Effect of stereochemistry on the anti-HIV activity of chiral thiourea compounds
Chiral derivatives of several substituted halopyridyl and thiazolyl PETT compounds were synthesized as non-nucleoside inhibitors of the reverse transcriptase (RT) enzyme (NNRTI) of the human immunodeficiency virus (HIV-1). Molecular modeling studies indic
Effect of stereo and regiochemistry towards wild and multidrug resistant HIV-1 virus: Viral potency of chiral PETT derivatives
Chiral derivatives of several substituted halopyridyl and thiazolyl PETT compounds were synthesized as non-nucleoside inhibitors of the reverse transcriptase (RT) enzyme of the human immunodeficiency virus (HIV-1). Molecular modeling studies indicated that because of the asymmetric geometry of the non-nucleoside inhibitors (NNRTI) binding pocket, the 'R' stereoisomers would fit the NNRTI binding pocket of the HIV-1 RT much better than the corresponding 'S' stereoisomers, as reflected by their 104-fold lower Ki values. The 'R' stereoisomers of several PETT derivatives inhibited the recombinant RT in vitro with lower IC50 values than their enantiomers. The active compounds were further evaluated for their ability to inhibit HIV-1 replication in human peripheral blood mononuclear cells (PBMCs). All the 'R' isomers again showed potent anti-HIV activity and inhibited the replication of the HIV-1 strains HTLVIIIB in PBMCs at nanomolar concentrations whereas their enantiomers were less potent. The lead compounds for the respective groups were further tested against A17 (NNRTI-resistant, Y181C mutant RT), and A17Var (NNI-resistant Y181C±K103N mutant RT) as well as multidrug resistant viral strains. The results indicated that the lead compounds were several logs more potent than the standard NNRTI drug nevirapine. Structure-activity relationship among the derivatives showed preference of pyridyl unit with halo substitutions primarily at 5-position demonstrating the importance of both the stereochemistry as well as regiochemistry. Our data provides experimental evidence that the stereochemistry and the regiochemistry of non-nucleoside inhibitors can profoundly affect their anti-HIV activity.
Venkatachalam, Taracad K.,Mao, Chen,Uckun, Fatih M.
Phenethylthiazolethiourea (PETT) compounds, a new class of HIV-1 reverse transcriptase inhibitors. 1. Synthesis and basic structure-activity relationship studies of PETT analogs
A novel series of potent specific HIV-1 inhibitory compounds is described. The lead compound in the series, N-(2-phenethyl)-N'-(2-thiazolyl)thiourea (1), inhibits HIV-1 RT using rCdG as the template with an IC50 of 0.9 μM. In MT-4 cells, compound 1 inhibits HIV-1 with an ED50 of 1.3 μM. The 50% cytotoxic dose in cell culture is >380 μM. The chemical structure-activity relationship (SAR) was developed by notionally dividing the lead compound in four quadrants. The SAR strategy had two phases. The first phase involved optimization of antiviral activity through independent variation of quadrants 1-4. The second phase involved the preparation of hybrid structures combining the best of these substituents. Further SAR studies and pharmacokinetic considerations led to the identification of N-(2-pyridyl)-N'-(5-bromo-2- pyridyl)-thiourea (62; LY300046 · HCl) as a candidate for clinical evaluation. LY300046 · HCl inhibits HIV-1 RT with an IC50 of 15 nM and in cell culture has an ED50 of 20 nM.