Structure--activity relationship studies of 1-(4-chloro-2,5-dimethoxyphenyl)-3-(3-propoxypropyl)thiourea, a non-nucleoside reverse transcriptase inhibitor of human immunodeficiency virus type-1.

The reverse transcriptase (RT) of the human immunodeficiency virus type-1 (HIV-1) is still a prime target for drug development due to the continuing need to block drug-resistant RT mutants by new inhibitors. We have previously identified 1-(4-chloro-2,5-dimethoxyphenyl)-3-(3-propoxypropyl)thiourea, compound 1, as a potent RT inhibitor from an available chemical library. Here, we further modified this compound to study structure--activity relationships when replacing various groups in the molecule. Different functional groups were systematically introduced on the aromatic ring and the aliphatic chain of the compound was modified. The effect of these modifications on viral infectivity was then evaluated. The most potent compound found was propyl 4-(amino-N-(4-chloro-2,5-dimethoxyphenyl)methanethioamino)butanoate, 45c, which inhibited infectivity with a calculated IC50 of about 1.1 μM. Docking studies identified potential important interactions between the top scoring ligands and HIV-1 RT, and the predicted relative affinity of the ligands was found to be in agreement with the experimental results.