Twenty-eight tetraketones (1-28) with variable substituents at C-7 were synthesized and evaluated as tyrosinase inhibitors. Remarkably compounds 25 (IC50 = 2.06 mu M), 11 (IC50 = 2.09 mu M), 15 (IC50 = 2.61 mu M), and 27 (IC50 = 3.19 mu M) were found to be the most active compounds of the series, even better than both standards kojic acid (IC50 = 16.67 mu M) and L-mimosine (IC50 = 3.68 mu M). This study may lead to the discovery of therapeutically potent agents against clinically very important dermatological disorders including hyperpigmentation as well as skin melanoma. (c) 2005 Elsevier Ltd. All rights reserved.