Tropolone, a ?tropone derivative with a?hydroxyl group?in the 2-position, is a precursor?of manyazulene derivatives such as?methyl 2-methylazulene-1-carboxylate. Tropolone is a potent inhibitor of mushroom tyrosinase with a IC50 of 0.4 μM, and the inhibition can be reversed by dialysis or by excess CU2+.