Comparison of UF and Eduf Technologies for Isolation and Concentration of In Vitro Anti-Diabetic Soy Peptides

Many soybean compounds have been identified for their health benefits and since a few decades, research interests were focused on soy peptides. However, few fractions have already been identified for their metabolic activities. In this context, two kinds of separation technologies (pressure-driven, ultrafiltration (UF); electrically-driven, electrodialysis with ultrafiltration membranes (EDUF)) were compared for their potential in separating of bioactive soy peptides. Moreover, two conditions were studied for each technology: for UF technology, two membrane configurations were studied (a 10 kDa spiral wound membrane (SW) and a 10 kDa hollow fiber membrane (HF)), while two electric strength/UF membrane cut-off ratios were investigated in EDUF (5 V/10 kDa vs 50 V/100 kDa). After separations, fractions were tested in vitro for their glucose up-take activities, using L6 muscular cells.

In spite of composition differences revealed by LCMS analysis, no effect was reported neither for HF configuration nor for EDUF at 5 V/10 kDa. However, significantly increased glucose uptakes were measured in cells treated with SW fractions (at 1 mg/ml) and EDUF 50 V/100 kDa fractions (at 1 µg/ml), with a dose/effect correlation, indicating a potential anti-diabetic effect. Moreover, it was demonstrated by western blot experiments that the AMPk pathway, one of the major non-insulino dependent glucose uptake pathway, was activated by the 50 V/100 kDa EDUF fractions. Hence, it appeared that EDUF treatment used at 50 V/100 kDa would be a convenient mean for isolating and concentrating in vitro anti-diabetic peptides form soy hydrolysate, more efficiently than UF technology.