ABSTRACT
Despite the use of conventional antifungal drugs, Candida spp resistance, especially mediated by biofilms formation remains recurrent. Therefore, new drugs to treat fungal infections are urgently needed. In this line, our study aimed to determine the anticandidal activity and the synergistic effect of essential oil fractions from Syzygium aromaticum, Cymbopogon citratus and Aeollanthus heliotropioides harvested in Cameroon using a combination approach. Essential oils have been obtained by hydrodistillation and their chemical composition was analysed by GC/MS. Antifungal activity was evaluated by the determination of minimum inhibitory concentration (MIC) using a micro-dilution method. The sorbitol and ergosterol binding ability and anti-biofilm activity were also assessed in order to evaluate the mode of action. The crude essential oils showed a good anticandidal activity, most probably due to the eugenol, linalool and citral content. The combination of two fractions F7 and F10 showed an improved growth inhibition of Candida spp compared to the crude essential oils. The inhibitory effect could be related with the presence of γ-dodecalactone and citronellol as main compounds. The best synergistic combination F7F10 inhibited biofilm formation at ten time reduced combination MIC. The active fractions targeted different fungal cell structures, including cell wall and membrane. Our study showed that the combination of selected essential oils fractions exhibited an increased antifungal activity against Candida spp compared to the crude essential oils. The combination approach of inner compound groups may be used as a promising strategy for the development of efficient recombined micro-essential oils as antifungal agents to face Candida resistance.
Subject(s)
Antifungal Agents/pharmacology , Candida/drug effects , Cymbopogon/chemistry , Lamiaceae/chemistry , Oils, Volatile/pharmacology , Syzygium/chemistry , Antifungal Agents/isolation & purification , Biofilms/drug effects , Cameroon , Candida/physiology , Candidiasis/drug therapy , Candidiasis/microbiology , Chemical Fractionation , Drug Synergism , Humans , Microbial Sensitivity Tests , Oils, Volatile/isolation & purification , Plant Extracts/chemistry , Plant Extracts/pharmacology , Plant Oils/isolation & purification , Plant Oils/pharmacologyABSTRACT
OBJECTIVE: The limitations encountered in the management of fungal infections are due to the resistance, high toxicity, and overuse of conventional antifungal drugs. For bringing solutions, the antifungal activity of Aeollanthus heliotropioides essential oil will be evaluated and optimized. MATERIAL AND METHODS: The aerial parts of A. heliotropioides were harvested and essential oil extracted by hydrodistillation. The chemical composition was determined using gas chromatography and gas chromatography coupled with mass spectrometry and nuclear magnetic resonance. The sensitivity of fungal strains was determined using broth microdilution method. The fungicidal parameters were checked by viability assay using methylene blue dye. The Fractional Inhibitory Concentration Index was determined according the two-dimensional checkboard methods. The efficiency of the simulated optimum concentrations confirmed experimentally on American type culture collection strains, through the Time Kill Kinetic Study. RESULTS: The yield of extraction of essential oil was 0.1%. The major compounds were linalool (38.5%), Z-α-farnesene (25.1%), 9-hexa-decen-1-ol (13.9%) saturated/unsaturated massoia and γ-lactones (4.5%). The MIC of extract on yeast isolates ranged from 0.6mg/mL to 5mg/mL. The combination of essential oil with thymol leads mainly to synergistic effects (0.5≤FICI). The optimums of essential oil (1.6±0.4µl/mL) and thymol (0.6±0.1mg/mL) revealed a total inhibition of yeast after 120 and 180minutes according to the yeasts strains used. CONCLUSION: This study highlights the in vitro antifungal activity of A. heliotropioides essential oil and it synergistic effect with thymol.
