Investigating the mechanisms of action of conglutin-γ in regulating D-glucose uptake: the role of intestinal barrier

Conglutin-γ (Cg) is the major glycoprotein from the edible seed L. albus, long studied for its postprandial glycaemic regulating action. Several cell model systems (liver, pancreatic, myoblast, musculoskeletal) have been used to investigate in vitro mechanisms of action, all attributable to insulin-mimetic actions. However, it still lacks clear information on what could happen at the meeting point between the protein and the organism: the intestinal barrier. We compared an in vitro system involving Caco2 and IPEC-J2 cells with an ex vivo system using pig jejunal segments to study Cg transport from the apical to the basolateral compartment, its effects on the D-glucose uptake and glucose transporters protein expression. Finally, we studied its potential in modulating glucose metabolism by assessing the possible inhibition of α-amylase and α-glucosidase. RP-HPLC analyses showed that Cg could be found in the basolateral side in the in vitro system but not in the pig intestines, where it causes tissue damage with albumin release. Cg dispensing was able to promote a decrease in glucose uptake in both cells and jejunum independently from the expression of the SGLT1 and GLUT2 transporters