Efeito do pH sobre a estabilidade da atividade antitríptica do inibidor de tripsina isolado de sementes de tamarindo nanoencapsulado

Abstract

Trypsin inhibitor (ITT) isolated from tamarind seed (Tamarindus indica L.) nanocapsulated in chitosan and isolated whey protein (EQPI) potentiated the effect of ITT in terms of antitryptic activity, and pH is a characteristic that may affect the efficiency and release of the particle. In order to better understand the properties of EQPI and the factors that may affect its action, this study investigated the effect of pH on the stability of antitryptic activity of EQPI compared to ITT. ITT was extracted from tamarind seeds, isolated by CNBr-activated trypsin-Sepharose 4B affinity chromatography, and characterized for antitryptic activity, protein quantification, and molecular mass. The nanoparticles were obtained by the technique of nanoprecipitation in organic solvent using chitosan (QP) and isolated whey protein (PI) as encapsulant in the ratio 1:2:2 (w/w) and then characterized for their morphology by scanning electron microscopy (SEM) and the efficiency of incorporation of ITT determined by the antitryptic activity of EQPI. To evaluate the effect of pH on the stability of the encapsulated inhibitor activity, the nanoparticles and ITT were exposed to different pH conditions (3.0 and 7.0) simulating digestion conditions. The behavior of EQPI and ITT exposed to the pH conditions was monitored by antitryptic activity using ITT (1.4 mg/mL), EQPI (7.0 mg/mL), and ITT (ITText) extracted from EQPI (7.0 mg/mL) as controls without passing through the pH conditions. As a result, it was found that the isolated ITT had an antitryptic activity of 98.56% (533.03 IU) and a molecular mass of about 20 kDa. The nanocapsulated ITT exhibited a spherical and smooth morphology, had an encapsulation efficiency (EE) of 95.57 % and showed no antitryptic activity. However, when ITText was exposed to active release conditions, it showed 98.21% antitryptic activity. Under oral, gastric and intestinal pH conditions, the percentage of inhibition of EQPI was 0% (2 min), 44.07% (2 hr) and 20.10% (2 hr), respectively, while for ITT it was 92.27%, 94.11% and 94.06%. It can be concluded that the ITT was isolated and protected during nanocapsulation, which ensures gradual release at specific sites of the gastrointestinal tract. Considering the stability of antitryptic activity at pH 7.0 and release at pH 3.0, EQPI represents an interesting particle for application in pharmaceutical products, considering the bioactivities already attributed to ITT and its action in the gastrointestinal tract.