Antifungal Effects of Combined Extracts of Euphorbia abyssinica and Coleus Species

Abstract

Although, different plant extracts have frequently been used singly and in combinations in folklore treatment of different ailments, the hidden truth behind their activity and efficacy is still to be fully scientifically established.  Aim: To evaluate the effects of combined 50% methanol extracts of Euphorbia abyssinica (Desert Candle), and Coleus sp. on Candida albicans, Trichophyton mentagrophytes, Microsporum gypseum and Epidermophyton floccossum. Study Design: The completely randomised block design, two-way analysis of variance was used to analyse the data and Duncan’s New Multiple Range Test, for mean separation. Place and Duration of Study: The research was carried out in the Department of Microbiology, University of Nigeria Nsukka, Enugu State, Nigeria, between April 2011 and August 2012. Methodology: All the fungal strains used in the research were collected from the University of Nigeria Teaching Hospital Enugu, Nigeria. Susceptibility testing was done using a pour-plate method, while the checkerboard and Time-kill assays were employed to evaluate the efficacy of the different combinations of the two plant extracts. Results: The individual plant extracts inhibited all the fungal strains tested at different concentrations; but Coleus sp. extracts were observed to be more active than Euphorbia abyssinica extracts. The extract combinations inhibited the test fungi for more than two weeks. In the Time Kill assay, the combinations showed synergy on E. Floccossum only.  It showed additive or antagonistic activity on the rest of the fungi tested. The Checkerboard combinations showed synergy on T. mentagrophytes, M. gypseum, and E. foccossum. Epidermophyton foccosum was the most susceptible among the fungi tested while C. albicans was the least susceptible. The control drug voriconazole also inhibited all the fungi tested. Significant antifungal activity (P=0.05) was observed in the checkerboard assay more than in the Time Kill assay. Conclusion: These findings simply authenticate some of the folklore claims that these plants have a wide range of curative uses, suggesting that they can be used as alternative sources of agents for the treatment of resistant fungal infections.