Abstract

EVALUATION OF TETRAKETONES AND XANTHENEDIONES AS TYROSINASE INHIBITORS OR ACTIVATORS

Marcelle S. Ferreira, Diego A.T. Pires and José D. Figueroa-Villar*

ABSTRACT

Inhibition or activation of Tyrosinase are important actions for treatment of skin cancer or hypopigmentation disease. Some compounds that were previously reported as inhibitors of this enzyme are tetraketones. In this work we prepared and tested some tetraketones as tyrosinase inhibitors, displaying low activity. Some of these compounds were also discovered by NMR that are easily transformed in solution as 25 oC to the respective xanthenediones in 100%. The respective xanthenediones were prepared and tested with this enzyme, indicating that some of them are the most effective Tyrosinase activators. The obtained results indicate that xanthenediones without or with a single para-R group on their benzyl ring are the most effective ones, being 9-phenyl-3,3,6,6-tetramethyl-3,4,6,7-tetrahydro-2H-
xanthene-1,8(5H,9H)-dione (4B) the most effective one (172.56 % activation).

Keywords: tetraketones, xanthenediones, tyrosinase, inhibitors, activators, hypopigmentation disease.