Abstract: Antibacterial quinolone derivatives represented by the following formula [I] and salts thereof are disclosed. ##STR1## wherein R.sup.1 means a hydrogen atom or a carboxyl-protecting group;R.sup.2 denotes a hydrogen or halogen atom or a hydroxyl, lower alkoxyl, amino, aralkylamino, or mono- or di-(lower alkyl)amino group;A represents an oxygen or sulfur atom or N-R.sup.3 in which R.sup.3 is a hydrogen atom or an amino-protecting group;X is a hydrogen or halogen atom;Y means a nitrogen atom or C-R.sup.4 in which R.sup.4 is a hydrogen or halogen atom or a lower alkyl or lower alkoxyl group; andZ denotes a halogen atom or a substituted or unsubstituted heterocyclic group having at least one nitrogen atom as a hetero atom.

Abstract: Antibacterial quinolone derivatives represented by the following formula [I] and salts thereof are disclosed. ##STR1## wherein R.sup.1 means a hydrogen atom or a carboxyl-protecting group; R.sup.2 denotes a hydrogen or halogen atom or a hydroxyl, lower alkoxyl, amino, aralkylamino, or mono- or di-(lower alkyl)amino group; A represents an oxygen or sulfur atom or N--R.sup.3 in which R.sup.3 is a hydrogen atom or an amino-protecting group; X is a hydrogen or halogen atom; Y means a nitrogen atom or C--R.sup.4 in which R.sup.4 is a hydrogen or halogen atom or a lower alkyl or lower alkoxyl group; and Z denotes a halogen atom or a substituted or unsubstituted heterocyclic group having at least one nitrogen atom as a hetero atom.

Abstract: Antibacterial quinolone derivatives represented by the following formula and salts thereof are disclosed. ##STR1## wherein R.sup.1 meawns a substituted or unsubstituted lower alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted lower alkenyl group or a substituted or unsubstituted phenyl group, R.sup.2 denotes a hydrogen atom or a carboxyl-protecting group, R.sup.3 represents a hydrogen or halogen atom or an amino, mono- or di-(lower alkyl)amino, hydroxyl or lower alkoxyl group, X is a hydrogen or halogen atom, Y means a nitrogen atom or a group C-R.sup.4 in which R.sup.4 is a hydrogen or halogen atom or a lower alkyl or lower alkoxyl group or is a group ##STR2## which forms a ring together with R.sup.1 (i.e., the asterisked carbon atoms are linked to the N(1) atom of the quinolone skeleton), and A denotes a specific N-containing group. Preparation processes of the quinolone derivatives and antibacterial agents containing the same are also disclosed.

Abstract: Isoindoline derivatives represented by the formula (I) and their salts are disclosed. ##STR1## There are many varieties for the compound depending on the types of residues R.sup.1 -R.sup.9 and X. The compounds can be prepared from quinoline derivatives of the formula (II) and an isoindoline derivatives of the formula (III). The compounds of formula (I) and their salts have excellent antibacterial activities against both gram positive and gram negative microorganisms. They can be used as a medicine, an agrichemical, and a food preservative.