Tropolone is a 2-position tropone derivative with a hydroxyl group and is a precursor to many Azulene derivatives, such as 2-methylazulene-1-carboxylChemicalbookate. Tropolone is a potent mushroomtyrosinase inhibitor with an IC50 of 0.4 μM, and its inhibitory effect can be reversed by dialysis or excess CU2+.