2-hydroxy-4-methoxybenzaldehyde: A potent tyrosinase inhibitor from African medicinal plants

By bioassay-guided fractionation using mushroom tyrosinase (EC 1.14.18.1), 2-hydroxy-4-methoxybenzaldehyde was characterized as the principal tyrosina se inhibitor from three East African medicinal plants, the root of Mondia w hitei (Hook) Skeels (Asclepiaceae), the root of Rhus vulgaris Meikle (Anaca rdiaceae), and the bark of Sclreocarya caffra Send (Anacardiaceae). It inhi bited the oxidation of L-3,4-dihydroxyphenylalanine (L-DOPA) by mushroom ty rosinase with an IDS, of 4.3 mu g/ml (0.03 mM). The inhibition kinetics ana lyzed by a Lineweaver-Burk plot found this simple benzaldehyde derivative t o be a mixed type inhibitor for this oxidation and affects on the enzyme in several ways. Based on finding this potent tyrosinase inhibitor, various r elated analogues were also tested in order to gain new insights into their inhibitory functions on a molecular basis.