title: MTD approach to quantitative structure-activity relationships for cardiotonic steroids.
abstract: A minimal topological difference (MTD) approach is made to describe quantitative structure-activity relationships (QSAR) for the Na+, K+-ATPase inhibitory activity of cardiotonic steroids. The calculations take into account 20 derivatives of digitoxigenin, digoxigenin, and gitoxigenin with small substituents at different sites of the steroid backbone. A multiple correlation coefficient of r = 0.916 is obtained using the MTD and an indicator variable for the presence of a 15 beta substituent. The corresponding receptor map reveals receptor wall vertices in the C11, C12, C15, and C22 regions. Both 3 beta and 16 beta substituents are found to contain receptor cavity vertices. The MTD results are discussed with respect to lactone-ring conformational investigations presented and they are compared with findings of previous structure-activity studies.
mesh_terms: D002301:Cardiac Glycosides / Q000494:pharmacology*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D008968:Molecular Conformation; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013329:Structure-Activity Relationship
chemical_list: D002301:Cardiac Glycosides; D000254:Sodium-Potassium-Exchanging ATPase