Determinação da estabilidade térmica e degradação das acrilamidas LQM330, LQM333, LQM336 e LQM338 ativas contra o vírus CHIKV

Abstract

The characterization of solids and liquids for the development of pharmaceuticals and medications is essential toensure their processing, transportation, and storage. Some acrylamides are active against Dengue virus (DENV) and Zika virus (ZIKV), showing significant biological activity and low toxicity in human cells. These substances are classified as organic molecules. In recent decades, there has been a growing number of suspected cases of Chikungunya virus (CHIKV) infection, a disease that is often neglected due to its symptoms being similar tothose of DENV and ZIKV. There is currently no vaccination or focused treatment available for CHIKV. The study and characterization of active molecules are of great importance for previously unknown or underexplored therapeutic alternatives. Therefore, thermal analysis and complementary analytical techniques are essential tools for the development of new medications, as they provide data on the thermal behavior and chemical structureofmaterials. The objective of this work was to determine the thermal stability and degradation of acrylamides LQM330, LQM333, LQM336, and LQM338, which are active against CHIKV. The characterization of the molecules was carried out using Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), Ultraviolet and Visible Spectrophotometry (UV-vis), Fourier Transform Infrared Spectroscopy (FTIR), Gas Chromatography-Mass Spectrometry (GC/MS), High-Performance Liquid Chromatography (HPLC), and Scanning Electron Microscopy (SEM). The results obtained indicated that the molecules LQM330, LQM333, LQM336, and LQM338 exhibited purity by GC/MS and HPLC in the range of 92.50% to 99.55% and 99.81%to98.88%, respectively. Thermogravimetric curves demonstrated that the molecules are stable at different heatingrates (10, 20, 30, 40, and 50 °C min-1). The thermal decomposition profile is very similar among the acrylamides, with the presence of an endothermic event, except for sample LQM330, which exhibited exothermic events by DSC. This technique also provided data on the purity of the molecules in the range of 96.31% to 98.82%. UV-vis spectra revealed that the maximum absorption bands were around 220 to 335 nm, and FTIR spectra showed the presence of C=O stretching and N-H stretching, identifying the compound structures. The samples displayed heterogeneous, brittle morphology with clusters in general, except for the samples at 600 °C, which exhibited complete and homogeneous cube-like shapes, as confirmed by SEM. Therefore, the good thermal stability of the molecules confirmed them as promising candidates for the development of future medications against CHIKV. The characterization through thermal analysis and complementary analytical techniques provided specific and crucial data for advancing research in the pharmaceutical sector.