Antibacterial Activity of Aqueous Root, Seed, Flower and Stem Bark Extracts of Acronychia pedunculata Grown in Sri Lanka

Abstract

In vitro antibacterial activity of six(06) different aqueous water extracts of Acronychia pedunculata found in Sri Lanka were investigated against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 35218). Disk diffusion antimicrobial susceptibility testing method was used to determine antibacterial activity of each aqueous extract. The results showed that there was a marked antibacterial activity against S.aureus (ATCC 25923) strain. The highest activity observed for the combined aqueous sample which had all ingredients( roots, stem barks, leaves, flowers and seeds) in the same aqueous solution and the antibacterial activity was observed in a concentration dependent (r2 = 0.97) manner. Lowest activity was recorded for seeds (r2 = 0.87) while root (r2 = 0.99) and stem bark (r2 = 0.87) aqueous solution showed second most and third most antibacterial activity against S.aureus (ATCC 25923) on a concentration dependent manner. Gentamicin (10 µg/disk) and distilled water were used as positive and negative controls. When compared with Gentamicin inhibition zone (14.03 ± 0.03mm), the combined aqueous sample at a concentration of 1000µg/disk, showed some potent, significant antibacterial activity with an inhibition zone of 11.26 ± 0.03 mm ,where aqueous root sample has an inhibition zone of 10.90 ± 0.06 mm. These two aqueous samples (combined sample and root sample) could be used further experiments as lead compounds for the development of potent, novel antibacterial agents from Acronychia pedunculata. However there was no antibacterial activity observed for all aqueous extracts against E.coli (ATCC 35218) and this observed phenomena needs to be further investigated with other Gram negative bacterial strains