Antioxidant and Antibacterial Activities of Spondias pinnata Kurz. Leaves

Aims: To evaluate the antibacterial and antioxidant potential of various extracts of S. pinnata leaves.

Study Design: Cold extraction of the leaves using various solvents followed by in vitro antioxidant and antibacterial assays.

Place and Duration of Study: Department of Pharmacy, North South University, Dhaka, Bangladesh, August 2011 to February 2012.

Methodology: Dried leaves were powdered and extracted with hexane, ethyl acetate and ethanol followed by screening for the presence of phytochemicals. The antioxidant potential of the extracts was evaluated using multiple in vitro models which included 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide and superoxide radical scavenging assays and reducing power estimation. Ascorbic acid and quercetin were used as the reference antioxidants. Total phenolic and total flavonoid contents were determined using Folin–Ciocalteu and aluminium chloride colorimetric method respectively. Antibacterial property of the extracts was evaluated against four gram-positive and four gram-negative bacteria using disc diffusion technique followed by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) determination.

Results: The extracts obtained in this study showed a varied level of scavenging activities. Ethanol extract exhibited the highest free radical scavenging activity at tested concentrations. High scavenging activity was also observed with ethyl acetate extract while hexane extract showed poor antioxidant activity. The reducing power increased with increasing amounts of extract in all cases. Ethanol extract displayed the highest total phenolic content (27.76±1.11 mg GAE/g extract) while the highest flavonoid content was shown by ethyl acetate extract (86.53±1.95 mg QE/ g extract). Again, all the extracts showed antibacterial activity with zone of inhibition ranging from 8.33±1.53 to 28.67±0.58 mm. The Lowest MIC and MBC values were found with ethanol extract which was 2.0 and 3.5 mg/ml respectively against Staphylococcus aureus.

Conclusion: The results suggest that extracts of S. pinnata leaf may serve as a potential source of natural antioxidant and antibacterial agents for pharmaceutical application.