Phytochemical analysis, antifungal activity and mode of action of methanol extracts from plants against pathogens.

Plants are reservoir of biological active compounds to combat various pathogens. Methanol extracts of five plants were tested for their antifungal activity against 10 phytopathogenic fungi and Candida albicans B017. Among all extracts, Lawsonia inermis showed greatest percent inhibition of mycelial growth of target fungi (76.47 87.77 %) followed by Withania somnifera (54.44 78.88 %). Other plant extracts also exhibited antifungal activity at varying percentage. Extract of Lawsonia inermis (1 %) increased the percent seed germination of chickpea (Cicer aeritinum L.) with 30 % and protected from Fusarium oxysporum in vivo. All extracts were analyzed for the detection of various secondary metabolites. Certain plant extracts contained alkaloids flavonoids, saponins, steroids and tannins. Saponin was found in all extracts. The mode of action of extracts was determined on cell wall and enzyme production of fungi. Lawsonia inermis inhibited the production of catalase in Aspergillus niger and Fusarium oxysporum. Thin layer chromatography was prepared in eight solvent systems. Out of which, toluene/ ethyl acetate (1:1) showed higher band separation in almost all extracts. Protein fractions of Lawsonia inermis and Withania somnifera exhibited four to five times more percent inhibition of mycelial growth of Bipolaris oryzae and Colletotrichum lindemuthianum than nonprotein fractions. The active compounds were proteinaceous in nature or proteins and they are effective against plant pathogens.