M2 Muscarinic Receptor Research Articles

How antipsychotics work in schizophrenia: a primer on mechanisms.

Antipsychotics effective for schizophrenia approved prior to 2024 shared the common mechanism of postsynaptic dopamine D2 receptor antagonism or partial agonism. Positive psychosis symptoms correlate with excessive presynaptic dopamine turnover and release, yet this postsynaptic mechanism improved positive symptoms only in some patients, and with concomitant risk for off-target motor and endocrine adverse effects; moreover, these agents showed no benefit for negative symptoms and cognitive dysfunction. The sole exception was data supporting cariprazine's superiority to risperidone for negative symptoms. The muscarinic M1/M4 agonist xanomeline was approved in September 2024 and represents the first of a new antipsychotic class. This novel mechanism improves positive symptoms by reducing presynaptic dopamine release. Xanomeline also lacks any D2 receptor affinity and is not associated with motor or endocrine side effects. Of importance, xanomeline treated patients with higher baseline levels of cognitive dysfunction in clinical trials data saw cognitive improvement, a finding likely related to stimulation of muscarinic M1 receptors. Treatment resistance is seen in one-third of schizophrenia patients. These individuals do not have dopamine dysfunction underlying their positive symptoms, and therefore show limited response to antipsychotics that target dopamine neurotransmission. Clozapine remains the only medication with proven efficacy for resistant schizophrenia, and with unique benefits for persistent impulsive aggression and suicidality. New molecules are being studied to address the array of positive, negative and cognitive symptoms of schizophrenia; however, until their approval, clinicians must be familiar with currently available agents and be adept at prescribing clozapine.

Chemogenomic Screening in a Patient-Derived 3D Fatty Liver Disease Model Reveals the CHRM1-TRPM8 Axis as a Novel Module for Targeted Intervention.

Metabolic dysfunction-associated steatohepatitis (MASH) is a leading cause of chronic liver disease with few therapeutic options. To narrow the translational gap in the development of pharmacological MASH treatments, a 3D liver modelfrom primary human hepatocytes and non-parenchymal cells derived from patients with histologically confirmed MASH was established. The model closely mirrors disease-relevant endpoints, such as steatosis, inflammation and fibrosis, and multi-omics analyses show excellent alignment with biopsy data from 306 MASH patients and 77 controls. By combining high-content imaging with scalable biochemical assays and chemogenomic screening, multiple novel targets with anti-steatotic, anti-inflammatory, and anti-fibrotic effects are identified. Among these, activation of the muscarinic M1 receptor (CHRM1) and inhibition of the TRPM8 cation channel result in strong anti-fibrotic effects, which are confirmed using orthogonal genetic assays. Strikingly, using biosensors based on bioluminescence resonance energy transfer, a functional interaction along a novel MASH signaling axis in which CHRM1 inhibits TRPM8 via Gq/11 and phospholipase C-mediated depletion of phosphatidylinositol 4,5-bisphosphate can be demonstrated. Combined, this study presents the first patient-derived 3D MASH model, identifies a novel signaling module with anti-fibrotic effects, and highlights the potential of organotypic culture systems for phenotype-based chemogenomic drug target identification at scale.

The cannabinoid CB2 receptor positive allosteric modulator EC21a exhibits complicated pharmacology in vitro

Schizophrenia is a complex disease involving the dysregulation of numerous brain circuits and patients exhibit positive symptoms (hallucinations, delusions), negative symptoms (anhedonia), and cognitive impairments. We have shown that the antipsychotic efficacy of positive allosteric modulators (PAMs) of both the M4 muscarinic receptor and metabotropic glutamate receptor 1 (mGlu1) involve the retrograde activation of the presynaptic cannabinoid type-2 (CB2) receptor, indicating that CB2 activation or potentiation could result in a novel therapeutic strategy for schizophrenia. We used two complementary assays, receptor-mediated phosphoinositide hydrolysis and GIRK channel activation, to characterize a CB2 PAM scaffold, represented by the compound EC21a, to explore its potential as a starting point to optimize therapeutics for schizophrenia. These studies revealed that EC21a acts as an allosteric inverse agonist at CB2 in both assays and exhibits a mixed allosteric agonist/negative allosteric modulator profile at CB1 depending upon the assay used for profiling. A series of compounds related to EC21a also functioned as CB2 inverse agonists. Overall, these results suggest that EC21a exhibits complicated and potentially assay-dependent pharmacology, which may impact interpretation of in vivo studies.

Reduced striatal M4-cholinergic signaling following dopamine loss contributes to parkinsonian and l-DOPA-induced dyskinetic behaviors.

A dynamic equilibrium between dopamine and acetylcholine (ACh) is essential for striatal circuitry and motor function, as imbalances are associated with Parkinson's disease (PD) and levodopa-induced dyskinesia (LID). Conventional theories posit that cholinergic signaling is pathologically elevated in PD as a result of increased ACh release, which contributes to motor deficits. However, using approaches to measure receptor-mediated signaling, we found that, rather than the predicted enhancement, the strength of cholinergic transmission at muscarinic M4 receptor synapses on direct pathway medium spiny neurons was decreased in dopamine-depleted mice. This adaptation was due to a reduced postsynaptic M4 receptor function, resulting from down-regulated receptors and downstream signaling. Restoring M4 transmission unexpectedly led to a partial alleviation of motor deficits and LID dyskinetic behavior, revealing an unexpected prokinetic effect in addition to the canonical antikinetic role of M4 receptors. These findings indicate that decreased M4 function differentially contributes to parkinsonian and LID pathophysiology, representing a promising target for therapeutic intervention.

The novel orthosteric agonist M1 muscarinic acetylcholine receptor reveals anti-Alzheimer’s disease activity

Cholinergic treatments with an emphasis on M1 muscarinic acetylcholine receptor (mAChR) agonists as potential modulating agents are a new approach in Alzheimer’s disease (AD) therapy. In previous research, we designed and characterized novel thiazolidine-2,4-dione (TZD)-derived compounds that possess anti-AD properties and enhance the expression of mAChRM1 in rats. This study evaluated a novel orthosteric agonist of mAChRM1 from related pathways that has shown promising anti-Alzheimer’s disease activity. PC12 cells were exposed to various concentrations of TZ4M before they were exposed to scopolamine (3 µM). Immunocytochemistry and western blot analyses revealed that TZ4M increased the expression of mAChRM1 in differentiated cells induced by scopolamine-treated PC12 cells. The results showed that TZ4M (3 and 5 µM) markedly upregulated PKC and ChAT protein expression, and the cells were significantly protected against increased ROS levels followed by neuronal cell loss, as evidenced by the MTT assay. TUNEL staining indicated that TZ4M impeded the shaping of apoptotic bodies. Analysis of the amino acid sequences of the ligand–protein binding site indicated that TZ4M is bound to the orthosteric site (acetylcholine site). This study revealed that TZ4M, a derivative of TZD, effectively protects against scopolamine-induced damage. TZ4M, a novel mACRM1 orthosteric agonist, is promising for treating AD.

Possible Mechanism for Perception of Auditory-Verbal Hallucinations in Schizophrenia and Approaches to Their Weakening

We put forward a hypothesis that the processing and perception of auditory-verbal hallucinations in schizophrenia — internally generated speech, occurs in the same neural circuits as speech from external sources. These topographically organized cortico—basal ganglia—thalamocortical neural circuits include auditory, language, and frontal neocortical areas. It follows from our proposed mechanism for sound processing, that the increased action on dopamine D2 receptors on striatal neurons, which is considered the cause of hallucinations, should lead to a determined reorganization of activity in these neural circuits. As a result of this reorganization, the inhibition of neurons in the thalamic nuclei, including the internal geniculate body, should decrease synergistically through the direct and indirect pathways in the basal ganglia, and the excitation of connected with them cortical neurons, in the activity of which speech is represented, should increase. From this mechanism it follows that in order to weaken the perception of auditory-verbal hallucinations, it is necessary to increase the inhibition of thalamic neurons. Taking into account the known data on the distribution of receptors of different types on neurons in the striatum, thalamus and neocortex, as well as the previously formulated unified modification rules for the effectiveness of synaptic transmission in different structures, we proposed that agonists of adenosine A1 and muscarinic M4 receptors located on striatonigral spiny cells, giving rise to a direct disinhibitory pathway through the basal ganglia as well as antagonists of delta-opioid and cannabinoid CB1 receptors, located on striatopallidal spiny cells, giving rise to an indirect inhibitory pathway through the basal ganglia may be useful to weaken the perception of hallucinations. In addition, activation of A1 receptors can directly weaken the activity of neurons in the thalamus and neocortex due to the induction of long-term depression in the efficiency of their excitation. Inactivation of cannabinoid CB1 receptors on the projection GABAergic cells of the reticular thalamic nucleus may enhance their inhibitory effect on neurons of different thalamic nuclei. Since the proposed substances only indirectly affect the dopaminergic system, their use should not cause such pronounced side effects as D2 receptor antagonists, antipsychotics that are widely used to suppress auditory-verbal hallucinations.

IUPHAR Review on muscarinic M1 and M4 receptors as drug treatment targets relevant to the molecular pathology of schizophrenia.

Cobenfy, a co-formulation of xanomeline and trospium, is the first drug not acting on the dopaminergic system of the CNS approved for the treatment of schizophrenia by the FDA. Xanomeline is a muscarinic M1 and M4 receptor (CHRM1 and CHRM4) agonist whilst trospium is a peripherally active CHRM antagonist that reduces the unwanted peripheral side-effects of xanomeline. Relevant to this exciting development, this review details the human CNS cholinergic systems and how those systems are affected by the molecular pathology of schizophrenia in a way suggesting activating the CHRM1 and 4 would be beneficial in treating the disorder. The CNS distribution of CHRMs is presented along with findings using CHRM knockout mice and mice treated with drugs that activate the CHRM1 and / or M4, these data explain why these CHRMs could be involved in the genesis of the symptoms of schizophrenia. Next, the process leading to the formulation of Cobenfy and the preclinical data on xanomeline are reviewed showing why Cobenfy was expected to be useful in treating schizophrenia. The pipeline of drugs targeting CHRM1 and /or M4 receptors to treat schizophrenia are discussed. Finally, the molecular pathology of two sub-groups within schizophrenia, separated based on the presence or absence of a deficit of cortical CHRM1, are reviewed to show how such approaches could identify new drug targets. In conclusion, developing Cobenfy highlights why fully understanding the pathophysiology of schizophrenia will suggest new treatment targets for the disorder and that pharmacologists can synthesise drugs to target these sites.

Structural determinants of M2R involved in inhibition by Sigma-1R

Sigma-1 receptor (S1R) is a multimodal chaperone protein which is implicated in various pathophysiological conditions including drug addiction, Alzheimer’s disease and amyotrophic lateral sclerosis (ALS). S1R interacts with various ion channels and receptors on endoplasmic reticulum or plasma membrane (PM). It has been reported that S1R colocalizes with the M2-muscarinic acetylcholine receptor (M2R) on the soma of motoneurons, although a functional interaction between these two proteins hasn’t been established. Here, we investigated the regulation of M2R signalling by S1R using electrophysiological recordings of GIRK currents in HEK293T cells. We observed that S1R strongly inhibited M2R-mediated activation of GIRK1/2, but the disease mutant linked to ALS, S1R E102Q, did not. The inhibitory effect of S1R was selective for M2R and wasn’t seen when S1R was co-expressed with other Gi/o coupled receptors including M4R. Chimeric and mutant receptors of M2R and M4R were generated and analysed, and this highlighted Ala401 in the transmembrane 6 domain (TM6) of M2R and Glu172 as well as Glu175 in the extracellular loop 2 region of M2R, as essential for the inhibition by S1R. Co-immunoprecipitation confirmed the physical interaction between M2R and S1R. Immunocytochemical labelling of M2R and S1R expressed in HeLa cells, HEK293T cells and cultured hippocampal neurons, showed clear PM expression of M2R throughout the cell which was decreased by coexpression with S1R but was still apparent. Taken together, our results show that S1R interacts with M2R to reduce both its PM expression and function, and this involves TM6 and the extracellular loop 2.

Local and Remote Chemogenetic Suppression of Hippocampal Seizures in Rats.

Innovative treatments of refractory epilepsy are widely desired, for which chemogenetic technology can provide region- and cell-type-specific modulation with relative noninvasiveness. We aimed to explore the specific applications of chemogenetics for locally and remotely networks controlling hippocampal seizures. A virus coding for a modified human Gi-coupled M4 muscarinic receptor (hM4Di) on pyramidal cells was injected into either the right hippocampal CA3 or the bilateral anterior nucleus of the thalamus (ANT) in rats. After one month, seizures were induced by 4-aminopyridine (4-AP) injection into the right CA3. Simultaneously, clozapine-N-oxide (CNO) (2.5 mg/kg) or clozapine (0.1 mg/kg), the specific ligands acting on hM4Di, were injected intraperitoneally. We also set up hM4Di control and clozapine control groups to eliminate the influence of viral transfection and the ligand alone on the experimental results. For both local and remote controls, the mean seizure duration was significantly reduced upon ligand application in the experimental groups. Seizure frequency, on the other hand, only showed a significant decrease in local control, with a lower frequency in the clozapine group than in the CNO group. Both the effects of CNO and clozapine were time-dependent, and clozapine was faster than CNO in local seizure control. This study shows the potency of chemogenetics to attenuate hippocampal seizures locally or remotely by activating the transfected hM4Di receptor with CNO or clozapine. ANT is suggested as a potentially safe chemogenetic application target in the epileptic network for focal hippocampal seizures.

M1 muscarinic receptor activation reverses age-related memory updating impairment in mice

Previously consolidated memories can become temporarily labile upon reactivation. Reactivation-based memory updating is chiefly studied in young subjects, so we aimed to assess this process across the lifespan. To do this, we developed a behavioural paradigm wherein a reactivated object memory is updated with contextual information; 3-month-old and 6-month-old male C57BL/6 mice displayed object memory updating, but 12-month-old mice did not. We found that M1 muscarinic acetylcholine receptor signaling during reactivation was necessary for object memory updating in the young mice. Next, we targeted this mechanism in an attempt to facilitate object memory updating in aging mice. Remarkably, systemic pharmacological M1 receptor activation reversed the age-related deficit. Quantification of cholinergic system markers within perirhinal cortex revealed subtle cellular changes that may contribute to differential performance across age groups. These findings suggest that natural cholinergic change across the lifespan contributes to inflexible memory in the aging brain.

Discovery of BAY 2413555, First Selective Positive Allosteric Modulator of the M2 Receptor to Restore Cardiac Autonomic Balance.

Autonomic disbalance, i.e., sympathetic overactivation and parasympathetic withdrawal, is a causal driver of disease progression in heart failure. While sympatholytic drugs are established treatments, no drug therapy restoring vagal control of cardiac function is available. We report here the HTS-based discovery of a novel class of 1,8-naphthyridin-4(1H)-one carboxamides acting as positive allosteric modulators (PAMs) of the M2 muscarinic acetylcholine receptor (M2R). M2R is the main postsynaptic myocyte receptor regulating heart rate, electrical conduction, and contractile strength. Extensive optimization of the screening hit in terms of potency, permeation, metabolic stability, and solubility ultimately resulted in the discovery of the first-in-class clinical candidate BAY 2413555 (27). With an overall technical profile compatible with once-daily oral administration in a phase 1 study, no apparent effects on blood pressure, and a mechanism that largely preserves autonomic regulatory capacity, BAY 2413555 could be the tool to finally study the restoration of autonomic balance.

Long-Term Neurotoxic Effects and Alzheimer's Disease Risk of Early EHDPP Exposure in Zebrafish: Insights from Molecular Mechanisms to Adult Pathology.

2-Ethylhexyl diphenyl phosphate (EHDPP), ubiquitously monitored in environmental media, is highly bioaccumulative and may pose long-term risks, even after short-term exposure. In this investigation, larval zebrafish were exposed to 0.05, 0.5, and 5.0 μg/L EHDPP from 4 to 120 h postfertilization (hpf) to examine the long-term neurotoxicity effects of early exposure. Exposure to 5.0 μg/L EHDPP yielded hyperactive locomotor behavior, which was characterized by increased swimming speed, larger turning angles, and heightened sensitivity to light-dark stimulation. The predicted targets of EHDPP (top 100 potential macromolecules) were primarily associated with brain diseases like Alzheimer's disease (AD). Comparisons of differentially expressed genes (DEGs) from AD patients (GSE48350) and RNA-seq data from EHDPP-exposed zebrafish confirmed consistently abnormal regulatory pathways. EHDPP's interaction with M1 and M5 muscarinic acetylcholine receptors likely disrupted calcium homeostasis, leading to mitochondrial dysfunction and neurotransmitter imbalance as well as abnormal locomotor behavior. Especially, 5.0 μg/L EHDPP exposure during early development (4-120 hpf) triggered early- and midstage AD-like symptoms in adulthood (180 dpf), characterized by cognitive confusion, aggression, blood-brain barrier disruption, and mitochondrial damage in brains. These findings provide deep insights into the long-term neurotoxicity effects and Alzheimer's disease risks of early EHDPP exposure at extremely low dosages.

Effects of Different Photoperiods on Growth Performance, Glucose Metabolism, Acetylcholine, and Its Relative Acetylcholine Receptor Modulation in Broiler Chickens.

Photoperiods are crucial environmental factors in the growth and health of modern intensive broiler chicken production. To date, the effects of different photoperiods on glucose metabolism, acetylcholine (ACh), and its relative acetylcholine receptor modulation in broilers remain elusive. Herein, we aimed to identify the effects of different photoperiods on regulating glucose metabolism, ACh, nicotinic acetylcholine receptor alpha 4 (α4 nAChR) mRNA, and M3 muscarinic acetylcholine receptor (M3 mAChR) modulation in broilers. A total of 216 healthy 5-day-old Arbor Acres (AA) male broilers was randomly assigned to 12L:12D, 18L:6D, and 24L:0D photoperiods for 4 weeks. The results show that, compared with the 12L:12D photoperiod, the 18L:6D and 24L:0D photoperiods significantly increase the average daily gain (ADG) and average daily feed intake (ADFI) of broilers (p < 0.05). However, the feed efficiency (FE) of broilers significantly decreased in the 18L:6D and 24L:0D photoperiods (p < 0.05). Moreover, compared with the 12L:12D photoperiod, the ACh concentrations and α4 nAChR mRNA expression levels in the hypothalamus and medulla oblongata of broilers significantly increased (p < 0.05); M3 mAChR mRNA expression levels in cecum significantly reduced in the 18L:6D photoperiod and the 24L:0D photoperiod (p < 0.05). Compared with the 12L:12D photoperiod, the serum glucose (GLU), serum insulin (INS), serum triglyceride (TG) levels, and homeostasis model assessment of insulin resistance (HOMA-IR) of broilers significantly enhanced in the 18L:6D and 24L:0D photoperiods (p < 0.05). Our results indicate that extending the photoperiod can promote the growth rate, ACh expression, and α4 nAChR mRNA expression of broilers while reducing the feed efficiency, inhibiting M3 mAChR mRNA expression, and inducing glucose metabolism disorders in broilers.

Photo-BQCA: Positive Allosteric Modulators Enabling Optical Control of the M1 Receptor.

The field of G protein-coupled receptor (GPCR) research has greatly benefited from the spatiotemporal resolution provided by light controllable, i.e., photoswitchable ligands. Most of the developed tools have targeted the Rhodopsin-like family (Class A), the largest family of GPCRs. However, to date, all such Class A photoswitchable ligands were designed to act at the orthosteric binding site of these receptors. Herein, we report the development of the first photoswitchable allosteric modulators of Class A GPCRs, designed to target the M1 muscarinic acetylcholine receptor. The presented benzyl quinolone carboxylic acid (BQCA) derivatives, Photo-BQCisA and Photo-BQCtrAns, exhibit complementary photopharmacological behavior and allow reversible control of the receptor using light as an external stimulus. This makes them valuable tools to further investigate M1 receptor signaling and a proof of concept for photoswitchable allosteric modulators at Class A receptors.

Herbal Amara extract induces gastric fundus relaxation via inhibition of the M2 muscarinic receptor.

Impaired gastric accommodation is one of the most frequent symptoms of functional dyspepsia. The safety and efficacy of conventional treatments remain to be proven and alternative herbal therapies have been proposed to alleviate gastrointestinal symptoms. This preclinical study examined the role of herbal Amara extract (containing Artemisia absinthium, Centaurium erythraea, Cichorium intybus, Gentiana lutea, Juniperus communis, Achillea millefolium, Peucedanum ostruthium, Salvia officinalis, and Taraxacum extracts) on gastric (fundus) accommodation and the possible implication of muscarinic receptors in its regulation. The effect of Amara extract on fundus motility was investigated in organ baths of smooth muscle strips isolated from the fundus of guinea pigs, and the role of the muscarinic receptor pathway was evaluated using functional and radioligand binding assays in cell lines expressing the M2 or M3 muscarinic receptor. Amara extract inhibited carbachol-induced contraction of guinea pig smooth muscle strips in a dose-dependent manner. This relaxant effect was not affected by the M3 antagonist J-104129. Amara extract also inhibited M2, but not M3, receptor activity in CHO-K1 cells (IC50 219 μg mL-1), and specifically bound the M2 receptor (IC50 294 μg mL-1). Of the nine herbal components of Amara extract, Juniperus communis, P. ostruthium, and Salvia officinalis inhibited M2 receptor activity (IC50 32.0, 20.8, and 20.1 μg mL-1, respectively), and P. ostruthium was sufficient to reverse carbachol-induced exvivo contraction of guinea pig fundic smooth muscles. Amara extract relaxes gastric smooth muscles by inhibiting the M2 muscarinic receptor. This study suggests the potential benefit of Amara extract for patients with impaired gastric accommodation.

A cholinergic signaling pathway underlying cortical circuit activation of quiescent neural stem cells in the lateral ventricle.

Neural stem cells (NSCs) in the subventricular zone (SVZ) located along the lateral ventricles (LVs) of the mammalian brain continue to self-renew to produce new neurons after birth and into adulthood. Quiescent LV cells, which are situated close to the ependymal cells lining the LVs, are activated by choline acetyltransferase-positive (ChAT+) neurons within the subependymal (subep) region of the SVZ when these neurons are stimulated by projections from the anterior cingulate cortex (ACC). Here, we uncovered a signaling pathway activated by the ACC-subep-ChAT+ circuit responsible for the activation and proliferation of quiescent LV NSCs specifically in the ventral area of the SVZ. This circuit activated muscarinic M3 receptors on quiescent LV NSCs, which subsequently induced signaling mediated by the inositol 1,4,5-trisphosphate receptor type 1 (IP3R1). Downstream of IP3R1 activation, which would be expected to increase intracellular Ca2+, Ca2+-/calmodulin-dependent protein kinase II δ and the MAPK10 signaling pathway were stimulated and required for the proliferation of quiescent LV NSCs in the SVZ. These findings reveal the mechanisms that regulate quiescent LV NSCs and underscore the critical role of projections from the ACC in promoting their proliferative activity within the ventral SVZ.

Discovery of VU6016235: A Highly Selective, Orally Bioavailable, and Structurally Distinct Tricyclic M4 Muscarinic Acetylcholine Receptor Positive Allosteric Modulator (PAM).

Herein, we report structure-activity relationship (SAR) studies to develop novel tricyclic M4 PAM scaffolds with improved pharmacological properties. This endeavor involved a "tie-back" strategy to replace a 5-amino-2,4-dimethylthieno[2,3-d]pyrimidine-6-carboxamide core, which led to the discovery of two novel tricyclic cores. While both tricyclic cores displayed low nanomolar potency against both human and rat M4 and were highly brain-penetrant, the 2,4-dimethylpyrido[4',3':4,5]thieno[2,3-d]pyrimidine tricycle core provided lead compound, VU6016235, with an overall superior pharmacological and drug metabolism and pharmacokinetics (DMPK) profile, as well as efficacy in a preclinical antipsychotic animal model.

An Improved and Efficient Practical Process for the Synthesis of Enantiomerically Pure Solifenacin Succinate as an Antimuscarinic Agent

Background: Solifenacin succinate is an active pharmaceutical drug molecule that is extremely effective in treating overactive bladder symptoms, such as urine incontinence, urgency, and frequent urination. The free base is yellow oil, and the salt solifenacin succinate forms yellowish crystals that are extremely stable and effective. Solifenacin is a very active antagonist due to its potent muscarinic M3 receptor antagonist characteristics. Furthermore, solifenacin is effective in the treatment of bowel syndrome (IBS) by blocking M3 receptors and a broad spectrum of bowel dysfunction. Objective: The objective of this study was to develop a practical and highly efficient scalable synthesis of enantiomerically pure solifenacin as an antimuscarinic agent. Methods: In this work, the Zn(OTf)2 catalyst was used to develop a novel, environmentally benign, high-yielding, and robust protocol for the synthesis of enantiomerically pure solifenacin succinate. Results: The synthesis of enantiomerically pure solifenacin succinate was achieved in seven steps using commercially available phenylethylamine and benzoyl chloride as the starting materials. We carried out the reaction optimization by treatment of (S)-1-phenyl-3,4-dihydroisoquinoline-2(1H)- carbonyl chloride and (R)-(-)-3-Quinuclidinolin in the presence of Zn(OTf)2 catalyst. Furthermore, the solifenacin-free base was treated with succinic acid to afford its corresponding salt. The highlight of this protocol is the use of 20 mol% Zn(OTf)2 catalyst for the first time. The readily available starting materials, robustness, easy operation, high yield, and low cost make the approach more attractive and highly applicable. Conclusion: In summary, we developed a novel Zn(OTf)2-catalysed environmentally benign, highyielding, and robust protocol for the synthesis of enantiomerically pure solifenacin succinate. The proposed strategy is highly cost-effective and avoids the use of hazardous and unsafe sensitive, strong bases as well as tedious work-up procedures. Effective synthesis was achieved using readily available starting materials and reagents. Thus, the protocol is highly efficient, compatible, and commercially viable for the synthesis of important solifenacin products.

“Muscarinic Receptor Antagonists: From Pharmacology to Folklore: Discovering Medications that Effectively Treat COPD and Asthma”

Acetylcholine is released into M3 muscarinic receptors by parasympathetic neurons, which give them dominating control over the smooth muscle of the airways in the lungs. Anticholinergic medications that inhibit muscarinic receptors have been used to treat respiratory disorders for more than 2,000 years. Clinical outcomes for antimuscarinic medications in asthma were inconsistent, despite pharmacologic data suggesting that they should be quite effective. As a result, the use of muscarinic antagonists decreased after β-adrenergic receptor agonists were found to be effective. Numerous reasons, such as undesirable side effects (which might range from dry mouth to coma) and the identification of other muscarinic receptor subtypes in the lungs that occasionally have conflicting effects, contribute to the lack of efficacy of muscarinic antagonists. Possibly the most significant issue is inefficient dosing as a result of poorly understood variations in administration routes is no reliable method for determining if antagonists block receptors that acetylcholine stimulates physically. Asthma and chronic obstructive pulmonary disease seem to respond well to the development of newer muscarinic receptor antagonists that address the issues of side effects and receptor specificity.

In vitro and in silico therapeutic properties of Artepillin C and Aromadendrin as collagenase and elastase inhibitors and investigation of anti-Ovarian cancer effects and antioxidant potential

In this investigation, the enzymes collagenase and elastase were inhibited by artepillin.C and aromadendrin molecules with excellent to good IC50 values of 16.65, and 0.79 μM for artepillin.C and 7.31, 19.38, and 10.56 μM for aromadendrin. Using the molecular modeling study, the chemical activity of these compounds against the enzymes, collagenase, and elastase were evaluated. The anti-cancer properties of the compounds were evaluated using the following cell lines: NIH: OVCAR-3, ES-2, UACC-1598, Hs 832(C).T [Hs832.Tc], TOV-21G, UWB1.289. The DPPH (1,1-diphenyl-2-pricrylhydrazyl) free radical scavenging assay was used to measure antioxidant activity, and the spectrophotometric method was used in this work. The chemical activities of artepillin.C and aromadendrin against collagenase and elastase were investigated utilizing the molecular docking study. The anti-cancer activities of the compounds were evaluated against NIH: OVCAR-3, ES-2, UACC-1598, Hs 832(C).T [Hs832.Tc], TOV-21G, UWB1.289 cell lines. Also, some cell lines had best results for aromadendrin like NIH: OVCAR-3, ES-2, UACC-1598, Hs 832(C).T [Hs832.Tc], TOV-21G, UWB1.289 (10.54 ± 0.94, 22.11 ± 2.52, 31.85 ± 4.73, 8.14 ± 1.52, 17.94 ± 1.88, and 24.31 ± 2.64 μM). The chemical activities of artepillin.C and aromadendrin against some of the expressed surface receptor proteins (folate receptor, CD44, EGFR, Formyl Peptide Receptor–Like 1, M2 muscarinic receptor, and estrogen receptors) in the mentioned cell lines were assessed using the molecular docking calculations. The outcomes provided information on potential interactions and their atomic-level properties. According to the docking scores, the compounds show a high affinity for binding to proteins and enzymes. Furthermore, these substances made good contact with the receptors and enzymes. As a result, these substances may have the ability to suppress cancer cells and enzymes.