Structure-activity relation among macrolide antibiotics in initiation of interdigestive migrating contractions in the canine gastrointestinal tract.

The relation between the chemical structure of commercially available macrolide antibiotics and their activity in inducing interdigestive migrating contractions (IMC) was studied in conscious dogs. It was found that the 14-membered macrolides erythromycin and oleandomycin are active in inducing IMC in the stomach in association with the endogenous release of motilin. These erythromycin- and oleandomycin-induced contractions in the stomach migrated through the small intestine in a caudad direction. Conversely, 16-membered macrolide antibiotics such as leucomycin, acetylspiramycin, and tylosin do not induce any contractions in the stomach or stimulate endogenous release of motilin. These findings suggest that the IMC-inducing activity in macrolides seems to be closely related to their chemical configuration, i.e., the structure of 14-membered macrolides with dimethylaminosugar (desosamine) bound at C-5 and neutralsugar at C-3 in glycosidic linkage in parallel is likely to be necessary for IMC-inducing activity. The mechanisms by which erythromycin and oleandomycin stimulate endogenous motilin release are not known.