Micronization of thymol by RESS and its larvicidal activity against Aedes aegypti (Diptera, Culicidae)

Abstract

Micronization techniques by supercritical fluid has been drawing attention from chemical and pharmaceutical industries due to its potential and innovation. Thymol is a phenolic compound with high antimicrobial and efficient antioxidant activities, due to its non-toxic and antimutagenic features is classified as Generally Recognized as Safe by the Food & Drug Administration. However, the highly volatile nature and low water-solubility allows the application of optimization technologies. Mosquitoes are vectors from devastating pathogens and parasites causing millions of deaths every year. Many studies have been carried out to identify new insecticides obtained from secondary metabolites of plants, looking for effective alternatives to vector control. Therefore, the present study sought to evaluate the method of micronization through Rapid Expansion of Supercritical Solutions in thymol, characterizing the particles by physicochemical properties and demonstrating the biological activity over fourth instar Aedes aegypti L. (Diptera, Culicidae) larvae in comparation to commercial thyme oil. The micronization process led to a reduction of 77.5 times in particle size and an increase of 37.28% in solubility, with improvement in larvicidal activity. Micronized thymol has shown higher effectiveness in cumulative mortality for Aedes aegypti (80% in 2 h) when compared with thyme essential oil (66.7% in 2 h) and in nature thymol (31.7% in 2 h). Micronization may increase bioavailability in order to optimize biological effects of chemicals compounds, opening new areas of study and new applications for this biochemical compound.