Quantification of the Isoflavones Genistein and Daidzein in Five Different Botanical Extracts

Genistein and daidzein are estrogen-like isoflavones found in vegetables, especially in soybeans (Glycine Max). These compounds are known as antioxidant and anticancer, acting against breast, prostate and uterine cancer, and also as effective on alleviating the menopause effects. Besides these effects, they are used in skin care products for reducing skin-aging, stimulating production of hyaluronic acid in fibroblasts, protecting from UVB photodamage and from skin cancer. Based on this, the aim of the study was to assay genistein and daidzein in different botanical extracts and select the one with the most considerable amount of the isoflavones to be used in skin care formulations. Five different botanical extracts (four Soybean and one Red Clover extract) were analyzed via HPLC, with external calibration. The analysis were performed on a Waters e2695 HPLC coupled with a PDA detector Waters 2998. The chosen column was a Merck RP-18 (5 um, 250 mm, 4 mm i.d.) and the mobile phase was 60:40 methanol:water, isocratic flow of 1.2 mL/min. The Empower software was used and the r² was above 0.98 for both standards. The results showed that one of the extracts has a substantial amount of daidzein (approx. 30%), while all of them contain very low amounts of genistein (less than 0.5%). In further studies, the chosen extract will be incorporated in topical formulations based in nanotechnology and the skin delivery of daidzein will be evaluated using Franz diffusion cell and pig skins. Supported by Natura, FAPESP and CNPq.