Characterization of Polyphenol Oxidase from Phyllanthus Amarus (Pokok Dukung Anak) Leaves

Abstract

Recently much attention has been paid to biologically active components of herbs, in this study the polyphenol oxidase (PPO) was extracted, purified and characterized from herb Phyllanthus amarus, the most popular medicinal herb in South East Asia. It was extracted and purified by ammonium sulphate (NH4)2SO4 precipitation, isolated by ion-exchange chromatography and purified by gel filtration chromatography and HPLC. The biochemical analysis revealed that the PPO extracted from Phyllanthus amarus leaves has higher affinity towards catechol (KM = 17.4mM and Vmax = 22,077 U/ml min-1) at an optimum pH of 7.1. The enzyme had an optimum temperature of 390C and was relatively stable up to 560C for a period of 90 minutes with almost 80% activity remaining. Among the various PPO inhibitors tested, ascorbic acid was found that it is the most effective inhibitor for the enzyme with 10mM catechol as substrate.