Objective: The present study was aimed at evaluating the in vitro antioxidant and antibacterial activities of methanol and aqueous extracts of Hopea ponga.
Methods: Hopea ponga leaf and stem sample were powdered and extracted with methanol and water. The extracts were screened for various phytochemical by HPLC and TLC studies. The total phenolic and flavonoid contents were assessed by spectrophotometric method and the antioxidant activity was estimated using 2,2 diphenyl-1-picrylhydrazyl (DPPH) free radical scavening activity and inhibition of lipid peroxidation assay. Antibacterial activity was evaluated by disc diffusion method & MIC by Broth dilution method.
Results: The methanol extracts exhibited significant (p <0.05) higher antioxidant activity with an IC50 value of 108µg/ml and 122 µg/ml in leaf and stem extracts respectively in the DPPH radical scavenging method, 147.2 µg/ml 136 µg/ml in the hydroxyl radical scavenging assay compared to aqueous extracts. The amount of total phenolics in methanol leaf and stem was around 286mg and 213mg gallic acid equivalent (GAE) respectively. The total flavonoid contents of methanol extracts of stem and leaf were around 108.3 mg and 86 mg catechin equivalents per gram respectively. Methanol leaf and stem extracts were found to possess maximum antibacterial activity with MIC ranging around167-648ug/ml against tested strains. High Performance Liquid Chromatography (HPLC) analysis indicated the presence of phenolic compounds such as quercetin, gallic acid, para hyroxybenzoic acid.
Conclusion: The results indicate that the extracts had significant free radical scavenging and antibacterial activity. The results suggest that Hopea ponga, may be a good source of natural antioxidants and antibacterial source
