HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors Research Articles

Structure-Activity Relationship Studies on Clinically Relevant HIV-1 NNRTIs

In addition to the nucleoside reverse transcriptase inhibitors (NRTIs), protease inhibitors (PIs) and integrase inhibitors (INIs), nonnucleoside reverse transcriptase inhibitors (NNRTIs) have contributed significantly in the treatment of HIV-1 infections. More than 60 structurally different classes of compounds have been identified as NNRTIs, which are specifically inhibiting HIV-1 reverse transcriptase (RT). Five NNRTIs (nevirapine, delavirdine, efavirenz, etravirine and rilpivirine) have been approved by US Food and Drug Administration (FDA) for clinical use. The NNRTIs bind with a specific 'pocket' site of HIV-1 RT (allosteric site) that is closely associated with the NRTI binding site. Due to mutations of the amino acid residues surrounding the NNRTI-binding site, NNRTIs are notorious for rapidly eliciting resistance. Though, the emergence of resistant HIV strains can be circumvented if the NNRTIs are used either alone or in combination with NRTIs (AZT, 3TC, ddI, ddC, TVD or d4T) and PIs (Indinavir, nelfinavir, saquinavir, ritonavir and lopinavir etc.) as shown by both a decrease in plasma HIV-1 RNA levels and increased CD4 T-cells. Here we are going to discuss recent advances in structure activity relationship studies on nevirapine, delavirdine, efavirenz, etravirine, rilpivirine and 4-thiazolidinones (privileged scaffold) HIV-1 NNRTIs.

Anti-HIV nucleoside drugs: A retrospective view into the future

The review considers the design of antiretroviral drugs based on nucleoside analogs. Approximately 30 drugs have been approved for treating HIV-infected patients over the past 25 years. Seven nucleoside drugs act as HIV reverse transcriptase (RT) inhibitors and are clinically used in combination with inhibitors of other viral enzymes, integrase and protease, and nonnucleoside inhibitors of HIV RT. Toxicity of nucleoside drugs and the possibility to obtain safe anti-HIV drugs by constructing their depot forms are discussed. The results of developing anti-HIV drugs in Russia are described. The future prospects of anti-HIV research are considered.

Synthesis and biological activity of new 6-benzylisocytosine derivatives: non-nucleoside HIV-1 reverse transcriptase inhibitors

New 6-benzylisocytosine derivatives were synthesized by aminolysis of 6-benzyl-2-(methylsulfanyl)pyrimidin-4(3H)-ones with aliphatic aromatic and cage-structured amines. Some of the synthesized compounds appeared to be effective HIV-1 reverse transcriptase inhibitors. Among these, 6-(2,6-difluorobenzyl)-5-methyl-2-[(2-phenylethyl)amino]pyrimidin-4(3H)-one showed the most pronounced inhibitory properties, being nine times more effective than the reference anti-HIV drug nevirapine.

Structure-based bioisosterism design, synthesis and biological evaluation of novel 1,2,4-triazin-6-ylthioacetamides as potent HIV-1 NNRTIs

The development of new HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) offers the possibility of generating novel chemical entities of increased potency. Previous investigations in our laboratory resulted in the discovery of several novel series of arylazolylthioacetanilides as potent NNRTIs. In this study, based on the structure-based bioisosterism strategy, novel 1,2,4-triazin-6-yl thioacetamide derivatives were designed, synthesized and evaluated for their anti-HIV activity in MT-4 cells. Among them, the most promising compound was 8b15 with double-digit nanomolar activity against wild-type HIV-1 (EC50=0.018±0.007μM) and moderate activity against the double mutant strain RES056 (EC50=3.3±0.1μM), which indicated that 1,2,4-triazin-6-yl thioacetamide can be used as a novel scaffold to develop a new class of potent NNRTIs active against both wild-type and drug-resistant HIV-1 strains. In addition, preliminary structure–activity relationship (SAR) and molecular modeling results are also briefly discussed, which provide some useful information for the further design of novel NNRTIs.

The Development of HEPT-Type HIV Non-Nucleoside Reverse Transcriptase Inhibitors and Its Implications for DABO Family

1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) was discovered as the first HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) in 1989. The research on HEPT derivatives (HEPTs) has been lasted for more than 20 years and HEPT family is probably the most investigated NNRTI. Extensive molecular modifications on HEPT have led to many highly potent compounds with broad-resistance spectrum and optimal pharmacokinetic profiles. Moreover, X-crystallographic studies of HEPTs/RT complexes revealed the binding mode of HEPTs and the action mechanism of NNRTI, which has greatly facilitated the design of novel NNRTIs. Recently, the development of HEPTs was accelerated by the application of the "follow-on"-based chemical evolution strategies, such as designed multiple ligands (DMLs) and molecular hybridization (MH). Herein, this article will provide an insight into the development of HEPTs, including structural modifications, crystal structure of RT complexed with HEPTs and its structure-activity relationship (SAR). Additionally, this review also covers the emerging HEPT related dual inhibitors and HEPT-pyridinone hybrids, as well as the contributions of HEPTs to the development of dihydro-alkoxy-benzyl-oxopyrimidine (DABO) family, thus highlighting the importance of HEPTs on the development of NNRTIs.

Nitroimidazoles Part 8. Synthesis and Anti-HIV Activity of New 4-Nitroimidazole Derivatives Using the Suzuki Cross-Coupling Reaction

The development of new HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs) offers the possibility of generating structures of increased potency. To this end, a series of 1-(1-benzyl-2-ethyl- 4-nitro-1H-imidazol-5-yl)-4-(1,1'-biaryl)-4-yl-piperazine derivatives (6a-l) was synthesized via the Suzuki coupling reaction. Analogously, coupling of the acid derivative 5, prepared from 4, with various amino acid methyl esters in the presence of HOBt/DCC reagents afforded the benzamide derivatives 8-11. The newly synthesized compounds were assayed against HIV-1 and HIV-2 in MT- 4 cells. All compounds are inactive, except compound 6f which showed inhibition of HIV-1 with EC50 = 2:60μgmL-1 with a selectivity index (SI) of 9

Design, Synthesis, and Preclinical Evaluations of Novel 4-Substituted 1,5-Diarylanilines as Potent HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI) Drug Candidates

Twenty-one new 4-substituted diarylaniline compounds (DAANs) (series 13, 14, and 15) were designed, synthesized, and evaluated against wild-type and drug resistant HIV-1 viral strains. As a result, approximately a dozen new DAANs showed high potency with low nano- to subnanomolar EC(50) values ranging from 0.2 to 10 nM. The three most promising compounds 14e, 14h, and 15h exhibited high potency against wild-type and drug-resistant viral strains with EC(50) values at the subnanomolar level (0.29-0.87 nM) and were comparable to or more potent than the new NNRTI drug riplivirine (2) in the same assays. Druglike physicochemical property assessments revealed that the most active DAANs (EC(50) < 10 nM) have better aqueous solubility (>1-90 μg/mL at pH 7.4 and pH 2) and metabolic stability in vitro than 2, as well as desirable log P values (<5) and polar surface areas (PSA) (<140 Å(2)). These promising results warrant further development of this novel compound class as potential potent anti-AIDS clinical trial candidates.

Nitroimidazoles Part 7. Synthesis and Anti-HIV Activity of New 4-Nitroimidazole Derivatives

Reverse transcriptase enzyme (RT) is an attractive target for the development of new drugs useful in AIDS therapy and HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs), and offers the possibility of generating structures of increased potency. On this basis, a series of 4-oxo-3-phenyl-2- (phenylimino)thiazolidin-5-ylidene, 3-hydroxypropyl, 3-azidopropyl, and 3-aminopropyl derivatives of 1-benzyl-2-ethyl-4-nitroimidazoles 6-8, as well as the substituted 1,2,3-triazolo analogs 12-14, the diazepam 15 and carboxamide derivatives 16 and 17 were synthesized. All compounds have been evaluated for their anti-HIV activity

Minority variants associated with resistance to HIV-1 nonnucleoside reverse transcriptase inhibitors during primary infection

BackgroundRecent data suggest that subjects harbouring low-frequency variants of HIV that are resistant to non-nucleoside reverse-transcriptase inhibitors (NNRTI) could suffer virological failure when treated with NNRTI-based therapy. Rilpivirine, a second-generation NNRTI, will be used in first-line regimen therapy, but the prevalence of minority variants that are resistant to rilpivirine is unknown. ObjectivesWe evaluated the presence of low-frequency NNRTI resistance associated mutations (RAMs) in 27 patients with a primary HIV-1 infection. Study designWe performed genotypic resistance test at baseline and used ultradeep pyrosequencing (UDPS) to detect minority RAMs. ResultsBulk genotyping identified NNRTI-resistant RAMs in 3/27 (11%) patients while UDPS identified NNRTI-resistant RAMs in 10/27 (37%) patients. The 11 RAMs not detected by bulk sequencing were A98G (n=2), L100I (n=3), K101E (n=2), V106I (n=3) and E138G (n=1). The prevalence of these minority variants was 0.34–18.26%. The absolute copy numbers of minority resistant variants were 3.21–5.53logcopies/mL. CRF02 harboured more minority resistant variants than subtypes B (P<0.05). Four samples (15%) had a major rilpivirine resistant mutation (E138G, K101E and E138A), 3 of which were detected by UDPS. ConclusionIn these primary HIV infected patients, as regards to the detection of RAMs at the cut-off level>15–25% of the virus population, the concordance between bulk genotypic and UDPS was perfect. UDPS detected additional major NNRTI-resistant mutations, including rilpivirine resistant variants. Further studies are needed to assess the impact of these minority variants on treatment efficacy.

Discovery of Phenylaminopyridine Derivatives as Novel HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors.

We identified a novel class of aryl-substituted triazine compounds as potent non-nucleoside reverse transcriptase inhibitors (NNRTIs) during a high-throughput screening campaign that evaluated more than 200000 compounds for antihuman immunodeficiency virus (HIV) activity using a cell-based full replication assay. Herein, we disclose the optimization of the antiviral activity in a cell-based assay system leading to the discovery of compound 27, which possessed excellent potency against wild-type HIV-1 (EC50 = 0.2 nM) as well as viruses bearing Y181C and K103N resistance mutations in the reverse transcriptase gene. The X-ray crystal structure of compound 27 complexed with wild-type reverse transcriptase confirmed the mode of action of this novel class of NNRTIs. Introduction of a chloro functional group in the pyrazole moiety dramatically improved hERG and CYP inhibition profiles, yielding highly promising leads for further development.

Novel Cyclopropyl-Indole Derivatives as HIV Non-Nucleoside Reverse Transcriptase Inhibitors.

The HIV pandemic represents one of the most serious diseases to face mankind in both a social and economic context, with many developing nations being the worst afflicted. Due to ongoing resistance issues associated with the disease, the design and synthesis of anti-HIV agents presents a constant challenge for medicinal chemists. Utilizing molecular modeling, we have designed a series of novel cyclopropyl indole derivatives as HIV non-nucleoside reverse transcriptase inhibitors and carried out their preparation. These compounds facilitate a double hydrogen bonding interaction to Lys101 and efficiently occupy the hydrophobic pockets in the regions of Tyr181/188 and Val179. Several of these compounds inhibited HIV replication as effectively as nevirapine when tested in a phenotypic assay.

The Pharmacokinetics of Lersivirine (UK-453,061) and HIV-1 Protease Inhibitor Coadministration in Healthy Subjects

Lersivirine (UK-453,061) is a next-generation nonnucleoside reverse transcriptase inhibitor, active against wild-type HIV-1 and several nonnucleoside reverse transcriptase inhibitor-resistant strains. Four studies evaluated the pharmacokinetic (PK) interactions between lersivirine and various HIV-1 protease inhibitors. Four phase I trials were conducted to assess the PK of lersivirine when coadministered with lopinavir/ritonavir, darunavir/ritonavir, or atazanavir with/without ritonavir, and to examine the effects of lersivirine on the PK of atazanavir with/without ritonavir. PK data included the area under the plasma concentration-time profile from time zero to the end of the dosing interval (AUC24), maximum plasma concentration (Cmax), minimum plasma concentration (Cmin, C24, or Ctrough), and time to Cmax (Tmax). Safety was assessed by recording adverse events, vital signs, and laboratory data. Coadministration of lersivirine with lopinavir/ritonavir, darunavir/ritonavir, or atazanavir/ritonavir decreased mean plasma lersivirine AUC24 by 43%, 22%, and 19%, respectively. Atazanavir had no effect on lersivirine exposure, except for a 16% decrease in lersivirine C24. Lersivirine had no effect on atazanavir AUC24 or Cmax, although Ctrough was reduced by 18% in the absence of ritonavir. Lersivirine exposure was reduced when coadministered with ritonavir-boosted protease inhibitors; a dose adjustment may be warranted. Unboosted atazanavir had no effect on lersivirine exposure, except for a small decrease in lersivirine C24. Lersivirine had no effect on atazanavir (with/without ritonavir) exposure, except for a decrease in Ctrough. Caution should be applied when unboosted atazanavir is coadministered with lersivirine. Coadministration of lersivirine with lopinavir/ritonavir, darunavir/ritonavir, or atazanavir with/without ritonavir seems to be generally well tolerated.

Chiral resolution, absolute configuration assignment and biological activity of racemic diarylpyrimidine CH(OH)-DAPY as potent nonnucleoside HIV-1 reverse transcriptase inhibitors

(+)-3a and (−)-3a were successfully separated from racemate (±)-3a by the chiral technique of supercritical fluid chromatography (SCF) with enantiomeric excess (ee%) >99% and purity >99%, and assigned for their absolute configuration as R and S, respectively, by the experimental electronic circular dichroism (ECD) spectrum and simulated ECD spectra calculated by time-dependent density functional theory (TDDFT) calculations. (+)-(R)-3a displayed excellent activity with an EC50 of 5.3nM against wild-type HIV-1, which was 12-fold more potent than (−)-(S)-3a. However, (−)-(S)-3a showed higher potency than (+)-(R)-3a against the double HIV-1 RT mutant (K103N+Y181C) as well as HIV-2 strain ROD. The possible reason for the difference of (R)- and (S)-3a in anti-HIV-1 activity was interpreted by molecular docking.

Benzimidazole: A short review of their antimicrobial activities

Benzimidazole is the heterocyclic compound formed from benzene and imidazole ring containing nitrogen, oxygen sulphor and its derivatives are of wide interest because of their diverse biological activity and clinical applications, they are remarkably effective compounds both with respect to their inhibitory activity and their favourable selectivity ratio. Reported nucleus is a constituent of vitamin-B12. Benzimidazoles are regarded as a promising class of bioactive heterocyclic compounds that exhibit a range of biological activities like anti-microbial, anti-viral, anti-diabetic, anti-cancer activity, numerous anti-oxidant, anti-parasitic, anti-helmintics, anti-proliferative, anti-HIV, anti-convulsant, anti-inflammatory, anti-hypertensive, anti-neoplastic, proton pump inhibitor and anti-trichinellosis. Benzimidazoles exhibit significant activity as potential antitumor agents, smooth muscle cell proliferation inhibitors, a treatment for intestinal cystitis, and in diverse area of chemistry. Some of the important benzimidazole derivatives have been reported as thyroid receptor agonist gonadotropin releasing hormone receptor antagonists, non-nucleoside HIV-1 reverse transcriptase inhibitors and interestingly alkynylbenzimidazoles as modulators of metabotropic glutamate receptors. The imidazole core is a common moiety in a large number of natural products and pharmacologically active compounds. The synthesis of novel benzimidazole derivatives remains a main focus of medicinal research. This comprehensive overview summarizes the chemistry of different derivative of substituted benzimidazole along with their anti-microbial activity containing anti-malarial anti-fungal, anti-bacterial, anti-viral activities.DOI: http://dx.doi.org/10.3329/icpj.v1i5.10284International Current Pharmaceutical Journal 2012, 1(5): 119-127

Synthesis, structure–activity relationships, and docking studies of N-phenylarylformamide derivatives (PAFAs) as non-nucleoside HIV reverse transcriptase inhibitors

A series of N-phenylarylformamide derivatives (PAFAs) with anti-wild-type HIV-1 activity (EC50 values) ranging from 0.3 nM to 5.1 nM and therapeutic index (TI) ranging from 10 616 to 271 000 were identified as novel non-nucleoside reverse transcriptase inhibitors. Among them, compound 13g (EC50 = 0.30 nM, TI = 184 578), 13l (EC50 = 0.37 nM, TI = 212 819), 13m (EC50 = 0.32 nM, TI = 260 617) and 13r (EC50 = 0.27 nM, TI = 271 000) displayed the highest activity against this type virus nearly as potent as lead compound GW678248. Moreover, all of them were also active to inhibit the double mutant strain A17 (K103N + Y181C) with EC50 values of 0.29 μM, 0.14 μM, 0.10 μM and 0.27 μM, respectively. In particular, compound 13m, which showed broad-spectrum anti-HIV activity, was also effective to inhibit the HIV-2 ROD replication within 4.37 μM concentration.

2-(Alkyl/Aryl)Amino-6-Benzylpyrimidin-4(3H)-ones as Inhibitors of Wild-Type and Mutant HIV-1: Enantioselectivity Studies

The single enantiomers of two pyrimidine-based HIV-1 non-nucleoside reverse transcriptase inhibitors, 1 (MC1501) and 2 (MC2082), were tested in both cellular and enzyme assays. In general, the R forms were more potent than their S counterparts and racemates and (R)-2 was more efficient than (R)-1 and the reference compounds, with some exceptions. Interestingly, (R)-2 displayed a faster binding to K103N RT with respect to WT RT, while (R)-1 showed the opposite behavior.

Synthesis, biological activity and docking study of imidazol-5-one as novel non-nucleoside HIV-1 reverse transcriptase inhibitors

A novel series of substituted imidazol-5-ones were designed, synthesized and evaluated for in vitro reverse transcriptase (RT) inhibition activity using reverse transcriptase assay kit (Roche, Colorimetric). It has been observed from in vitro screening that newly synthesized compounds possess RT inhibitory activity. Docking study was performed to study the binding orientation and affinity of synthesized compounds for RT enzyme.

Prodrug design, synthesis and pharmacokinetic evaluation of (3′R, 4′R)-3-hydroxymethyl-4-methyl-3′, 4′-di-O-(S)-camphanoyl-(+)-cis-khellactone

3-Hydroxymethyl-4-methyl-DCK (3, HMDCK) was discovered previously as a potent HIV non-nucleoside reverse transcriptase inhibitor (NNRTIs) (EC50: 0.004μM, TI: 6225) with a novel mechanism of action. It exerts anti-HIV activity by inhibiting the production of HIV-1 double-stranded viral DNA from a single-stranded DNA intermediate, rather than blocking the generation of single-stranded DNA from a RNA template, which is the mechanism of action of current HIV-1 RT inhibitors. However, the insufficient metabolic stability of 3 limits its further clinical development. In the current study, a series of ester prodrugs of 3 was designed and synthesized to explore the new drug candidates as NNRTIs. The l-alanine ester prodrug 10 exhibited desirable pharmacokinetic properties in vitro and in vivo and showed improved oral bioavailability of 26% in rat, and would be a potential clinical candidate as a new anti-AIDS drug.

Vaginal Film Drug Delivery of the Pyrimidinedione IQP-0528 for the Prevention of HIV Infection

Polymeric quick-dissolving films were developed as a solid dosage topical microbicide formulation for the vaginal delivery of the highly potent and non-toxic, dual-acting HIV nonnucleoside reverse transcriptase inhibitor (NNRTI) pyrimidinedione, IQP-0528. Formulated from approved excipients, a polyvinyl alcohol (PVA) based film was manufactured via solvent casting methods. The film formulations were evaluated based upon quantitative physicochemical evaluations defined by a Target Product Profile (TPP) RESULTS: Films dosed with 0.1% (w/w) of IQP-0528 disintegrated within 10min with over 50% of drug released and near 100% total drug released after 30min. The IQP-0528 films were found to be non-toxic in in vitro CEM-SS and PBMC cell-based assays and biologically active with sub-nanomolar efficacy against HIV-1 infection. In a 12month stability protocol, the IQP-0528 films demonstrated no significant degradation at International Conference on Harmonization (ICH) recommended standard (25°C/65% relative humidity (R.H.)) and accelerated (40°C/75% R.H.) environmental conditions. Based on the above evaluations, a vaginal film formulation has been identified as a potential solid dosage form for the vaginal delivery of the topical microbicide candidate IQP-0528.

Recent Advances in the Research of 2,3-Diaryl-1,3-thiazolidin-4-one Derivatives as Potent HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors

Derived from the structure of 1H,3H-thiazolo[3,4-a]benzimidazoles (TBZs), 2,3-diaryl-1,3-thiazolidin-4-one derivatives became a novel class of HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs). Under the guidance of continuous structure-activity relationship (SAR) analysis and molecular modeling, various structural modifications were carried out on nearly all the positions of the thiazolidin-4-one nucleus. Some of the derivatives proved to be highly effective against HIV-1 replication at 10-40 nanomolar concentration ranges with minimal cytotoxicities. In this article, the whole development of 2,3-diaryl-1,3-thiazolidin-4-one series from the discoveries to recent advances, their panoramic SAR studies and binding modes based on molecular modeling were reviewed, and also some enlightenments for further investigation were presented.