Original Articles: 2011 Vol: 3 Issue: 4
Antimicrobial and antioxidant activities of condensed tannin from Rhizophora apiculata barks
Abstract
Condensed tannin from Rhizophora apiculata barks was subjected to antimicrobial screening test. The extract was tested in vitro against 18 bacteria species, 12 filamentous fungal species, and 4 yeast by agar diffusion and broth dilution methods. Condensed tannin demonstrated good antimicrobial activity against certain bacterial and yeasts tested (P<0.05) but not on filamentous fungal species. The MIC (minimum inhibitory concentration), MBC (minimum bacteriocidal concentration) and MYC (minimum yeastocidal concentration) were ranged from 3.13 mg/ml to 12.50 mg/ml. The antioxidant activity of the extract was evaluated by using DPPH (2,2-diphenyl-1-picrylhydrazyl) and hydrogen peroxide scavenging methods with (±)-catechin, butylated hydroxytoluene (BHT), α-tocopherol and L-(+)-ascorbic acid as standards. In the DPPH assay, the condensed tannin showed higher percentage of DPPH scavenging activity compared to other standards. The condensed tannin also showed stronger hydrogen peroxide scavenging activity than the α-tocopherol and BHT standards. Scavenging activity in both DPPH assay and hydrogen scavenging activities increased as the tannin concentration increased. The results presented here suggested that condensed tannin extracted from R. apiculata barks can be used to discover bioactive natural product that may serve as leads in the development of new pharmaceuticals in food and also as antimicrobial agent against certain food spoilage organisms.