Phenolic content and in vitro inhibitory effects on oxidation and protein glycation of some Thai medicinal plants.

Fifteen medicinal plant extracts were investigated for: total phenolic content and free radical scavenging effect by DPPH and ABTS assays; anti-lipid peroxidation activity by TBARS; and for antiglycation activity. The results revealed that the total phenolic content showed good correlation with free radical scavenging by ABTS (r = 0.721) and anti-lipid peroxidation by TBARS (r = -0.659), but showed no correlation with antiglycation. Three extracts from Tamarindus indica, Camellia sinensis and Artocarpus lakoocha demonstrated a significant antioxidant effect, and also showed a promising antiglycation effect. The IC50 (mg/ml) were 0.9-0.16 for the DPPH method; TEAC values (mg Trolox/mg sample) of 1.72-2.83 for the ABTS method; IC50 (mg/ml) of 0.64-1.22 for the TBARS method; and IC50 ranging from 0.01 to 3.20 for the antiglycation method. These three herbs were found to possess effective antioxidant and antiglycation activities, and could be further developed for use in anti-aging cosmetics.