COMPARATIVE ANALYSIS OF ANTIOXIDANT AND ANTIBACTERIAL ACTIVITY OF AQUEOUS EXTRACT OF LEAF, BARK, FLOWER AND FRUIT PULP OF CASSIA FISTULA

The present study investigated total phenolic contents (TPC), antioxidant activity, and antibacterial activities of aqueous extracts of leaf, bark, flower, and fruit pulp of C. fistula. The TPC of the extracts was determined by the Folin-Ciocalteu method. The 2, 2'-azino-bis 3-ethylbenzothiazoline-6sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and superoxide radical scavenging assays were used to evaluate antioxidant activity. Antibacterial activities were assessed using the well diffusion assay, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The bacteria tested were Staphylococcus aureus (MTCC 7443) and Escherichia coli (MTCC 2991). It was found that bark extract contained the highest TPC (22.56 ± 0.91 mg of gallic acid equivalent /g of extract). The bark extract also showed the strongest ABTS scavenging activity (IC50=180.13µg/ml), DPPH scavenging activity (IC50=318.77µg /ml), and Superoxide radical scavenging activity (IC50=478.31µg/ml). Zones of Inhibition were observed in all the aqueous extracts against Staphylococcus aureus (MTCC 7443) and Escherichia coli (MTCC 2991). The antibacterial potential of the extracts was found to be dosedependent. At 100 mg/ml, the highest average Zone of Inhibition of 14.33±0.33 mm and 16.0±0.58 mm was recorded in aqueous bark extract against S. aureus (MTCC 7443), and E. coli (MTCC 2991) respectively. The bark extract of C. fistula was most potent against E. coli (MTCC 2991) and S. aureus (MTCC 7443), with MIC values of 3.125 mg/mL and 6.25 mg/mL, respectively.