Quantitative structure-activity relationship studies on cyclic cyanoguanidines acting as HIV-1 protease inhibitors

A quantitative structure-activity relationship study has been performed on some cyclic cyanoguanidines that inhibit the enzyme HIV-1 protease (HIV-1-PR) and exhibit antiviral potency, and the results have been compared with those of cyclic urea derivatives. Both the enzyme inhibition activity and antiviral potency in cyclic cyanoguanidines as well as in cyclic urea derivatives are found to be primarily governed by hydrophobic property of substituents attached to nitrogen (P2/P2') and further enhanced by OH or NH2 group, if any, present in the substituents. However, aromatic substituents are found to be unfavourable to both the activities of cyclic cyanoguanidines but not to any activity of cyclic urea derivatives. Cyclic urea derivatives are indicated to be more potent than cyclic cyanoguanidines. A model for the interaction of cyclic cyanoguanidines with the receptor is proposed.