Quantitative structure-activity relationships of Ca(2+)-antagonistic semotiadil congeners

Structure-Ca2+ antagonistic activity relationships of semotiadil (1) congeners having a benzothiazine cyclic system were studied quantitatively by the Hansch-Fujita method. A quadratic dependency of the activity on ClogP, a lipophilic descriptor, of terminal arylalkylamine moieties was suggested. A correlation between the dipole moment component of the 5'-substituted 2-phenylbenzothiazine parts and the potency was also suggested. Additionally, quantitative analysis was successfully shown for the 2-substituted 1 congeners. The results gave information about the mode of binding of 1 with Ca2+ receptor.