Soy Extract

What is soy extract?

Soybeans contain many components with biological activity in the skin. Soy is composed mainly of phospholipids (45-60%) and essential fatty oils (30-35%). It is the minor components however that include the most active compounds, such as isoflavones and protease inhibitors (R).

Isoflavones are phytoestrogens, plant-derived compounds with estrogenic activity (R). In soybeans, they are bound to sugar molecules and hence present as the glycosides genistin, daidzin, and glycitin. Fermentation or digestion of soybeans releases the sugar molecules, leaving the isoflavone aglycones genistein, daidzein, and glycitein. It is these aglycones, particularly genistein and daidzein, that have been the most studied for their beneficial effects on the skin.

Soybeans also contain the protease inhibitors soybean trypsin inhibitor (STI) and Bowman-Birk inhibitor (BBI) (R), which have been studied for their effects on skin depigmentation (R).