein (p=0.061) with glucose. Discussion: The concentrations of isoflavones are high in the Japanese, approximately 50 times greater than those of N. Americans. Associations between the isoflavones and various outcomes were very weak for the Japanese men. This possibly reflects a plateau of isoflavone concentration has been reached that precludes observing any associations. Although, many correlations were calculated the positive associations of total isoflavones and daidzein with HDLc among women may be real. HDLc concentrations are high in Japanese women which may reflect the estrogenic actions of isoflavones.