Antioxidant activity and total phenolics of some mangroves in Sundarbans

The antioxidant activity of 23 extracts from different plant parts (leaves, stem bark and root) of 6 mangroves and 4 mangrove associates was examined. The content of total phenolics in the extracts was calculated as gallic acid equivalent (GAE) and anti-radical activity was estimated as IC50 values using 1,1-diphenyl-2-picrylhydrazyl (DPPH). Remarkable high phenolic content (GAE > 25 mg/g), strong reducing ability (ascorbic acid equivalent, AAE > 3.5 mg/g) and anti-radical activity (IC50 < 2.9 mg/ml) were found in 11 different extracts comprising of 6 mangrove and 4 mangrove associate species. The best results were obtained for Ceriops decandra stem bark extract (phenolic content as GAE = 94.4 mg/g, reducing power as AAE = 13.04 mg/g and DPPH radical scavenging ability as IC50 = 0.65 mg/ml). A significant correlation was observed between GAE and AAE of respective extracts. The results indicate promising mangrove species for the utilization as significant source of natural antioxidant.