Synthesis, anti-HIV-1 activity, and modeling studies of N-3 Boc TSAO compound

[d4U]-spacer-[HI-236] double-drug inhibitors of HIV-1 reverse-transcriptase

Four double-drug HIV NRTI/NNRTI inhibitors 15a-d of the type [d4U]-spacer-[HI-236] in which the spacer is varied as 1-butynyl (15a), propargyl-1-PEG (15b), propargyl-2-PEG (15c) and propargyl-4-PEG (15d) have been synthesized and biologically evaluated as RT inhibitors against HIV-1. The key step in their synthesis involved a Sonogashira coupling of 5-iodo d4U's benzoate with an alkynylated tethered HI-236 precursor followed by introduction of the HI-236 thiourea functionality. Biological evaluation in both cell-culture (MT-2 cells) as well as using an in vitro RT assay revealed 15a-c to be all more active than d4T. However, overall the results indicate the derivatives are acting as chain-extended NNRTIs in which for 15b-d the nucleoside component is likely situated outside of the pocket but with no evidence for any synergistic double binding between the NRTI and NNRTI sites. This is attributed, in part, to the lack of phosphorylation of the nucleoside component of the double-drug as a result of kinase recognition failure, which is not improved upon with the phosphoramidate of 15d incorporating a 4-PEG spacer.

Specific targeting of highly conserved residues in the HIV-1 reverse transcriptase primer grip region. 2. Stereoselective interaction to overcome the effects of drug resistant mutations

Starting from the prototypic compound 4, we describe new, potent, and broad-spectrum pyrrolobenzo(pyrido)oxazepinones antivirals. A biochemical and enzymological investigation was performed for defining their mechanism of inhibition at either recombinant HIV-1 RT wild type and non-nucleoside reverse transcriptase inhibitors (NNRTIs)-resistant mutants. For the novel compounds (S)-(+)-5 and (S)-(-)-7, a clear-cut stereoselective mechanism of enzyme inhibition was found. Molecular modeling studies were performed for revealing the underpinnings of this behavior.