Abstract: Production of a benzothiazole compound of the formula (I) ##STR1## wherein R.sup.1 is a halogen atom, R.sup.2 and R.sup.3 may be the same or different and each is a hydrogen atom or a halogen atom, R.sup.4 is a hydrogen atom, a halogen atom, a lower alkyl, an alkoxy or an alkyl mercapto and R.sup.5 is a hydrogen atom or a lower alkyl, or a pharmaceutically acceptable salt thereof.The compound of the formula (I) and a pharmaceutically acceptable salt thereof of the present invention have an aldose reductase inhibitory activity in mammals inclusive of human and have superior safety. Accordingly, they are useful as pharmaceutical compositions for the treatment of the complications of diabetes, such as faulty union of corneal injury, cataract, neurosis, retinopathy and nephropathy, particularly cataract and neurosis.

Abstract: 1,4-Benzothiazine-2-acetic acid derivatives having an excellent aldose reductase inhibitory activity which are useful for the prevention and treatment of diabetic complications, such as diabetic cataract, retinopathy, nephropathy and neuropathy.

Abstract: An agent for treating or preventing cerebral circulation disorder, cerebral metabolism disorder, or memory disturbance is disclosed. The agent comprises as an effective component a phenylalkanoylamine derivative represented by the following formula (I), ##STR1## wherein A represents a 1,3-thiazolidin-3-yl group, a 1,2,3,6-tetrahydropyridin-1-yl group, a morpholino group, a thiomorpholin-4-yl group, or a 3-pyrrolin-1-yl group, R.sup.1 and R.sup.2, which may be the same or different, represent a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group, a nitro group, an amino group, a guanidino group, or a group ##STR2## (wherein R.sup.3 and R.sup.4 independently represent a lower alkyl group or form in combination 5- or 6-membered heterocyclic group), and n represents an integer of 2-6, or a salt thereof.

Abstract: Novel condensed benzene derivatives having prolyl endopeptidase inhibitory, anti-hypoxic, and anti-amnesic activities are disclosed. The compounds are represented by the following (I), ##STR1## wherein A represents a methylene, ethylene, or propylene group, B represents a methylene or ethylene group, m denotes an integer of 0-5, X and Y, which may be same or different, individually represent a methylene group or sulfur atom, R.sup.1 represents a hydrogen atom, a carboxyl, lower alkyloxycarbonyl, hydroxymethyl, or formyl group, R.sup.2 represents a hydrogen atom, a halogen atom, a lower alkyl, lower alkoxy, nitro, or amino group, R.sup.3 represents a hydrogen atom or a lower alkyl group, and the dotted line may optionally be present. They are useful as a medicine for treating or preventing cerebral circulation disorder, cerebral metabolism disorder, or memory disturbance.

Abstract: Novel N-substituted amino acid imide derivatives are disclosed. The compounds are represented by formula (I): ##STR1## wherein n represents an integer of 0 to 5, and X and Y, which may be the same or different, represent a methylene group or a sulfur atom, provided that not both X and Y are methylene groups at the same time. The compounds are useful as a medicine for treating or preventing cerebral circulation disorder, cerebral metabolism disorder, or memory disturbance.