Identification of novel potent HIV-1 inhibitors by exploiting the tolerant regions of the NNRTIs binding pocket

Discovery of potent HIV-1 NNRTIs by CuAAC click-chemistry-based miniaturized synthesis, rapid screening and structure optimization

In addressing the urgent need for novel HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) to combat drug resistance, we employed CuAAC click chemistry to construct a diverse 312-member diarylpyrimidine (DAPY) derivative library. This rapid synthesis approach facilitated the identification of A6N36, demonstrating exceptional HIV-1 RT inhibitory activity. Moreover, it was demonstrated with EC50 values of 1.8-8.7 nM for mutant strains L100I, K103 N, Y181C, and E138K, being equipotent or superior to that of ETR. However, A6N36's efficacy was compromised against specific resistant strains (Y188L, F227L + V106A and RES056), highlighting a need for further optimization. Through scaffold hopping, we optimized this lead to develop 10c, which exhibited broad-spectrum activity with EC50 values ranging from 3.2 to 57.5 nM and superior water solubility. Molecular docking underscored the key interactions of 10c within the NNIBP. Our findings present 10c as a promising NNRTI lead, illustrating the power of click chemistry and rational design in combatting HIV-1 resistance.

Advances in diarylpyrimidines and related analogues as HIV-1 nonnucleoside reverse transcriptase inhibitors (2019-2023)

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) have emerged as a vital cornerstone of highly active antiretroviral therapy (HAART) regimens, owing to their unique antiviral activity, low toxicity and high specificity. Diarylpyrimidines (DAPYs) as the second generation NNRTIs, represented by etravirine and rilpivirine, have attracted extensive attention due to their high anti-HIV potency. However, rapid emergence of resistant mutations, suboptimal pharmacokinetics (PK), and toxicity remain significant challenges. Recent structural modifications of DAPY analogues have focused on improving resistance profiles, optimizing PK properties (such as half-life and bioavailability), diversifying core structures through scaffold hopping, refining side-chain structures to enhance activity and selectivity, and reducing toxicity and side effects. Moreover, developing new DAPY analogues with broad-spectrum antiviral activity has become a key research priority. This review provides a comprehensive overview of the evolution of DAPYs from 2019 to 2023, including scaffold hopping and structural modifications of the right wing, left wing, central pyrimidine core, and linker, affording valuable insights for the future development of effective HIV-1 inhibitors.

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.

Strategies in the Design and Development of Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)

AIDS (acquired immunodeficiency syndrome) is a potentially life-threatening infectious disease caused by human immunodeficiency virus (HIV). To date, thousands of people have lost their lives annually due to HIV infection, and it continues to be a big public health issue globally. Since the discovery of the first drug, Zidovudine (AZT), a nucleoside reverse transcriptase inhibitor (NRTI), to date, 30 drugs have been approved by the FDA, primarily targeting reverse transcriptase, integrase, and/or protease enzymes. The majority of these drugs target the catalytic and allosteric sites of the HIV enzyme reverse transcriptase. Compared to the NRTI family of drugs, the diverse chemical class of non-nucleoside reverse transcriptase inhibitors (NNRTIs) has special anti-HIV activity with high specificity and low toxicity. However, current clinical usage of NRTI and NNRTI drugs has limited therapeutic value due to their adverse drug reactions and the emergence of multidrug-resistant (MDR) strains. To overcome drug resistance and efficacy issues, combination therapy is widely prescribed for HIV patients. Combination antiretroviral therapy (cART) includes more than one antiretroviral agent targeting two or more enzymes in the life cycle of the virus. Medicinal chemistry researchers apply different optimization strategies including structure- and fragment-based drug design, prodrug approach, scaffold hopping, molecular/fragment hybridization, bioisosterism, high-throughput screening, covalent-binding, targeting highly hydrophobic channel, targeting dual site, and multi-target-directed ligand to identify and develop novel NNRTIs with high antiviral activity against wild-type (WT) and mutant strains. The formulation experts design various delivery systems with single or combination therapies and long-acting regimens of NNRTIs to improve pharmacokinetic profiles and provide sustained therapeutic effects.

N-Phenyl-1-(phenylsulfonyl)-1H-1,2,4-triazol-3-amine as a New Class of HIV-1 Non-nucleoside Reverse Transcriptase Inhibitor

Highly active antiretroviral therapy (HAART) has revolutionized human immunodeficiency virus (HIV) healthcare, turning it from a terminal to a potentially chronic disease, although some patients can develop severe comorbidities. These include neurological complications, such as HIV-associated neurocognitive disorders (HAND), which result in cognitive and/or motor function symptoms. We now describe the discovery, synthesis, and evaluation of a new class of N-phenyl-1-(phenylsulfonyl)-1H-1,2,4-triazol-3-amine HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTI) aimed at avoiding HAND. The most promising molecule, 12126065, exhibited antiviral activity against wild-type HIV-1 in TZM cells (EC50 = 0.24 nM) with low in vitro cytotoxicity (CC50 = 4.8 μM) as well as retained activity against clinically relevant HIV mutants. 12126065 also demonstrated no in vivo acute or subacute toxicity, good in vivo brain penetration, and minimal neurotoxicity in mouse neurons up to 10 μM, with a 50% toxicity concentration (TC50) of >100 μM, well below its EC50.

Discovery of diarylpyrimidine derivatives bearing piperazine sulfonyl as potent HIV-1 nonnucleoside reverse transcriptase inhibitors

HIV-1 reverse transcriptase is one of the most attractive targets for the treatment of AIDS. However, the rapid emergence of drug-resistant strains and unsatisfactory drug-like properties seriously limit the clinical application of HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs). Here we show that a series of piperazine sulfonyl-bearing diarylpyrimidine-based NNRTIs were designed to improve the potency against wild-type and NNRTI-resistant strains by enhancing backbone-binding interactions. Among them, compound 18b1 demonstrates single-digit nanomolar potency against the wild-type and five mutant HIV-1 strains, which is significantly better than the approved drug etravirine. The co-crystal structure analysis and molecular dynamics simulation studies were conducted to explain the broad-spectrum inhibitory activity of 18b1 against reverse transcriptase variants. Besides, compound 18b1 demonstrates improved water solubility, cytochrome P450 liability, and other pharmacokinetic properties compared to the currently approved diarylpyrimidine (DAPY) NNRTIs. Therefore, we consider compound 18b1 a potential lead compound worthy of further study.

Contemporary Medicinal Chemistry Strategies for the Discovery and Development of Novel HIV-1 Non-nucleoside Reverse Transcriptase Inhibitors

Currently, HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) are a major component of the highly active anti-retroviral therapy (HAART) regimen. However, the occurrence of drug-resistant strains and adverse reactions after long-term usage have inevitably compromised the clinical application of NNRTIs. Therefore, the development of novel inhibitors with distinct anti-resistance profiles and better pharmacological properties is still an enormous challenge. Herein, we summarize state-of-the-art medicinal chemistry strategies for the discovery of potent NNRTIs, such as structure-based design strategies, contemporary computer-aided drug design, covalent-binding strategies, and the application of multi-target-directed ligands. The strategies described here will facilitate the identification of promising HIV-1 NNRTIs.

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.