Abstract: Novel peptide derivatives of the following formula ##STR1## wherein each symbol is as defined in the specification, pharmaceutically acceptable acid addition salts thereof and analogous copounds thereof.Since the derivatives and their pharmaceutically acceptable acid addition salts of the present invention possess stronger actions on central nervous system (e.g. antagonistic action against hypothermia, locomotor stimulant action, signal reflex stimulant action), they are of use as a therapeutic medicament for central nervous disorders such as impaired consciousness, depression, hypomnesia, the like in association association with schizophrenia, melancholia, senile dementia, sequelae of cerebrovascular disorders, head trauma, epilepsy and spinocerebellar degeneracy.

Abstract: Amino acid derivatives of the formula ##STR1## wherein: Q is W--(CH.sub.2).sub.m --(A).sub.n --CO--B-- whereinA is oxygen atom or --NH--;B is ##STR2## or --(CH.sub.2).sub.l -- wherein X is sulfur atom or --CH.sub.2 --, and l is an integer from 1 to 3;W is ##STR3## wherein Hal is halogen atom; n is an integer of 0 or 1; andm is an integer from 0 to 3;Y is sulfur atom or --CH.sub.2 --; andR is hydrogen atom, formyl group, C.sub.1-5 alkoxycarbonyl group, --C.tbd.N or ##STR4## wherein R.sup.1 is hydrogen atom, andR.sup.2 is hydroxyl group, C.sub.1-5 alkylcarboxy group, phenylcarboxy group, C.sub.1-5 alkoxy group or phenyl C.sub.1-5 alkoxy group;with the proviso that when R is hydrogen atom, formyl group or C.sub.1-5 alkoxycarbonyl group, W is ##STR5## The compounds mentioned above specifically inhibit prolyl endopeptidase activity and are useful as agents for the treatment and prevention of dementia and amnesia.

Abstract: Benzolactam compounds of the general formula ##STR1## or isomers thereof as well as salts thereof inclusive of hydrates and/or solvates forms thereof, and benzolactam compounds of the general formula ##STR2## wherein each of the symbols is as defined in the specification. The compound (I) exhibit antiamnesic activity, and are useful as brain function-improving drugs. The compounds (a) and (b) are useful as an intermediate for said compounds (I). Futher, the compound (a) show diuretic or antiulcer activity, and are useful as a diuretic or antiulcer agent.

Abstract: A hydrouracil compound of the formula: ##STR1## or a pharmaceutically acceptable acid addition salt thereof, wherein A represents --CH.dbd.CH--CH.sub.2 -- or --CH.sub.2 CH.sub.2 --, and R represents hydrogen or methyl. Such compounds are useful as analgesics.