Abstract:

To investigate the inhibition effects of some inhibitors such as glutathione, L-cysteine, VC and NaF, (-)-epicatechin was used as the substrate of polyphenol oxidase in this study. Glutathione and L-cysteine showed strong inhibition effects even at low concentration (0.1 mmol/L). VC could delay the enzymatic oxidation but almost had no inhibition effect on reaction speed at concentrates less than 0.2 mmol/L., NaF displayed only a little inhibition effect at high concentration (3 mmol/L), which was weaker than those of GSH and L- cysteine. Meanwhile, the study showed that the inhibitors, which could inhibit the enzymatic oxidation of (-)-epicatechin, also could inhibit the enzymatic oxidation of polyphenol extract from litchi pericarp.

Key words: (-)-epicatechin(EC), litchi, polyphenol oxidase(PPO), enzymatic oxidation, inhibition effects