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

BACKGROUNDWith 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. RESULTSThe most potent acetophenones were 4-nitroacetophenone and 4-iodoacetophenone, with EC50/24 h values of 125 and 15 +/- 4mgL(-1) respectively, somewhat weaker than that of the chemical control fosthiazate in our previous experiments (EC50/24 h 0.4 +/- 0.3mgL(-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 +/- 17mgL(-1)). Moreover, (E)-3-(2-hydroxy-5-iodophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one showed better activity (EC50/24 h value 26 +/- 15mgL(-1)) than 4-methoxyacetophenone (EC50/24 h value 43 +/- 10mgL(-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. (c) 2015 Society of Chemical Industry