Advances in diarylpyrimidines and related analogues as HIV-1 nonnucleoside reverse transcriptase inhibitors

Identification of 6,9-dihydro-5H-pyrrolo[3,2-h]quinazolines as a new class of F508del-CFTR correctors for the treatment of cystic fibrosis

Although substantial advances have been obtained in the pharmacological treatment of cystic fibrosis (CF) with the approval of Kaftrio, a combination of two correctors (VX-661, VX-445) and one potentiator (VX-770), new modulators are still needed to rescue F508del and other CFTR mutants with trafficking defects. We have previously identified PP compounds based on a tricyclic core as correctors with high efficacy in the rescue of F508del-CFTR on native epithelial cells of CF patients, particularly in combination with class 1 correctors (VX-809, VX-661). Compound PP028 was found as a lead candidate for the high rescue of F508del-CFTR and used for mechanistic insight indicating that PP028 behaves as a class 3 corrector, similarly to VX-445. From the exploration of the chemical space around the hit structure, based on iterative cycles of chemical synthesis and functional testing, the class of 6,9-dihydro-5H-pyrrolo [3,2-h]quinazolines with corrector activity was discovered. Within a series of 38 analogues, two derivatives emerged as promising candidates and used for further insight to assess the mechanism of action. Both compounds, decorated with a benzensulfonylamino group at the pyrimidine moiety, were able to generate a dose-dependent increase in CFTR function, particularly in the presence of VX-809. Half-effective concentrations (EC50) were in the single digit micromolar range and decreased in the presence of VX-809 thus indicating a synergistic interaction with class 1 correctors. Synergy was also observed with corr-4a (class 2 corrector) but not with VX-445 and PP028 (class 3 correctors) indicating that the new compounds behave as class 3 correctors. These results suggest that tricyclic pyrrolo-quinazolines interact with CFTR at a site different from that of VX-809 and represent a novel class of CFTR correctors suitable for combinatorial pharmacological treatments for the basic defect in CF.

Discovery of 2,4,6-trisubstituted pyrimidine derivatives as novel potent HIV-1 NNRTIs by exploiting the tolerant region II of the NNIBP

The rapid emergence of drug resistance severely reduces the clinical response of human immunodeficiency virus-1 (HIV-1) to non-nucleoside reverse transcriptase inhibitors (NNRTIs). Herein, a series of 2,4,6-trisubstituted pyrimidine derivatives was designed and synthesized, with the aim to identify novel anti-HIV-1 agents with improved drug resistance profiles. The antiviral activity results demonstrated that all compounds showed excellent potency to wild-type (WT) HIV-1 strain (EC50 = 3.61-15.5 nM). Moreover, 13c was proved to be the most potent inhibitor against the whole tested viral panel, with EC50 ranging from 4.68 to 229 nM. In addition, 13c yielded moderate HIV-1 RT inhibition with IC50 value of 0.231 μM, which demonstrated it was a classical NNRTI. Molecular docking was further conducted to illustrate its binding mode with HIV-1 RT. These encouraging results indicated that 13c can be used as a lead compound for further study.

Structure-based design and optimization lead to the identification of novel dihydrothiopyrano[3,2-d]pyrimidine derivatives as potent HIV-1 inhibitors against drug-resistant variants

With our continuous endeavors in seeking potent anti-HIV-1 agents, we reported here the discovery, biological characterization, and druggability evaluation of a class of nonnucleoside reverse transcriptase inhibitors. To fully explore the chemical space of the NNRTI-binding pocket, novel series of dihydrothiopyrano [3,2-d]pyrimidines were developed by employing the structure-based design strategy. Most of the derivatives were endowed with prominent antiviral activities against HIV-1 wild-type and resistant strains at nanomolar levels. Among them, compound 23h featuring the aminopiperidine moiety was identified as the most potent inhibitor, with EC50 values ranging from 3.43 to 21.4 nmol/L. Especially, for the challenging double-mutants F227L + V106A and K103N + Y181C, 23h exhibited 2.3- to 14.5-fold more potent activity than the first-line drugs efavirenz and etravirine. Besides, the resistance profiles of 23h achieved remarkable improvement compared to efavirenz and etravirine. The binding target of 23h was further confirmed to be HIV-1 reverse transcriptase. Molecular modeling studies were also performed to elucidate the biological evaluation results and give guidance for the optimization campaign. Furthermore, no apparent inhibition of the major CYP450 enzymes and hERG channel was observed for 23h. Most importantly, 23h was characterized by good pharmacokinetic properties and excellent safety in vivo. Collectively, 23h holds great promise as a potential candidate for its effective antiviral efficacy and favorable drug-like profiles.

Medicinal chemistry perspectives on the development of piperazine-containing HIV-1 inhibitors

The Human immunodeficiency virus (HIV) is the causative agent of acquired immunodeficiency syndrome (AIDS), one of the most perilous diseases known to humankind. A 2023 estimate put the number of people living with HIV around 40 million worldwide, with the majority benefiting from various antiretroviral therapies. Consequently, the urgent need for the development of effective drugs to combat this virus cannot be overstated. In the realm of medicinal and organic chemistry, the synthesis and identification of novel compounds capable of inhibiting HIV enzymes at different stages of their life cycle are of paramount importance. Notably, the spotlight is on the progress made in enhancing the potency of HIV inhibitors through the use of piperazine-based compounds. Multiple studies have revealed that the incorporation of a piperazine moiety results in a noteworthy enhancement of anti-HIV activity. The piperazine ring assumes a pivotal role in shaping the pharmacophore responsible for inhibiting HIV-1 at critical stage, including attachment, reverse transcription, integration, and protease activity. This review also sheds light on the various opportunities that can be exploited to develop effective antiretroviral targets and eliminate latent HIV reservoirs. The advancement of highly potent analogues in HIV inhibitor research has been greatly facilitated by contemporary medicinal strategies, including molecular/fragment hybridization, structure-based drug design, and bioisosterism. These techniques have opened up new avenues for the development of compounds with enhanced efficacy in combating the virus.

Current insights and molecular docking studies of HIV-1 reverse transcriptase inhibitors

Human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS), a lethal disease that is prevalent worldwide. According to the Joint United Nations Programme on HIV/AIDS (UNAIDS) data, 38.4 million people worldwide were living with HIV in 2021. Viral reverse transcriptase (RT) is an excellent target for drug intervention. Nucleoside reverse transcriptase inhibitors (NRTIs) were the first class of approved antiretroviral drugs. Later, a new type of non-nucleoside reverse transcriptase inhibitors (NNRTIs) were approved as anti-HIV drugs. Zidovudine, didanosine, and stavudine are FDA-approved NRTIs, while nevirapine, efavirenz, and delavirdine are FDA-approved NNRTIs. Several agents are in clinical trials, including apricitabine, racivir, elvucitabine, doravirine, dapivirine, and elsulfavirine. This review addresses HIV-1 structure, replication cycle, reverse transcription, and HIV drug targets. This study focuses on NRTIs and NNRTIs, their binding sites, mechanisms of action, FDA-approved drugs and drugs in clinical trials, their resistance and adverse effects, their molecular docking studies, and highly active antiretroviral therapy (HAART).

5-Cyano substituted diarylpyridines as potent HIV-1 NNRTIs: Rational design, synthesis, and activity evaluation

To develop more potent HIV-1 inhibitors against a variety of NNRTIs-resistant strains, a series of 5-cyano substituted diarylpyridines was designed based on the cocrystal structural analysis. Among them, I-5b showed the greatest potency (EC50 = 5.62-171 nM) against the wild-type (WT) and mutant HIV-1 strains. Especially for K103 N, I-5b exhibited outstanding activity with EC50 values of 9.37 nM, being much superior to that of NVP (EC50 = 5128 nM) and EFV (EC50 = 114 nM) and comparable to that of ETR (EC50 = 3.45 nM). In addition, the target of all compounds was turned out to be HIV-1 RT with moderate RT enzyme inhibitory activity (IC50 = 0.094-12.0 μM). Moreover, the binding mode of representative compounds with RT was elaborated via molecular docking.

Hydroxyalkynyl uracil derivatives as NNRTIs against HIV-1: in silico predictions, synthesis, docking and molecular dynamics simulation studies

To improve rationally the efficacy of the non-nucleoside human immunodeficiency virus (HIV-1) inhibitors, it is important to have a precise and detailed understanding of the HIV-1 reverse transcriptase (RT) and inhibitor interactions. For the 1-[(2-hydroxyethoxy) methyl]-6-(phenylthio) thymine (HEPT) type of nucleoside reverse transcriptase inhibitors (NNRTIs), the H-bond between the N-3H of the inhibitor and the backbone carbonyl group of K101 represents the major hydrophilic interaction. This H-bond contributes to the NNRTI binding affinity. The descriptor analyses of different uracil derivatives proved their good cell internalization. The bioactivity score reflected higher drug likeness score and the ligands showed interesting docking results. All molecules were deeply buried and stabilized into the allosteric site of HIV-1 RT. For majority of molecules, residues Lys101, Lys103, Tyr181 and Tyr188 were identified as key protein residues responsible for generation of H-bond and major interactions were similar to all known NNRTIs while very few molecules interacted with residues Phe227 and Tyr318. The TOPKAT protocol available in Discovery Studio 3.0 was used to predict the pharmacokinetics of the designed uracil derivatives in the human body. The molecular dynamics (MD) and post-MD analyses results reflected that the complex HIVRT:5 appeared to be more stable than the complex HIVRT:HEPT, where HEPT was used as reference. Different uracil derivatives have been synthesized by using uracil as starting material and commercially available propargyl bromide. The N-1 derivative of uracil was further reacted with sodamide and different aldehydes/ketones bearing alkyl and phenyl ring to obtain hydroxyalkynyl uracil derivatives as NNRTIs.Communicated by Ramaswamy H. Sarma.

Identification of a Non-Nucleoside Reverse Transcriptase Inhibitor against Human Immunodeficiency Virus-1

The HIV-1 infection epidemic remains a global health problem. Current antiretroviral treatments are effective in controlling the progression of a severe infection. However, the emergence of drug resistance requires an urgent identification of new treatment regimes. HIV-1 reverse transcriptase (RTs) has been a successful therapeutic target owing to its high specificity and potent antiviral properties; therefore, it has become an essential component of current HIV-1 standard treatments. This study identified a new HIV-1 RTs inhibitor (Compound #8) that is structurally unique and greatly effective against HIV-1 through chemical library screening and a medicinal chemistry program by analyzing the structure-activity relationship (SAR). Further analysis of molecular docking and mechanisms of action demonstrated that Compound #8 is a novel type of HIV-1 non-nucleoside reverse transcriptase inhibitor (NNRTI) with a flexible binding mode. Therefore, it exhibits great therapeutic potential when combined with other existing HIV-1 drugs. Our current studies suggest that Compound #8 is a promising novel scaffold for the development of new HIV-1 treatments.

Fluorine in anti-HIV drugs approved by FDA from 1981 to 2023

Human immunodeficiency virus (HIV) is the etiological agent of acquired immunodeficiency syndrome (AIDS). Nowadays, FDA has approved over thirty antiretroviral drugs grouped in six categories. Interestingly, one-third of these drugs contain different number of fluorine atoms. The introduction of fluorine to obtain drug-like compounds is a well-accepted strategy in medicinal chemistry. In this review, we summarized 11 fluorine-containing anti-HIV drugs, focusing on their efficacy, resistance, safety, and specific roles of fluorine in the development of each drug. These examples may be of help for the discovery of new drug candidates bearing fluorine in their structures.

Quinolines and isoquinolines as HIV-1 inhibitors: Chemical structures, action targets, and biological activities

Human immunodeficiency virus type 1 (HIV-1), a lentivirus that causes acquired immunodeficiency syndrome (AIDS), poses a serious threat to global public health. Since the advent of the first drug zidovudine, a number of anti-HIV agents acting on different targets have been approved to combat HIV/AIDS. Among the abundant heterocyclic families, quinoline and isoquinoline moieties are recognized as promising scaffolds for HIV inhibition. This review intends to highlight the advances in diverse chemical structures and abundant biological activity of quinolines and isoquinolines as anti-HIV agents acting on different targets, which aims to provide useful references and inspirations to design and develop novel HIV inhibitors for medicinal chemists.

Hybrids of delavirdine and piperdin-4-yl-aminopyrimidines (DPAPYs) as potent HIV-1 NNRTIs: Design, synthesis and biological activities

The hybrids of delavirdine and piperdin-4-yl-aminopyrimidine (DPAPYs) were designed from two excellent HIV-1 NNRTIs delavirdine and piperidin-4-yl-aminopyrimidine via molecular hybridization. The target compounds 4a-r were prepared and evaluated for their cellular anti-HIV activities and cytotoxicities as well as the inhibitory activities against HIV-1 reverse transcriptase (RT). All the newly synthesized compounds demonstrated moderate to excellent potency against wild-type (WT) HIV-1 with EC50 values in a range of 5.7 to 0.0086 μM and against RT with IC50 values ranging from 12.0 to 0.11 μM, indicating that the DPAPYs were specific RT inhibitors. Among all, 4d displayed the most potent activity against WT HIV-1 (EC50 = 8.6 nM, SI = 2151). Gratifyingly, it exhibited good to excellent potency against the single HIV-1 mutants L100I, K103N, Y181C, Y188L, E138K, as well as the double mutant F227L + V106A. Furthermore, the preliminary structure-activity relationships were summarized, molecular modeling was conducted to explore the binding mode of DPAPYs and HIV-1 RT, and their physicochemical properties were also predicted.

Identification of Novel Diarylpyrimidines as Potent HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitors by Exploring the Primer Grip Region

HIV-1 reverse transcriptase (RT) plays a crucial role in the viral replication cycle, and RT inhibitors can represent a promising pathway in treating AIDS. To explore the primer grip region of HIV-1 RT, using -CH2O- as a linker, substituted benzene or pyridine rings were introduced into the left wing of diarylpyrimidines (DAPYs). A total of 17 compounds with new structures were synthesized. It showed that all compounds exhibited anti-HIV-1 (wild-type) activity values ranging from 7.6−199.0 nM. Among them, TF2 (EC50 = 7.6 nM) showed the most potent activity, which was better than that of NVP (EC50 = 122.6 nM). Notably, compared with RPV (CC50 = 3.98 μM), TF2 (CC50 > 279,329.6 nM) showed low cytotoxicity. For HIV-1 mutant strains K103N and E138K, most compounds showed effective activities. Especially for K103N, TF2 (EC50 = 28.1 nM), TF12 (EC50 = 34.7 nM) and TF13 (EC50 = 28.0 nM) exhibited outstanding activity, being superior to that of NVP (EC50 = 7495.1 nM) and EFV (EC50 = 95.1 nM). Additionally, TF2 also showed the most potent activity against E138K (EC50 = 44.0 nM) and Y181C mutant strains (EC50 = 139.3 nM). In addition, all the compounds showed strong enzyme inhibition (IC50 = 0.036−0.483 μM), which demonstrated that their target was HIV-1 RT. Moreover, molecular dynamics simulation studies were implemented to predict the binding mode of TF2 in the binding pocket of wild-type and K103N HIV-1 RT.

Design of the naphthyl-diarylpyrimidines as potent non-nucleoside reverse transcriptase inhibitors (NNRTIs) via structure-based extension into the entrance channel

A series of novel naphthyl-diarylpyrimidine (DAPY) derivatives were designed and synthesized to explore the entrance channel of the non-nucleoside reverse transcriptase inhibitors binding pocket (NNIBP) by incorporating different flexible side chains at the C-6 position. The biological evaluation results showed that all analogues possessed promising HIV-1 inhibitory activity at the nanomolar concentration range. Three compounds (7, 9 and 39) displayed excellent potency against WT HIV-1 strain with EC₅₀ values ranging from 5 to 10 nM and high selectivity indexes (SI = 3504, 30488 and 22846, respectively), which were higher than for nevirapine and comparable to the values for etravirine. The RT inhibition activity, preliminary structure-activity relationship and molecular docking study showed that the side chain at the C-6 position of the DAPYs occupied the entrance channel and significantly influenced anti-HIV activity and selectivity. Additionally, the physicochemical properties were investigated to evaluate the drug-like features, which indicated that introducing various substituents on the pyrimidine ring can improve solubility.

Structure-Based Design and Discovery of Pyridyl-Bearing Fused Bicyclic HIV-1 Inhibitors: Synthesis, Biological Characterization, and Molecular Modeling Studies

Two series of new pyridyl-bearing fused bicyclic analogues designed to target the dual-tolerant regions of the non-nucleoside reverse transcriptase inhibitor (NNRTI)-binding pocket were synthesized and evaluated for their anti-HIV activities. Several compounds, such as 6, 14, 15, 21, 30, and 33, were found to be potent inhibitors against the wild-type (WT) HIV-1 strain or multiple NNRTI-resistant strains at low nanomolar levels. Detailed structure-activity relationships were obtained by utilizing the variation of moieties within the corresponding pharmacophores. In vitro metabolic stability profiles and some drug-like properties of selected compounds were assessed, furnishing the preliminary structure-metabolic stability relationships. Furthermore, molecular modeling studies elucidated the binding modes of compounds 6, 15, 21, and 30 in the binding pocket of WT, E138K, K103N, or Y181C HIV-1 RTs. These promising compounds can be used as lead compounds and warrant further structural optimization to yield more active HIV-1 inhibitors.

Improving Druggability of Novel Diarylpyrimidine NNRTIs by a Fragment-Based Replacement Strategy: From Biphenyl-DAPYs to Heteroaromatic-Biphenyl-DAPYs

A series of novel heteroaromatic-difluoro-biphenyl-diarylpyrimidines were designed as non-nucleoside anti-HIV inhibitors targeting reverse transcriptase by a fragment-based replacement strategy with the purpose of improving the druggability. Hopping five- or six-membered heterocycle groups on the biphenyl moiety as bioisosterism for intrinsically cyanophenyl gave 23 derivatives. All of these compounds possessed excellent HIV-1 inhibitory activity in the nanomolar range. Among them, 12g with a 4-pyridine group displayed excellent inhibitory activity toward WT and mutant HIV virus possessing significant selectivity. Moreover, this compound exhibited a decent improvement in druggability than etravirine and rilpivirine: (1) The hydrochloric acid salt of 12g exhibited significantly improved water solubility in different pH conditions. (2) 12g did not show apparent CYP enzymatic inhibitory activity or acute toxicity. (3) Excellent oral bioavailability was also revealed (F = 126%, rats) in 12g. Collectively, these novel heteroaromatic-biphenyl-DAPYs represent promising drug candidates for HIV clinical therapy.

Hydrophobic Pocket Occupation Design of Difluoro-Biphenyl-Diarylpyrimidines as Non-Nucleoside HIV-1 Reverse Transcriptase Inhibitors: from N-Alkylation to Methyl Hopping on the Pyrimidine Ring

Considering the nonideal metabolic stability of the difluoro-biphenyl-diarylpyrimidine lead compound 4, a series of novel alkylated difluoro-biphenyl-diarylpyrimidines were designed and synthesized based on their structure. Introducing alkyl or substituted alkyl groups on the linker region to block the potential metabolic sensitive sites generated 22 derivatives. Among them, compound 12a with an N-methyl group displayed excellent anti-HIV-1 activity and selectivity. The methyl group was hopped to the central pyrimidine to occupy the small linker region and maintain the water-mediated hydrogen bond observed in the binding of compound 4 with RT. The resulting compound 16y exhibited an improved anti-HIV-1 activity, much lower cytotoxicity, and nanomolar activity toward multiple mutants. In addition, 16y has a better stability in human liver microsomes than 4. Moreover, no apparent in vivo acute toxicity was observed in 16y-treated female, especially pregnant mice. This series of alkylated compounds with highly potency and safety represent a promising lead template for future discovery.

Druggability modification strategies of the diarylpyrimidine-type non-nucleoside reverse transcriptase inhibitors

Drug discovery of human immunodeficiency virus (HIV) is a hot field in medicinal chemistry community for many years. The diarylpyrimidines (DAPYs) are the second-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs) targeting reverse transcriptase, playing a great irreplaceable role in HIV transcriptional therapy. However, fast-growing drug-resistant mutations as nonnegligible challenge are still unpredictably appeared in the clinical practice, leading to deactivate or reduce the existing drugs. In the last 20 years, more and more novel DAPY derivatives have developed with the purpose to counter the mutants. Nevertheless, most of them have dissatisfactory pharmacokinetics (PK) or poor antiviral activity toward resistant mutant strains. In this article, we will analyze the NNRTI derivatives with promising druggability, and summarize a series of druggability modification strategies to improve the antiviral activity, reduce toxicity and improve the PK properties in recent years. The prospects of DAPYs and the directions for future efforts will be discussed.

Exploiting the tolerant region I of the non-nucleoside reverse transcriptase inhibitor (NNRTI) binding pocket. Part 2: Discovery of diarylpyrimidine derivatives as potent HIV-1 NNRTIs with high Fsp3 values and favorable drug-like properties

To yield potent HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) with favorable drug-like properties, a series of novel diarylpyrimidine derivatives targeting the tolerant region I of the NNRTI binding pocket were designed, synthesized and biologically evaluated. The most active inhibitor 10c exhibited outstanding antiviral activity against most of the viral panel, being about 2-fold (wild-type, EC₅₀ = 0.0021 μM), 1.7-fold (K103N, EC₅₀ = 0.0019 μM), and slightly more potent (E138K, EC₅₀ = 0.0075 μM) than the NNRTI drug etravirine (ETR). Additionally, 10c was endowed with relatively low cytotoxicity (CC₅₀ = 18.52 μM). More importantly, 10c possessed improved drug-like properties compared to those of ETR with an increased Fsp³ (Fraction of sp³ carbon atoms) value. Furthermore, the molecular dynamics simulation and molecular docking studies were implemented to reveal the binding mode of 10c in the binding pocket. Taken together, 10c is a promising lead compound that is worth further investigation.

Recent discoveries in HIV-1 reverse transcriptase inhibitors

HIV-1 reverse transcriptase inhibitors (RTIs) are indispensable components of highly active antiretroviral therapy (HAART), which has achieved great success in controlling AIDS epidemic in reducing drastically the morbidity and mortality of HIV-infected patients. RTIs are divided into two categories, nucleoside reverse transcriptase inhibitors (NRTIs) and nonnucleoside reverse transcriptase inhibitors (NNRTIs). In this review, the recent discoveries in NRTIs and NNRTIs, including approved anti-HIV drugs and noteworthy drug candidates in different development stages, are summarized, and their future direction is prospected.

1,2,3-Triazole hybrids with anti-HIV-1 activity

The human immunodeficiency virus type 1 (HIV-1) is the major etiological agent responsible for the acquired immunodeficiency syndrome (AIDS), which is a serious infectious disease and remains one of the most prevalent problems at present. Currently, combined antiretroviral therapy is the primary modality for the treatment and management of HIV/AIDS, but the long-term use can result in major drawbacks such as the development of multidrug-resistant viruses and multiple side effects. 1,2,3-Triazole is the common framework in the development of new drugs, and its derivatives have the potential to inhibit various HIV-1 enzymes such as reverse transcriptase, integrase, and protease, consequently possessing a potential anti-HIV-1 activity. This review covers the recent advances regarding the 1,2,3-triazole hybrids with potential anti-HIV-1 activity; it focuses on the chemical structures, structure-activity relationship, and mechanisms of action, covering articles published from 2010 to 2020.

Structure-based non-nucleoside inhibitor design: Developing inhibitors that are effective against resistant mutants

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) inhibit reverse transcription and block the replication of HIV-1. Currently, NNRTIs are usually used as part of a three-drug combination given to patients as antiretroviral therapy. These combinations involve other classes of anti-HIV-1 drugs, commonly nucleoside reverse transcriptase inhibitors (NRTIs). However, attempts are being made to develop two-drug maintenance therapies, some of which involve an NNRTI and an integrase strand transfer inhibitor. This has led to a renewed interest in developing novel NNRTIs, with a major emphasis on designing compounds that can effectively inhibit the known NNRTI-resistant mutants. We have generated and tested novel rilpivirine (RPV) analogs. The new compounds were designed to exploit a small opening in the upper right periphery of the NNRTI-binding pocket. The best of the new compounds, 12, was a more potent inhibitor of the NNRTI-resistant mutants we tested than either doravirine or efavirenz but was inferior to RPV. We describe the limitations on the modifications that can be appended to the "upper right side" of the RPV core and the effects of substituting other cores for the central pyrimidine core of RPV and make suggestions about how this information can be used in NNRTI design.

Design, synthesis, and biological evaluation of piperidinyl-substituted [1,2,4]triazolo[1,5-a]pyrimidine derivatives as potential anti-HIV-1 agents with reduced cytotoxicity

Taking the previously reported compound BH-7d as the lead, we designed and synthesized a series of piperidinyl-substituted [1,2,4]triazolo[1,5-a]pyrimidines, and their anti-HIV activities as well as cytotoxicities were evaluated. Several compounds exhibited moderate anti-HIV (IIIB) potency, among which 2b was the most active one (EC₅₀  = 4.29 μM). Structure-activity relationships derived from the antiretroviral results were analyzed. Additionally, most compounds demonstrated reduced cytotoxicity (CC₅₀  > 200 μM) compared with those of BH-7d and etravirine. Molecular docking study further revealed the binding conformation of 2b in the binding pocket of HIV-1 reverse transcriptase.

Development of non-nucleoside reverse transcriptase inhibitors (NNRTIs): our past twenty years

Human immunodeficiency virus (HIV) is the primary infectious agent of acquired immunodeficiency syndrome (AIDS), and non-nucleoside reverse transcriptase inhibitors (NNRTIs) are the cornerstone of HIV treatment. In the last 20 years, our medicinal chemistry group has made great strides in developing several distinct novel NNRTIs, including 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT), thio-dihydro-alkoxy-benzyl-oxopyrimidine (S-DABO), diaryltriazine (DATA), diarylpyrimidine (DAPY) analogues, and their hybrid derivatives. Application of integrated modern medicinal strategies, including structure-based drug design, fragment-based optimization, scaffold/fragment hopping, molecular/fragment hybridization, and bioisosterism, led to the development of several highly potent analogues for further evaluations. In this paper, we review the development of NNRTIs in the last two decades using the above optimization strategies, including their structure–activity relationships, molecular modeling, and their binding modes with HIV-1 reverse transcriptase (RT). Future directions and perspectives on the design and associated challenges are also discussed.

Fragment hopping-based discovery of novel sulfinylacetamide-diarylpyrimidines (DAPYs) as HIV-1 nonnucleoside reverse transcriptase inhibitors

The fragment hopping approach is widely applied in drug development. A series of diarylpyrimidines (DAPYs) were obtained by hopping the thioacetamide scaffold to novel human immunodeficiency virus type 1 (HIV-1) nonnucleoside reverse transcriptase inhibitors (NNRTIs) to address the cytotoxicity issue of Etravirine and Rilpivirine. Although the new compounds (11a-l) in the first-round optimization possessed less potent anti-viral activity, they showed much lower cytotoxicity. Further optimization on the sulfur led to the sulfinylacetamide-DAPYs exhibiting improved anti-viral activity and a higher selectivity index especially toward the K103N mutant strain. The most potent compound 12a displayed EC₅₀ values of 0.0249 μM against WT and 0.0104 μM against the K103N mutant strain, low cytotoxicity (CC₅₀ > 221 μM) and a high selectivity index (SI _WT > 8873, SI _K103N > 21186). In addition, this compound showed a favorable in vitro microsomal stability across species. Computational study predicted the binding models of these potent compounds with HIV-1 reverse transcriptase thus providing further insights for new developments.

Delay of cell growth and loss of stemness by inhibition of reverse transcription in human mesenchymal stem cells derived from dental tissue

The present study investigated the cellular properties in the dental tissue-derived mesenchymal stem cells (DSCs) exposed to nevirapine (NVP), an inhibitor of reverse transcriptase (RTase). After a prolonged exposure of DSCs for 2 weeks, the population doubling time (PDT) was significantly (P < .05) increased by delayed cell growth in the DSCs treated with 250 and 500 μM NVP, compared with untreated DSCs. Furthermore, the G1 phase of cell cycle with high activity of senescence-associated β-galactosidase was also significantly (P < .05) increased in the 250 μM NVP-treated DSCs, compared with untreated DSCs. The level of telomerase activity was unchanged between control and treatment. However, following the treatment of NVP, negative surface markers for mesenchymal stem cells (MSCs), such as CD34 and CD45, were significantly (P < .05) increased, while positive surface markers for MSCs, such as CD90 and CD105, were significantly (P < .05) decreased in the NVP-treated DSCs than those of untreated DSCs. Furthermore, the differentiation capacity into mesodermal lineage was gradually decreased, and a significant (P < .05) decrease of expression level of NANOG, OCT-4 and SOX-2 transcripts was observed in the DSCs treated with NVP, compared with untreated control DSCs. Taken together, the present results have revealed that inhibition of RTase by NVP induces delayed cell growth and loss of stemness.

Evolution of HIV-1 reverse transcriptase and integrase dual inhibitors: Recent advances and developments

HIV infection is a major challenge to mankind and a definitive cure or a viable vaccine for HIV is still elusive. HIV-1 is constantly evolving and developing resistant against clinically used anti-HIV drugs thus posing serious hurdles in the treatment of HIV infection. This prompts the need to developed new anti-HIV drugs; preferentially adopting intelligent ways to counteract an evolving virus. Highly Active Anti-Retroviral Therapy (HAART): a strategy involving multiple targeting through various drugs has proven beneficial in the management of AIDS. However, it is a complex regimen with high drug load, increased risk of drug interactions and adverse effects, which lead to poor patient compliance. Reverse transcriptase (RT) and Integrase (IN) are two pivotal enzymes in HIV-1 lifecycle with high structural and functional analogy to be perceived as drug-able targets for novel dual-purpose inhibitors. Designed multi-functional ligand (DML) is a modern strategy by which multiple targets can be exploited using a single chemical entity. A single chemical entity acting on multiple targets can be much more effective than a complex multi-drug regimen. The development of such multifunctional ligands is highly valued in anti-HIV drug discovery with the proposed advantage of being able to stop two or more stages of viral replication cycle. This review will encompass the evolution of the RT-IN dual inhibitory scaffolds reported so far and the contribution made by the leading research groups over the years in this field.