Antioxidant tannins from Syzygium cumini fruit

Abstract

Hydrolysable and condensed tannins in the fruit of Syzygium cumini were identified using NMR, MALDITOF MS and HPLC analyses. Hydrolysable tannins were identified as ellagitannins, consisting of a glucose core surrounded by gallic acid and ellagic acid units. Condensed tannins were identified as Btype oligomers of epiafzelechin (propelargonidin) with a degree of polymerization up to eleven. The antioxidant activity were measured by two vitro models: 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing/antioxidant power (FRAP). Tannins extracted from S. cumini fruit showed a very good DPPH radical scavenging activity and ferric reducing/antioxidant power. The
results are promising thus indicating the utilization of the fruit of S. cumini as a significant source of natural antioxidants.