Molecular recognition of morphine and fentanyl by the human µ-opioid receptor.

Morphine and fentanyl are among the most used opioid drugs that confer analgesia and unwanted side effects through both G protein and arrestin signaling pathways of µ-opioid receptor (µOR). Here, we report structures of the human µOR-G protein complexes bound to morphine and fentanyl, which uncover key differences in how they bind the receptor. We also report structures of µOR bound to TRV130, PZM21, and SR17018, which reveal preferential interactions of these agonists with TM3 side of the ligand-binding pocket rather than TM6/7 side. In contrast, morphine and fentanyl form dual interactions with both TM3 and TM6/7 regions. Mutations at the TM6/7 interface abolish arrestin recruitment of µOR promoted by morphine and fentanyl. Ligands designed to reduce TM6/7 interactions display preferential G protein signaling. Our results provide crucial insights into fentanyl recognition and signaling of µOR, which may facilitate rational design of next-generation analgesics.

Oral Simnotrelvir for Adult Patients with Mild-to-Moderate Covid-19.

BACKGROUND: Simnotrelvir is an oral 3-chymotrypsin-like protease inhibitor that has been found to have in vitro activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and potential efficacy in a phase 1B trial. METHODS: In this phase 2-3, double-blind, randomized, placebo-controlled trial, we assigned patients who had mild-to-moderate coronavirus disease 2019 (Covid-19) and onset of symptoms within the past 3 days in a 1:1 ratio to receive 750 mg of simnotrelvir plus 100 mg of ritonavir or placebo twice daily for 5 days. The primary efficacy end point was the time to sustained resolution of symptoms, defined as the absence of 11 Covid-19-related symptoms for 2 consecutive days. Safety and changes in viral load were also assessed. RESULTS: A total of 1208 patients were enrolled at 35 sites in China; 603 were assigned to receive simnotrelvir and 605 to receive placebo. Among patients in the modified intention-to-treat population who received the first dose of trial drug or placebo within 72 hours after symptom onset, the time to sustained resolution of Covid-19 symptoms was significantly shorter in the simnotrelvir group than in the placebo group (180.1 hours [95% confidence interval {CI}, 162.1 to 201.6] vs. 216.0 hours [95% CI, 203.4 to 228.1]; median difference, -35.8 hours [95% CI, -60.1 to -12.4]; P = 0.006 by Peto-Prentice test). On day 5, the decrease in viral load from baseline was greater in the simnotrelvir group than in the placebo group (mean difference [±SE], -1.51±0.14 log10 copies per milliliter; 95% CI, -1.79 to -1.24). The incidence of adverse events during treatment was higher in the simnotrelvir group than in the placebo group (29.0% vs. 21.6%). Most adverse events were mild or moderate. CONCLUSIONS: Early administration of simnotrelvir plus ritonavir shortened the time to the resolution of symptoms among adult patients with Covid-19, without evident safety concerns. (Funded by Jiangsu Simcere Pharmaceutical; ClinicalTrials.gov number, NCT05506176.).

TPN10466 ameliorates Concanavalin A-induced autoimmune hepatitis in mice via inhibiting ERK/JNK/p38 signaling pathway.

Autoimmune hepatitis (AIH) eventually progresses to liver fibrosis, cirrhosis, and even hepatocellular carcinoma, causing irreversible damage to the liver. Concanavalin A-induced hepatitis in mice is a well-established model with pathophysiology similar to that of immune-mediated liver injury in human viral and autoimmune hepatitis, and it has been widely used to explore the pathogenesis and clinical treatment of human immune hepatitis. Artemisinin has been shown to exhibit anti-inflammatory effects through unclear mechanisms. In this study, we aimed to assess the effect of the artemisinin derivative TPN10466 on AIH. In vitro studies showed that TPN10466 dose dependently inhibited the percentage of IFN-γ-producing T cells. Further studies showed that TPN10466 attenuated the disease severity of AIH by downregulating the ability of lymphocytes to secrete IFN-γ and by reducing lymphocyte number in the liver. In addition, we found that TPN10466 treatment reduced T-cell responses by inhibiting JNK, ERK, and p38 pathways. In conclusion, our work suggests that TPN10466 provides protection against the autoimmune disease AIH by suppressing the inflammatory response of T cells, suggesting that TPN10466 may be a promising potential agent for the treatment of AIH.

An Alternative Approach to Synthesize Sildenafil via Improved Copper-Catalyzed Cyclization.

A facile synthetic pathway for sildenafil has been developed. This approach is characterized by a ligand-free Ullmann-type copper-catalyzed coupling reaction to construct sildenafil and its derivative, pyrrazolo[4,3-d]pyrimidin-7-one ring, with yields of 79% and 82%, respectively, in a convergent fashion by connecting key building blocks halo-pyrazole moiety 16c with 2-ethoxybenzamidine and 2-ethoxy-5-[(4-methylpiperazin-1-yl)sulfonyl]benzamidine in a one-pot reaction. Thus, this approach circumvents the need to use nitric/sulfuric acid for nitration, a costly Pd-catalyst for reduction, and coupling agents encountered in the reported processes.

Discovery of the potent covalent inhibitor with an acrylate warhead for SARS-CoV-2 3CL protease.

COVID-19 has caused severe consequences in terms of public health and economy worldwide since its outbreak in December 2019. SARS-CoV-2 3C-like protease (3CLpro), crucial for the viral replications, is an attractive target for the development of antiviral drugs. In this study, several kinds of Michael acceptor warheads were utilized to hunt for potent covalent inhibitors against 3CLpro. Meanwhile, novel 3CLpro inhibitors with the P3-3,5-dichloro-4-(2-(dimethylamino)ethoxy)phenyl moiety were designed and synthesized which may form salt bridge with residue Glu166. Among them, two compounds 12b and 12c exhibited high inhibitory activities against SARS-CoV-2 3CLpro. Further investigations suggested that 12b with an acrylate warhead displayed potent activity against HCoV-OC43 (EC50 = 97 nM) and SARS-CoV-2 replicon (EC50 = 45 nM) and low cytotoxicity (CC50 > 10 µM) in Huh7 cells. Taken together, this study devised two series of 3CLpro inhibitors and provided the potent SARS-CoV-2 3CLpro inhibitor (12b) which may be used for treating coronavirus infections.

Design, synthesis, and evaluation of novel oxyacanthine derivatives for anti-SARS-CoV-2 activity.

Here, we report the synthesis of a series of oxyacanthine derivatives and evaluation for their anti-SARS-CoV-2 activity in Vero E6 cells. In order to eliminate the potential metabolic activation caused by para-methylene phenol moiety in oxyacanthine, totally 29 derivatives were designed and synthesized, resulting in 23 compounds with antivirus IC50 below 5.00 µM and 9 compounds with antivirus IC50 below 1.00 µM. Among them, amides compound 4a and 4d exhibited potent anti-SARS-CoV-2 activity and the most favorable selectivity index (SI) in vitro with the SI values of 115 and 70, respectively. The pharmacokinetic properties of 4a and 4d were also assessed. Much more improved exposure in mice, longer half-life (T1/2), and increased oral bioavailability were observed for both compounds 4a and 4d compared with oxyacanthine.

A review of the synthetic strategies toward the antiviral drug tecovirimat.

This review provides a comprehensive analysis of synthetic routes for tecovirimat, an antiviral drug used to treat orthopoxvirus infections, including monkeypox and smallpox. We focus on the scale-up synthesis of key intermediates, including cycloheptatriene, as documented in the published literature and patent records. The review highlights the efficiency, yield, and purity of these approaches, as well as the minimization of genotoxic and in-process impurities. Furthermore, we critically evaluate the recently reported optimized industrial-scale synthesis process, highlighting its advantages and limitations, and identifying avenues for further improvement. By obtaining insights from the published literature and patent records, this review elucidates the current state of knowledge regarding key synthesis parameters influencing tecovirimat production and emphasizes the critical importance of optimizing synthesis techniques to achieve remarkable improvements in safety and environmental impact. This review serves as a valuable resource for researchers and industry professionals in the field of R&D and production of APIs, particularly in expediting the safe and efficient industrial production of tecovirimat.

Design, synthesis, and biological evaluation of novel 1-amido-2-one-4-thio-deoxypyranose as potential antitumor agents for multiple myeloma.

This study reported the design and synthesis of novel 1-amido-2-one-4-thio-deoxypyranose as inhibitors of potential drug target TRIP13 for developing new mechanism-based therapeutic agents in the treatment of multiple myeloma (MM). In comparison with the positive control DCZ0415, the most active compounds C16, C18, C20 and C32 exhibited strong anti-proliferative activity against human MM cell lines (ARP-1 and NCI-H929) with IC50 values of 1 âˆ¼ 2 µM. While the surface plasmon resonance (SPR) and ATPase activity assays demonstrated that the representative compound C20 is a potent inhibitor of TRIP13, C20 also showed good antitumor activity in vivo on BALB/c nude mice xenografted with MM tumor cells. An initial structure-activity study showed that the carbonyl group is crucial for anticancer activity. Overall, this study provided novel 1-amido-2-one-4-thio-deoxypyranoses, which are entirely different from previously reported potent inhibitor structures of TRIP13, and thus would aid the development of carbohydrate-based novel agents in MM pharmacotherapy.

Glimepiride, a novel soluble epoxide hydrolase inhibitor, protects against heart failure via increasing epoxyeicosatrienoic acids.

BACKGROUND: Epoxyeicosatrienoic acids (EETs), which exert multiple endogenous protective effects, are hydrolyzed into less active dihydroxyeicosatrienoic acids (DHETs) by soluble epoxide hydrolase (sEH). However, commercial drugs related to EETs or sEH are not yet in clinical use. METHODS: Firstly, the plasma concentration of EETs and DHETs of 316 patients with heart failure (HF) were detected and quantitated by liquid chromatography-tandem mass spectrometry. Then, transverse aortic constriction (TAC)-induced HF was introduced in cardiomyocyte-specific Ephx2-/- mice. Moreover, Western blot, real-time PCR, luciferase reporter, ChIP assays were employed to explore the underlying mechanism. Finally, multiple sEH inhibitors were designed, synthesized, and validated in vitro and in vivo. RESULTS: The ratios of DHETs/EETs were increased in the plasma from patients with HF. Meanwhile, the expression of sEH was upregulated in the heart of patients and mice with HF, especially in cardiomyocytes. Cardiomyocyte-specific Ephx2-/- mice ameliorated cardiac dysfunction induced by TAC. Consistently, Ephx2 knockdown protected Angiotensin II (AngII)-treated cardiomyocytes via increasing EETs in vitro. Mechanistically, AngII could enhance the expression of transcript factor Krüppel-like factor 15 (KLF15), which in turn upregulated sEH. Importantly, glimepiride was identified as a novel sEH inhibitor, which benefited from the elevated EETs during HF. CONCLUSIONS: Glimepiride attenuates HF in mice in part by increasing EETs. CLINICAL TRIAL IDENTIFIER: NCT03461107 (https://clinicaltrials.gov).

Synthesis and evaluation of NHC derivatives and 4'-fluorouridine prodrugs.

ß-D-N4-Hydroxycytidine (NHC) derivatives with structural modifications at the C4', O4' or C6 position and 4'-fluorouridine prodrugs were synthesized and evaluated for their antiviral activities against respiratory syncytial virus (RSV) or influenza virus (IFV) in vitro. The NHC derivatives were found inactive, but 4'-fluorouridine and its prodrugs had potent anti-RSV and anti-IFV activities. 4'-Fluorouridine was proved to be a nucleoside with poor stability, but the tri-ester prodrugs exhibited enhanced stability, especially tri-isobutyrate ester 1a. This prodrug also showed excellent oral pharmacokinetic properties in rats, with potential to be an oral antiviral candidate.

Design, synthesis and biological evaluation of covalent peptidomimetic 3CL protease inhibitors containing nitrile moiety.

In this paper, a series of peptidomimetic SARS-CoV-2 3CL protease inhibitors with new P2 and P4 positions were synthesized and evaluated. Among these compounds, 1a and 2b exhibited obvious 3CLpro inhibitory activities with IC50 of 18.06 nM and 22.42 nM, respectively. 1a and 2b also showed excellent antiviral activities against SARS-CoV-2 in vitro with EC50 of 313.0 nM and 170.2 nM, respectively, the antiviral activities of 1a and 2b were 2- and 4-fold better than that of nirmatrelvir, respectively. In vitro studies revealed that these two compounds had no significant cytotoxicity. Further metabolic stability tests and pharmacokinetic studies showed that the metabolic stability of 1a and 2b in liver microsomes was significantly improved, and 2b had similar pharmacokinetic parameters to that of nirmatrelvir in mice.

Pharmacokinetics, mass balance, and metabolism of [14C]TPN171, a novel PDE5 inhibitor, in humans for the treatment of pulmonary arterial hypertension.

TPN171 is a novel phosphodiesterase-5 (PDE5) inhibitor used to treat pulmonary arterial hypertension (PAH) and erectile dysfunction (ED), which currently is undergoing phase II clinical trials in China. In this single-center, single-dose, nonrandomized, and open design study, radiolabeled [14C]TPN171 was used to investigate the metabolic mechanism, pharmacokinetic characteristics, and clearance pathways of TPN171 in 6 healthy Chinese male volunteers. Each volunteer was administered a single oral suspension of 10 mg (100 µCi) of [14C]TPN171. We found that TPN171 was absorbed rapidly in humans with a peak time (Tmax) of 0.667 h and a half-life (t1/2) of approximately 9.89 h in plasma. Excretion of radiopharmaceutical-related components was collected 216 h after administration, accounting for 95.21% of the dose (46.61% in urine and 48.60% in feces). TPN171 underwent extensive metabolism in humans. Twenty-two metabolites were detected in human plasma, urine, and feces using a radioactive detector combined with a high-resolution mass spectrometer. According to radiochromatograms, a glucuronide metabolite of O-dealkylated TPN171 exceeded 10% of the total drug-related components in human plasma. However, according to the Food and Drug Administration (FDA) guidelines, no further tests are needed to evaluate the safety of this metabolite because it is a phase II metabolite, but the compound is still worthy of attention. The main metabolic biotransformation of TPN171 was mono-oxidation (hydroxylation and N-oxidation), dehydrogenation, N-dealkylation, O-dealkylation, amide hydrolysis, glucuronidation, and acetylation. Cytochrome P450 3A4 (CYP3A4) mainly catalyzed the formation of metabolites, and CYP2E1 and CYP2D6 were involved in the oxidative metabolism of TPN171 to a lesser extent. According to the incubation data, M1 was mainly metabolized to M1G by UDP-glucuronosyltransferase 1A9 (UGT1A9), followed by UGT1A7 and UGT1A10.

Artemisinin derivative TPN10466 suppresses immune cell migration and Th1/Th17 differentiation to ameliorate disease severity in experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) was one of the major conditions causing neurological dysfunction and was an incurable progressive central nervous system disease. Experimental autoimmune encephalomyelitis (EAE) was the most commonly used experimental model of MS. Artemisinin have been shown to exhibit anti-inflammatory effects through unclear mechanisms. In this study, we aimed to evaluate the effect of administration of the artemisinin derivative TPN10466 in EAE. TPN10466 alleviated the severity of disease in EAE. Further studies showed that TPN10466 inhibited lymphocyte migration by downregulating chemokine expression and adhesion molecules. In addition, studies showed that TPN10466 directly inhibited Th1 and Th17 differentiation and reduced Th1 and Th17 infiltration into the central nervous system. In conclusion, our work demonstrated that TPN10466 provided protection against the autoimmune disease EAE by inhibiting the migration of immune cells and suppressing Th1/Th17 differentiation, suggesting that TPN10466 could be a potential for promising potential agent for the treatment of MS/EAE.

Synthesis and biological evaluation of artemisinin derivatives as potential MS agents.

In this paper, a series of artemisinin derivatives were synthesized and evaluated. Studies have shown that IFN-γ produced by Th1 CD4+ T cells and IL-17A secreted by Th17 CD4+ T cells played critical roles in the treatment of multiple sclerosis. We used different concentrations of artemisinin derivatives to inhibit Th1 / Th17 differentiation in naive CD4+ T cells and to characterize IFN-γ / IL-17A in in vitro experiments. The preliminary screening results showed that ester compound 5 exhibited obvious inhibitory activities on Th1 and Th17 (IFN-γ decreased from 41% to 3% and IL-17A decreased from 24% to 8% at the concentration of 10 nM to 10 µM), and carbamate compounds also had obvious inhibitory activities against Th17 at high concentration. Moreover, we investigated the effect of compound 5 on myelin oligodendrocyte glycoprotein (MOG)-induced mice experimental autoimmune encephalomyelitis (EAE) model in vivo. 100 mg/kg compound 5 effectively reduced the disease severity of EAE compared with the vehicle group. This research revealed that compound 5 could be a promising avenue as potential MS inhibitor.

Safety, tolerability, and pharmacokinetics of VV116, an oral nucleoside analog against SARS-CoV-2, in Chinese healthy subjects.

VV116 (JT001) is an oral drug candidate of nucleoside analog against SARS-CoV-2. The purpose of the three phase I studies was to evaluate the safety, tolerability, and pharmacokinetics of single and multiple ascending oral doses of VV116 in healthy subjects, as well as the effect of food on the pharmacokinetics and safety of VV116. Three studies were launched sequentially: Study 1 (single ascending-dose study, SAD), Study 2 (multiple ascending-dose study, MAD), and Study 3 (food-effect study, FE). A total of 86 healthy subjects were enrolled in the studies. VV116 tablets or placebo were administered per protocol requirements. Blood samples were collected at the scheduled time points for pharmacokinetic analysis. 116-N1, the metabolite of VV116, was detected in plasma and calculated for the PK parameters. In SAD, AUC and Cmax increased in an approximately dose-proportional manner in the dose range of 25-800 mg. T1/2 was within 4.80-6.95 h. In MAD, the accumulation ratio for Cmax and AUC indicated a slight accumulation upon repeated dosing of VV116. In FE, the standard meal had no effect on Cmax and AUC of VV116. No serious adverse event occurred in the studies, and no subject withdrew from the studies due to adverse events. Thus, VV116 exhibited satisfactory safety and tolerability in healthy subjects, which supports the continued investigation of VV116 in patients with COVID-19.

Synthesis and anti-SARS-CoV-2 activity of deuterated GS-441524 analogs.

The COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is continuing to spread around the world. GS-441524 is the parent nucleoside of remdesivir which is the first drug approved for the treatment of COVID-19, and demonstrates strong activity against SARS-Cov-2 in vitro and in vivo. Herein, we reported the synthesis of a series of deuterated GS-441524 analogs, which had deuterium atoms up to five at the ribose and the nucleobase moieties. Compared to GS-441524, all the deuterated compounds showed similar inhibitory activities against SARS-CoV-2 in vitro.

TPN672: A Novel Serotonin-Dopamine Receptor Modulator for the Treatment of Schizophrenia.

TPN672 [7-(2-(4-(benzothiophen-4-yl) piperazin-1-yl)ethyl)quinolin-2(1H)-one maleate] is a novel antipsychotic candidate with high affinity for serotonin and dopamine receptors that is currently in clinical trial for the treatment of psychiatric disorders. In vitro binding study showed that TPN672 exhibited extremely high affinity for serotonin 1A receptor (5-HT1AR) (K i = 0.23 nM) and 5-HT2AR (K i = 2.58 nM) as well as moderate affinity for D3R (K i = 11.55 nM) and D2R (K i = 17.91 nM). In vitro functional assays demonstrated that TPN672 acted as a potent 5-HT1AR agonist, D2R/D3R partial agonist, and 5-HT2AR antagonist. TPN672 displayed robust antipsychotic efficacy in rodent models (e.g., blocking phencyclidine-induced hyperactivity), significantly better than aripiprazole, and ameliorated negative symptoms and cognitive deficits in the sociability test, dark avoidance response, Morris water maze test, and novel object recognition test. The results of electrophysiological experiments showed that TPN672 might inhibit the excitability of the glutamate system through activating 5-HT1AR in medial prefrontal cortex, thereby improving cognitive and negative symptoms. Moreover, the safety margin (the ratio of minimum catalepsy-inducing dose to minimum effective dose) of TPN672 was about 10-fold, which was superior to aripiprazole. In conclusion, TPN672 is a promising new drug candidate for the treatment of schizophrenia and has been shown to be more effective in attenuating negative symptoms and cognitive deficits while having lower risk of extrapyramidal symptoms and hyperprolactinemia. SIGNIFICANCE STATEMENT: TPN672 is a promising new drug candidate for the treatment of schizophrenia and has been shown to be more effective in attenuating negative symptoms and cognitive deficits while having a lower risk of extrapyramidal symptoms and hyperprolactinemia. A phase I clinical trial is now under way to test its tolerance, pharmacokinetics, and pharmacodynamic effects in human volunteers. Accordingly, the present results will have significant impact on the development of new antischizophrenia drugs.

Weinreb Amide Approach to the Practical Synthesis of a Key Remdesivir Intermediate.

Currently, remdesivir is the first and only FDA-approved antiviral drug for COVID-19 treatment. Adequate supplies of remdesivir are highly warranted to cope with this global public health crisis. Herein, we report a Weinreb amide approach for preparing the key intermediate of remdesivir in the glycosylation step where overaddition side reactions are eliminated. Starting from 2,3,5-tri-O-benzyl-d-ribonolactone, the preferred route consisting of three sequential steps (Weinreb amidation, O-TMS protection, and Grignard addition) enables a high-yield (65%) synthesis of this intermediate at a kilogram scale. In particular, the undesirable PhMgCl used in previous methods was successfully replaced by MeMgBr. This approach proved to be suitable for the scalable production of the key remdesivir intermediate.

One step stereoselective synthesis of oxazoline-fused saccharides and their conversion into the corresponding 1,2-cis glycosylamines bearing various protected groups.

Herein we disclosed a straightforward synthesis of oxazoline-fused saccharides (oxazolinoses) from peracetylated saccharides and benzonitriles under acidic conditions with stoichiometric amounts of water. The density functional theory (DFT) calculations have revealed the origin of the stereoselectivity and the key role of water in promoting the departure of the acetyl group at C-2. The resulting oxazolinoses can be concisely converted into the corresponding 1,2-cis glycosylamines bearing various protected groups, allowing the access to schisandrin derivatives.

Potency and pharmacokinetics of GS-441524 derivatives against SARS-CoV-2.

The nucleoside metabolite of remdesivir, GS-441524 displays potent anti-SARS-CoV-2 efficacy, and is being evaluated in clinical as an oral antiviral therapeutic for COVID-19. However, this nucleoside has a poor oral bioavailability in non-human primates, which may affect its therapeutic efficacy. Herein, we reported a variety of GS-441524 analogs with modifications on the base or the sugar moiety, as well as some prodrug forms, including five isobutyryl esters, two l-valine esters, and one carbamate. Among the new nucleosides, only the 7-fluoro analog 3c had moderate anti-SARS-CoV-2 activity, and its phosphoramidate prodrug 7 exhibited reduced activity in Vero E6 cells. As for the prodrugs, the 3'-isobutyryl ester 5a, the 5'-isobutyryl ester 5c, and the tri-isobutyryl ester 5g hydrobromide showed excellent oral bioavailabilities (F = 71.6%, 86.6% and 98.7%, respectively) in mice, which provided good insight into the pharmacokinetic optimization of GS-441524.