Development of fluorine-substituted NH2-biphenyl-diarylpyrimidines as highly potent non-nucleoside reverse transcriptase inhibitors: Boosting the safety and metabolic stability

Our recent studies for nonnucleoside reverse transcriptase inhibitors identified a highly potent compound JK-4b against WT HIV-1 (EC50 = 1.0 nmol/L), but the poor metabolic stability in human liver microsomes (t 1/2 = 14.6 min) and insufficient selectivity (SI = 2059) with high cytotoxicity (CC50 = 2.08 μmol/L) remained major issues associated with JK-4b. The present efforts were devoted to the introduction of fluorine into the biphenyl ring of JK-4b, leading to the discovery of a novel series of fluorine-substituted NH2-biphenyl-diarylpyrimidines with noticeable inhibitory activity toward WT HIV-1 strain (EC50 = 1.8-349 nmol/L). The best compound 5t in this collection (EC50 = 1.8 nmol/L, CC50 = 117 μmol/L) was 32-fold in selectivity (SI = 66,443) compared to JK-4b and showed remarkable potency toward clinically multiple mutant strains, such as L100I, K103N, E138K, and Y181C. The metabolic stability of 5t was also significantly improved (t 1/2 = 74.52 min), approximately 5-fold higher than JK-4b in human liver microsomes (t 1/2 = 14.6 min). Also, 5t possessed good stability in both human and monkey plasma. No significant in vitro inhibition effect toward CYP enzyme and hERG was observed. The single-dose acute toxicity test did not induce mice death or obvious pathological damage. These findings pave the way for further development of 5t as a drug candidate.

Picomolar inhibitor of reverse transcriptase featuring significantly improved metabolic stability

Considering the undesirable metabolic stability of our recently identified NNRTI 5 (t1/2 = 96 min) in human liver microsomes, we directed our efforts to improve its metabolic stability by introducing a new favorable hydroxymethyl side chain to the C-5 position of pyrimidine. This strategy provided a series of novel methylol-biphenyl-diarylpyrimidines with excellent anti-HIV-1 activity. The best compound 9g was endowed with remarkably improved metabolic stability in human liver microsomes (t1/2 = 2754 min), which was about 29-fold longer than that of 5 (t1/2 = 96 min). This compound conferred picomolar inhibition of WT HIV-1 (EC50 = 0.9 nmol/L) and low nanomolar activity against five clinically drug-resistant mutant strains. It maintained particularly low cytotoxicity (CC50 = 264 μmol/L) and good selectivity (SI = 256,438). Molecular docking studies revealed that compound 9g exhibited a more stable conformation than 5 due to the newly constructed hydrogen bond of the hydroxymethyl group with E138. Also, compound 9g was characterized by good safety profiles. It displayed no apparent inhibition of CYP enzymes and hERG. The acute toxicity assay did not cause death and pathological damage in mice at a single dose of 2 g/kg. These findings paved the way for the discovery and development of new-generation anti-HIV-1 drugs.

Discovery of novel sulfonamide substituted indolylarylsulfones as potent HIV-1 inhibitors with better safety profiles

Indolylarylsulfones (IASs) are classical HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) with a unique scaffold and possess potent antiviral activity. To address the high cytotoxicity and improve safety profiles of IASs, we introduced various sulfonamide groups linked by alkyl diamine chain to explore the entrance channel of non-nucleoside inhibitors binding pocket. 48 compounds were designed and synthesized to evaluate their anti-HIV-1 activities and reverse transcriptase inhibition activities. Especially, compound R10L4 was endowed with significant inhibitory activity towards wild-type HIV-1 (EC50(WT) = 0.007 μmol/L, SI = 30,930) as well as a panel of single-mutant strains exemplified by L100I (EC50 = 0.017 μmol/L, SI = 13,055), E138K (EC50 = 0.017 μmol/L, SI = 13,123) and Y181C (EC50 = 0.045 μmol/L, SI = 4753) which were superior to Nevirapine and Etravirine. Notably, R10L4 was characterized with significantly reduced cytotoxicity (CC50 = 216.51 μmol/L) and showed no remarkable in vivo toxic effects (acute and subacute toxicity). Moreover, the computer-based docking study was also employed to characterize the binding mode between R10L4 and HIV-1 RT. Additionally, R10L4 presented an acceptable pharmacokinetic profile. Collectively, these results deliver precious insights for next optimization and indicate that the sulfonamide IAS derivatives are promising NNRTIs for further development.

Structure-based design of novel heterocycle-substituted ATDP analogs as non-nucleoside reverse transcriptase inhibitors with improved selectivity and solubility

Following on our recently developed biphenyl-ATDP non-nucleoside reverse transcriptase inhibitor ZLM-66 (SI = 2019.80, S = 1.9 μg/mL), a series of novel heterocycle-substituted ATDP derivatives with significantly improved selectivity and solubility were identified by replacement of the biphenyl moiety of ZLM-66 with heterocyclic group with lower lipophilicity. Evidently, the representative analog 7w in this series exhibited dramatically enhanced selectivity and solubility (SI = 12,497.73, S = 4472 μg/mL) in comparison with ZLM-66 (SI = 2019.80, S = 1.9 μg/mL). This new NNRTI conferred low nanomolar inhibition of wild-type HIV-1 strain and tested mutant strains (K103N, L100I, Y181C, E138K, and K103N + Y181C). The analog also demonstrated favorable safety and pharmacokinetic profiles, as evidenced by its insensitivity to CYP and hERG, lack of mortality and pathological damage, and good oral bioavailability in rats (F = 27.1%). Further development of 7w for HIV therapy will be facilitated by this valuable information.

Exploring the hydrophobic channel of NNIBP leads to the discovery of novel piperidine-substituted thiophene3,2-pyrimidine derivatives as potent HIV-1 NNRTIs

In this report, a series of novel piperidine-substituted thiophene[3,2-]pyrimidine derivatives were designed to explore the hydrophobic channel of the non-nucleoside reverse transcriptase inhibitors binding pocket (NNIBP) by incorporating an aromatic moiety to the left wing of the lead . The newly synthesized compounds were evaluated for anti-HIV potency in MT-4 cells and inhibitory activity to HIV-1 reverse transcriptase (RT). Most of the synthesized compounds exhibited broad-spectrum activity toward wild-type and a wide range of HIV-1 strains carrying single non-nucleoside reverse transcriptase inhibitors (NNRTI)-resistant mutations. Especially, compound exhibited the most potent activity against wild-type and a panel of single mutations (L100I, K103N, Y181C, Y188L and E138K) with an EC ranging from 6.02 to 23.9 nmol/L, which were comparable to those of etravirine (ETR). Moreover, the RT inhibition activity, preliminary structure-activity relationship and molecular docking were also investigated. Furthermore, exhibited favorable pharmacokinetics (PK) profiles and with a bioavailability of 33.8%. Taken together, the results could provide valuable insights for further optimization and compound holds great promise as a potential drug candidate for the treatment of HIV-1 infection.

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 (-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.

Improving the positional adaptability: structure-based design of biphenyl-substituted diaryltriazines as novel non-nucleoside HIV-1 reverse transcriptase inhibitors

In order to improve the positional adaptability of our previously reported naphthyl diaryltriazines (NP-DATAs), synthesis of a series of novel biphenyl-substituted diaryltriazines (BP-DATAs) with a flexible side chain attached at the C-6 position is presented. These compounds exhibited excellent potency against wild-type (WT) HIV-1 with EC values ranging from 2.6 to 39 nmol/L and most of them showed low nanomolar anti-viral potency against a panel of HIV-1 mutant strains. Compounds and had the best activity against WT, single and double HIV-1 mutants and reverse transcriptase (RT) enzyme comparable to two reference drugs (EFV and ETR) and our lead compound NP-DATA (). Molecular modeling disclosed that the side chain at the C-6 position of DATAs occupied the entrance channel of the HIV-1 reverse transcriptase non-nucleoside binding pocket (NNIBP) attributing to the improved activity. The preliminary structure-activity relationship and PK profiles were also discussed.

Non-nucleoside reverse transcriptase inhibitors (Part 18): synthesis and anti-HIV activity of 4-allylamino or 4-azido substituted diaryltriazines / 药学学报

Eight new diaryltriazine derivatives containing 4-allylamino and 4-azido substitutes guided by molecular docking have been designed and synthesized based on our previous work. The evaluation of HIV inhibitory activity demonstrated that all compounds were potent against HIV-1 replication. The most active compound 7c exhibited activity against HIV-1 (IC50 = 0.034 micromol x L(-1), SI = 6,475) and the double mutant strain (IC50 = 9.39 micromol x L(-1)) in the micromolar range, which was more potent than nevirapine.