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The leading cause of steroid-induced femoral head osteonecrosis (ONFH) is the imbalance of bone homeostasis. Bone marrow-derived mesenchymal stem cell (BMSC) differentiation and fate are closely associated with bone homeostasis imbalance. Blocking monoacylglycerol lipase (MAGL) could effectively ameliorate ONFH by mitigating oxidative stress and apoptosis in BMSCs induced by glucocorticoids (GC). Nevertheless, whether MAGL inhibition can modulate the balance during BMSC differentiation, and therefore improve ONFH, remains elusive. Our study indicates that MAGL inhibition can effectively rescue the enhanced BMSC adipogenic differentiation caused by GC and promote their differentiation toward osteogenic lineages. Cannabinoid receptor 2 (CB2) is the direct downstream target of MAGL in BMSCs, rather than cannabinoid receptor 1(CB1). Using RNA sequencing analyses and a series of in vitro experiments, we confirm that the MAGL blockade-induced enhancement of BMSC osteogenic differentiation is primarily mediated by the phosphoinositide 3-kinases (PI3K)/ the serine/threonine kinase (AKT)/ (glycogen synthase kinase-3 beta) GSK3β pathway. Additionally, MAGL blockade can also reduce GC-induced bone resorption by directly suppressing osteoclastogenesis and indirectly reducing the expression of receptor activator of nuclear factor kappa-Β ligand (RANKL) in BMSCs. Thus, our study proposes that the therapeutic effect of MAGL blockade on ONFH is partly mediated by restoring the balance of bone homeostasis and MAGL may be an effective therapeutic target for ONFH. [ABSTRACT FROM AUTHOR]

The endocannabinoid system, known for its regulatory role in various physiological processes, relies on the activities of several hydrolytic enzymes, such as fatty acid amide hydrolase (FAAH), N-acylethanolamine-hydrolyzing acid amidase (NAAA), monoacylglycerol lipase (MAGL), and α/β-hydrolase domains 6 (ABHD6) and 12 (ABHD12), to maintain homeostasis. Accurate measurement of these enzymes' activities is crucial for understanding their function and for the development of potential therapeutic agents. Fluorometric assays, which offer high sensitivity, specificity, and real-time monitoring capabilities, have become essential tools in enzymatic studies. This review provides a comprehensive overview of the principles behind these assays, the various substrates and fluorophores used, and advances in assay techniques used not only for the determination of the kinetic mechanisms of enzyme reactions but also for setting up kinetic assays for the high-throughput screening of each critical enzyme involved in endocannabinoid degradation. Through this comprehensive review, we aim to highlight the strengths and limitations of current fluorometric assays and suggest future directions for improving the measurement of enzyme activity in the endocannabinoid system. [ABSTRACT FROM AUTHOR]

AbstractThermophilic Geobacillus kaustophilus HTA426 genome possesses a monoacylglycerol lipase (MAGL) gene. MAGLs can synthesize emulsifiers for use in the food and pharmaceutical industries from fatty acids and glycerol. They can also be used to analyze monoacylglycerol (MAG) levels in serum and food. The MAGL gene from strain HTA426 was artificially synthesized and heterologously expressed in Escherichia coli BL21(DE3). The recombinant His-tag fused MAGL (GkMAGL) was purified using a Ni2+-affinity column. The purified enzyme showed a temperature optimum at 65 °C and was stable up to 75 °C after 30 min incubation. In addition, the enzyme exhibited a pH optimum of 7.5 and was stable from pH 5.0 to 11.0. The enzyme hydrolyzed monoacylglycerols and showed the highest activity toward 1-monolauroylglycerol. The enzyme was stable in the presence of various organic solvents and detergents. The addition of Triton X-100 significantly increased GkMAGL activity. The thermal stability of the enzyme was higher than that of thermostable MAGL from Geobacillus sp. 12AMOR1 (12AMOR1_MAGL). Circular dichroism spectral analysis showed that the conformational stability of the GkMAGL was higher than that of 12AMOR1_MAGL at higher temperatures. These results indicate that the GkMAGL has useful features that can be used for various biotechnological applications. [ABSTRACT FROM AUTHOR]

Purpose: The monoacylglycerol lipase (MAGL) plays a pivotal role in modulating the endocannabinoid system and is considered an attractive therapeutic target for diseases in both the central nervous system and periphery. The current study aimed to develop and evaluate a suitable carbon-11 labeled tracer for imaging MAGL in preclinical studies.(R)-YH168 was synthesized via a multi-step pathway and its half-maximal inhibitory concentration (IC50) values were measured using an enzymatic assay. Radiosynthesis of (R)-[11C]YH168 was accomplished by 11C-methylation via Suzuki cross-coupling of a pinacol boron precursor. In vitro autoradiography was performed using brain tissues from MAGL knockout and the corresponding wild-type mice. The metabolic stability of (R)-[11C]YH168 in mouse brain and plasma was assessed 5 min after injection. Dynamic PET scans were conducted on anesthetized mice and rhesus monkey. For studies in non-human primates, arterial blood samples were analyzed to obtain the input function for kinetic modeling. Blocking studies with the irreversible MAGL inhibitor PF-06795071 were performed to assess the binding specificity of (R)-[11C]YH168.(R)-[11C]YH168 was synthesized via Suzuki coupling of the phenyl boronic ester with [11C]CH3I in the presence of palladium catalyst. In vitro autoradiography revealed a heterogeneous distribution pattern of (R)-[11C]YH168 with higher binding to MAGL-rich brain regions in wild-type mouse brain slices compared to that of MAGL knockout mice. Dynamic PET imaging in wild-type and MAGL knockout mice confirmed its high specificity and selectivity in mouse brains. In the rhesus monkey, (R)-[11C]YH168 displayed good brain permeability. High levels of radioactivity uptake were seen in the cingulate cortex, frontal cortex, cerebellum, occipital cortex, and hippocampus, consistent with MAGL expression. The one-tissue compartment model was appropriate for fitting the regional time-activity curves and provided reliable volume of distribution values across all brain regions. Pretreatment with PF-06795071 (0.1 mg/kg) resulted in almost complete blockade (> 95%) of radioactivity uptake, demonstrating binding specificity of (R)-[11C]YH168 to MAGL in the non-human primate brain. The regional non-displaceable binding potential follows the rank order of cingulate cortex ~ frontal cortex ~ insula > putamen > temporal cortex > caudate ~ occipital cortex ~ thalamus > nucleus accumbens ~ hippocampus ~ cerebellum ~ globus pallidus > substantia nigra > amygdala.(R)-[11C]YH168 is a promising PET probe for imaging and quantifying MAGL in the brains of mice and non-human primates. This 11C-labeled tracer holds great potential for translation into human subjects and offers the possibility of performing multiple PET scans on the same subject within a single day.Methods: The monoacylglycerol lipase (MAGL) plays a pivotal role in modulating the endocannabinoid system and is considered an attractive therapeutic target for diseases in both the central nervous system and periphery. The current study aimed to develop and evaluate a suitable carbon-11 labeled tracer for imaging MAGL in preclinical studies.(R)-YH168 was synthesized via a multi-step pathway and its half-maximal inhibitory concentration (IC50) values were measured using an enzymatic assay. Radiosynthesis of (R)-[11C]YH168 was accomplished by 11C-methylation via Suzuki cross-coupling of a pinacol boron precursor. In vitro autoradiography was performed using brain tissues from MAGL knockout and the corresponding wild-type mice. The metabolic stability of (R)-[11C]YH168 in mouse brain and plasma was assessed 5 min after injection. Dynamic PET scans were conducted on anesthetized mice and rhesus monkey. For studies in non-human primates, arterial blood samples were analyzed to obtain the input function for kinetic modeling. Blocking studies with the irreversible MAGL inhibitor PF-06795071 were performed to assess the binding specificity of (R)-[11C]YH168.(R)-[11C]YH168 was synthesized via Suzuki coupling of the phenyl boronic ester with [11C]CH3I in the presence of palladium catalyst. In vitro autoradiography revealed a heterogeneous distribution pattern of (R)-[11C]YH168 with higher binding to MAGL-rich brain regions in wild-type mouse brain slices compared to that of MAGL knockout mice. Dynamic PET imaging in wild-type and MAGL knockout mice confirmed its high specificity and selectivity in mouse brains. In the rhesus monkey, (R)-[11C]YH168 displayed good brain permeability. High levels of radioactivity uptake were seen in the cingulate cortex, frontal cortex, cerebellum, occipital cortex, and hippocampus, consistent with MAGL expression. The one-tissue compartment model was appropriate for fitting the regional time-activity curves and provided reliable volume of distribution values across all brain regions. Pretreatment with PF-06795071 (0.1 mg/kg) resulted in almost complete blockade (> 95%) of radioactivity uptake, demonstrating binding specificity of (R)-[11C]YH168 to MAGL in the non-human primate brain. The regional non-displaceable binding potential follows the rank order of cingulate cortex ~ frontal cortex ~ insula > putamen > temporal cortex > caudate ~ occipital cortex ~ thalamus > nucleus accumbens ~ hippocampus ~ cerebellum ~ globus pallidus > substantia nigra > amygdala.(R)-[11C]YH168 is a promising PET probe for imaging and quantifying MAGL in the brains of mice and non-human primates. This 11C-labeled tracer holds great potential for translation into human subjects and offers the possibility of performing multiple PET scans on the same subject within a single day.Results: The monoacylglycerol lipase (MAGL) plays a pivotal role in modulating the endocannabinoid system and is considered an attractive therapeutic target for diseases in both the central nervous system and periphery. The current study aimed to develop and evaluate a suitable carbon-11 labeled tracer for imaging MAGL in preclinical studies.(R)-YH168 was synthesized via a multi-step pathway and its half-maximal inhibitory concentration (IC50) values were measured using an enzymatic assay. Radiosynthesis of (R)-[11C]YH168 was accomplished by 11C-methylation via Suzuki cross-coupling of a pinacol boron precursor. In vitro autoradiography was performed using brain tissues from MAGL knockout and the corresponding wild-type mice. The metabolic stability of (R)-[11C]YH168 in mouse brain and plasma was assessed 5 min after injection. Dynamic PET scans were conducted on anesthetized mice and rhesus monkey. For studies in non-human primates, arterial blood samples were analyzed to obtain the input function for kinetic modeling. Blocking studies with the irreversible MAGL inhibitor PF-06795071 were performed to assess the binding specificity of (R)-[11C]YH168.(R)-[11C]YH168 was synthesized via Suzuki coupling of the phenyl boronic ester with [11C]CH3I in the presence of palladium catalyst. In vitro autoradiography revealed a heterogeneous distribution pattern of (R)-[11C]YH168 with higher binding to MAGL-rich brain regions in wild-type mouse brain slices compared to that of MAGL knockout mice. Dynamic PET imaging in wild-type and MAGL knockout mice confirmed its high specificity and selectivity in mouse brains. In the rhesus monkey, (R)-[11C]YH168 displayed good brain permeability. High levels of radioactivity uptake were seen in the cingulate cortex, frontal cortex, cerebellum, occipital cortex, and hippocampus, consistent with MAGL expression. The one-tissue compartment model was appropriate for fitting the regional time-activity curves and provided reliable volume of distribution values across all brain regions. Pretreatment with PF-06795071 (0.1 mg/kg) resulted in almost complete blockade (> 95%) of radioactivity uptake, demonstrating binding specificity of (R)-[11C]YH168 to MAGL in the non-human primate brain. The regional non-displaceable binding potential follows the rank order of cingulate cortex ~ frontal cortex ~ insula > putamen > temporal cortex > caudate ~ occipital cortex ~ thalamus > nucleus accumbens ~ hippocampus ~ cerebellum ~ globus pallidus > substantia nigra > amygdala.(R)-[11C]YH168 is a promising PET probe for imaging and quantifying MAGL in the brains of mice and non-human primates. This 11C-labeled tracer holds great potential for translation into human subjects and offers the possibility of performing multiple PET scans on the same subject within a single day.Conclusion: The monoacylglycerol lipase (MAGL) plays a pivotal role in modulating the endocannabinoid system and is considered an attractive therapeutic target for diseases in both the central nervous system and periphery. The current study aimed to develop and evaluate a suitable carbon-11 labeled tracer for imaging MAGL in preclinical studies.(R)-YH168 was synthesized via a multi-step pathway and its half-maximal inhibitory concentration (IC50) values were measured using an enzymatic assay. Radiosynthesis of (R)-[11C]YH168 was accomplished by 11C-methylation via Suzuki cross-coupling of a pinacol boron precursor. In vitro autoradiography was performed using brain tissues from MAGL knockout and the corresponding wild-type mice. The metabolic stability of (R)-[11C]YH168 in mouse brain and plasma was assessed 5 min after injection. Dynamic PET scans were conducted on anesthetized mice and rhesus monkey. For studies in non-human primates, arterial blood samples were analyzed to obtain the input function for kinetic modeling. Blocking studies with the irreversible MAGL inhibitor PF-06795071 were performed to assess the binding specificity of (R)-[11C]YH168.(R)-[11C]YH168 was synthesized via Suzuki coupling of the phenyl boronic ester with [11C]CH3I in the presence of palladium catalyst. In vitro autoradiography revealed a heterogeneous distribution pattern of (R)-[11C]YH168 with higher binding to MAGL-rich brain regions in wild-type mouse brain slices compared to that of MAGL knockout mice. Dynamic PET imaging in wild-type and MAGL knockout mice confirmed its high specificity and selectivity in mouse brains. In the rhesus monkey, (R)-[11C]YH168 displayed good brain permeability. High levels of radioactivity uptake were seen in the cingulate cortex, frontal cortex, cerebellum, occipital cortex, and hippocampus, consistent with MAGL expression. The one-tissue compartment model was appropriate for fitting the regional time-activity curves and provided reliable volume of distribution values across all brain regions. Pretreatment with PF-06795071 (0.1 mg/kg) resulted in almost complete blockade (> 95%) of radioactivity uptake, demonstrating binding specificity of (R)-[11C]YH168 to MAGL in the non-human primate brain. The regional non-displaceable binding potential follows the rank order of cingulate cortex ~ frontal cortex ~ insula > putamen > temporal cortex > caudate ~ occipital cortex ~ thalamus > nucleus accumbens ~ hippocampus ~ cerebellum ~ globus pallidus > substantia nigra > amygdala.(R)-[11C]YH168 is a promising PET probe for imaging and quantifying MAGL in the brains of mice and non-human primates. This 11C-labeled tracer holds great potential for translation into human subjects and offers the possibility of performing multiple PET scans on the same subject within a single day. [ABSTRACT FROM AUTHOR]

Degumming is essential to eliminate undesired phospholipids from crude vegetable oils before being processed into high-quality products. The degumming efficiency is hampered by the separation of oil and water. To overcome this problem, we introduced an innovative enzymatic degumming strategy for various vegetable oils (rice bran, peanut and flaxseed oil) by combining phospholipase A1 with monoacylglycerol lipase. Compared to using phospholipase A1, the combination of the two enzymes significantly reduced phosphorus content, indicating better hydrolysis of phospholipids. Additionally, the primary hydrolysates by the combined enzymes were glycerylphosphorylcholine and glycerylphosphorylethanolamine that were more affinitive to water to improve oil-water separation and oil yield. Characteristic markers obtained from Partial Least Squares Discriminant Analysis model confirmed the advantages of combined enzymes over single enzyme. This advantage of combined enzymes was further validated in a simulated degumming process. Our findings provide a new enzymatic degumming strategy to expand the toolkit for crude oil refinery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Evidence suggests that monoacylglycerol lipase (MAGL) inhibitors can potentially treat HIV symptoms by increasing the concentration of 2-arachidonoylglycerol (2-AG). We examined a selective MAGL inhibitor ABX1431 in the context of neuroHIV. Methods: To assess the effects of ABX1431, we conducted in vitro and in vivo studies. In vitro calcium imaging on frontal cortex neuronal cultures was performed to evaluate the role of ABX1431 (10, 30, 100 nM) on transactivator of transcription (Tat)-induced neuronal hyperexcitability. Following in vitro experiments, in vivo experiments were performed using Tat transgenic male mice. Mice were treated with 4 mg/kg ABX1431 and assessed for antinociception using tail-flick and hot plate assays followed by locomotor activity. After the behavioral experiments, their brains were harvested to quantify endocannabinoids (eCB) and related lipids through mass spectrometry, and cannabinoid type-1 and -2 receptors (CB 1 R and CB 2 R) were quantified through western blot. Results: In vitro studies revealed that adding Tat directly to the neuronal cultures significantly increased intracellular calcium concentration, which ABX1431 completely reversed at all concentrations. Preincubating the cultures with CB 1 R and CB 2 R antagonists showed that ABX1431 exhibited its effects partially through CB 1 R. In vivo studies demonstrated that acute ABX1431 increased overall total distance traveled and speed of mice regardless of their genotype. Mass spectrometry and western blot analyses revealed differential effects on the eCB system based on Tat expression. The 2-AG levels were significantly upregulated following ABX1431 treatment in the striatum and spinal cord. Arachidonic acid (AA) was also upregulated in the striatum of vehicle-treated Tat(+) mice. No changes were noted in CB 1 R expression levels; however, CB 2 R levels were increased in ABX1431-treated Tat(-) mice only. Conclusion: Findings indicate that ABX1431 has potential neuroprotective effects in vitro partially mediated through CB 1 R. Acute treatment of ABX1431 in vivo shows antinociceptive effects, and seems to alter locomotor activity, with upregulating 2-AG levels in the striatum and spinal cord.

Carbamate has been extensively used as a scaffold in the recent era of drug discovery and is a common structural motif of many approved drugs. The carbamate moiety's unique amide-ester hybrid (-O-CO-NH-) feature offers the designing of specific drug-target interactions. Despite the discovery of numerous carbamate derivatives that act on the endocannabinoid system (ECS), the development of clinically effective carbamates remains a challenge. In this review, we highlight the therapeutic potential of carbamate inhibitors of endocannabinoid degrading enzymes as a breakthrough in discovering neurotherapeutic drugs. We discuss the design strategies and medicinal chemistry aspects involved in developing carbamate-based molecular architectures that modulate the endocannabinoid signaling pathway by interfering with fatty acid amide hydrolase (FAAH), monoacylglycerol lipase (MAGL), and α/β-Hydrolase domain-containing 6 (ABHD6). Additionally, we highlight the dual activity profile of carbamates against FAAH and MAGL, FAAH and cholinesterase, and FAAH and TRPV1 channels. Furthermore, we illustrate the pharmacophores of O-functionalized carbamates and N-cyclic carbamates that are crucial for FAAH and MAGL inhibitory activities, respectively., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Osteoarthritis (OA) is a progressive degenerative joint disease that presents with significant pain and functional disability. The endocannabinoid 2-arachidonoylglycerol activates cannabinoid receptors to reduce pain while its hydrolysis by the enzyme monoacylglycerol lipase (MAGL) generates arachidonic acid, the direct precursor to proalgesic eicosanoids synthesized by cyclooxygenase-2 (COX-2), highlighting the potential for crosstalk between MAGL and COX-2. While COX-2 expression in human OA cartilage has been described, the distribution of MAGL in knee osteochondral tissue has not been reported and was the goal of the current study. Methods: MAGL and COX-2 expression in International Cartilage Repair Society grade II and grade IV knee osteochondral tissue obtained from male and female subjects with OA was investigated through immunohistochemistry. Immunolocalization of both proteins was investigated within articular cartilage and subchondral bone. Results: MAGL is expressed throughout the cartilage of grade II arthritic tissue, with prominent distribution in the superficial and deep zones. Elevated expression of MAGL was evident in grade IV samples, with additional distribution observed in subchondral bone. COX-2 expression followed a similar pattern, with uniform distribution in cartilage and increased expression in grade IV tissue. Conclusions: This study establishes MAGL expression in arthritic cartilage and subchondral bone of subjects with OA. The proximity between MAGL and COX-2 suggests the potential for crosstalk between endocannabinoid hydrolysis and eicosanoid signaling in the maintenance of OA pain.

[Display omitted] • A series of naphthyl amide derivatives were designed and synthesized as a another type of reversible MAGL inhibitors. • The naphthyl amide derivative ± 34 , were identified as potent reversible MAGL inhibitor. • Compound ± 34 showed appreciable antiproliferative activities against several cancer cells, including H460, HT29, CT-26, Huh7 and HCCLM-3. Monoacylglycerol lipase (MAGL) is a key enzyme responsible for the metabolism of the endocannabinoid 2-arachidonoylglycerol (2-AG), and has attracted great interest due to its involvement in various physiological and pathological processes, such as cancer progression. In the past, a number of covalent irreversible inhibitors have been reported for MAGL, however, experimental evidence highlighted some drawbacks associated with the use of these irreversible agents. Therefore, efforts were mainly focused on the development of reversible MAGL inhibitor in recent years. Here, we designed and synthesized a series of naphthyl amide derivatives (12 – 39) as another type of reversible MAGL inhibitors, exemplified by ± 34 , which displayed good MAGL inhibition with a pIC 50 of 7.1, and the potency and selectivity against endogenous MAGL were further demonstrated by competitive ABPP. Moreover, the compound showed appreciable antiproliferative activities against several cancer cells, including H460, HT29, CT-26, Huh7 and HCCLM-3. The investigations culminated in the discovery of the naphthyl amide derivative ± 34 , and it may represent as a new scaffold for MAGL inhibitor development, particularly for the reversible ones. [ABSTRACT FROM AUTHOR]

2-Arachidonoylglycerol (2-AG) is the most prevalent endocannabinoid involved in maintaining brain homeostasis. Previous studies have demonstrated that inactivating monoacylglycerol lipase (MAGL), the primary enzyme responsible for degrading 2-AG in the brain, alleviates neuropathology and prevents synaptic and cognitive decline in animal models of neurodegenerative diseases. However, we show that selectively inhibiting 2-AG metabolism in neurons impairs cognitive function in mice. This cognitive impairment appears to result from decreased expression of synaptic proteins and synapse numbers, impaired long-term synaptic plasticity and cortical circuit functional connectivity, and diminished neurogenesis. Interestingly, the synaptic and cognitive deficits induced by neuronal MAGL inactivation can be counterbalanced by inhibiting astrocytic 2-AG metabolism. Transcriptomic analyses reveal that inhibiting neuronal 2-AG degradation leads to widespread changes in expression of genes associated with synaptic function. These findings suggest that crosstalk in 2-AG signaling between astrocytes and neurons is crucial for maintaining synaptic and cognitive functions and that excessive 2-AG in neurons alone is detrimental to cognitive function.

Intracellular pH is a valuable index for predicting neuronal damage and injury. However, no PET probe is currently available for monitoring intracellular pH in vivo . In this study, we developed a new approach for visualizing the hydrolysis rate of monoacylglycerol lipase, which is widely distributed in neurons and astrocytes throughout the brain. This approach uses PET with the new radioprobe [ 11 C]QST-0837 (1,1,1,3,3,3-hexafluoropropan-2-yl-3-(1-phenyl-1 H -pyrazol-3-yl)azetidine-1-[ 11 C]carboxylate), a covalent inhibitor containing an azetidine carbamate skeleton for monoacylglycerol lipase. The uptake and residence of this new radioprobe depends on the intracellular pH gradient, and we evaluated this with in silico , in vitro and in vivo assessments. Molecular dynamics simulations predicted that because the azetidine carbamate moiety is close to that of water molecules, the compound containing azetidine carbamate would be more easily hydrolyzed following binding to monoacylglycerol lipase than would its analogue containing a piperidine carbamate skeleton. Interestingly, it was difficult for monoacylglycerol lipase to hydrolyze the azetidine carbamate compound under weakly acidic (pH 6) conditions because of a change in the interactions with water molecules on the carbamate moiety of their complex. Subsequently, an in vitro assessment using rat brain homogenate to confirm the molecular dynamics simulation-predicted behaviour of the azetidine carbamate compound showed that [ 11 C]QST-0837 reacted with monoacylglycerol lipase to yield an [ 11 C]complex, which was hydrolyzed to liberate 11 CO 2 as a final product. Additionally, the 11 CO 2 liberation rate was slower at lower pH. Finally, to indicate the feasibility of estimating how the hydrolysis rate depends on intracellular pH in vivo , we performed a PET study with [ 11 C]QST-0837 using ischaemic rats. In our proposed in vivo compartment model, the clearance rate of radioactivity from the brain reflected the rate of [ 11 C]QST-0837 hydrolysis (clearance through the production of 11 CO 2 ) in the brain, which was lower in a remarkably hypoxic area than in the contralateral region. In conclusion, we indicated the potential for visualization of the intracellular pH gradient in the brain using PET imaging, although some limitations remain. This approach should permit further elucidation of the pathological mechanisms involved under acidic conditions in multiple CNS disorders., Competing Interests: The authors report no competing interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain.)

Monoacylglycerol lipase (MAGL) plays a crucial role in the degradation of 2-arachidonoylglycerol (2-AG), one of the major endocannabinoids in the brain. Inhibiting MAGL could lead to increased levels of 2-AG, which showed beneficial effects on pain management, anxiety, inflammation, and neuroprotection. In the current study, we report the characterization of an enantiomerically pure (R)-[ 11 C]YH132 as a novel MAGL PET tracer. It demonstrates an improved pharmacokinetic profile compared to its racemate. High in vitro MAGL specificity of (R)-[ 11 C]YH132 was confirmed by autoradiography studies using mouse and rat brain sections. In vivo, (R)-[ 11 C]YH132 displayed a high brain penetration, and high specificity and selectivity toward MAGL by dynamic PET imaging using MAGL knockout and wild-type mice. Pretreatment with a MAGL drug candidate revealed a dose-dependent reduction of (R)-[ 11 C]YH132 accumulation in WT mouse brains. This result validates its utility as a PET probe to assist drug development. Moreover, its potential application in neurodegenerative diseases was explored by in vitro autoradiography using brain sections from animal models of Alzheimer's disease and Parkinson's disease., (© 2024 The Authors. ChemBioChem published by Wiley-VCH GmbH.)

The degradation of the endocannabinoid 2-arachidonoylglycerol is mediated by the enzyme monoacylglycerol lipase (MAGL), thus generating arachidonic acid, the precursor of prostaglandins and other pro-inflammatory mediators. MAGL also contributes to the hydrolysis of monoacylglycerols into glycerol and fatty acids in peripheral body districts, which may act as pro-tumorigenic signals. For this reason, MAGL inhibitors have been considered as interesting therapeutic agents for their anti-nociceptive, anti-inflammatory, antioxidant and anti-cancer properties. So far, only a limited series of reversible MAGL inhibitors, which are devoid of side effects shown by irreversible inhibitors in animal models, have been reported. Here we optimized a class of benzylpiperidine and benzylpiperazine-based compounds for a reversible MAGL inhibition. The best MAGL inhibitors of this class, compounds 28 and 29 , showed a very good inhibition potency, both on the isolated enzyme and in U937 cells, as confirmed by molecular modeling studies that predicted their binding mode into the MAGL active site. Both compounds are characterized by a high selectivity for MAGL versus other serine hydrolases including enzymes of the endocannabinoid system, as confirmed by ABPP experiments in mouse brain membranes. Moreover, very good properties concerning ADME parameters and low in vivo toxicity have been observed for both compounds. [Display omitted] • Novel benzylpiperidine and benzylpiperazine derivatives were synthesized and tested for their inhibition activities of MAGL. • Compounds 13 , 16 , 28 and 29 are the most potent and selective reversible MAGL inhibitors of this series of compounds. • Compounds 28 and 29 show very good ADME properties and low in vivo toxicity. [ABSTRACT FROM AUTHOR]

Glycerol-3-phosphate dehydrogenase (GPD1) and monoacylglycerol lipase (MAGL) levels are known to be significantly downregulated in both the tissue and serum samples of patients with triple-negative breast cancer (TNBC), compared with other BC subtypes and healthy controls. As such, the association between GPD1 and MAGL levels and lymph node metastasis was evaluated in the present study. Utilizing western blotting, lymph node protein extracts from metastasized BC subtypes were analyzed and a significant downregulation of GPD1 and MAGL protein expression levels in the lymph node metastases was demonstrated in the TNBC subtype, compared with healthy controls. This finding further highlighted the potential use of these two proteins in early BC onset and metastasis detection. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate ( R )-[ 18 F]YH134 as a novel PET tracer for imaging monoacylglycerol lipase (MAGL). Considering the ubiquitous expression of MAGL throughout the whole body, the impact of various MAGL inhibitors on ( R )-[ 18 F]YH134 brain uptake and its application in brain-periphery crosstalk were explored. Methods: MAGL knockout and wild-type mice were used to evaluate ( R )-[ 18 F]YH134 in in vitro autoradiography and PET experiments. To explore the impact of peripheral MAGL occupancy on ( R )-[ 18 F]YH134 brain uptake, PET kinetics with an arterial input function were studied in male Wistar rats under baseline and blocking conditions. Results: In in vitro autoradiography, ( R )-[ 18 F]YH134 revealed a heterogeneous distribution pattern with high binding to MAGL-rich brain regions in wild-type mouse brain slices, whereas the radioactive signal was negligible in MAGL knockout mouse brain slices. The in vivo brain PET images of ( R )-[ 18 F]YH134 in wild-type and MAGL knockout mice demonstrated its high specificity and selectivity in mouse brain. A Logan plot with plasma input function was applied to estimate the distribution volume ( V T ) of ( R )-[ 18 F]YH134. V T was significantly reduced by a brain-penetrant MAGL inhibitor but was unchanged by a peripherally restricted MAGL inhibitor. The MAGL target occupancy in the periphery was estimated using ( R )-[ 18 F]YH134 PET imaging data from the brain. Conclusion: ( R )-[ 18 F]YH134 is a highly specific and selective PET tracer with favorable kinetic properties for imaging MAGL in rodent brain. Our results showed that blocking of the peripheral target influences brain uptake but not the V T of ( R )-[ 18 F]YH134. ( R )-[ 18 F]YH134 can be used for estimating the dose of MAGL inhibitor at half-maximal peripheral target occupancy., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)