[Synthesis and analysis of cyclic analogs of angiotensin]. / Sintez i issledovanie tsiklicheskikh analogov angiotenzina.

Five angiotensin cycloanalogues have been synthesised by classical methods of peptide chemistry, cyclisation being carried out via pentafluorophenyl esters. Cycloanalogues (I-IV) with a fixed potential turn in the C-terminal part of the angiotensin molecule inferred on the basis of physico-chemical data do not possess angiotensin-like activity. Compounds (V) with enlarged cycle shows decreased pressor effects as compared with angiotensin. By means of circular dichroism chiroptical properties of the compounds in water and ethanol were examined.

[Synthesis and biological activity of cyclic analogs of angiotensin]. / Sintez i biologicheskaia aktivnost' tsiklicheskikh analogov angiotenzina.

Biological properties of five novel angiotensin analogues synthesized, using the conventional methods of peptide chemistry, have been studied. Cyclization was attained by means of amide linkage with the aid of diphenylphosphorylazide or pentafluorophenyl esters. Unlike the natural hormone, the cyclic analogues of angiotensin show no pressor activity, but elicit a depressor effect untypical of angiotensin. A slight pressor activity was exhibited by the compound containing aspartic acid in position 1. The cyclic analogues in question release histamine from peritoneal mast cells in rats.

[Cyclic analogs of angiotensin with depressor and histamine-liberating activity]. / Tsiklicheskie analogi angiotenzina s depressornoi i gistaminvysvobozhdaiushchei aktivnost'iu.

The synthesis and biological properties of 10 angiotensin cyclic analogues are described. These compounds exhibit prolong depressor effects and act as potent histamine-releasing agents.