Larvicidal activity of thiazolidinedione derivatives against Aedes aegypti larvae and toxicological studies with zebrafish embryos

BACKGROUND: Diseases caused by arboviruses are currently a worldwide public health problem. These diseases have the Aedes aegypti mosquito as the main transmission vector, and the main strategy to combat their spread is the interruption of the mosquito life cycle in its early stages. In this study, we synthesized thirteen thiazolidinedione derivatives (3a-3m) that were applied in a larvicide-based strategy against the Ae. aegypti vector and submitted to evaluation of toxicological effects. RESULTS: Microwave process intensification was utilized for the synthesis of thiazolidinedione derivatives (3a-3m). One thiazolidinedione derivative stands out (3a) with lethal concentrations (LC50-24 h) of 7.71 μg mL-1 (32.16 μmol L-1). It showed embryotoxicity to zebrafish at concentrations up to 1.0 μg mL-1 and mortality from 3.1 up to 100 μg mL-1. No biochemical disturbances occurred based on GST and LDH measurements. A para-substituted chlorine atom instead of hydrogen improves toxicity profile. CONCLUSION: The substitution pattern with a chlorine atom suggests a larvicidal activity. From the compounds tested, (Z)-5-(4-chlorobenzylidene)thiazolidine-2,4-dione (3a) was the most effective against Ae. Aegypti, showing embryotoxicity to zebrafish

Prolonged mosquitocidal activity of Siparuna guianensis essential oil encapsulated in chitosan nanoparticles.

BackgroundThe use of synthetic insecticides is one of the most common strategies for controlling disease vectors such as mosquitos. However, their overuse can result in serious risks to human health, to the environment, as well as to the selection of insecticidal resistant insect strains. The development of efficient and eco-friendly insect control is urgent, and essential oils have been presented as potential alternatives to synthetic insecticides. Moreover, nanoencapsulation techniques can enhance their efficiency by protecting from degradation and providing a controlled release rate.ResultsWe assessed the potential of chitosan nanoparticles in encapsulating Siparuna guianensis essential oil, and maintaining its efficiency and prolonging its activity for the control of Aedes aegypti larvae. The encapsulation was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), with an encapsulation efficiency ranging from 84.8% to 88.0%. Toxicity studies have demonstrated efficacy against mosquito larvae over 50% for 19 days with 100% mortality during the first week. This persistent action is presumably due to the enhanced contact and slow and maintained release conferred by chitosan nanoparticles. Furthermore, the exposure of aquatic non-target organisms (e.g. embryos and small adult fishes) revealed adequate selectivity of these nanoparticles.ConclusionsThe encapsulation of S. guianensis essential oil in chitosan nanoparticles showed promising potential as a larvicide control alternative and should be considered within strategies for fighting Ae. aegypti