Structure-Activity Relationship Studies on a Novel Family of Specific HIV-1 Reverse Transcriptase Inhibitors

Structure−Activity Relationships of [2‘,5‘-Bis-O-(tert-butyldimethylsilyl)-β-d-ribofuranosyl]- 3‘-spiro-5‘ ‘-(4‘ ‘-amino-1‘ ‘,2‘ ‘-oxathiole-2‘ ‘,2‘ ‘-dioxide)thymine Derivatives as Inhibitors of HIV-1 Reverse Transcriptase Dimerization

The polymerase activity of HIV-1 reverse transcriptase (RT) is entirely dependent on the heterodimeric structure of the enzyme. Accordingly, RT dimerization represents a target for the development of a new therapeutic class of HIV inhibitors. We previously demonstrated that the N-3-ethyl derivative of 2',5'-bis-O-(tert-butyldimethylsilyl)-beta-D-ribofuranosyl]-3'-spiro-5' '-(4' '-amino-1' ',2' '-oxathiole-2' ',2' '-dioxide)thymine (TSAO-T) destabilizes the inter-subunit interactions of HIV-1 RT [Sluis-Cremer, N.; Dmietrinko, G. I.; Balzarini, J.; Camarasa, M.-J.; Parniak, M. A. Biochemistry 2000, 39, 1427-1433]. In the current study, we evaluated the ability of 64 TSAO-T derivatives to inhibit RT dimerization using a novel screening assay. Five derivatives were identified with improved activity compared to TSAO-T. Four of these harbored hydrophilic or aromatic substituents at the N3 position. Furthermore, a good correlation between the ability of the TSAO-T derivatives to inhibit RT dimerization and the enzyme's polymerase activity was also observed. This study provides an important framework for the rational design of more potent inhibitors of RT dimerization.

Novel [2‘,5‘-Bis-O-(tert-butyldimethylsilyl)-β-d-ribofuranosyl]- 3‘-spiro-5‘ ‘-(4‘ ‘-amino-1‘ ‘,2‘ ‘-oxathiole-2‘ ‘,2‘ ‘-dioxide) Derivatives with Anti-HIV-1 and Anti-Human-Cytomegalovirus Activity

New [2',5'-bis-O-(tert-butyldimethylsilyl)-beta-d-ribofuranosyl]-3'-spiro-5' '-(4''-amino-1'',2''-oxathiole-2'',2''-dioxide) (TSAO) derivatives substituted at the 4' '-amino group of the spiro moiety with different carbonyl functionalities have been designed and synthesized. Various synthetic procedures, on the scarcely studied reactivity of the 3'-spiroaminooxathioledioxide moiety, have been explored. The compounds were evaluated for their inhibitory effect on both wild-type and TSAO-resistant HIV-1 strains, in cell culture. The presence of a methyl ester (10) or amide groups (12) at the 4''-position conferred the highest anti-HIV-1 activity, while the free oxalyl acid derivative (11) was 10- to 20-fold less active against the virus. In contrast, the presence at this position of (un)substituted ureido or acyl groups markedly diminished or annihilated the anti-HIV-1 activity. Surprisingly, some of the target compounds also showed inhibition of human cytomegalovirus (HCMV) replication at subtoxic concentrations. This has never been observed previously for TSAO derivatives. In particular, compound 26 represents the first TSAO derivative with dual anti-HIV-1 and -HCMV activity.