Estudo de compatibilidade e estabilidade térmica da própolis vermelha associada a diferentes excipientes na obtenção de membranas poliméricas

Abstract

Red propolis from Alagoas is a sticky resin made from a complex mixture of biologically active substances with great biotechnological potential. Several studies have shown that red propolis extracts have a wide variety of biological activities as an antioxidant. Drug-excipient compatibility testing is one of the most fundamental phases in the pre-formulation research process. The objective of this research is to evaluate compatibility and thermal stability of red propolis associated with different excipients in obtaining polymeric membranes. The ethanolic extract of red propolis was obtained by maceration. Assays were carried out to quantify the content of phenolic compounds, using the Folin-Ciocalteu reagent method, and flavonoids, using the aluminum chloride method of the EEPV. The investigation of the antioxidant activity of Red Propolis Ethanol Extract (EEPV) was carried out by the DPPH method. Synthetic membranes were prepared using the solvent evaporation method. And the physical-chemical properties of thermal stability of membranes, components, and binary mixtures were analyzed by Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetric Analysis (DSC). It was estimated that the content of total phenolic compounds was 208.0 mg EAG.g-1 , and the content of total flavonoids was 45.3 mg EAG.g-1 . The analysis of the antioxidant activities of EEPV by the DPPH method varied between 59.36% and 88.31%. The thermal profile obtained by the EEPV TGA showed 4 thermal degradation events, none of which were superimposed. Thermogravimetric thermal analyzes (TGA) showed sodium benzoate as the most stable excipient. In the second curve there was the decomposition of sodium benzoate, forming solid Na2CO3, and gaseous H2 and CO. Propylene glycol was the least stable excipient and its degradation in the N2 atmosphere is explained by a dehydration process that is the formation of propionaldehyde and acetone through the formation of the intermediate propylene oxide. The MX1 membrane was the most thermally stable due to the high amount of citrus pectin, high amount of sodium benzoate and low amount of propylene glycol. The MX2 membrane has intermediate thermal stability, as it has a low amount of citrus pectin and a low amount of sorbitol and an intermediate amount of sodium benzoate. The MX3 membrane was the membrane with the lowest thermal stability due to the large amount of sorbitol, intermediate amount of propylene glycol. Thus, the red propolis ethanolic extract showed good thermal stability. And, among the excipients, sodium benzoate was the most thermally stable. In contrast, propylene glycol was the excipient with the lowest thermal stability. And all excipients were compatible with red propolis ethanolic extract. All membranes were successfully obtained, however thermogravimetric analyzes (TGA) determined that MX1 has better thermal stability.