Antimicrobial Activity of Crude Extracts of Oldenlandia auricularia against Some Selected Human Pathogens

Aims: Currently there is a high demand on novel anti-microbial agents derived from natural sources due to low cost and less adverse effects. The present study was designed to screen the anti-microbial activity of different extracts of Oldenlandia auricularia against common pathogenic bacteria and fungi.

Study Design: Experimental study.

Place and Duration of Study: Department of Basic Sciences at Faculty of Allied Health Sciences and Research Laboratory at Faculty of Medicine, General Sir John Kotelawala Defence University, Ratmalana, Sri Lanka, between July 2018 and November 2018.

Methodology: The aqueous, methanol, acetone and hexane extracts were prepared with the leaves, roots and stem of the plant Oldenlandia auricularia separately. The agar well diffusion method and broth macro dilution method were applied in order to screen the anti -microbial activity of each test extract against the Escherichia coli, Salmonella enterica, Shigella dysenteriae, Candida albicans and Staphylococcus aureus.

Results: The zone of inhibition of most of the test extracts showed a significant (P =.05) difference, when compared with the negative control. The lowest MIC value for test extracts was 31.25 mg/ml, while the highest was 250 mg/ml. The acetone extract of the stem showed the lowest MIC value against E. coil. The highest anti-bacterial activity against S. enterica exerted by the root of the plant. All three tested parts of the plant were active against S. aureus and the maximum activity against C. albicans was shown by the leave extracts. The lowest MIC value against S. dysenteriae was 62.5 mg/ml, which indicated that the plants materials are less sensitive to the S. dysenteriae than the other tested pathogens. The results of the quantitative assay confirmed the results obtained from the qualitative assay.

Conclusion: The different parts of Oldenlandia auricularia plant displayed potential antimicrobial activity against different pathogens.