Total polyphenols and phytoestrogens concentration and DPPH-radical scavenging activity in soybean of different origin
Phytoestrogens (isoflavones) are phytochemicals of phenolic origin found in a variety of plants, including soybean. As bioactive compounds structurally similar to estrogen, they bind to estrogen receptors either activating or blocking them, depending on the type of estrogen receptors. Many potential health benefits of phytoestrogens from soybean (Glycine max (L.) Merr.) products have been investigated, including effects on cancer, vascular disease, osteoporosis and menopausal symptoms.
Phytoestrogens may act as natural antioxidants, as well. The biochemical properties of polyphenols have been extensively studied in regard to their free radical scavenging activity [1,2] and multiple biological activities, including vasodilatory, anticarcinogenic, antiinflammatory, antibacterial, immune-stimulating, antiallergic and antiviral effects.
In order to determine the effect of genotype origin on total polyphenols and phytoestrogens concentration we compared twenty soybean genotypes of different origin (USA, Russia, Serbia and China) using HPLC analysis and spectrophotometry. The antioxidant activities of all samples, expressed as DPPH-radical scavenging capacity, were also evaluated and correlated with total polyphenols and phytoestrogens concentration.
Results showed that total phytoestrogens concentration ranged from 1.45 to 4.59mg/g fresh weight with malonyl daidzin as the most abundant component. Total polyphenols concentration ranged from 2.13 to 3.45 gallic acid equivalent/g fresh weight. Serbian genotypes showed highest total phytoestrogens and daidzein concentrations while Chinese genotypes presented the lowest IC50 values (1.91mg/ml, in average).
References:1. Malenčić, Dj. et al. (2007) Molecules 12:576–581.
2. Malenčić, Dj. et al. (2007) Bioresour Technol (in press), doi:10.1016/j.biortech.2007.11.040.