Abstract: Prostaglandin E.sub.1 analogues of general formula: ##STR1## [wherein R.sup.1 represents a bond or a straight- or branched-chain alkylene group containing from 1 to 5 carbon atom(s), and R.sup.2 represents a hydrogen atom, a straight- or branched-chain alkyl group containing from 1 to 8 carbon atom(s), a cycloalkyl group containing from 4 to 7 carbon atoms in the ring and unsubstituted or substituted by at least one stright- or branched-chain alkyl group containing from 1 to 8 carbon atom(s) or a phenyl or phenoxy group unsubstituted or substituted by at least one halogen atoms, trifluoromethyl group or straight- or branched-chain alkyl group containing from 1 to 4 carbon atom(s), with the proviso that, when R.sup.1 represents a bond, R.sup.2 does not represent a phenoxy group,] possess inhibitory activity or gastric ulceration and cytoprotective activity.

Abstract: Prostaglandin analogues of the formula: ##STR1## (wherein R.sup.1 represents an alkyl group containing from 1 to 4 carbon atoms, R.sup.2 represents a single bond or an alkylene group containing from 1 to 5 carbon atoms, R.sup.3 represents a hydrogen atom, an alkyl or alkoxy group containing from 1 to 8 carbon atoms, a cycloalkyl or cycloalkyloxy group containing from 4 to 7 carbon atoms and being unsubstituted or substituted by at least one alkyl group containing from 1 to 8 carbon atoms, or a phenyl or phenoxy group unsubstituted or substituted by at least one halogen atom, trifluoromethyl group or alkyl group containing from 1 to 4 carbon atoms, R.sup.

Abstract: 15-Cycloalkyl-prostaglandins of the formula:- ##STR1## wherein A represents a grouping of the formula:- ##STR2## X represents ethylene of cis-vinylene, Y represents ethylene or trans-vinylene, B represents ethylene or trans-vinylene, R represents hydrogen or alkyl of 1 through 4 carbon atoms, R.sup.1 represents cycloalkyl of 4 through 7 carbon atoms, and R.sup.2 represents hydrogen or alkyl of 1 through 12 carbon atoms, are new compounds possessing the useful pharmacological properties typical of prostaglandins; they are of especial interest in the inhibition of blood platelet aggregation.