Rhapontigenin was produced from rhapontin isolated from a methanol extract of Rheum undulatum roots by enzymatic transformation. Rhapontin and rhapontigenin exhibited dose-dependent inhibition of tyrosinase activity and melanin synthesis in B16F10 melanoma cells, but the inhibitory activity of rhapontigenin was greater than that of rhapontin. Thus the bioconversion of rhapontin enhanced its ability to inhibit cellular tyrosinase activity and melanin synthesis.
