Thirty-three crude drug extracts were screened for their tyrosinase inhibitory activity. Among them, the acetone extract of the rhizomes of Rheum officinale Baillon showed the strongest inhibitory activity. Tyrosinase inhibitory activity-guided fractionation and chemical analysis led to the isolation of two potent compounds, 3,4',5-trihydroxystilbene-4'-O-β-D-(2''-O-galloyl)glucopyranoside (1) and 3,4',5-trihydroxystilbene-4'-O-β-D-(6-O-galloyl)glucopyranoside (2). These compounds showed a competitive inhibition against tyrosinase and also inhibited the melanin biosynthesis.
ASJC Scopus subject areas