Abstract

The antifungal properties of methanol extracts of selected plant (Adansonia digitata, Ambrosia maritiama, Moringa oleifera, Ocimum basilicum, Ocimum canum, Ocimum gratissimum and Vernonia cinerea) leaves on fungi isolated from a selected landrace of sorghum sold in Sabon Gari market, Kaduna State, Nigeria was investigated. Extraction and quantification of phytochemicals from the leaves, and the minimum inhibitory and fungicidal concentrations was done using standard methods. Antifungal activity of the extracts was evaluated by comparing the mycelial growth inhibition (MGI) with standard antifungal drug Mancozeb at concentrations of 50mg/ml and 20mg/ml. Nine phytochemicals were found associated with the extracts and there were significant variation in the quantities of phytochemicals, with O. canum having the highest concentrations of Alkaloids (59.96mg/g), Flavonoids (101.09mg/g), Saponins (62.71mg/g), Phenols (160.08mg/g), Tannins (115mg/g) and Steroids (55.09mg/g); while A. maritiama, O. basilicum and M. oleifera had the highest concentrations of Carbohydrates (356.98mg/g), Tritipenes (32.76mg/g) and C/glycosides (66.53mg/g) respectively. There is significant variation (p˂0.05) in the effect of leaf extracts and Mancozeb on the MGI of isolated fungi with O. canum having highest efficacy against four fungi species (Aspergillus flavus, Aspergillus niger, Fusarium oxysporum and Fusarium solani), recording 100% MGI. Sensitivity of fungi to the extract showed that M.  oleifera extract had minimum inhibitory concentration (MIC) on the isolates only at 50mg/ml. O. canum extract had its MIC against A. flavus, Didymaria sp. and Curvularia lunata at 25mg/ml. Its MIC against Penicillium chrysogenum, F. oxysporum and F. solani was further observed at 12.5mg/ml. Ocimum basilicum extract had its MIC against Dydimaria sp and C. lunata at 25mg/ml. Extract from Ambrosia maritiama had its MIC against Dydimaria sp and C. lunata at 25mg/ml and 12.5 mg/ml respectively. Extract of O. canum had its MFC against P. chrysogenum and F. oxysporum at concentration of 25mg/ml each. Extract from Ocimum basilicum had its MFC at 50mg/ml against Dydimaria sp and C. lunata whereas A. maritiama had its MFC against C. lunata at 25mg/ml. Investigations into the mechanisms by which O. canum extract inhibits the growth of A. flavus, A. niger, F. oxysporum, and F. solani can aid in developing new antifungal agents since it is the most active in terms of antifungal activity.