Indian Journal of Science and Technology

Abstract

The toxicity of chloroform, Petroleum ether and Methanol leaf extracts of Aspilia africana against Collectotrichum gloesporiodes and Curvularia lunatus, the pathogens of leafspot disease of paw-paw was investigated. The fungi were cultured in potato dextrose-leaf extract agar medium at the concentrations of 20mg/ml, 40mg/ml, 80mg/ml, 160mg/ml, 320mg/ml and the mycelial extension growth rate were observed. All the extracts showed significant (p<0.05) activity and concentration-dependent growth inhibition against the leafspot fungi with the percentage inhibition range from 35–100% at various concentrations. Only methanol extract gave 100% inhibition of fungal growth at 160mg/ml and 320mg/ml. C. lunatus was more sensitive to the extract than C. gloeosporioides. Preliminary phytochemical screening of the extracts revealed the presence of alkaloids, anthraquinones, flavonoids, glycosides, phenols, saponins, tannins and terpenes in varying degrees. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of the extracts showed a complex mixture of compounds which included 8 in methanol and petroleum ether extracts and 7 in chloroform extract. The implication of these findings is that extracts of A. africana could be a good antifungal agent with potential applications in agriculture against foliar diseases of paw-paw so as to improve production.
Keywords: Chemical Constituents, Antifungal Activity, Aspilia africana, Leaf Extracts, Leafspot Fungi, Carica papaya.