Quantification of gallic acid and ellagic acid from longan (Dimocarpus longan Lour.) seed and mango (Mangifera indica L.) kernel and their effects on antioxidant activity

Gallic acid (GA) and ellagic acid (EA) have been identified in longan seed and mango kernel by the use of reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with photodiode array detection (DAD). The ethanolic extract of longan seed contained 23.3 and 156 mg/100 seeds of GA and EA, respectively. The ethanolic extracts of mango kernel contained approximately 87% more GA than the longan seed ethanolic extracts but about 32% less EA. After heat treatment and acid hydrolysis, mango kernel had higher concentrations of GA and EA, contributing to more potent antioxidant activity. The results demonstrated rich sources of GA and EA in longan seed and mango kernel which might provide a novel source of these natural antioxidants.