Chemical Composition of Essential Oil of Mondia whitei and Antifungal Activities Against Aspergillus flavus and Penicillium sp., The Mold Associated on Yams (Dioscorea rotundata Poir.) Tuber Rot

Abstract

The aim of this work was to determine the chemical composition of essential oil of roots of Mondia whitei and to evaluate their antifungal potential against Aspergillus flavus and Penicillium sp. Oil was obtained by hydro-distillation and gas chromatography was used to analyze their chemical constituents. The fungi were isolated from post-harvest yams (Dioscorea rotundata) showing typical symptoms of tuber rot. Antifungal activities of the oil were tested in vitro against mycelia growth and conidia germination. In situ test was carried out on healthy yams by application of the oil after (preventive test) and before (curative test) infection with pathogens. Results showed that yield of root Mondia whitei essential oil was 2.57 % and the Menth-1-en-7-al <3-oxo-P-> was found to be the main component. Significant reduction of mycelia growth was obtained with minimal inhibitory concentration (MIC) at 500 μl/l and 525 μl/l respectively for Aspergillus flavus and Penicillium sp. This oil completely inhibited the conidia germination of Penicillium sp. with MIC at 525 μl/l while 65.38 % inhibitory was obtained at 1000 μl/l against Aspergillus flavus. In situ test showed significant reduction of necrosis of yam tuber rot. At 2500 μl/l we obtained 47.41 % and 72 % of necrosis inhibition respectively, for preventive and curative healing for Aspergillus flavus, while for Penicillium sp., we obtained at 2625 μl/l, 31.8 % and 43.07 % of the necrosis inhibition, respectively. This study demonstrated that essential oil from roots of Mondia whitei could be promising alternative for management yam tuber loose induced by mold.