IDENTIFICATION OF ANTIFUNGAL COMPOUNDS FROM THE SEED OIL OF AZADIRACHTA-INDICA

Evaluation of the activity of the cold expeller neem oil (Azadirachta indica A. Juss.) and the fractions derived through solvent partitionin g, against Drechslera oryzae, Fusarium oxysporum and Alternaria tenuis showed that the active antifungal fraction is a mixture of tetranortr iterpenoids. Further, testing the triterpenoidal mixture derived from the 90% methanol (MeOH) extract of neem oil against 13 phytopathogenic fungi revealed that various species were inhibited to different degre es. Direct preparative High Performance Liquid Chromatography (HPLC) o f the active fractions and subsequent bioassay of the semi-pure fracti ons indicated that the active fractions contained major compounds such as 6-deacetylnimbin, azadiradione, nimbin, salannin and epoxyazadirad ione. Pure azadiradione, nimbin, salannin and epoxy-azadiradione did n ot have appreciable activity. However, when these terpenoids were mixe d and bioassayed, they showed antifungal activity, indicating possible additive/synergistic effects.