Chemical characterization and antimycotic potential of Azadirachta indica L. leaf extracts against Penicillium digitatum of kinnow fruit

We assessed the antimycotic potential of various ethanolic extracts of Azadirachta indica leaves against the post-harvest fungus P. digitatum of Kinnow (Citrus reticulata Blanco). The Gas Chromatography-Mass Spectrometry (GC-MS) analysis revealed the presence of various active compounds [phytol (13.14 %), lycoxanthin (8.55 %) in powdered ethanol extract (PEE) and 9,12,15- octadecatrienoic acid, (Z, Z, Z)- (43.5 %), 9 alpha-Fluoro-17 alpha-methyl-4-androsten-3 alpha,6 beta,11 beta,17 beta-tetra-ol (13.07%) in partitioned fresh ethanol extract (PFEE)]. Absorption spectra were measured in 1000-4000 cm(-1) domain using Fourier transform infrared spectrophotometer (FTIR). PFEE had greater antimycotic potential against the test pathogen P. digitatum than PEE as evident from reduction in colony number and diameter. The optical and scanning electron microscopy (SEM) analysis of extract-pathogen post interaction events also showed a biocidal effect on fungal hyphae showing swollen, perforated and collapsed hyphae with other distortions, probably caused by these allelochemicals.