Mohd Sajjad Ahmad Khan* and Iqbal Ahmad
Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh-202002, INDIA.
Background: Curing of invasive and superficial mycoses by the available antifungal drugs is limiting because of the host toxicity and emergence of drug resistance in fungi. This has triggered search for anti-infective agents from natural products and alternative modes of antifungal therapy. Objective: The aim of this study was to evaluate in vitro antifungal activity of oil of Cymbopogon citratus and its major active compound citral alone and in combination with fluconazole against azole-resistant strains of Aspergillus spp and Trichophyton spp. Materials and Methods: The methodology adapted in this work included disc diffusion, broth macrodilution, time kill methods and checkerboard microtiter tests. Results: Test fungal strains exhibited higher levels of resistance to fluconazole and itraconazole (MIC range from 100 to 800 μg ml–1). Both the oil of C. citratus and citral exhibited promising antifungal activity (zone of inhibition from 24.66 to 42.00 mm) and killing potency against Aspergillus fumigatus MTCC2550 and Trichophyton rubrum IOA-9. Citral showed strongest synergy with fluconazole against A. fumigatus and T. rubrum by reducing the minimum inhibitory concentration of fluconazole up to eight-fold. Conclusion: The study has highlighted the broad spectrum antifungal activity of oil of C. citratus and citral and their synergy with fluconazole against azoleresistant strains of Aspergillus spp and Trichophyton spp.
Keywords: Cymbopogon citratus, citral, azole-resistance, synergy.