Control of Aedes aegypti larvae with Aea-TMOF mimics: aromatic derivatives of enoic acid

Based on the 3D conformation of the N-terminus of TMOF in solution, six aromatic derivatives of enoic acid: 7-biphenyl-4-yl-hept-4-enoic acid (BPHE), 7-(4-butyl-phenyl)-hept-4-enoic acid (BuPHE), 7-cyclohexyl-hept-4-enoic acid (CyHE), 10-phenyl-dec-7-enoic acid (PDE), 7-p-tolyl-hept-2-enoic acid ethyl ester (THEEE) and 7-(4-methoxy-phenyl)-hept-2-enoic acid ethyl ester (MPEEE) were computer-modeled and synthesized. Treating first instar Aedes aegypti larvae with different concentrations of the TMOF mimics showed that addition of butyl to the benzyl ring, use of p-tolyl or converting the benzyl ring into cyclohexane increased the biological activity of the mimics by 5.2, 5.0 and 3.8-fold, respectively. Esterifying the carboxyl terminus into ethyl ester and addition of a methoxy group to the benzyl ring also increased, by 2-fold, the biological activity of the derivative. The position of the double bond in the aliphatic chain is important for enhanced biological activity. Aea-TMOF and CyHE fed to mosquito larvae equally inhibited trypsin biosynthesis in larvae for the first 24 h. The biological activity of CyHE, however, rapidly declined 2-3 days later, whereas TMOF activity stayed stable. These results indicate that TMOF organic mimics, although potent, need to be formulated in order to be more stable for future field applications.