%0 Journal Article
%T Effects of Quercetin on Mushroom Tyrosinase and B16-F10 Melanoma Cells
%A Isao Kubo
%A Teruhiko Nitoda
%A Ken-ichi Nihei
%J Molecules
%D 2007
%I MDPI AG
%R 10.3390/12051045
%X In searching for tyrosinase inhibitors from plants using L-3,4-dihydroxyphenylalanine (L-DOPA) as a substrate, quercetin was found to be partially oxidized to the corresponding o-quinone under catalysis by mushroom tyrosinase (EC 1.14.18.1). Simultaneously, L-DOPA was also oxidized to dopaquinone and both o-quinones were further oxidized, respectively. The remaining quercetin partially formed adducts with dopaquinone through a Michael type addition. In general, flavonols form adducts with dopaquinone as long as their 3-hydroxyl group is free. Quercetin enhanced melanin production per cell in cultured murine B16-F10 melanoma cells, but this effect may be due in part to melanocytotoxicity. The concentration leading to 50% viable cells lost was established as 20 ¦ÌM and almost complete lethality was observed at 80 ¦ÌM.
%K Quercetin
%K mushroom tyrosinase
%K adducts
%K murine B16-F10 melanoma cells
%K cytotoxicity
%U http://www.mdpi.com/1420-3049/12/5/1045