Nematicidal activity of flavonoids with structure activity relationship (SAR) studies against root knot nematode Meloidogyne incognita

In continuation of our work on Tagetes spp., the current study deals with the nematicidal activity of flavonoids, which are structurally related to two marker compounds, patuletin and patulitrin isolated from Tagetes patula flowers. The activity was determined against root-knot nematode, Meloidogyne incognita to establish structure activity relationship. In vitro examination of flavonoids belonging to flavone and flavonol classes revealed significant differences in nematicidal ability depending on their structural motif, concentration, and time of exposure. In case of flavonols the most efficient compounds were found to be fisetin, galangin, isorhamnetin, morin, and myricetin which exhibited 100% mortality of 2nd stage juveniles after 24 h of incubation. Whereas, among flavones which showed the same excellent activity parameters, were simple flavone, 6-hydroxy flavone, chrysin, 6-methoxy apigenin, apigenin-7-O-glucoside and 6-methoxy luteolin. These results revealed that flavonoids possess promising nematicidal activity and may have potential use in crop management as active agents.