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.

Antiviral Drug Discovery.

A vast and painful price has been paid in the battle against viruses in global health [...].

Design and optimization of piperidine-substituted thiophene[3,2-d]pyrimidine-based HIV-1 NNRTIs with improved drug resistance and pharmacokinetic profiles.

HIV-1 reverse transcriptase (RT) has received great attention as an attractive therapeutic target for acquired immune deficiency syndrome (AIDS), but the inevitable drug resistance and side effects have always been major challenges faced by non-nucleoside reverse transcriptase inhibitors (NNRTIs). This work aimed to identify novel chemotypes of anti-HIV-1 agents with improved drug-resistance profiles, reduced toxicity, and excellent druggability. A series of diarylpyrimidine (DAPY) derivatives were prepared via structural modifications of the leads K-5a2 and 25a. Among them, 15a with dimethylphosphine oxide moiety showed the most prominent antiviral potency against all of the tested viral panel, being 1.6-fold (WT, EC50 = 1.75 nmol/L), 3.0-fold (L100I, EC50 = 2.84 nmol/L), 2.4-fold (K103N, EC50 = 1.27 nmol/L), 3.3-fold (Y181C, EC50 = 5.38 nmol/L), 2.9-fold (Y188L, EC50 = 7.96 nmol/L), 2.5-fold (E138K, EC50 = 4.28 nmol/L), 4.8-fold (F227L/V106A, EC50 = 3.76 nmol/L) and 5.3-fold (RES056, EC50 = 15.8 nmol/L) more effective than that of the marketed drug ETR. Molecular docking results illustrated the detailed interactions formed by compound 15a and WT, F227L/V106A, and RES056 RT. Moreover, 15a·HCl carried outstanding pharmacokinetic (t 1/2 = 1.32 h, F = 40.8%) and safety profiles (LD50 > 2000 mg/kg), which demonstrated that 15a HCl is a potential anti-HIV-1 drug candidate.

Structure-based design, synthesis, and biological characterization of indolylarylsulfone derivatives as novel human immunodeficiency virus type 1 inhibitors with potent antiviral activities and favorable drug-like profiles.

In the current antiretroviral landscape, continuous efforts are still needed to search for novel chemotypes of human immunodeficiency virus type 1 (HIV-1) inhibitors with improved drug resistance profiles and favorable drug-like properties. Herein, we report the design, synthesis, biological characterization, and druggability evaluation of a class of non-nucleoside reverse transcriptase inhibitors. Guided by the available crystallographic information, a series of novel indolylarylsulfone derivatives were rationally discovered via the substituent decorating strategy to fully explore the chemical space of the entrance channel. Among them, compound 11h bearing the cyano-substituted benzyl moiety proved to be the most effective inhibitor against HIV-1 wild-type and mutant strains (EC50 = 0.0039-0.338 µM), being far more potent than or comparable to etravirine and doravirine. Besides, 11h did not exhibit cytotoxicity at the maximum test concentration. Meanwhile, the binding target of 11h was further confirmed to be reverse transcriptase (IC50 = 0.055 µM). Preliminary structure-activity relationship were discussed to guide further optimization work. Molecular docking and dynamics simulation studies were investigated in detail to rationalize the biological evaluation results. Further drug-likeness assessment indicated that 11h possessed excellent physicochemical properties. Moreover, no apparent hERG blockade liability and cytochrome P450 inhibition were observed for 11h. Notably, 11h was characterized by favorable in vitro metabolic stability with moderate clearance rates and long half-lives in human plasma and liver microsomes. Overall, 11h holds great promise as an ideal Anti-HIV-1 lead compound due to its potent antiviral efficacy, low toxicity, and favorable drug-like profiles.

A review of research advances and perspectives on the habitat ecology of Sichuan and golden takins: 2001 to 2022.

The Sichuan takin (Budorcas tibetanus) and the golden takin (Budorcas bedfordi) are endemic to China. Studies of their habitat ecology have attracted attention, but dedicated reviews of the topic have not been published. To fill this gap, research advances on the habitat ecology of these takin species were reviewed based on published journal papers from 2001-2022, covering habitat selection and use, as well as habitat assessment and protection. Habitat selection and use by the takins received the most frequent reports in a few protected areas, such as the Tangjiahe Nature Reserve in Sichuan and the Foping Nature Reserve in Shaanxi. Higher herb cover characterized some of the Sichuan takin habitats, while some of the golden takin population exhibited seasonal altitude migration. The focus on habitat assessment and protection differed between the two species. Studying the habitat of the Sichuan takin involves the relationship between its habitat and the protected areas and habitat status in various ranges while studying the habitat of the golden takin involves habitat distribution and change, protection effects, and corridor planning. Some issues worthy of consideration in future research are proposed, including basic habitat information, impacts of human disturbances, habitat restoration, and theoretical, independent, and comprehensive studies on both takins. Habitat conservation frameworks should be formulated for both takins to improve protection and restoration effects. This review provides convenient information to help understand the habitat characteristics of the two takins and is a reference for future research.

Discovery of GluN2A subtype-selective N-methyl-d-aspartate (NMDA) receptor ligands.

The N-methyl-d-aspartate (NMDA) receptors, which belong to the ionotropic Glutamate receptors, constitute a family of ligand-gated ion channels. Within the various subtypes of NMDA receptors, the GluN1/2A subtype plays a significant role in central nervous system (CNS) disorders. The present article aims to provide a comprehensive review of ligands targeting GluN2A-containing NMDA receptors, encompassing negative allosteric modulators (NAMs), positive allosteric modulators (PAMs) and competitive antagonists. Moreover, the ligands' structure-activity relationships (SARs) and the binding models of representative ligands are also discussed, providing valuable insights for the clinical rational design of effective drugs targeting CNS diseases.

Discovery of Novel Aryl Triazolone Dihydropyridines (ATDPs) Targeting Highly Conserved Residue W229 as Promising HIV-1 NNRTIs.

NNRTI is an important component of the highly active antiretroviral therapy (HAART), but the rapid emergence of drug resistance and poor pharmacokinetics limited their clinical application. Herein, a series of novel aryl triazolone dihydropyridines (ATDPs) were designed by structure-guided design with the aim of improving drug resistance profiles and pharmacokinetic profiles. Compound 10n (EC50 = 0.009-17.7 µM) exhibited the most active potency, being superior to or comparable to that of doravirine (DOR) against the whole tested viral panel. Molecular docking was performed to clarify the reason for its higher resistance profiles. Moreover, 10n demonstrated excellent pharmacokinetic profile (T1/2 = 5.09 h, F = 108.96%) compared that of DOR (T1/2 = 4.4 h, F = 57%). Additionally, 10n was also verified to have no in vivo acute or subacute toxicity (LD50 > 2000 mg/kg), suggesting that 10n is worth further investigation as a novel oral NNRTIs for HIV-1 therapy.

Structure-based design of diarylpyrimidines and triarylpyrimidines as potent HIV-1 NNRTIs with improved metabolic stability and drug resistance profiles.

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are an important component of anti-acquired immunodeficiency syndrome treatment regimen. In the present work, with the previously reported compound K-16c as lead, a series of novel 2,4,5-trisubstituted pyrimidine derivatives were designed based on the cocrystal structure of K-16c/RT, with the aim to improve the anti-human immunodeficiency virus type-1 (HIV-1) activities and metabolic stability properties. Compound 11b1 exhibited the most potent antiviral activity against wild-type (WT) and a panel of single mutant HIV-1 strains (EC50 = 2.4-12.4 nM), being superior to or comparable to those of the approved drug etravirine. Meanwhile, 11b1 exhibited moderate cytotoxicity (CC50 = 4.96 µM) and high selectivity index (SI = 1189) toward HIV-1 WT strain. As for HIV-1 RT inhibition test, 11b1 possessed excellent inhibitory potency (IC50 = 0.04 µM) and confirmed its target was RT. Moreover, the molecular dynamics simulation was performed to elucidate the improved drug resistance profiles. Moreover, 11b1 was demonstrated with favorable safety profiles and pharmacokinetic properties in vivo, indicating that 11b1 is a potential anti-HIV-1 drug candidate worthy of further development.

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.

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.

Structure-Based Design of Novel G-Protein-Coupled Receptor TAAR1 Agonists as Potential Antipsychotic Drug Candidates.

The existing available antipsychotics have failed to manage the cognitive impairment of schizophrenia and induced a number of seriously undesirable effects. Trace amine-associated receptor 1 (TAAR1) has emerged as an ideal target for the design of antischizophrenia drugs, with the ability to mediate multiple psychological functions by sensing endogenous amine-containing metabolites without the side effects of catalepsy. In this work, a series of novel TAAR1 agonists were designed based on the structural analysis of the TAAR1 activation pocket. Among them, 6e displayed a potent TAAR1-Gs/Gq dual-pathway activation property, being different from that of the clinical drug candidate SEP-363856 with only TAAR1-Gs pathway activation. In rodent models, 6e significantly alleviated MK-801-induced schizophrenia-like cognitive phenotypes without inducing catalepsy. Furthermore, 6e·HCl exhibited favorable pharmacokinetic (T1/2 = 2.31 h, F = 39%) and safety properties. All these demonstrated that 6e·HCl may be used as a novel drug candidate for schizophrenia treatment.

Structural and signaling mechanisms of TAAR1 enabled preferential agonist design.

Trace amine-associated receptor 1 (TAAR1) senses a spectrum of endogenous amine-containing metabolites (EAMs) to mediate diverse psychological functions and is useful for schizophrenia treatment without the side effects of catalepsy. Here, we systematically profiled the signaling properties of TAAR1 activation and present nine structures of TAAR1-Gs/Gq in complex with EAMs, clinical drugs, and synthetic compounds. These structures not only revealed the primary amine recognition pocket (PARP) harboring the conserved acidic D3.32 for conserved amine recognition and "twin" toggle switch for receptor activation but also elucidated that targeting specific residues in the second binding pocket (SBP) allowed modulation of signaling preference. In addition to traditional drug-induced Gs signaling, Gq activation by EAM or synthetic compounds is beneficial to schizophrenia treatment. Our results provided a structural and signaling framework for molecular recognition by TAAR1, which afforded structural templates and signal clues for TAAR1-targeted candidate compounds design.

Multifunctional agents against Alzheimer's disease based on oxidative stress: Polysubstituted pyrazine derivatives synthesized by multicomponent reactions.

As Alzheimer's disease (AD) is a neurodegenerative disease with a complex pathogenesis, the exploration of multi-target drugs may be an effective strategy for AD treatment. Multifunctional small molecular agents can be obtained by connecting two or more active drugs or privileged pharmacophores by multicomponent reactions (MCRs). In this paper, two series of polysubstituted pyrazine derivatives with multifunctional moieties were designed as anti-AD agents and synthesized by Passerini-3CR and Ugi-4CR. Since the oxidative stress plays an important role in the pathological process of AD, the antioxidant activities of the newly synthesized compounds were first evaluated. Subsequently, selected active compounds were further screened in a series of AD-related bioassays, including Aß1-42 self-aggregation and deaggregation, BACE-1 inhibition, metal chelation, and protection of SH-SY5Y cells from H2O2-induced oxidative damage. Compound A3B3C1 represented the best one with multifunctional potencies. Mechanism study showed that A3B3C1 acted on Nrf2/ARE signaling pathway, thus increasing the expression of related antioxidant proteins NQO1 and HO-1 to normal cell level. Furthermore, A3B3C1 showed good in vitro human plasma and liver microsome stability, indicating a potential for further development as multifunctional anti-AD agent.

In situ click chemistry-based discovery of 1,2,3-triazole-derived diarylpyrimidines as novel HIV-1 NNRTIs by exploiting the tolerant region I in binding pocket.

HIV-1 reverse transcriptase (RT) is considered as one of the most significant targets for the anti-HIV-1 drug design due to their determined mechanism and well-decoded crystal structure. As a part of our continuous efforts towards the development of potent HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) by exploiting the tolerant region I of NNRTIs binding pocket (NNIBP), the miniaturized parallel synthesis via CuAAC click chemistry reaction followed by in situ biological screening have been performed in this work. The in situ enzyme inhibition screening results showed that 14 compounds exhibited higher or equivalent inhibitory activity compared to the lead K-5a2 and ETR. Anti-HIV-1 activity results indicated that C1N51 displayed the most potent activity (EC50 = 0.01-0.26 µM) against wild-type and a panel of NNRTIs-resistant strains. Moreover, the molecular simulation demonstrated that the newly introduced triazole ring could develop new hydrogen bonds with Lys103 and Pro236, which explained the feasibility of introducing triazole in the tolerant region I of the RT binding pocket.

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.

Ligand recognition and G protein coupling of the human itch receptor MRGPRX1.

MRGPRX1, a Mas-related GPCR (MRGPR), is a key receptor for itch perception and targeting MRGPRX1 may have potential to treat both chronic itch and pain. Here we report cryo-EM structures of the MRGPRX1-Gi1 and MRGPRX1-Gq trimers in complex with two peptide ligands, BAM8-22 and CNF-Tx2. These structures reveal a shallow orthosteric pocket and its conformational plasticity for sensing multiple different peptidic itch allergens. Distinct from MRGPRX2, MRGPRX1 contains a unique pocket feature at the extracellular ends of TM3 and TM4 to accommodate the peptide C-terminal "RF/RY" motif, which could serve as key mechanisms for peptidic allergen recognition. Below the ligand binding pocket, the G6.48XP6.50F6.51G6.52X(2)F/W6.55 motif is essential for the inward tilting of the upper end of TM6 to induce receptor activation. Moreover, structural features inside the ligand pocket and on the cytoplasmic side of MRGPRX1 are identified as key elements for both Gi and Gq signaling. Collectively, our studies provide structural insights into understanding itch sensation, MRGPRX1 activation, and downstream G protein signaling.

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.

Discovery of novel diarypyrimidine derivatives bearing six-membered non-aromatic heterocycles as potent HIV-1 NNRTIs with improved anti-resistance and drug-like profiles.

Taking our previously reported HIV-1 NNRTIs BH-11c and XJ-10c as lead compounds, series of novel diarypyrimidine derivatives bearing six-membered non-aromatic heterocycles were designed to improve anti-resistance and drug-like profiles. According to the three rounds of in vitro antiviral activity screening, compound 12g was the most active inhibitor against wild-type and five prevalent NNRTI-resistant HIV-1 strains with EC50 values ranging from 0.024 to 0.0010 µM. This is obviously better than the lead compound BH-11c and the approved drug ETR. Detailed structure-activity relationship was investigated to provide valuable guidance for further optimization. The MD simulation study indicated that 12g could form additional interactions with residues around the binding site in HIV-1 RT, which provided reasonable explanations for its improved anti-resistance profile compared to ETR. Furthermore, 12g showed significant improvement in water solubility and other drug-like properties compared to ETR. The CYP enzymatic inhibitory assay indicated that 12g was unlikely to induce CYP-mediated drug-drug interactions. 12g pharmacokinetics parameters were investigated and it displayed a long half-life of 6.59 h in vivo. The properties of compound 12g make it a promising lead compound for the development of new generation of antiretroviral drugs.

In Silico Discovery of Small-Molecule Inhibitors Targeting SARS-CoV-2 Main Protease.

The COVID-19 pandemic has caused severe health threat globally, and novel SARS-Cov-2 inhibitors are urgently needed for antiviral treatment. The main protease (Mpro) of the virus is one of the most effective and conserved targets for anti-SARS-CoV-2 drug development. In this study, we utilized a molecular docking-based virtual screening approach against the conserved catalytic site to identify small-molecule inhibitors of SARS-CoV-2 Mpro. Further biological evaluation helped us identify two compounds, AF-399/40713777 and AI-942/42301830, with moderate inhibitory activity. Besides that, the in silico data, including molecular dynamics (MD) simulation, binding free energy calculations, and AMDET profiles, suggested that these two hits could serve as the starting point for the future development of COVID-19 intervention treatments.