Abstract: Disclosed are a thiazole derivative represented by the following formula, a pharmaceutically acceptable salt thereof and leukotriene antagonist containing the same as the active ingredients: ##STR1## wherein R.sub.1 and R.sub.2 each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a lower alkoxycarbonyl group or a substituted or unsubstituted phenyl group or cooperatively represent a tetramethylene group corresponding to a fused cyclohexane ring or a butadienylene group which is unsubstituted or substituted with a halogen atom, a lower alkoxy group, a lower alkoxycarbonyl group or an alkyl group having 1 to 3 carbon atoms corresponding to a fused benzene ring; R.sub.3, R.sub.4, R.sub.5 and R.sub.

Abstract: Disclosed are an aminostyryl compound represented by Formula I: ##STR1## wherein A represents a linking group having 3 to 4 chain members; B represents an unsubstituted or substituted 5 to 6-membered monocyclic type heterocyclic residue containing 1 to 2 hetero atoms, an unsubstituted or substituted condensed heterocyclic residue which contains 5 to 6-membered monocyclic type heterocycle containing 1 to 2 hetero atoms, a naphthyl group or an alkyl group having 5 to 7 carbon atoms,a composition having leukotriene antagonism which contains an aminostyryl compound represented by Formula I as the effective ingredient, and a method of antagonizing SRS based on leukotriene antagonistic activity by employing the same.

Abstract: A .gamma.-butyrolactone derivative represented by the following formula: ##STR1## wherein R.sup.1 represents a hydrogen atom, a straight or branched alkyl group having 1-8 carbon atoms, a phenyl group; R.sup.2 and R.sup.3 may be the same or different and each represents a hydrogen atom, a straight or branched alkyl group having 1-8 carbon atoms, a cycloalkyl group having 3-10 carbon atoms, a benzyl group, a phenyl group, a phenyl group substituted with a substituent selected from the group consisting of a halogen atom, an alkoxy group, a nitro group, an amino group, an alkyl group having 1-4 carbon atoms, a nitrile group and an alkoxycarbonyl group; R.sup.2 and R.sup.3 may be linked to form an alkylene group having 4-6 carbon atoms; X represents a hydrogen atom, a straight or branched alkyl group having 1-8 carbon atoms, a cycloalkyl group having 3-10 carbon atoms, a benzyl group or a substituent represented by the formula ##STR2## (wherein R.sup.