A 3D QSAR APPROACH TO THE SEARCH FOR GEOMETRICAL SIMILARITY IN A SERIES OF NONPEPTIDE ANGIOTENSIN-II RECEPTOR ANTAGONISTS

A 3D QSAR methodology based on the combined use of conformational anal ysis and chemometrics was applied to perform a comparative analysis of the 3D conformational features of 13 nonpeptide angiotensin II recept or antagonists showing different levels of binding affinity. Conformat ional analysis by using a molecular mechanics MM2 method was carried o ut for each of these structures to obtain conformational minima. These minima were described by ten interatomic distances which define the r elative spatial disposition of five significant atoms belonging to rel evant functional groups present in all the 13 molecules. The structure -activity relationship between the interatomic distances and the biolo gical activity was then assessed by using chemometric methods (cluster analysis, principal component analysis, classification methods). With our indirect approach based on the search for geometrical similarity it was possible, even though structural information on the receptor ac tive site was lacking, to identify the 3D geometrical requirements for the binding affinity of nonpeptide angiotensin II receptor inhibitors .