Luminescent Properties of ß-(hydroxyaryl)-butenolides and Fluorescence Quenching in Water.

This work describes the luminescent properties of the new compound ß-(hydroxyaryl)-butenolides recently discovered. The compounds were subjected to UV-Vis absorption and fluorescence analyzes when diluted in different solvents. Through the results, it was possible to observe that the ß-hydroxyarylutenolides have two absorption bands, one at 289-291 nm and the other with higher intensity at 328-354 nm. The emission band between 385-422 nm is observed under excitation at 324-327 nm. The compounds showed solvatochromism as a function of the analyzed solvent. In water, fluorescence quenching of all compounds occurs. Therefore, studies with compound containing the methylenedioxy group attached in phenyl ring were carried at different concentrations of water in DMSO. The decrease in the fluorescence intensity of this compound is linearly proportional to the increase in the amount of water in the DMSO, with a minimum detection volume of 0.028%. Quantum yields of three compounds were evaluated in different solvents, showing that the relationship between the structure of the compound and the solvent is essential for a high value. The fluorescence quantum yield was also measured by Thermal Lens Spectroscopy (TLS) using DMSO as the solvent, confirming the high value for the analyzed samples. Despite being preliminary, the studies revealed that these compounds have luminescent properties that could be applied in the development of chemical sensors for detecting water in DMSO.

Synthesis of (-) - 6, 6'-dinitrohinokinin from hinokinin natural product and in silico and in vitro trypanocidal activity assessment

Chagas disease is a public health problem affecting approximately seven million people worldwide. Thus, there is a need to discover drugs for the adequate treatment of this disease because currently available drugs have serious side effects. Therefore, this study aimed to evaluate the in vitro trypanocidal activity of (-)-6,6'-dinitrohinokinin, obtained from the partial synthesis of (-)-hinokinin, on the trypomastigotes and amastigotes forms. For the trypomastigote assay, blood was collected from mice infected with Trypanosoma cruzi through cardiac puncture at the parasitemic peak. The results show that (-)-6,6'-dinitrohinokinin was effective against the trypomastigote forms, presenting an IC50 of 19.83 µM and lysis percentage values ​​of 78.4% and 69.4% at concentrations of 200 and 100 µM, respectively. Molecular docking calculations indicate that (-)-6,6'-dinitrohinokinin favorably interacts with the amino acids present in the active site of the protein trypanothione reductase, a typical target for anti-trypanosomal drug development. According to the results, the (-)-6,6'-dinitrohinokinin showed more significant trypanocidal activity with IC50 of 1.83 µM than benzonidazole positive control with IC50 of 53.2 µM, showing to be a prototype molecule promising for the development of a new antiparasitic drug.