Anti-fungal Activity of Plectranthus amboinicus (Lour.) Spreng and Plectranthus zatarhendi E. A. Bruce Grown in Sri Lanka.

Abstract

Background: Since ancient times, traditional medicine has relied on the use of medicinal plants to combat a range of infectious diseases. Plectranthus amboinicus and Plectranthus zatarhendi (family Lamiaceae) have been utilized in traditional medicine in Sri Lanka as a remedy for skin disorders, inflammatory conditions and microbial infections for a long period. Objective: To evaluate the in vitro antifungal activity of crude extracts of P. amboinicus (Lour.) and P. zatarhendi E. A. Bruce grown in Sri Lanka Methods: The plants were authenticated and the aqueous and hexane extracts were prepared from matured leaves and stems. For the extracts, the antifungal assay was performed against Candida species (clinical isolate) and a fungal strain obtained from a clinical sample of pityriasis versicolor patient. The assay was performed at two different concentrations of 500 and 1000 mg/mL by using disk diffusion method and well diffusion method, respectively and each test was triplicated. Ketoconazole was used as the positive control while distilled water and DMSO were used as the negative controls. The zone of inhibition (ZOI) was measured and the results were analyzed by One-way ANOVA test. Results: At a concentration of 500 mg/mL, the hexane extracts of both plants displayed significantly higher activity against Candida species compared to the aqueous counterpart by the disk diffusion method. ZOI was not significantly higher in P. amboinicus compared to P. zatarhendi. The highest ZOI at 1000 mg/mL was observed for the hexane extract of P. amboinicus with a ZOI of 15.00±1.40 mm by well diffusion method. Interestingly the highest ZOI against the fungal strain was obtained for the hexane extract of P. amboinicus (1000 mg/mL) with a ZOI of 17.36 ±1.55 mm by well diffusion method. Conclusion: The study revealed that hexane extracts of P. amboinicus and P. zatarhendi possessed a higher antifungal activity against Candida species and the fungal strain obtained from pityriasis versicolor patient compared to the respective aqueous extracts.