Abstract: A novel prolinal derivative of general formula: ##STR1## [whereinA represents a group of the general formula: ##STR2## (wherein one of R.sup.1 and R.sup.2 represents hydrogen atom and the other represents alkyl group of from 2 to 5 carbon atoms, alkoxy group of from 1 to 5 carbon atom(s), phenyl group, benzyl group, cycloalkyl group of from 4 to 6 carbon atoms or (cycloalkyl group of from 4 to 6 carbon atoms) - methyl group or R.sup.1 and R.sup.2 each represents, same or different, alkyl group of from 1 to 4 carbon atom(s).)or a group of the general formula: ##STR3## (wherein m represents an integer of from 3 to 6.) n represents an integer of from 3 to 10.D represents carbocyclic or heterocyclic ring unsubstituted or substituted by from one to three of halogen atom, nitro group, trifluoromethyl group, alkyl or akloxy group of from 1 to 4 carbon atom(s).]possess inhibitory activity on prolyl endopeptidase, and therefore be useful for treating and/or preventing agent for amnesia.

Abstract: A novel prolinal derivative of general formula: ##STR1## wherein A represents alkylene group of from 1 to 4 carbon atom(s) or saturated hydrocarbon ring of from 3 to 7 carbon atoms, n represents a number 2, 3 or 4, D represents carbocyclic or heterocyclic ring unsubstituted or substituted by from one to three of halogen atom, alkyl or alkoxy group of from 1 to 4 carbon atom(s), nitro group or trifluromethyl group posses inhibitory activity on prolyl endopeptidase, and therefore are useful for treating and/or preventing agent for amnesia.

Abstract: Novel prolinal derivatives of the general formula: ##STR1## wherein A represents alkylene group of from 1 to 8 carbon atoms or alkenylene group of from 2 to 8 carbon atom(s) or a saturated hydrocarbon ring of from 3 to 7 carbon atoms, R represents hydrogen atom, phenyl group, benzyl group, alkyl group of from 1 to 8 carbon atom(s) or cycloalkyl group of from 3 to 7 carbon atoms,B represents alkylene group of from 1 to 8 atom(s) unsubstituted or substituted by phenyl group or benzyl group, or a single bond,D represents carbocyclic or heterocyclic ring unsubstituted or substituted by from one to three of halogen atom, alkyl or alkoxy group of from 1 to 4 carbon atom(s), nitro group or trifluoromethyl groupwhich prolinal derivatives possess inhibitory activity on prolyl endopeptidase, and therefore are useful as a treating or preventing agent for amnesia.

Abstract: A novel thiazolidine derivative of general formula: ##STR1## [wherein R represents a group of general formula:G-E-D-B-A-(wherein A represents single bond, alkylene group of from 1 to 6 carbon atom(s), alkylene group of from 2 to 6 carbon atoms, a group of general formula: ##STR2## or saturated hydrocarbon ring of from 4 to 7 carbon atoms or single heterocyclic ring.Y represents alkylene group of from 1 to 4 carbon atom(s) or alkenylene group of from 2 to 4 carbon atoms.B represents single bond or alkylene group of from 1 to 6 carbon atom(s).D represents single bond, oxygen atom, carbonyl group or a group of general formula: ##STR3## R.sup.1 represents hydrogen atom, alkyl group of from 1 to 4 carbon atom(s), phenyl group or benzyl group.E represents single bond, alkylene group of from 1 to 8 carbon atom(s) or alkylene group of from 1 to 8 carbon atom(s) substituted by phenyl group or benzyl group.

Abstract: Prostaglandin I.sub.2 analogues of the formula: ##STR1## [wherein X represents trans-vinylene or an ethylene group unsubstituted or substituted by a bromine atom at the C-5 position, Y represents trans-vinylene or ethylene, R.sup.1 represents hydrogen or an alkyl group containing from 1 to 12 carbon atoms, R.sup.2 represents hydrogen or methyl or ethyl, R.sup.3 represents a single bond or an alkylene group containing from 1 to 4 carbon atoms, R.sup.4 represents hydrogen, an alkyl group containing from 1 to 8 carbon atoms, a cycloalkyl group containing from 4 to 7 carbon atoms unsubstituted or substituted by at least one alkyl group containing from 1 to 8 carbon atoms, or a phenyl or phenoxy group unsubstituted or carrying at least one substituent selected from halogen atoms, the trifluoromethyl group and alkyl groups containing from 1 to 3 carbon atoms, and the wavy line attached to the carbon atoms in positions 6, 11 and 15 depicted in the formula represents .alpha.- or .beta.

Abstract: Prostaglandin I.sub.2 analogues of the formula: ##STR1## [wherein R.sup.1 represents hydrogen, alkyl of 1 to 12 carbon atoms, aralkyl of 7 to 12 carbon atoms, cycloalkyl of 4 to 7 carbon atoms optionally substituted by alkyl of 1 to 4 carbon atoms, phenyl optionally substituted by chlorine, trifluoromethyl, alkyl of 1 to 4 carbon atoms or phenyl, or represents a group --C.sub.p H.sub.2p COOR.sup.5, --C.sub.q H.sub.2q OR.sup.6 or ##STR2## (wherein R.sup.5, R.sup.7 and R.sup.8 represent alkyl of 1 to 4 carbon atoms, R.sup.6 represents hydrogen or alkyl of 1 to 4 carbon atoms, p represents an integer of from 1 to 12, and q represents an integer of from 2 to 12), R.sup.2, R.sup.3 and R.sup.

Abstract: Prostaglandin I.sub.2 analogues of the formula: ##STR1## [wherein Y represents ethylene or trans-vinylene, R.sup.1 represents hydrogen, alkyl of 1 to 12 carbon atoms, aralkyl of 7 to 12 carbon atoms, cycloalkyl of 4 to 7 carbon atoms optionally substituted by at least one alkyl group containing from 1 to 4 carbon atoms, phenyl unsubstituted or substituted by at least one chlorine atom, trifluoromethyl group, alkyl group containing from 1 to 4 carbon atoms or phenyl group, a --C.sub.m H.sub.2m COOR.sup.4 group (wherein m is an integer from 1 to 12 and R.sup.4 represents alkyl of 1 to 4 carbon atoms), a C.sub.n H.sub.2n OR.sup.5 group (wherein n is an integer from 2 to 12 and R.sup.5 represents hydrogen or alkyl of 1 to 4 carbon atoms), or a ##STR2## (wherein n is as hereinbefore defined and R.sup.6 and R.sup.7 each represent alkyl of 1 to 4 carbon atoms), R.sup.2 represents hydrogen, methyl or ethyl, X represents a --C.sub.p H.sub.2p --group (wherein p is an integer from 2 to 8) or a ##STR3## (wherein R.sup.

Abstract: Prostaglandin analogues of the general formula: ##STR1## [wherein Y represents ethylene or trans-vinylene, R.sup.1 represents a group --C.sub.m H.sub.2m COOR.sup.5, --C.sub.n H.sub.2n OR.sup.6 or ##STR2## (wherein R.sup.5 represents an alkyl group containing from 1 to 4 carbon atoms, R.sup.6 represents a hydrogen atom or an alkyl group containing from 1 to 4 carbon atoms, R.sup.7 and R.sup.8, which may be the same or different, each represents an alkyl group containing from 1 to 4 carbon atoms, m represents an integer of from 1 to 12 and n represents an integer of from 2 to 12), R.sup.2 represents a hydrogen atom or a methyl or ethyl group, R.sup.3 represents a single bond, or an alkylene group containing from 1 to 4 carbon atoms, R.sup.

Abstract: Prostaglandin I.sub.2 analogues of the formula: ##STR1## (wherein Y represents trans-vinylene or ethylene, R.sup.1 represents hydrogen or an alkyl group containing from 1 to 12 carbon atoms, R.sup.2 represents hydrogen, methyl or ethyl, R.sup.3 represents a single bond, or an alkylene group containing from 1 to 4 carbon atoms, R.sup.4, R.sup.5 and R.sup.6, which may be the same or different, each represent hydrogen or an alkyl group containing from 1 to 8 carbon atoms, n represents 3, 4, 5 or 6, the wavy line attached to the carbon atoms in positions 11 and 15 depicted in the formula represents .alpha.- or .beta.-configuration or mixtures thereof, and the double bond between C.sub.6 -C.sub.6 is Z or E) are new compounds possessing pharmacological properties typical of prostaglandins, for example PGI.sub.2.