Nanoemulsions and solid microparticles with soybean lecitin Containing Pentyl Cinnamate for Combating the Aedes aegypti
Aedes aegypti. Larvicide. Natural product. Pentyl cinnamate. Nanoemulsion. Solid microparticles.
The main strategy for controlling diseases transmitted by the Aedes aegypti mosquito is the elimination of the vector, mainly in its larval stage. Despite the proven effectiveness of commercial larvicides and insecticides, these products have environmental toxicity. The literature shows the use of natural products as an alternative to this problem. The aim of this study was to develop and characterize formulations containing pentyl cinnamate and to evaluate its larvicidal activity for Aedes aegypti. The pentyl cinnamate was obtained by semisynthesis through the esterification of cinnamic acid. This compound was characterized and its purity determined by NMR 1H e 13C, GC-MS and UHPLC-MS/MS. Pentyl cinnamate activity tests were performed on L3 larvae and on adult mosquitoes of A. aegypti, obtaining a larvicidal activity with LD50 of 19.9 μg.mL-1, and against adult mosquitoes at 200 μg per bottle test, 80.8 ± 3.8% mortality in 2 h. Nanoemulsions were produced with PHOSAL® 50+ (PHO), LIPOID® S 20 (L20) and LIPOID® S 75-3 (L75) lecithins by homogenization with mechanical agitation and ultra turrax. The nanoemulsions were subjected to spray drying to obtain solid microparticles characterized by FTIR, SEM and thermal analysis by DSC and TG. The nanoemulsions obtained by agitation with turrax had smaller droplet sizes, being that of PHO: 81.0 ± 1.8 nm; L20: 120.4 ± 4.9 nm and L75 with 150.9 nm. The PHO nanoemulsions proved to be the most stable during 30 days of observation, they were also the ones that showed higher content of pentyl cinnamate whith 66.0 ± 0.5%. The images obtained by SEM showed that the microparticles formed by the different lecithins had a similar aspect between them. In the FTIR spectra, stretching signals characteristic of the pentyl cinnamate and excipients were observed and by DSC and TG techniques it was possible to see an increase in the stability of the compound incorporated in solid microparticles. The preliminary study of toxicity in zebrafish showed evidence of toxicity of pentyl cinnamate in low concentrations, however future studies may be carried out for the influence of the solvent in this type of model. The nanoemulsions and microparticles produced proved to be suitable for making the use of this ester in water with potential use as a larvicide and adulticide feasible, opening perspectives for studies with other compounds.