Nematicidal activity of acetophenones and chalcones against Meloidogyne incognita and structure-activity considerations

BACKGROUND: With the ultimate goal of identifying new compounds active against root-knot nematodes, a set of 14 substituted chalcones were synthesised, starting from acetophenones. These chalcones and various acetophenones were tested in vitro against Meloidogyne incognita. RESULTS: The most potent acetophenones were 4-nitroacetophenone and 4-iodoacetophenone, with EC50 /24 h values of 12 ± 5 and 15 ± 4 mg L-1 respectively, somewhat weaker than that of the chemical control fosthiazate in our previous experiments (EC50 /24 h 0.4 ± 0.3 mg L-1 ). When we converted the acetophenones to chalcones, the nematicidal activity differed, based on their substitution pattern. The condensation of 4-nitroacetophenone with 2,4,6-trihydroxybenzaldehyde to give the corresponding chalcone (E)-1-(4-nitrophenyl)-3-(2,4,6-trihydroxyphenyl)prop-2-en-1-one led to a slight reduction in activity (EC50 /24 h value 25 ± 17 mg L-1 ). Moreover, (E)-3-(2-hydroxy-5-iodophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one showed better activity (EC50 /24 h value 26 ± 15 mg L-1 ) than 4-methoxyacetophenone (EC50 /24 h value 43 ± 10 mg L-1 ). CONCLUSIONS: Acetophenones and chalcones may represent good leads in the discovery of new nematicidal compounds and may have potential use in crop management as active ingredients.