STEREOISOMERIC EFFECT ON ANTIMICROBIAL ACTIVITY OF A SERIES OF QUATERNARY AMMONIUM-SALTS

Two homologous series of diastereoisomeric racemic +/- cis and +/- eth yl-N-alkyl-2-benzoyloxycyclohexylmethylammonium bromides with the numb er of carbon atoms in the alkyl chain from six to twenty (m = 6,8...20 ) were synthesised. Their structures have been elucidated by IR, UV an d in some cases also with H-1 and C-13 NMR spectrometry. The title com pounds were assayed for their antimicrobial activity on microorganisms S. aureus, E. coli and C. albicans. The highest antimicrobial activit y was observed against S. aureus (log 1/MIC = 5.5 mol(-1) dm(3)) and t he lowest against E, coli (log 1/MIC = 4.5 mol(-1) dm(3)). The +/- cis and +/- trans stereoisomers of all eight couples of diastereoisomeric compounds show differences in their physico-chemical characteristics (including partition coefficient and lipophilicity) which is also refl ected in the different antimicrobial activity of these diastereoisomer s. (C) 1998 Elsevier Science S.A.