2-Hydroxylation of Genistein Enhanced Antioxidant and Antiproliferative Activities in MCF-7 Human Breast Cancer Cells

Bioconversion of the isoflavonoid genistein to 2'- hydroxygenistein (2'-HG) was performed using isoflavone 2'-hydroxylase (CYP81E1) heterologously expressed in yeast. A monohydroxylated product was analyzed by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) and NMR spectrometry and was identified as 2'-HG. An initial bioconversion rate of 6% was increased up to 14% under optimized conditions. After recovery, the biological activity of 2'-HG was evaluated. Bioconverted 2'-HG showed higher antioxidant activity against 1,1- diphenyl-2-picryl hydrazine (DPPH) and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radicals than did genistein. Furthermore, 2'-HG exhibited greater antiproliferative effects in MCF-7 human breast cancer cells than did genistein. These results suggest that 2'- hydroxylation of genistein enhanced its antioxidant activity and cell cytotoxicity in MCF-7 human breast cancer cells.