Inhibitory Effects On Tyrosinase And Antibacterial Activity Of Benzoic Acid Family Compounds

Tyrosinase (EC 1.14.18.1) is a kind of redoxidase containing copper, which is of the activity of monophenolase and diphenolase, widely distributed in nature. It is a key enzyme during the melanin biosynthesis. Its inhibitors can be used widely in many fields including whitening agents, keeping fruits and vegetables fresh, insecticides.In this paper, it mainly is of two parts. One part is study the inhibitory effect of the tyrosinase inhibitors. It studied the inhibitory mechanism of analogs of benzoic acid on the activity of monophenolase and diphenolase, and their kinetic constants were determined. The effects of o-hydroxy benzoic acid, m-hydroxy benzoic acid and p-hydroxy benzoic acid on mushroom tyrosinase were studied. o-Hydroxy benzoic acid, m-hydroxy benzoic acid and p-hydroxy benzoic acid can inhibit the monophenolase activity and diphenolase activity.The inhibitory capacity of p-hydroxy benzoic acid was the best. They were all competitive inhibitors. The effects of five dihydroxy benzoic acids on mushroom tyrosinase were studied. 2,3-Dihydroxy benzoic acid, 2,4-dihydroxy benzoic acid and 2,5-dihydroxy benzoic acid can't inhibit the diphenolase activity. But, 2,4-Dihydroxy benzoic acid and 2,5-dihydroxy benzoic acid can inhibit apparently the monophenolase activity, and 2,3-dihydroxy benzoic acid can't inhibit the monophenolase activity. When the concentrations of 3,4-dihydroxy benzoic acid and 3,5-dihydroxy benzoic acid were less than 5 mmol/L, the inhibitory rates were less than 50%. 3,4-Dihydroxy benzoic acid and 3,5-dihydroxy benzoic acid had a little inhibitory effect on the diphenolase activity.It studied the inhibitory effects of toluic acids on the activity of monophenolase and diphenolase. They all can inhibit the activity of monophenolase and diphenolase. p-Toluic acid was of most strong inhibitory effect of the three compounds. p-Toluic acid was a uncompetitive inhibitor, while o-toluic acids and m-toluic acids were mixed-type inhibitors.The inhibitory effects of 4-halobenzoic acids on mushroom tyrosinase were elucidated, too. 4-Fluorobenzoic acid, 4-chlorobenzoic acid and 4-bromobenzoic acid all can inhibit the activity of monophenolase and diphenolase. The inhibitory effect of 4-bromobenzoic acid was more strong than 4-fluorobenzoic acid and 4-chlorobenzoic acid. Furthermore, they were all non-competitive inhibitors of diphenolase.