THE POTENTIAL USE OF TOMATO LECTIN FOR ORAL-DRUG DELIVERY .1. LECTIN-BINDING TO RAT SMALL-INTESTINE IN-VITRO

Tomato lectin, an apparently non-toxic dietary glycoprotein with a molecular mass of 71 kDa, was isolated from ripe tomato fruits. Its potential as an intestinal bioadhesive was examined using an in vitro organ culture system and Western blotting. The lectin was shown to bind avidly to rings of small intestine and this binding could be inhibited with specific competing sugars. After electrophoretic separation and transfer onto nitrocellulose, several of the proteins located on the small intestinal brush border membranes were found to bind tomato lectin, particularly those in the 160-116 kDa molecular mass range. These correspond to intestinal brush border digestive enzymes, which are known to be complex glycoproteins. The specific binding of tomato lectin to the enterocyte cell surface may give it potential for increasing the gastrointestinal residence time as a component of an oral drug formulation.