Methyl Esters of (E)‑Cinnamic Acid: Activity against the Plant-Parasitic Nematode Meloidogyne incognita and In Silico Interaction with Histone Deacetylase

(E)-Cinnamaldehyde is very active against Meloidogyne incognita but has low persistence in soil. To circumvent this problem, esters of cinnamic acid were evaluated as a substitute for (E)-cinnamaldehyde. The best results under assays with M. incognita second-stage juveniles (J2) were obtained for the methyl esters of (E)-p-fluoro- (13), (E)-p-chloro- (14), and (E)-p-bromocinnamic acid (15), which showed lethal concentrations to 50% (LC50) J2 of 168, 95, and 216 μg/mL, respectively. Under the same conditions, the LC50 values for the nematicides carbofuran and fluensulfone were 160 and 34 μg/mL, respectively. Substances 13–15 were also active against nematode eggs, which account for most of the M. incognita population in the field. According to an in silico study, substances 13–15 can act against the nematode through inhibition of histone deacetylase. Therefore, esters 13–15 and histone deacetylase are potentially useful for the rational design of new nematicides for the control of M. incognita.