Full Length ArticleAnti-nemic secondary metabolites produced by Fusarium oxysporum f. sp. ciceris

•Isolation and identification of five secondary metabolites of Fusarium oxysporum f. sp. ciceris•Nematicidal activity of metabolites on Meloidogyne incognita and Rotylenchulus reniformis•Considerable anti-nemic activity of fusarubin and its analogues against Meloidogyne incognita•Structure anti-nemic activity relationship of isolated secondary metabolites

Several nonpathogenic strains of Fusarium oxysporum have been selected as potential biological control agents. Culture filtrate of F. oxysporum f. sp. ciceris was extracted sequentially with ethyl acetate (EtOAc) and n-butanol (n-BuOH). Chromatographic separation of EtOAc concentrate has afforded five compounds, bikaverin (1), 3-O-methyl-8-O-methyl fusarubin (2), 8-O-methyl fusarubin (3), anhydrofusarubin (4) and fusarubin (5). Structures of these compounds were elucidated by detailed NMR and LC/ESI-MS spectra. Anti-nemic activity of the extracts and secondary metabolites were evaluated against root-knot nematode, Meloidogyne incognita and reniform nematode, Rotylenchulus reniformis. EtOAc concentrate was found to be strongly active against M. incognita (LC50 56.2 μg mL− 1) followed by n-BuOH concentrate (LC50 97.4 μg mL− 1). However, these concentrates were moderately effective on R. reniformis (LC50 134.5-189.2 μg mL− 1). Fusarubin (LC50 248.9 μg mL− 1) was found to be highly active followed by anhydrofusarubin (LC50 257.6 μg mL− 1) against M. incognita. Structure anti-nemic activity relationship indicated comparatively more polar molecule with naphthoquinone nucleus as most active. Fusarubin analogues could be exploited further to develop standard nematicidal liquid formulation.

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