Inhibitory activities of selected medicinal plants on mushroom tyrosinase

Tyrosinase is a key enzyme in melanin synthesis from tyrosine. Using tyrosinase inhibitors has become increasingly important in medicinal and cosmetic products to prevent or treat pigmentation disorders (1).To evaluate inhibitory effects the extracts of Urginea maritima (L.) Baker [1], Zhumeria majdae Rech.f. & Wendelbo [2] and Physalis divaricata D.Don [3] on mushroom tyrosinase this study was designed. L-Dopa as used as substrate.

Ethanolic extracts of U. maritima[bulb], Z. majdae [leaves] and P. divaricata [air organs] were used for their inhibitory effect in vitro on diphenolase activity of tyrosinase, using a specterometric method.

The extracts showed anti tyosinase activity weaker than positive control (Kojic acid). The inhibitory activity of tested plants Urginea maritima, Zhumeria majdae and Physalis divaricata against mushroom tyrosinase is expressed using IC₅₀ (concentration of inhibitor that inhibited 50% of tyrosinase activity) values of 2.79, 2.37, 3.34mg/ml respectively.The kinetic study indicated that all extracts were uncompetitive inhibitors for tyrosinase.

Keywords: Urginea maritima, Zhumeria majdae, physalis divaricata, mushroom tyrosinase, Inhibitor

Acknowledgement: This research is a part of a project granted by Ahvaz Jundishapur University of Medical Sciences.

References: Zhang X Hu et al. (2009) Biological and Pharmaceutical Bulletin 32(1): 86–90.