Privileged scaffold inspired design of novel oxime-biphenyl-DAPYs in treatment of HIV-1

Deciphering the enigmas of non-nucleoside reverse transcriptase inhibitors (NNRTIs): A medicinal chemistry expedition towards combating HIV drug resistance

The pivotal involvement of reverse transcriptase activity in the pathogenesis of the progressive HIV virus has stimulated gradual advancements in drug discovery initiatives spanning three decades. Consequently, nonnucleoside reverse transcriptase inhibitors (NNRTIs) have emerged as a preeminent category of therapeutic agents for HIV management. Academic institutions and pharmaceutical companies have developed numerous NNRTIs, an essential component of antiretroviral therapy. Six NNRTIs have received Food and Drug Administration approval and are widely used in clinical practice, significantly improving the quality of HIV patients. However, the rapid emergence of drug resistance has limited the effectiveness of these medications, underscoring the necessity for perpetual research and development of novel therapeutic alternatives. To supplement the existing literatures on NNRTIs, a comprehensive review has been compiled to synthesize this extensive dataset into a comprehensible format for the medicinal chemistry community. In this review, a thorough investigation and meticulous analysis were conducted on the progressions achieved in NNRTIs within the past 8 years (2016-2023), and the experiences and insights gained in the development of inhibitors with varying chemical structures were also summarized. The provision of a crucial point of reference for the development of wide-ranging anti-HIV medications is anticipated.

A survey of isatin hybrids and their biological properties

The emergence of diverse infections worldwide, which is a serious global threat to human existence, necessitates the urgent development of novel therapeutic candidates that can combat these diseases with efficacy. Molecular hybridization has been established as an efficient technique in designing bioactive molecules capable of fighting infections. Isatin, a core nucleus of an array of compounds with diverse biological properties can be modified at different positions leading to the creation of novel drug targets, is an active area of medicinal chemistry. This review containing published articles from 2005 to 2022 highlights isatin hybrids which have been synthesized and reported in the literature alongside a discussion on their biological properties. The enriched structure-activity relationship studies discussed provides insights for the rational design of novel isatin hybrids with tailored biological properties as effective therapeutic candidates inspired by nature.

Design and synthesis of Fsp3-enriched spirocyclic-substituted diarylpyrimidine derivatives as novel HIV-1 NNRTIs

In this study, a novel series of diarylpyrimidine derivatives with Fsp3-enriched spirocycles were designed and synthesized to further explore the chemical space of the hydrophobic channel of the NNRTI-binding pocket. The biological evaluation results showed that most of the compounds displayed effective inhibitory potency against the HIV-1 wild-type strain, with EC50 values ranging from micromolar to submicromolar levels. Among them, TT6 turned out to be the most effective inhibitor with an EC50 value of 0.17 μM, demonstrating up to 47 times more active than that of reference drug 3TC (EC50 = 8.01 μM). More encouragingly, TT6 was found to potently inhibit the HIV-1 mutant strain K103N with an EC50 value of 0.69 μM, being about 6-fold more potent than 3TC (EC50 = 3.68 μM) and NVP (EC50 = 4.62 μM). Furthermore, TT6 exhibited the most potent inhibitory activity toward HIV-1 reverse transcriptase with an IC50 value of 0.33 μM. Additionally, molecular simulation studies were conducted to investigate the binding modes between TT6 and NNRTI-binding pocket, which may provide valuable clues for the follow-up structural optimizations.

3D-QSAR, molecular docking, and molecular dynamics analysis of novel biphenyl-substituted pyridone derivatives as potent HIV-1 NNRTIs

When designing new medications targeting HIV-1, drug designers concentrate on reverse transcriptase (RT), the central enzyme of their concern. This is due to its vital role in converting single-stranded RNA into double-stranded DNA throughout the life cycle of HIV-1. In recent reports, a series of newly discovered pyridone derivatives with biphenyl substitutions have emerged as highly potent HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs), displaying impressive antiviral activity. To analyse the three-dimensional quantitative structure-activity relationship (3D-QSAR) of pyridone inhibitors with biphenyl substitutions, we employed CoMFA and CoMSIA methods in this study. The dataset comprises a total of 51 compounds. The findings of this research demonstrate that both the CoMFA (q2=0.688, r2=0.976, rpred2=0.831) and CoMSIA/SHE (q2=0.758, r2=0.968, rpred2=0.828) models exhibit excellent predictive capability and reliable estimation stability. According to the findings of the model, we designed a collection of eleven molecules that exhibit the potential for significantly improved predictive activity. We proceeded to investigate the binding patterns of these compounds to receptor proteins utilizing the molecular docking technique. To ensure the reliability of the docking results, we went on to validate them by conducting molecular dynamics simulations and performing accurate calculations of the binding free energy. Moreover, based on initial ADMET predictions, the results consistently indicate that the newly created molecule possesses favourable pharmacokinetic properties. This study will help to facilitate the development of efficient novel inhibitors that specifically target HIV-1's non-nucleoside reverse transcriptase (NNRTIs).Communicated by Ramaswamy H. Sarma.

Design and Synthesis of Novel HIV-1 NNRTIs with Bicyclic Cores and with Improved Physicochemical Properties

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) represent cornerstones of current regimens for treatment of human immunodeficiency virus type 1 (HIV-1) infections. However, NNRTIs usually suffer from low aqueous solubility and the emergence of resistant viral strains. In the present work, novel bicyclic NNRTIs derived from etravirine (ETV) and rilpivirine (RPV), bearing modified purine, tetrahydropteridine, and pyrimidodiazepine cores, were designed and prepared. Compounds 2, 4, and 6 carrying the acrylonitrile moiety displayed single-digit nanomolar activities against the wild-type (WT) virus (EC50 = 2.5, 2.7, and 3.0 nM, respectively), where the low nanomolar activity was retained against HXB2 (EC50 = 2.2-2.8 nM) and the K103N and Y181C mutated strains (fold change, 1.2-6.7×). Most importantly, compound 2 exhibited significantly improved phosphate-buffered saline solubility (10.4 μM) compared to ETV and RPV (≪1 μM). Additionally, the binding modes of compounds 2, 4, and 6 to the reverse transcriptase were studied by X-ray crystallography.

Synthesis and antiviral activity of diverse heterocyclic scaffolds

Heterocyclic moieties form a major part of organic chemistry as they are widely distributed in nature and have wide scale practical applications ranging from extensive clinical use to diverse fields such as medicine, agriculture, photochemistry, biocidal formulations, and polymer science. By virtue of their therapeutic properties, they could be employed in combating many infectious diseases. Among the common infectious diseases, viral infections are of great public health importance worldwide. Thus, there is an urgent need for the discovery and development of antiviral drugs and clinical methods to prevent various viral infections so as to increase the life expectancy. This review presents the comprehensive overview of the synthesis and antiviral activity of different heterocyclic compounds 2015 onwards, which aids in present knowledge and helps the researchers and other stakeholders to explore their field.

Design, synthesis, and antiviral evaluation of novel piperidine-substituted arylpyrimidines as HIV-1 NNRTIs by exploring the hydrophobic channel of NNIBP

Herein, alkenylpiperidine and alkynylpiperidine moieties were introduced into the left wing of DAPYs (diarylpyrimidines) to explore the new site of the NNIBP (non-nucleoside inhibitor binding pocket) protein-solvent interface region via the structure-based drug design strategy. All the synthesized compounds displayed nanomolar to submicromolar activity against WT (wild-type) HIV-1. Among all, compound FT1 (EC₅₀ = 19 nM) was found to be the most active molecule, which is better than NVP (EC₅₀ = 0.10 μM). In addition, most of the compounds displayed micromolar activity against K103N and E138K mutant strains, while FT1 (EC_50(K103N) = 50 nM, EC_50(E138K) = 0.19 µM) still has the most effective activity. The molecular dynamics simulation studies revealed that the presence of pyridine moiety of FT1 was essential and played a significant role in its binding with RT (reverse transcriptase).

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.