Studying the anti-tyrosinase effect of Arbutus andrachne L. extracts.

Arbutus andrachne L. is widely distributed in Jordan. Tyrosinase is the key enzyme in the biosynthesis of melanin. This preliminary study was carried out to assess the possible anti-tyrosinase activity of A. andrachne extracts. Arbutin, hydroquinone and kojic acid were selected as inhibitor standards. Five different extracts (chloroform, butanol, ethanol, methanol and water) were prepared from A. andrachne stems and their activities were compared with the selected tyrosinase inhibitors. IC(50) was measured for both, standard and plant extracts. Among the different extracts, the methanolic extract exhibited the highest anttyrosinase activity with an IC(50) value (1 mg mL(-1)). Furthermore, 9 mg A. andrachne methanolic extract showed 97.49% inhibition of tyrosinase activity. Arbutin, hydroquinone, beta-sitosterol and ursolic acid were identified in the different extracts of A. andrachne by thin layer chromatography (TLC) and isolated by preparative TLC from the methanolic and chloroform stem extracts, respectively.