Estudio de la actividad antioxidante de aislados proteicos de harina de haba pallar (Phaseolus Iunatus L.) y su digestibilidad gástrica y duodenal (in vitro)

Abstract

In this research, the protein present in the lima - bean (Phaseolus lunatus L.) was isolated by isoelectric precipitation at pH 3, 4, 5 and 6, obtaining a superior yield at pH 6 (32, 58percent more less 0,30). In addition, quantification of protein isolates was carried out using the Biuret and Kjeldahl method, obtaining in both cases the higher protein content in the treatment at pH 5 corresponding to 71,33 percent and 42,31 percent, respectively. The protein isolates were characterized by the SDS-PAGE electrophoresis technique with the use of 2-mercaptoethanol, obtaining from it, high molecular weight protein fractions such as 7 S and 11 S globulins (acid and basic subunit) and 2 S albumins low molecular weight. Gastric digestion (DG) of the protein (in vitro) was carried out at pH 1.2, 2 and 3.2 by the action of the enzyme pepsin and duodenal digestion (DD) was carried out at pH 3.2 with pancreatin, both in the DG and DD, only the high molecular weight fraction corresponding to 7S globulins were digested, while proteins of molecular weight smaller than 45 kDa showed a low digestibility. Biologic activities: such as anti-inflammatory and antioxidant, were evaluated by the protein denaturation and the TBARS method, respectively; using the bean protein at different concentrations (100, 200, 500 and 1000) ug per ml. At pH 3 at a concentration of 1000ug per ml, the highest anti-inflammatory inhibition was obtained, corresponding to 37,55 percent, while at pH 6 the best antioxidant activity (68 percent) was obtained at a concentration of 1000 ug/ml, compared to the other pH studied.