Antioxidant activity of longan (<i>Dimocarpus longan</i>) barks and leaves

Abstract

In this paper, the barks and leaves of longan (Dimocarpus longan Lour.) were extracted with 80% methanol. The antioxidant activity and the contents of ellagic acid (EA) in the extracts were investigated. For the evaluation of antioxidant activities, the extracts possess almost the same 2,2- diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power. Besides, the antioxidant activity was concomitant with the development of the reducing power with high correlation coefficients. The contents of EA in the extracts were 0.91 and 3.723 mg/g dry samples, respectively. After hydrolysis, the EA contents increased almost three and four times. Therefore, the ellagic acid in longan barks and leaves exist mostly in the form of ellagitannins. The research showed that longan barks and leaves not only were excellent sources of free-radical inhibitors, but also had potential use in the production of ellagic acid.

Key words: Antioxidant activity, ellagic acid, longan, barks, leaves.