Gastrointestinal transit and mucoadhesion of colloidal suspensions of Lycopersicon esculentum L. and Lotus tetragonolobus lectin-PLA microsphere conjugates in rats

Purpose. To investigate in vivo the fate and the behavior of lectin-particl e conjugates after oral administration. Methods. Two plant lectins were selected, namely Lycopersicon esculentum L, and Lotus tetragonolobus lectins, which have been reported to be specific for oligomers of N-acetyl-D-glucosamine and L-fucose, respectively, and con jugated to small poly(lactide) microspheres. Their intestinal transit was i nvestigated in detail using radiolabeled particles. The transport and the d istribution of the particles along the intestine, as well as their interact ions with the intestinal mucosa, were determined after oral administration in rat. Results. The overall transit of the particles was shown to be strongly dela yed when the microspheres were conjugated to the lectins, mainly due to the gastric retention of the particles. A significant fraction of the conjugat es adhered to the gastric and intestinal mucosae. No significant difference s were observed after a preliminary incubation of lectin-microsphere conjug ates with specific sugars. Conclusion. Although specific interactions could not be excluded, especiall y in the stomach, it was likely that adhesion was predominantly due to nons pecific interactions. These results could be attributed both to unfavorable physicochemical characteristics of the conjugates and to premature adsorpt ion of soluble mucin glycoproteins, preventing any further specific adhesio n.