Synthesis, spasmolytic activity and structure–activity relationship study of a series of polypharmacological thiobenzanilides

Recently we presented a series of benzanilide derivatives with a selective spasmolytic effect on terminal ileum preparations of the guinea pig. In this report we demonstrate a further development of these compounds. The exchange of the amide oxygen against a sulfur atom resulted in an up to 325 fold increase of the antispasmodic activity of the thiobenzanilide (IC 50 of 0.1 μM) compared to its benzanilide derivative. Considering their mode of action the compounds interacted with several molecular targets, suggesting that we identified a chemical identity able to modulate multiple targets simultaneously. Furthermore, based on this data set, we present a structure–activity relationship study supporting the important role of the sulfur atom.