Anti-nemic secondary metabolites produced by Fusarium oxysporum f. sp ciceris

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 mu g mL(-1)) followed by n-BuOH concentrate (LC50 97.4 mu g mL(-1)). However, these concentrates were moderately effective on R. reniformis (LC50 134.5-189.2 mu g mL(-1)). Fusarubin (LC50 248.9 pg mL(-1)) was found to be highly active followed by anhydrofusarubin (LC50 257.6 mu g 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. (C) 2016 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society. Published by Elsevier B.V. All rights reserved.