1-Substituted 7--1-pyrrolidinyl>-6,8-difluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic Acids. New Quantitative Structure-Activity Relationships at N1 for the Quinolone Antibacterials

Article abstract of DOI:10.1021/jm00400a017

A series of 18 1-substituted 7-<3-<(ethylamino)methyl>-1-pyrrolidinyl>-6,8-difluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid (N₁ analogues of CI-934) was synthesized and evaluated for antibacterial activity and DNA-gyrase inhibition.Correlations between the inhibition of DNA gyrase and antibacterial potency were established.A quantitative structure-activity relationship (QSAR) was derived by using the antibacterial potency of each of 11 strains of bacteria and the Gram-negative mean.The equations indicated that antibacterial potency was strongly dependent on STERIMOL length and width and the level of unsaturation of the N₁ substituent.Some strains also showed a dependence on the presence of heteroatoms (O, N, S) in the N₁ group.No significant correlations between gyrase inhibition and correlations of these parameters were found.These QSAR results are discussed in conjunction with the conformational analyses from molecular modeling studies.The substituent that most enhanced the activity of the quinolone in all regards was the cyclopropyl group.This analogue, 1-cyclopropyl-7-<3-<(ethylamino)methyl>-1-pyrrolidinyl>-6,8-difluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid (PD 117558), demonstrated outstanding broad spectrum activity both in vitro and in vivo when compared to relevant standards.