Abstract: The present invention relates to optical isomers of quinoline compounds of Formula (IA) or Formula (IA'), their pharmaceutically acceptable salts and their intermediates: ##STR1## In the above formulae, A represent nitrogen or ##STR2## in which Y represents hydrogen, halogen such as fluorine or chlorine, lower alkyl or lower alkoxy such as methoxy, or together with R.sub.1 forms --CH.sub.2 CH.sub.2 CH.sub.2 --, --CH.sub.2 CH.sub.2 CH(CH.sub.3)--, --OCH.sub.2 CH.sub.2 --, --OCH.sub.2 CH(CH.sub.3)--, --SCH.sub.2 CH.sub.2 -- or --SCH.sub.2 CH(CH.sub.3)--;R.sub.1 is as defined above or represents straight chain or cyclic lower alkyl group having 1 to 3 carbon atoms, a straight chain or cyclic lower alkyl group having 1 to 3 carbon atoms which is substituted with a halogen atom, a phenyl group or a phenyl group substituted with one or two halogen atoms, such as ethyl, cyclopropyl or 2,4-difluorophenyl;R.sup.