Isolation of nematicidal constituents from essential oil of Kaempferia galanga L rhizome and their activity against Heterodera avenae Wollenweber

Purpose: To explore the nematicidal activities of the essential oil of Kaempferia galanga rhizomes and its isolated constituents against Heterodera avenae Methods: Essential oil of K. galanga rhizomes was obtained by hydrodistillation and characterized by gas chromatography/mass spectrometric (GC/MS) analysis using HP-5MS column. Evaluation of nematicidal toxicity was performed against juveniles (J2) of H. avenae. The bioactive constituent compounds were isolated and identified from the oil based on bioactivity-directed fractionation. Results: Forty-one components were identified and the main components of the essential oil of K. galanga are as follows: ethyl-rho-methoxy cinnamate (34.79 %), ethyl cinnamate (20.72%), 1,8-cineole (8.96 %), trans-cinnamaldehyde (7.03%) and borneol (5.64 %). The essential oil exhibited nematicidal activity against the cereal cyst nematode with an LC50 value of 91.78 mu g/mL. Ethyl cinnamate, ethyl.methoxy cinnamate and trans-cinnamaldehyde (median lethal concentration LC50 = 100.60 mu g/ml, 83.04 mu g/mL and 94.75 mu g/mL, respectively) exhibited stronger nematicidal toxicity than borneol (LC50 = 734.89 mu g/mL) and 1,8-cineole (LC50 = 921.21 mu g/mL) against the cereal cyst nematode. Conclusion: The results indicate that the essential oil of K. galanga and its isolated constituents have a potential for development into natural nematicides for the control of cereal cyst nematodes.