Maria-Cruz Bonache

Novel N-3 substituted TSAO-T derivatives: synthesis and anti-HIV-evaluation.

Novel derivatives of the anti-HIV-1 agent, TSAO-T, bearing at the N-3 position alkylating groups or photoaffinity labels were prepared and evaluated for their anti-HIV activity. All of these compounds demonstrated pronounced anti-HIV-1 activity and inhibited HIV-1 RT; however, we were unable to detect stable covalent linkages between inhibitor and enzyme. In addition, compounds with an alcohol functional group connected to the N-3 position through a cis or trans double bond have been prepared. These compounds have been useful to study how the conformational restriction of the linker affects in the interaction between the N-3 substituent and the HIV-1 RT enzyme.

One-pot synthesis of polycyclic nucleosides with unusual molecular skeletons.

An alpha hydroxy pyrrolidine tricyclic nucleoside 3 and its spontaneous reaction with acetone is described. In this transformation highly functionalized polycyclic nucleosides with rather unusual molecular skeletons are formed in a complete regio- and stereoselective way. The reaction involves the formation of three new bonds, two of them novel carbon-carbon bonds, in a one-pot way. An enamine-iminium mechanism with participation of carbinolamine, iminium ion, and enamine intermediates is proposed as a plausible explanation for this transformation. The scope of the reaction is briefly studied concluding that the nature of the ketone (R(1)COR(2)) is critical for the initial attack of the NH to the carbonyl group.

N-3 Substituted TSAO Derivatives as a Probe to Explore the Dimeric Interface of HIV-1 Reverse Transcriptase

Reverse transcriptases (RTs) from both human immunodeficiency viruses type 1 (HIV-1) and 2 (HIV-2) are obligatory dimers and only dimeric forms of this enzyme are actives. It has been suggested that the dimerization of RT might be a good target for therapeutic intervention in AIDS. TSAO-T bearing at N-3 an ethyl moiety (TSAO-eT) belongs to a unique family of HIV-1-specific non-nucleoside RT inhibitors (NNRTIs). It is the only small molecule that has been shown to interfere with the HIV-1 RT dimerization process by destabilizing the p66=p51 and p66=p66 dimeric forms of HIV-1 RT. Recently, we have reported a model of interaction of TSAO derivatives with the HIV-1 RT. In this model, TSAO straddles between the subunits at the p66=p51 interface. The N3 substituents of the thymine base of the TSAO compounds are positioned parallel to the subunit interface.

Structure-activity relationship studies on a novel family of specific HIV-1 reverse transcriptase inhibitors.

We have previously reported the discovery and preliminary structure-activity relationships of a new class of specific HIV-1 reverse transcriptase (RT) inhibitors whose prototype compound is the 1-[2′,5′-bis-O-(tert-butyldimethylsilyl)-β-D-ribofuranosyl]-3-N-[(carboxy) methyl]-thymine. In an attempt to increase the inhibitory efficacy against HIV-1 RT of this new class of nucleosides, and to further explore the structural features required for anti-HIV-1 activity, different types of modifications have been carried out on the prototype compound. These include substitution of the tert-butyldimethylsilyl groups by other liphophilic groups, replacement of the carboxy group at the N-3 position of the nucleobase by other functional groups, change in the length of the spacer between the thymine and the carboxylic acid residue and substitution of the thymine moiety by other pyrimidine (uracil, 5-ethyluracil) or purine (hypoxanthine) nucleobases. In addition, the most salient structural features of this new class of HIV-1-specific nucleosides have been incorporated into classical HIV RT nucleoside inhibitors such as ddI, AZT, d4T. Our studies demonstrate that both the carboxymethyl moiety at the nucleobase and tert-butyldimethylsilyl groups at the sugar are important structural components since deletion of either of them is detrimental to the antiviral activity.

Identification of a novel family of nucleosides that specifically inhibit HIV-1 reverse transcriptase

N-3-Benzyloxycarbonylmethyl- and N-3-carboxymethyl-TBDMS-substituted nucleosides were synthesized and evaluated for activity against HIV replication. It was found that the N-3-carboxymethyl-TBDMS-substituted nucleosides were specific inhibitors of HIV-1 replication. They should be considered as members of a novel and original class of NNRTIs.