Antioxidant and Antibacterial Activity of Aquaethanolic Extract of Flowers of Cassia fistula

In the present investigation total phenolic contents (TPC), in vitro antioxidant activity and in vitro antibacterial activity of aquaethanolic extracts of flowers of cassia fistula were evaluated. The TPC of the extracts were determined by Folin-Ciocalteu method. 2, 2’-azino-bis 3-ethylbenzothiazoline-6-sulfonic 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). Bacteria tested were Staphylococcus aureus (MTCC 7443) and Escherichia coli (MTCC 2991). TPC in the flower extract were 10.56 ± 3.61 mg of gallic acid equivalent /g of extract. Flower extract also showed good ABTS scavenging activity (IC₅₀=206.52 µg /ml), DPPH scavenging activity (IC₅₀=360.24µg /ml) and Superoxide radical scavenging activity (IC₅₀=671.16 µg /ml). At 100mg/ml, the highest average inhibition zone was recorded in aquaethanolic flower extract against E. coli (MTCC 2991) (12.33±0.58mm) and S. aureus (MTCC 7443) (14.67±0.33mm). MIC value of flower extract against E. coli was 25mg/ml and MBC >100mg/ml while MIC against S. aureus was 6.25mg/ml and MBC 50mg/ml.