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 EC 50 /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 ( EC 50 /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 ( EC 50 /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 ( EC 50 /24 h value 26 ± 15 mg L −1 ) than 4‐methoxyacetophenone ( EC 50 /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. © 2015 Society of Chemical Industry