Co-cristalização da curcumina com d-manitol: caracterização e aplicações sobre larvas do Aedes aegypti (Linnaeus, 1762)
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The search for new compounds to eliminate Aedes aegypti mosquito larvae is a strategy used by several researchers. Brazil, for example, has been facing major problems due to the high number of cases of arboviruses transmitted by the mosquito. In order to reduce the speed of selection of populations resistant to chemical insecticides, photodynamic inactivation (IFD) in Ae. aegypti has been used as an alternative. Curcumin (CUR), a pigment extracted from the roots of Curcuma longa has been discovered as a potential photolarvicide. Despite advances in this area, CUR still has some limitations, such as its low stability, bioavailability and water solubility. Thus, the objective of this study was to develop formulations based on CUR and D-mannitol via co-crystallization, in order to obtain an improvement in their solubility and, consequently, enable their application in Ae. aegypti. The characterization of the formulations carried out: absorption spectroscopy (UV-vis), infrared spectroscopy (FTIR), fluorescence spectroscopy, confocal microscopy, solubility tests at pH 2, 7 and 11, the degradation test (of the most effective formulation) in fluorescent lamps (0.5 mW/cm²) 24h. For efficacy trials, the formulations were used at concentrations between 0.00625; 0.0125; 0.025; 0.05; 0.1; 0.2; 0.4; 0.8 mg.L-1 with 18W white fluorescent lamps, 0.5 mW/cm2 irradiance and after 24h larvae mortality were recorded. The determination of the internalization and elimination time of the formulations in the digestive system of Ae. aegypti through optical microscope images. Acute toxicity tests and simulated field application (of the most effective formulation) were carried out. And the analysis of microbiota activity in artificial breeding waters and in the simulated field where the formulations were placed by counting the log of colony forming units. Among the formulations, formulation 1 had the best solubility, followed by 2, 3 and 4, however, in relation to photolarvicidal efficacy, formulation 3 had the best performance, with a LC50 value of 0. 01 mg.L-1, in addition, had the shortest internalization time and the longest elimination time, 30 minutes and 8 days, respectively. With its best results, formulation 3 was chosen as the most effective, in addition to presenting an environmental safety, as it does not present mortality in acute ecotoxicity tests and maintains its persistence in the field for 14 days in light and 6 days in the shade.
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