A compound represented by the following Formula (I):
##STR1##
(wherein A represents oxygen atom or —NR3— (R3
represents hydrogen atom or lower alkyl group); R1 represents
nitro group, lower alkoxycarbonyl group, carbamoyl group unsubstituted or mono-
or di-substituted by lower alkyl group, unprotected or protected hydroxyl group,
unprotected or protected carboxyl group, lower alkyl group substituted by unprotected
or protected hydroxyl group, or tetrazolyl group; and R2 represents
hydrogen atom, cyano group or lower alkylsulfonyl group, provided that when A is
—NR3—, it is excluded that R1 represents unprotected
or protected hydroxyl group or lower alkyl group substituted by unprotected or
protected hydroxyl group) or its salt, and method for producing the compound, and
a pharmaceutical composition containing the compound as active ingredient.