Genistein

What is genistein?

Genistein is a phytoestrogen belonging to the class of organic compounds known as isoflavones. It and its glucoside, genistin, occur naturally in many legumes, but is most commonly found in soy, where it is among the most active components (R). Most Asian and American soy products, with the exception of soy sauce, contain isoflavones such as genistein (R). The leaves of the Indian bread root also contains remarkably high concentrations of genistein of over 2g/kg dry weight (R).

Does genistein get absorbed?

Like most polyphenols, the solubility and intradermal delivery of genistein is limited (R). Systems have therefore been developed to improve its permeability into the skin.

Genistein seems to have great affinity for the skin, as it did not permeate across pig skin in an in vitro experiment even after 24 hours (R). Transdermal absorption of genistein through the skin has also been observed, but its retention increases with repeated applications (R, R).

Due to the lipophilic nature of the stratum corneum, genistein in its non-ionized form at pH 6 exhibits better skin deposition than its ionized form at pH 10.8 (R). Formulations of genistein in a liposomal gel (R), water-in-oil type microemulsions (R), nanoemulsions (R, R, R, R) and with chemical penetration enhancers (R), have also been demonstrated to significantly increase the penetration of genistein into the deeper skin layers, and its accumulation in the skin.