A compound having the following formula (I): wherein --R.sup.1 is hydrogen, optionally substituted lower alkyl, cyclo(lower)alkyl, cyclo(higher)alkyl, optionally substituted aryl, optionally substituted heterocyclyl, or aryl-fused cyclo(lower)alkyl, R.sup.2 is hydrogen or halogen, Z is CH or N, X is formula (II) R.sup.3 is lower alkyl which may be substituted with --OH or optionally substituted aryl, or lower alkanoyl, R.sup.4 is hydrogen or lower alkyl, Y is optionally substituted lower alkylene, or a salt thereof. The compound is useful as a histone deacetylase inhibitor. ##STR00001##