ANTIOXIDANT AND ANTITYROSINASE PROPERTIES OF MALAYSIAN BAMBOO LEAF EXTRACTS
Keywords:Superoxide and free radical scavenging, skin whitening, phenolic compounds, p-coumaric acid
The aqueous and ethanolic extracts of Malaysian bamboo species, namely, Gigantochloa scorterchinii, G. levis, G. ligulata and Schizotachyum zollingeri were tested for their antioxidant properties using three bioassay systems: (1) ferric thiocyanate (FTC) method, (2) xanthine/xanthine oxidase superoxide scavenging activity (X/XOD) method and (3) free radical scavenging activity (2,2-diphenyl-2-picrylhydrazyl, DPPH) method. Tyrosinase inhibitory assay was used to evaluate the skin whitening properties of the four bamboo species studied. The aqueous of all species studied showed very high (> 90% superoxide scavenging activity and the activity increased with an increase in the total phenolic content (TPC) . Ethanolic extracts of G. ligulata and S. zollingeri at the concentration of 1.0 mg/ml each demonstrated very high tyrosinase inhibitory activities, 98.9 and 100% respectively. This indicated that these strong active extracts have the ability to inhibit the enzymatic pathway of melanin pigment biosynthesis. The high performance liquid chromatography (HPLC) fingerprint developed for the four bamboo species revealed the presence of p-coumaric acid as major phenolic compound in the extracts.