NEMATICIDAL ACTIVITY OF STRYCHNOS NUXVOMICA LEAF AND ITS CONSTITUENTS AGAINST THE ROOT-KNOT NEMATODE, MELOIDOGYNE INCOGNITA

Abstract

Studies were undertaken on the nematicidal activity of Strychnos nuxvomica leaf extracts and its constituents on the second stage juveniles of the root-knot nematode, Meloidogyne incognita. Aqueous leaf extracts at 2% concentration caused 100% mortality of second stage juveniles of the nematode. The biological activity of the known phytochemicals from S. nuxvomica, evaluated by in silico analysis through prediction of activity spectra for substances (PASS) software, indicated that seven phytochemicals were expected to show nematicidal activity at various levels. In silico studies showed that the values of Pa (probability to be active) for brucine and strychnine were 0.986 and 0.785, respectively. Bioassay-guided fractionation of the leaf extract of S. nuxvomica indicated that the active fractions contained brucine and strychnine as major components. The nematicidal activity of brucine and strychnine was validated through in vitro bioassays and LD50 values were determined to be 665 ppm and 833 ppm, respectively.