Tyrosinase inhibitory effect of quercetin 4'-O-β-D-glucopyranoside from dried skin of red onion (Allium cepa).

In an effort to find a new whitening agent, we focused our attention on Allium cepa (red onion). Based on biologically guided fractionation using mushroom tyrosinase, quercetin 4'-O-β-D-glucopyranoside was isolated from the dried skin of A. cepa. Quercetin 4'-O-β-D-glucopyranoside showed tyrosinase inhibitory activity using L-tyrosine or L-DOPA as a substrate, with IC(50) values of 4.3 and 52.7 µM, respectively. Based on the results obtained, the dried skin of red onion possesses ingredients with potential for skin-whitening cosmetics with anti-tyrosinase activity.