Phytochemical analysis and in vitro antifungal evaluation of Jatropha curcas against Late Leaf Spot disease on groundnut

Abstract

This study was done to evaluate the antifungal efficacy of Jatropha curcas leaf extracts against groundnut late leaf spot disease caused by Phaeosariopsis personata (P. personata) and identify their bioactive compounds responsible for antifungal effects. Jatropha curcas leaves extracted sequentially through chloroform, ethyl acetate and methanol solvents were evaluated against the mycelial growth of P. personata by food poisoning method. About 0.1, 0.25 or 0.5 mg/ml (plant extract/water) of each extract were mixed in molten PDA poured into Petri dishes. Thereafter solidified amended PDA with extracts was kept at room temperature for 24 hours. A seven-day-old fungal plug (4mm diameter) of P. personata was plated at the middle of the Petri dishes in triplicates. Inoculation on PDA plates amended with fungicide Chlorothalonil (720g/L) or water was included as positive and negative control respectively. The results proved that J. curcas leaf extracts possessed fungicidal properties since they inhibited the growth of P. personata. Moreover the antifungal effect of J. curcas leaf extracts increased as concentration increased. Moreover, J. curcas leaf extracts highly inhibited mycelial growth by (85.78%) similar to standard fungicide (chlorothalonil) (88.37%) in this experiment. The presence of important compounds found in J. curcas leaf extracts by GC-MS supported their ability against P. personata pathogen. Among the major compounds identified with antifungal activity were hexadecanoic acid methyl ester, hexadecanoic acid ethyl ester, hexadecane, n-hexadecanoic acid, octadecanoic acid ethyl ester, phytol and 9, 12- octadecadienoic acid (Z,Z)-methyl ester. The potentiality of J. curcas extracts in managing groundnut late leaf spot disease was confirmed by their ability to inhibit the growth of P. personata and possession of important phytochemical compounds.