thiourea and Acquired-Immunodeficiency-Syndrome

Non-nucleoside inhibitors of HIV-1 reverse transcriptase (NNRTI) are an integral part of combination therapy comprising three classes of antiretroviral drugs for the management of HIV/AIDS. NNRTIs are chemically diverse compounds that bind to a common allosteric site of HIV-1 RT and noncompetitively inhibit DNA polymerization. Resistance to NNRTIs arises rapidly upon drug treatment and results from mutation of the amino acids lining the HIV-1 RT binding pocket. Nevertheless, rationally designed NNRTIs deduced from changes in binding pocket size, shape, and residue character that result from clinically observed NNRTI resistance mutations exhibit broad-spectrum anti-HIV-1 activity. Notably, membrane permeable tight binding NNRTIs have utility as topical microbicides since they are capable of blocking cell-free and cell-associated mucosal HIV-1 infection without metabolic activation. This review summarizes the discovery of highly potent tight binding phenethyl-thiazolyl-thiourea (PETT) derivatives targeting the NNI binding pocket of HIV-1 RT. These NNRTIs were rationally designed by molecular docking using a composite binding pocket constructed by superimposing the crystal structure coordinate data of several NNI/RT ligand-binding site complexes. Molecular modeling and score functions such as molecular surface area, the buried surface, and binding affinity values were used to analyze how drug-resistant mutations would change the RT binding pocket shape, volume, and chemical make-up of these NNRTIs, and how these changes could affect drug binding. Several ligand derivatization sites were identified for docked compounds that fit the binding pocket. The best fit was determined by calculating an inhibition constant (Ludi Ki) of the docked compound for the composite binding pocket. Compounds with a Ludi Ki of <1 microM were identified as the most promising tight binding NNRTIs. This review highlights novel lipophilic thiourea NNRTIs that display high binding affinity and selective indices with robust anti-HIV-1 activity against the wild type as well as drug-resistant isolates carrying multiple RT gene mutations. The increasing prevalence of drug-escape mutants among recent HIV seroconverters makes the discovery of these broad-spectrum thiourea NNRTIs useful as a component of topical microbicide for the prevention of mucosal HIV transmission.

Topics: Acquired Immunodeficiency Syndrome; Animals; Anti-HIV Agents; Binding Sites; Drug Design; Drug Resistance, Viral; HIV Reverse Transcriptase; Humans; Models, Molecular; Reverse Transcriptase Inhibitors; Thiourea

Sexually active women represent the fastest growing HIV/AIDS (human immunodeficiency virus/acquired immunodeficiency syndrome) risk group. In an effort to develop a vaginal microbicidal contraceptive potentially capable of preventing HIV transmission as well as providing fertility control, we have synthesized novel non-nucleoside inhibitors (NNIs) of HIV-1 reverse transcriptase (RT) and examined them for dual-function anti-HIV and spermicidal activity. Structure-based drug design by use of a computer docking procedure for the NNI binding pocket generated from nine RT-NNI crystal structures led to the synthesis of three novel NNIs: N-[2-(2, 5-dimethoxyphenethyl)]-N'-[2-(5-bromopyridyl)]-thiourea (D-PBT); N-[2-(2-fluorophenethyl)]-N'-[2-(5-bromopyridyl)]-thiourea (F-PBT); and 5-isopropyl-2-[(methylthiomethyl)thio]-6-(benzyl)-pyrimidin-4-(1H)-on e (S-DABO). The anti-HIV activity of these NNIs was compared with that of trovirdine and virucidal/spermicide, nonoxynol-9 (N-9), by measuring viral RT activity and p24 antigen production as markers of viral replication using HTLVIIIB-infected human peripheral blood mononuclear cells (PBMCs). The effects on sperm motion kinematics and sperm membrane integrity were examined by computer-assisted sperm analysis and by confocal laser scanning microscopy (CLSM), respectively. The growth-inhibitory effects of NNI versus N-9 against normal human ectocervical and endocervical epithelial cells were tested using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay. All three NNIs were potent inhibitors of purified recombinant HIV RT and abrogated HIV replication in PBMCs at nanomolar concentrations (IC50 < 1 nM) when compared with N-9 or trovirdine (IC50 values of 2.2 microM and 0.007 microM, respectively). Two NNIs, F-PBT and S-DABO, also exhibited concentration- and time-dependent spermicidal activity. The drug concentration required to inhibit sperm motility by 50% (EC50 values) for the lead compound F-PBT versus N-9 was 147 microM and 81 microM, respectively. Sperm-immobilizing activity induced by F-PBT and S-DABO was rapid (t1/2 = 7-13 min) and irreversible. Unlike that of N-9, spermicidal activity of F-PBT and S-DABO was not accompanied by loss of acrosomal membrane as detected by fluorescent-lectin binding assay and CLSM. Whereas N-9 was cytotoxic to normal human ectocervical and endocervical cells at spermicidal doses, both F-PBT and S-DABO were selectively spermicidal. We conclude that as pote

Topics: Acquired Immunodeficiency Syndrome; Anti-HIV Agents; Cell Membrane; Computers; Detergents; Drug Design; Female; HIV-1; Humans; Male; Microscopy, Confocal; Pyridines; Pyrimidinones; Reverse Transcriptase Inhibitors; Sexually Transmitted Diseases; Sperm Motility; Spermatocidal Agents; Spermatozoa; Sulfides; Thiourea; Virus Replication