scholarly journals Reverse Transcriptase Inhibitors as Potential Colorectal Microbicides

2009 ◽  
Vol 53 (5) ◽  
pp. 1797-1807 ◽  
Author(s):  
Carolina Herrera ◽  
Martin Cranage ◽  
Ian McGowan ◽  
Peter Anton ◽  
Robin J. Shattock
Keyword(s):  
Reverse Transcriptase ◽  
Rational Design ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Single Point ◽  
Point Mutations ◽  
Peripheral Blood Mononuclear ◽  
Rectal Microbicides ◽  
The Individual ◽  
Hiv 1

ABSTRACT We investigated whether reverse transcriptase (RT) inhibitors (RTI) can be combined to inhibit human immunodeficiency virus type 1 (HIV-1) infection of colorectal tissue ex vivo as part of a strategy to develop an effective rectal microbicide. The nucleotide RTI (NRTI) PMPA (tenofovir) and two nonnucleoside RTI (NNRTI), UC-781 and TMC120 (dapivirine), were evaluated. Each compound inhibited the replication of the HIV isolates tested in TZM-bl cells, peripheral blood mononuclear cells, and colorectal explants. Dual combinations of the three compounds, either NRTI-NNRTI or NNRTI-NNRTI combinations, were more active than any of the individual compounds in both cellular and tissue models. Combinations were key to inhibiting infection by NRTI- and NNRTI-resistant isolates in all models tested. Moreover, we found that the replication capacities of HIV-1 isolates in colorectal explants were affected by single point mutations in RT that confer resistance to RTI. These data demonstrate that colorectal explants can be used to screen compounds for potential efficacy as part of a combination microbicide and to determine the mucosal fitness of RTI-resistant isolates. These findings may have important implications for the rational design of effective rectal microbicides.

scholarly journals Interferon Induction By HbS, SERINC5 Upregulation and Reduction of HIV-1 Nef and AP2 Contribute to HIV-1 Restriction in Sickle Cell Disease

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 5-6
Author(s):  
Namita Kumari ◽  
Marina Jerebtsova ◽  
Songping Wang ◽  
Sharmin Diaz ◽  
Sergei Nekhai
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Mononuclear Cells ◽  
Conflicts Of Interest ◽  
Ex Vivo ◽  
Interferon Response ◽  
Cell Disease ◽  
Restriction Factors ◽  
Peripheral Blood Mononuclear ◽  
Hiv 1

Concerted action of numerous positively acting cellular factors is essential for Human immunodeficiency virus type 1 (HIV-1) replication but in turn is challenged by anti-viral restriction factors. Previously we showed that ex vivo one round HIV-1 replication and replication of fully competent T-tropic HIV-1(IIIB) is significantly reduced in peripheral blood mononuclear cells (PBMCs) obtained from patients with Sickle Cell Disease (SCD). Further, we identified and confirmed CDKN1A (p21) and CH25H as host restriction factors expressed in SCD PBMCs that may contribute to the HIV-1 inhibition, in addition to the previously reported SAMHD1 and IKBα. Since CH25H is an interferon stimulated gene (ISG), we analyzed IRFs and interferon expression in SCD PBMCs. Higher levels of IRF7 and IFNβ mRNA were observed in SCD PBMCs compared to controls. We probed further to ascertain if hemin or sickle Hb was responsible for interferon response. We found upregulation of IFNβ in THP-1 - derived macrophages treated with lysates of HbSS RBCs or purified HbS as compared to untreated or HbA treated controls. HbSS RBCs lysates and purified HbS inhibited HIV-1 gag mRNA expression in monocyte-derived macrophages infected with HIV-1(Ba-L). Recent clinical study showed increased levels of CD4 in HIV-1 infected SCD patients in Africa. Thus we analyzed CD4 levels in HIV-1 IIIB infected SCD PBMCs, and found them to be higher compared to controls. Levels of HIV-1 nef mRNA, that controls CD4 expression was lower in HIV-1 IIIB infected SCD PBMCs. As Nef counteracts SERINC3/5 restriction factor, we analyzed its expression as well as the expression of AP2 clathrin adaptor that is required for Nef mediated internalization of CD4. AP2 expression was lower and SERINC5 expression was higher in SCD PBMCs. CONCLUSIONS: SCD PBMCs could resist HIV-1 infection because of the increased IFNβ production by macrophages exposed to HbSS or sickle cell RBCs. SCD PBMC have increased levels of SERNIC5 and lower levels of HIV-1 Nef and host AP2 expression that, culumlatively, can increased CD4 levels and lead to the overall improved immunological health of SCD patients. ACKNOWLEDGMENTS: This work was supported by NIH Research Grants (1P50HL118006, 1R01HL125005, 1SC1HL150685, 5U54MD007597, 1UM1AI26617 and P30AI087714). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Disclosures No relevant conflicts of interest to declare.

scholarly journals F18, a Novel Small-Molecule Nonnucleoside Reverse Transcriptase Inhibitor, Inhibits HIV-1 Replication Using Distinct Binding Motifs as Demonstrated by Resistance Selection and Docking Analysis

2011 ◽  
Vol 56 (1) ◽  
pp. 341-351 ◽  
Author(s):  
Xiaofan Lu ◽  
Li Liu ◽  
Xu Zhang ◽  
Terrence Chi Kong Lau ◽  
Stephen Kwok Wing Tsui ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Small Molecule ◽  
Mononuclear Cells ◽  
Binding Motif ◽  
Drug Resistant ◽  
Peripheral Blood Mononuclear ◽  
Docking Analysis ◽  
Hiv 1 ◽  
Calanolide A

ABSTRACTNonnucleoside reverse transcriptase inhibitors (NNRTIs) are one of the key components of antiretroviral therapy drug regimen against human immunodeficiency virus type 1 (HIV-1) replication. We previously described a newly synthesized small molecule, 10-chloromethyl-11-demethyl-12-oxo-calanolide A (F18), a (+)-calanolide A analog, as a novel anti-HIV-1 NNRTI (H. Xue et al., J. Med. Chem. 53:1397–1401, 2010). Here, we further investigated its antiviral range, drug resistance profile, and underlying mechanism of action. F18 consistently displayed potent activity against primary HIV-1 isolates, including various subtypes of group M, circulating recombinant form (CRF) 01_AE, and laboratory-adapted drug-resistant viruses. Moreover, F18 displayed distinct profiles against 17 NNRTI-resistant pseudoviruses, with an excellent potency especially against one of the most prevalent strains with the Y181C mutation (50% effective concentration, 1.0 nM), which was in stark contrast to the extensively used NNRTIs nevirapine and efavirenz. Moreover, we induced F18-resistant viruses byin vitroserial passages and found that the mutation L100I appeared to be the dominant contributor to F18 resistance, further suggesting a binding motif different from that of nevirapine and efavirenz. F18 was nonantagonistic when used in combination with other antiretrovirals against both wild-type and drug-resistant viruses in infected peripheral blood mononuclear cells. Interestingly, F18 displayed a highly synergistic antiviral effect with nevirapine against nevirapine-resistant virus (Y181C). Furthermore,in silicodocking analysis suggested that F18 may bind to the HIV-1 reverse transcriptase differently from other NNRTIs. This study presents F18 as a new potential drug for clinical use and also presents a new mechanism-based design for future NNRTI.

scholarly journals Restriction of HIV-1 Infection in Sickle Cell Trait

2021 ◽  
Author(s):  
Namita Kumari ◽  
Seyed Mehdi Nouraie ◽  
Asrar Ahmad ◽  
Hatajai Lassiter ◽  
Javed I Khan ◽  
...  
Keyword(s):  
Sickle Cell ◽  
Mononuclear Cells ◽  
Sickle Cell Trait ◽  
Ex Vivo ◽  
Heme Oxygenase 1 ◽  
Mrna Levels ◽  
Peripheral Blood Mononuclear ◽  
Protein Levels ◽  
Living With Hiv ◽  
Hiv 1

Patients with Sickle cell disease (SCD) have lower risk for HIV-1 infection. We showed restriction of ex vivo HIV-1 infection in SCD peripheral blood mononuclear cells (PBMCs) that was due, in part, to the upregulation of antiviral, inflammatory and hemolytic factors including heme oxygenase-1 (HO-1). Here, we investigated whether individuals with sickle cell trait (SCT), who develop mild hemolysis, also restrict HIV-1 infection. Ex vivo infection of SCT PBMCs demonstrated ~2-fold reduction of HIV-1 replication and lower levels of HIV-1 reverse transcription products, 2-Long Terminal Repeats (LTR) circles, HIV-1 integration and gag RNA expression. SCT PBMCs had higher HO-1 mRNA and protein levels and reduced ribonucleotide reductase 2 (RNR2) protein levels. HO-1 inhibition by tin porphyrin eliminated ex vivo HIV-1 restriction. Among Howard University clinic recruits, higher levels of HO-1 and RNR2 mRNA and lower HIV-1 env mRNA levels were found in SCT individuals living with HIV-1. To determine the population level effect of SCT on HIV-1 prevalence, we assessed SCT trait among women living with HIV (WLH) in the Women Interagency HIV-1 Study (WIHS). Among WIHS African American participants, prevalence of SCT was lower among women with HIV compared with uninfected women (8.7% vs 14.2%; OR 0.57; 95%CI = 0.36-0.92, p=0.020). WIHS WLH with SCT had higher levels of CD4+/CD8+ ratios over 20 years of follow up (p=0.003) than matched WLH without SCT. Together, our findings suggest that HIV-1 restriction factors including HO-1 and RNR2 might restrict HIV-1 infection among individuals with SCT and limit the pathogenicity of HIV.

scholarly journals Function of ex vivo stimulated Natural killer T cells from patients with chronic HIV-1 infection

2019 ◽  
Author(s):  
Prakash Thapa ◽  
Pramod Nehete ◽  
Hong He ◽  
Bharti Nehete ◽  
Stephanie J. Buchl ◽  
...  
Keyword(s):  
Natural Killer ◽  
Peripheral Blood Mononuclear Cells ◽  
Immune Cells ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Nkt Cells ◽  
Peripheral Blood Mononuclear ◽  
Blood Mononuclear Cells ◽  
Hiv 1

AbstractNatural killer T (NKT) cells are innate immune cells that are responsible for the first line of antiviral defense, through crosstalk with downstream antigen-presenting cells, natural killer cells, and adaptive immune cells. Previous studies have indicated that NKT cell function is severely impaired in patients with chronic HIV-1 infection. It was reported that alpha-galactosylceramide, a potent agonist antigen for NKT cells, failed to trigger the expansion of NKT cells, or the production of anti-viral cytokines by NKT cells from HIV-1 infected patients in an in vitro assay, in which peripheral blood mononuclear cells (PBMCs) were cultured in the presence of alpha-galactosylceramide. In this study, we stimulated banked peripheral blood mononuclear cells from HIV-1-infected patients with dendritic cells (DC) generated ex vivo and loaded with alpha-galactosylceramide. The results showed that NKT cells were expanded in HIV infected subjects except in patients with advanced AIDS. Expanded NKT cells were capable of producing antiviral cytokines. Our results indicate that NKT cells in HIV infected individuals are potential targets for therapeutic intervention.

scholarly journals In Vitro Interactions between Apricitabine and Other Deoxycytidine Analogues

2007 ◽  
Vol 51 (8) ◽  
pp. 2948-2953 ◽  
Author(s):  
R. Bethell ◽  
J. De Muys ◽  
J. Lippens ◽  
A. Richard ◽  
B. Hamelin ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
High Performance ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Transcriptase Inhibitor ◽  
Reverse Transcriptase Activity ◽  
Peripheral Blood Mononuclear ◽  
Reverse Transcriptase Inhibitor ◽  
Hiv 1

ABSTRACT Apricitabine is a novel deoxycytidine analogue reverse transcriptase inhibitor that is under development for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Apricitabine is phosphorylated to its active triphosphate by deoxycytidine kinase, which is also responsible for the intracellular phosphorylation of lamivudine (3TC) and emtricitabine (FTC); hence, in vitro studies were performed to investigate possible interactions between apricitabine and these agents. Human peripheral blood mononuclear cells (PBMC) were incubated for 24 h with various concentrations of 3H-labeled or unlabeled apricitabine, 3TC, or FTC. Intracellular concentrations of parent compounds and their phosphorylated derivatives were measured by high-performance liquid chromatography. In other experiments, viral reverse transcriptase activity was measured in PBMC infected with HIV-1 bearing M184V in the presence of various concentrations of apricitabine and 3TC. [3H]apricitabine and [3H]3TC were metabolized intracellularly to form mono-, di-, and triphosphates. 3TC and FTC (1 to 10 μM) produced concentration-dependent decreases in apricitabine phosphorylation; in contrast, apricitabine at concentrations of up to 30 μM had no effect on the phosphorylation of 3TC or FTC. The combination of apricitabine and 3TC reduced the antiviral activity of apricitabine against HIV-1: apricitabine concentrations producing 50% inhibition of viral reverse transcriptase were increased two- to fivefold in the presence of 3TC. These findings suggest that nucleoside reverse transcriptase inhibitors with similar modes of action may show biochemical interactions that affect their antiviral efficacy. It is therefore essential that potential interactions between combinations of new and existing agents be thoroughly investigated before such combinations are introduced into clinical practice.

scholarly journals Pharmacokinetic and Pharmacodynamic Evaluation following Vaginal Application of IQB3002, a Dual-Chamber Microbicide Gel Containing the Nonnucleoside Reverse Transcriptase Inhibitor IQP-0528 in Rhesus Macaques

2015 ◽  
Vol 60 (3) ◽  
pp. 1393-1400 ◽  
Author(s):  
Lara E. Pereira ◽  
Pedro M. M. Mesquita ◽  
Anthony Ham ◽  
Tyana Singletary ◽  
Frank Deyounks ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Human Peripheral Blood ◽  
Rhesus Macaques ◽  
Transcriptase Inhibitor ◽  
Viral Inhibition ◽  
Nonnucleoside Reverse Transcriptase Inhibitor ◽  
Reverse Transcriptase Inhibitor ◽  
Hiv 1

We evaluated thein vivopharmacokinetics and used a complementaryex vivococulture assay to determine the pharmacodynamics of IQB3002 gel containing 1% IQP-0528, a nonnucleoside reverse transcriptase inhibitor (NNRTI), in rhesus macaques (RM). The gel (1.5 ml) was applied vaginally to 6 simian-human immunodeficiency (SHIV)-positive female RM. Blood, vaginal fluids, and rectal fluids were collected at 0, 1, 2, and 4 h. RM were euthanized at 4 h, and vaginal, cervical, rectal, and regional lymph node tissues were harvested. Anti-human immunodeficiency virus (HIV) activity was evaluatedex vivoby coculturing fresh or frozen vaginal tissues with activated human peripheral blood mononuclear cells (PBMCs) and measuring the p24 levels for 10 days after an HIV-1Ba-Lchallenge. The median levels of IQP-0528, determined using liquid chromatography-tandem mass spectroscopy (LC-MS/MS) methods, were between 104and 105ng/g in vaginal and cervical tissue, between 103and 104ng/g in rectal tissues, and between 105and 107ng/ml in vaginal fluids over the 4-h period. The vaginal tissues protected the cocultured PBMCs from HIV-1 infectionex vivo, with a viral inhibition range of 81 to 100% in fresh and frozen tissues that were proximal, medial, and distal relative to the cervix. No viral inhibition was detected in untreated baseline tissues. Collectively, the median drug levels observed were 5 to 7 logs higher than thein vitro50% effective concentration (EC50) range (0.21 ng/ml to 1.29 ng/ml), suggesting that 1.5 ml of the gel delivers IQP-0528 throughout the RM vaginal compartment at levels that are highly inhibitory to HIV-1. Importantly, antiviral activity was observed in both fresh and frozen vaginal tissues, broadening the scope of theex vivococulture model for future NNRTI efficacy studies.

scholarly journals Formulation Development of Retrocyclin 1 Analog RC-101 as an Anti-HIV Vaginal Microbicide Product

2011 ◽  
Vol 55 (5) ◽  
pp. 2282-2289 ◽  
Author(s):  
A. B. Sassi ◽  
M. R. Cost ◽  
A. L. Cole ◽  
A. M. Cole ◽  
D. L. Patton ◽  
...  
Keyword(s):  
Reproductive Tract ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Formulation Development ◽  
Peripheral Blood Mononuclear ◽  
Vaginal Microbicide ◽  
Safety Studies ◽  
Film Formulation ◽  
Hiv 1

ABSTRACTRC-101 is a synthetic microbicide analog of retrocyclin, which has shownin vitroactivity against X4 and R5 HIV-1. In an effort to develop a safe and effective RC-101 vaginal microbicide product, we assessed safety inex vivomacaque and human models and efficacy usingin vitroandex vivomodels. A polyvinyl-alcohol vaginal film containing RC-101 (100 μg/film) was developed. Formulation assessment was conducted by evaluating disintegration, drug content, mechanical properties, and stability. Efficacy was evaluated byin vitroperipheral blood mononuclear cells (PBMC) assay andex vivohuman ectocervical tissue explant model.Ex vivosafety studies were conducted by exposing RC-101 to an excised monkey reproductive tract and excised human ectocervical tissue. RC-101 100 μg films were shown to be safe to human and monkey tissue and effective against HIV-1in vitroandex vivoin human ectocervical tissue. The 90% inhibitory concentration (IC90) for RC-101 films at 2,000 μg (IC90= 57.5 μM) using anex vivomodel was 10-fold higher than the IC90observed using anin vitromodel (IC90= 5.0 μM). RC-101 films were stable for 1 month at 25°C, within vitrobioactivity maintained for up to 6 months. RC-101 was developed in a quick-dissolve film formulation that was shown to be safe in anex vivomodel and effective inin vitroandex vivomodels. RC-101 film formulations were shown to maintain bioactivity for a period of 6 months. Findings from the present study contribute to the development of a safe and effective topical microbicide product.

scholarly journals An Enhanced Emtricitabine-Loaded Long-Acting Nanoformulation for Prevention or Treatment of HIV Infection

2016 ◽  
Vol 61 (1) ◽  
Author(s):  
Subhra Mandal ◽  
Michael Belshan ◽  
Ashley Holec ◽  
You Zhou ◽  
Christopher J. Destache
Keyword(s):  
Hiv Infection ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Antiretroviral Drugs ◽  
Volume Distribution ◽  
Major Drawback ◽  
Peripheral Blood Mononuclear ◽  
Long Acting ◽  
Hiv 1

ABSTRACT Among various FDA-approved combination antiretroviral drugs (cARVs), emtricitabine (FTC) has been a very effective nucleoside reverse transcriptase inhibitor. Thus far, FTC is the only deoxycytidine nucleoside analog. However, a major drawback of FTC is its large volume distribution (averaging 1.4 liters/kg) and short plasma half-life (8 to 10 h), necessitating a high daily dosage. Thus, we propose an innovative fabrication method of loading FTC in poly(lactic-co-glycolic acid) polymeric nanoparticles (FTC-NPs), potentially overcoming these drawbacks. Our nanoformulation demonstrated enhanced FTC loading (size of <200 nm and surface charge of −23 mV) and no to low cytotoxicity with improved biocompatibility compared to those with FTC solution. An ex vivo endosomal release assay illustrated that NP entrapment prolongs FTC release over a month. Intracellular retention studies demonstrate sustained FTC retention over time, with approximately 8% (24 h) to 68% (96 h) release with a mean retention of ∼0.74 μg of FTC/105 cells after 4 days. An in vitro HIV-1 inhibition study demonstrated that FTC-NP treatment results in a 50% inhibitory concentration (IC50) ∼43 times lower in TZM-bl cells (0.00043 μg/ml) and ∼3.7 times lower (0.009 μg/ml) in peripheral blood mononuclear cells (PBMCs) than with FTC solution (TZM-bl cells, 0.01861, and PBMCs, 0.033 μg/ml). Further, on primary PBMCs, FTC-NPs also illustrate an HIV-1 infection blocking efficacy comparable to that of FTC solution. All the above-described studies substantiate that FTC nanoformulation prolongs intracellular FTC concentration and inhibition of HIV infection. Therefore, FTC-NPs potentially could be a long-acting, stable formulation to ensure once-biweekly dosing to prevent or treat HIV infection.

scholarly journals Genotypic Correlates of Phenotypic Resistance to Efavirenz in Virus Isolates from Patients Failing Nonnucleoside Reverse Transcriptase Inhibitor Therapy

2001 ◽  
Vol 75 (11) ◽  
pp. 4999-5008 ◽  
Author(s):  
Lee Bacheler ◽  
Susan Jeffrey ◽  
George Hanna ◽  
Richard D'Aquila ◽  
Lany Wallace ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Mononuclear Cells ◽  
Site Directed Mutagenesis ◽  
Cross Resistance ◽  
Peripheral Blood Mononuclear ◽  
In Vitro Susceptibility ◽  
Virus Isolates ◽  
Hiv 1

ABSTRACT Efavirenz (also known as DMP 266 or SUSTIVA) is a potent nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity and of HIV-1 replication in vitro and in vivo. Most patients on efavirenz-containing regimens have sustained antiviral responses; however, rebounds in plasma viral load have been observed in some patients in association with the emergence of mutant strains of HIV-1. Virus isolates from the peripheral blood mononuclear cells (PBMCs) of patients with such treatment failures, as well as recombinant viruses incorporating viral sequences derived from patient plasma, show reduced in vitro susceptibility to efavirenz in association with mutations in the RT gene encoding K103N, Y188L, or G190S/E substitutions. Patterns of RT gene mutations and in vitro susceptibility were similar in plasma virus and in viruses isolated from PBMCs. Variant strains of HIV-1 constructed by site-directed mutagenesis confirmed the role of K103N, G190S, and Y188L substitutions in reduced susceptibility to efavirenz. Further, certain secondary mutations (V106I, V108I, Y181C, Y188H, P225H, and F227L) conferred little resistance to efavirenz as single mutations but enhanced the level of resistance of viruses carrying these mutations in combination with K103N or Y188L. Viruses with K103N or Y188L mutations, regardless of the initial selecting nonnucleoside RT inhibitor (NNRTI), exhibited cross-resistance to all of the presently available NNRTIs (efavirenz, nevirapine, and delavirdine). Some virus isolates from nevirapine or delavirdine treatment failures that lacked K103N or Y188L mutations remained susceptible to efavirenz in vitro, although the clinical significance of this finding is presently unclear.

Piperidinylethyl, Phenoxyethyl and Fluoroethyl Bromopyridyl Thiourea Compounds with Potent Anti-HIV Activity

2000 ◽  
Vol 11 (5) ◽  
pp. 329-336 ◽  
Author(s):  
TK Venkatachalam ◽  
Elise A Sudbeck ◽  
Chen Mao ◽  
Fatih M Uckun
Keyword(s):  
Reverse Transcriptase ◽  
Mononuclear Cells ◽  
Human Peripheral Blood ◽  
Phenyl Group ◽  
Piperidine Ring ◽  
Peripheral Blood Mononuclear ◽  
Thiourea Derivatives ◽  
Methyl Substitution ◽  
Anti Hiv ◽  
Hiv 1

Derivatives of piperidinylethyl, phenoxyethyl and fluoroethyl bromopyridyl thioureas were designed and synthesized as non-nucleoside reverse transcriptase inhibitors (NNRTIs) of HIV-1 reverse transcriptase (RT). The anti-HIV activity of these compounds was examined by determining their ability to inhibit the replication of the HIV-1 strain HTLVIIIB in human peripheral blood mononuclear cells. The unsubstituted parent pyridyl thiourea compound N-[2-(1-piperidine)ethyl]-N′-[2-(pyridyl)] thiourea (1) exhibited no anti-HIV activity, even at 100 μM. However, the thiourea derivatives that contain a bromo- or chloro-substituted pyridyl group, compounds 2 and 5, inhibited HIV-1 replication at nanomolar concentrations. The addition of a methyl group onto the piperidine ring significantly altered the potency of these compounds; while methyl substitution at the 3-position of the piperidine ring reduced the activity, methyl substitution at the 2-position enhanced the anti-HIV activity. The IC50 value of the lead piperidinyl compound, N-[2-(2-methylpiperidinylethyl)]-N′-[2-(5-bromopyridyl)] thiourea (4) was >0.001 μM. All three phenoxyethyl derivatives, including the unsubstituted parent phenoxyethyl pyridyl thiourea compound N-[2-(phenoxy)ethyl]-N-[2-(pyridyl)]thiourea (8) and the bromo-/chloro-substituted phenoxyethyl halopyridyl thiourea compounds N-[2-(phenoxy)ethyl]-N-[2-(5-chloropyridyl)]thiourea (9) and N-[2-(phenoxy)ethyl]-N-[2-(5-bromopyridyl)]thiourea (10) exhibited potent anti-HIV activity with nanomolar IC50 values. The corresponding fluoroethyl halopyridyl thiourea compounds β-fluoro[2-phenethyl]-N′[2-(5-chloropyridyl)]thiourea (11) and β-fluoro[2-phenethyl]-N′[2-(5-bromopyridyl)]thiourea (12) inhibited HIV-1 replication in PBMC with subnanomolar IC50 values and selectivity indices <30000. Compared to the corresponding phenoxyethyl thiourea compounds 9 and 10, these compounds were <4–5–fold more active as anti-HIV agents. Notably, the lead fluorothiourea compounds 11 and 12 were both substantially more active against the NNRTI-resistant HIV strains RT-MDR (V106A) and A17 (Y181C) than nevirapine or delavirdine. Taken together, our results provide additional experimental evidence that the structural features of the ‘linker unit” between the pyridyl and phenyl moieties and changes in the phenyl group of PETT-related thiourea compounds significantly affects their biological activity as NNRTIs of HIV-1 RT.

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