Inhibitory effects of methyl trans-cinnamate on mushroom tyrosinase and its antimicrobial activities.

The control of food browning and growth of disease-causing microorganisms is critical to maintaining the quality and safety of food. Tyrosinase is the key enzyme in food browning. The inhibitory effect of methyl trans-cinnamate on the activity of tyrosinase has been investigated. Methyl trans-cinnamate can strongly inhibit both monophenolase and diphenolase activity of mushroom tyrosinase. When the concentration of methyl trans-cinnamate reached 2.5 mM, the lag time was lengthened from 32 to 160 s and the steady-state activity was lost about 65%. The IC(50) value was 1.25 mM. For the diphenolase activity, the inhibition of methyl trans-cinnamate displayed a reversible and noncompetitive mechanism. The IC(50) value was 1.62 mM, and the inhibition constant (K(I)) was determined to be 1.60 mM. Moreover, the antibacterial activity against Escherichia coli, Bacillus subtilis and Staphyloccocus aureus and antifungal activity against Candida albicans were tested. The results showed that methyl trans-cinnamate possessed an antimicrobial ability.