Tyrosinase inhibitory effect of quercetin 4'-O--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--D-glucopyranoside was isolated from the dried skin of A. cepa. Quercetin 4'-O--D-glucopyranoside showed tyrosinase inhibitory activity using L-tyrosine or L-DOPA as a substrate, with IC50 values of 4.3 and 52.7 mu M, respectively. Based on the results obtained, the dried skin of red onion possesses ingredients with potential for skin-whitening cosmetics with anti-tyrosinase activity.