Full Agonist Research Articles

Endocannabinoid control of neuroinflammation in traumatic brain injury by monoacylglycerol lipase in astrocytes.

Endocannabinoid control of neuroinflammation in traumatic brain injury by monoacylglycerol lipase in astrocytes.

Colon-Targeted Trans-Cinnamic Acid Ameliorates Rat Colitis by Activating GPR109A

We designed colon-targeted trans-cinnamic acid (tCA) and synthesized its conjugates with glutamic acid (tCA-GA) and aspartic acid (tCA-AA). We evaluated the anti-colitic activity of colon-targeted tCA using a dinitrobenzenesulfonic acid-induced rat colitis model. The conjugates lowered the distribution coefficient and Caco-2 cell permeability of tCA and converted to tCA in the cecum, with higher rates and percentages with tCA-GA than with tCA-AA. Following oral gavage, tCA-GA delivered a higher amount of tCA to the cecum and exhibited better anti-colitic effects than tCA and sulfasalazine (SSZ), which is the current treatment for inflammatory bowel disease. In the cellular assay, tCA acted as a full agonist of GPR109A (EC50: 530 µM). The anti-colitic effects of tCA-GA were significantly compromised by the co-administration of the GPR109A antagonist, mepenzolate. Collectively, colon-targeted tCA potentiated the anti-colitic activity of tCA by effectively activating GPR109A in the inflamed colon, enabling tCA to elicit therapeutic superiority over SSZ.

AM-879, a PPARy non-agonist and Ser273 phosphorylation blocker, promotes insulin sensitivity without adverse effects in mice

Obesity is one of the main risk factors for type 2 diabetes, and peroxisome proliferator-activated receptor γ (PPARγ) is considered a promising pathway on insulin sensitivity and adipose tissue metabolism. The search for molecules acting as insulin sensitizers have increased, especially for molecules that block PPARγ-Ser273 phosphorylation, without reaching full agonism. We evaluated the in vivo effects of AM-879, a PPARγ non-agonist, and found that AM-879 exerts different effects in mice depending on the dose. At lower doses, this ligand decreased BAT, increased leptin and Crh expression. However, at a higher dose, it promoted improvement on insulin sensitivity, ameliorates expression of metabolism-related genes, decreased the expression of genes related to liver toxicity, maintaining body weight and adipocyte size. These results present a new lead molecule to ameliorates insulin resistance and confirm AM-879 as a PPARγ non-agonist which blocks Ser273 phosphorylation as a good strategy to modulate insulin sensitivity without developing the adverse effects promoted by PPARγ full agonists.

Development of N-(1-Adamantyl)benzamides as Novel Anti-Inflammatory Multitarget Agents Acting as Dual Modulators of the Cannabinoid CB2 Receptor and Fatty Acid Amide Hydrolase.

Cannabinoid type 2 receptor (CB2R), belonging to the endocannabinoid system, is overexpressed in pathologies characterized by inflammation, and its activation counteracts inflammatory states. Fatty acid amide hydrolase (FAAH) is an enzyme responsible for the degradation of the main endocannabinoid anandamide; thus, the simultaneous CB2R activation and FAAH inhibition may be a synergistic anti-inflammatory strategy. Encouraged by principal component analysis (PCA) data identifying a wide chemical space shared by CB2R and FAAH ligands, we designed a small library of adamantyl-benzamides, as potential dual agents, CB2R agonists, and FAAH inhibitors. The new compounds were tested for their CB2R affinity/selectivity and CB2R and FAAH activity. Derivatives 13, 26, and 27, displaying the best pharmacodynamic profile as CB2R full agonists and FAAH inhibitors, decreased pro-inflammatory and increased anti-inflammatory cytokines production. Molecular docking simulations complemented the experimental findings by providing a molecular rationale behind the observed activities. These multitarget ligands constitute promising anti-inflammatory agents.

Buprenorphine Microdosing Cross Tapers: A Time for Change

Buprenorphine is a partial opioid agonist that is Food and Drug Administration (FDA) approved to treat chronic pain and opioid use disorder (OUD). The national prescribing guidelines in the United States (US) recommend that patients transitioning from full opioid agonists to buprenorphine first undergo 12 or more hours of active opioid withdrawal, in order to avoid buprenorphine-precipitated opioid withdrawal. This opioid-free period imposes a significant barrier for many patients. Evidence is accumulating that using microdoses of buprenorphine to cross taper from full-agonist opioids to buprenorphine is a safe and effective way to avoid opioid withdrawal and uncontrolled pain. This microdose cross-tapering strategy is already being used across the US. The US prescribing guidelines and buprenorphine training would benefit from acknowledging this new approach. Additionally, to facilitate this strategy, the FDA should approve transdermal buprenorphine formulations for OUD and manufacturers could produce lower dose formulations of sublingual buprenorphine. The time has come for us to embrace buprenorphine microdosing cross tapers as a new standard of care.

A structural mechanism of nuclear receptor biased agonism

Efforts to decrease the adverse effects of nuclear receptor (NR) drugs have yielded experimental agonists that produce better outcomes in mice. Some of these agonists have been shown to cause different, not just less intense, on-target transcriptomic effects; however, a structural explanation for such agonist-specific effects remains unknown. Here, we show that partial agonists of the NR peroxisome proliferator-associated receptor γ (PPARγ), which induce better outcomes in mice compared to clinically utilized type II diabetes PPARγ-binding drugs thiazolidinediones (TZDs), also favor a different group of coactivator peptides than the TZDs. We find that PPARγ full agonists can also be biased relative to each other in terms of coactivator peptide binding. We find differences in coactivator-PPARγ bonding between the coactivator subgroups which allow agonists to favor one group of coactivator peptides over another, including differential bonding to a C-terminal residue of helix 4. Analysis of all available NR-coactivator structures indicates that such differential helix 4 bonding persists across other NR-coactivator complexes, providing a general structural mechanism of biased agonism for many NRs. Further work will be necessary to determine if such bias translates into altered coactivator occupancy and physiology in cells.

Delta Opioid Receptor-Mediated Antidepressant-Like Effects of Diprenorphine in Mice.

Major depressive disorder is a highly common disorder, with a lifetime prevalence in the United States of approximately 21%. Traditional antidepressant treatments are limited by a delayed onset of action and minimal efficacy in some patients. Ketamine is effective and fast-acting, but there are concerns over its abuse liability. Thus, there is a need for safe, fast-acting antidepressant drugs. The opioid buprenorphine shows promise but also has abuse liability due to its mu-agonist component. Preclinical evidence indicates that the delta-opioid system contributes to mood disorders, and delta-opioid agonists are effective in preclinical models of depression- and anxiety-like states. In this study, we test the hypothesis that the mu-opioid antagonist diprenorphine by virtue of its partial delta opioid agonist activity may offer a beneficial profile for an antidepressant medication without abuse liability. Diprenorphine was confirmed to bind with high affinity to all three opioid receptors, and functional experiments for G protein activation verified diprenorphine to be a partial agonist at delta- and kappa-opioid receptors and a mu-antagonist. Studies in C57BL/6 mice demonstrated that an acute dose of diprenorphine produced antidepressant-like effects in the tail suspension test and the novelty-induced hypophagia test that were inhibited in the presence of the delta-selective antagonist, naltrindole. Diprenorphine did not produce convulsions, a side effect of many delta agonists but rather inhibited convulsions caused by the full delta agonist SNC80; however, diprenorphine did potentiate pentylenetetrazole-induced convulsions. Diprenorphine, and compounds with a similar pharmacological profile, may provide efficient and safe rapidly acting antidepressants. SIGNIFICANCE STATEMENT: The management of major depressive disorder, particularly treatment-resistant depression, is a significant unmet medical need. Here we show that the opioid diprenorphine, a compound with mu-opioid receptor antagonist activity and delta- and kappa-opioid receptor partial agonist activities, has rapid onset antidepressant-like activity in animal models. Diprenorphine and compounds with a similar pharmacological profile to diprenorphine should be explored as novel antidepressant drugs.

Design, synthesis, and structure-activity relationships of diindolylmethane derivatives as cannabinoid CB2 receptor agonists.

3,3'-Diindolylmethane (DIM), a natural product-derived compound formed upon ingestion of cruciferous vegetables, was recently described to act as a partial agonist of the anti-inflammatory cannabinoid (CB) receptor subtype CB2 . In the present study, we synthesized and evaluated a series of DIM derivatives and determined their affinities for human CB receptor subtypes in radioligand binding studies. Potent compounds were additionally evaluated in functional cAMP accumulation and β-arrestin recruitment assays. Small substituents in the 4-position of both indole rings of DIM were beneficial for high CB2 receptor affinity and efficacy. Di-(4-cyano-1H-indol-3-yl)methane (46, PSB-19837, EC50 : cAMP, 0.0144 µM, 95% efficacy compared to the full standard agonist CP55,940; β-arrestin, 0.0149 µM, 67% efficacy) was the most potent CB2 receptor agonist of the present series. Di-(4-bromo-1H-indol-3-yl)methane (44, PSB-19571) showed higher potency in β-arrestin (EC50 0.0450 µM, 61% efficacy) than in cAMP accumulation assays (EC50 0.509 µM, 85% efficacy) while 3-((1H-indol-3-yl)methyl)-4-methyl-1H-indole (149, PSB-18691) displayed a 19-fold bias for the G protein pathway (EC50 : cAMP, 0.0652 µM; β-arrestin, 1.08 µM). DIM and its analogs act as allosteric CB2 receptor agonists. These potent CB2 receptor agonists have potential as novel drugs for the treatment of inflammatory diseases.

Application of Fabric Phase Sorptive Extraction (FPSE) Engaged to Tandem LC-MS/MS for Quantification of Brorphine in Oral Fluid.

Brorphine (1-[1-[1-(4-bromophenyl) ethyl]-piperidin-4-yl]-1,3-dihydro-2H-benzo [d]imidazol-2-one) is one of the most recent novel synthetic opioids (NSOs) on the novel psychoactive substances (NPSs) market, involved in over 100 deaths in 2020. Brorphine is a substituted piperidine-benzimidazolone analogue that retains structural similarities to fentanyl, acting as a full agonist at the μ-opioid receptor. Oral Fluid (OF) is an alternative matrix, frequently analyzed for the detection of NPS. Fabric phase sorptive extraction (FPSE) is a superior, green-sample -preparation technology recently applied for drug analysis. This contribution presents the development and validation of a method, based on the application of FPSE and liquid chromatography-tandem mass spectrometry (LC-MS/MS), to determine/quantitate brorphine in OF. The method's linearity ranged between 0.05 and 50 ng/mL (R2 = 0.9993), the bias ranged between 12.0 and 16.8%, and inter- and intra-day precisions ranged between 6.4 and 9.9%. Accuracy and extraction efficiency lied between 65 and 75%. LOD/LOQ were 0.015 ng/mL/0.05 ng/mL. Analyte's post-preparative stability was higher than 95%, while no matrix interferences and carryover between runs were observed. This is the first report introducing the application of FPSE for NPS determination, specifically, the quantification of brorphine in OF, thereby presenting a simple, rapid, sensitive, specific, effective, and reliable procedure engaged to LC-MS/MS that is suitable for routine application and the analysis of more NPSs.

A FFAR1 full agonist restores islet function in models of impaired glucose-stimulated insulin secretion and diabetic non-human primates.

The free fatty acid receptor 1 (FFAR1/GPR40) mediates fatty acid-induced insulin secretion from pancreatic β-cells. At least 3 distinct binding sites exist on the FFAR1 receptor and numerous synthetic ligands have been investigated for their anti-diabetic actions. Fasiglifam, binds to site-1 and stimulates intra-cellular calcium release and improves glycemic control in diabetic patients. Recently, small molecule FFAR1 agonists were discovered which bind to site-3, stimulating both intra-cellular calcium and cAMP, resulting in insulin and glucagon-like peptide-1 (GLP-1) secretion. The ability of our site-3 FFAR1 agonist (compound A) to control blood glucose was evaluated in spontaneously diabetic cynomolgus monkeys during an oral glucose tolerance test. In type-2 diabetic (T2D) animals, significant reductions in blood glucose and insulin were noted. To better understand the mechanism of these in vivo findings, we evaluated the effect of compound A in islets under several conditions of dysfunction. First, healthy human and non-human primate islets were treated with compound A and showed potentiation of insulin and glucagon secretion from both species. Next, we determined glucose-responsive insulin secretion under gluco-lipotoxic conditions and from islets isolated from type-2 diabetic humans. Despite a dysfunctional phenotype that failed to secrete insulin in response to glucose, site-3 FFAR1 agonism not only enhanced insulin secretion, but restored glucose responsiveness across a range of glucose concentrations. Lastly, we treated ex vivo human islets chronically with a sulfonylurea to induce secondary beta-cell failure. Again, this model showed reduced glucose-responsive insulin secretion that was restored and potentiated by site-3 FFAR1 agonism. Together these data suggest a mechanism for FFAR1 where agonists have direct effects on islet hormone secretion that can overcome a dysfunctional T2D phenotype. These unique characteristics of FFAR1 site-3 agonists make them an appealing potential therapy to treat type-2 diabetes.

Discovery of (R)-2-amino-3-triazolpropanoic acid derivatives as NMDA receptor glycine site agonists with GluN2 subunit-specific activity.

N-Methyl-d-aspartate (NMDA) receptors play critical roles in central nervous system function and are involved in variety of brain disorders. We previously developed a series of (R)-3-(5-furanyl)carboxamido-2-aminopropanoic acid glycine site agonists with pronounced variation in activity among NMDA receptor GluN1/2A-D subtypes. Here, a series of (R)-2-amino-3-triazolpropanoic acid analogues with a novel chemical scaffold is designed and their pharmacological properties are evaluated at NMDA receptor subtypes. We found that the triazole can function as a bioisostere for amide to produce glycine site agonists with variation in activity among NMDA receptor subtypes. Compounds 13g and 13i are full and partial agonists, respectively, at GluN1/2C and GluN1/2D with 3- to 7-fold preference in agonist potency for GluN1/2C-D over GluN1/2A-B subtypes. The agonist binding mode of these triazole analogues and the mechanisms by which the triazole ring can serve as a bioisostere for amide were further explored using molecular dynamics simulations. Thus, the novel (R)-2-amino-3-triazolpropanoic acid derivatives reveal insights to agonist binding at the GluN1 subunit of NMDA receptors and provide new opportunities for the design of glycine site agonists.

Mass spectrometry captures biased signalling and allosteric modulation of a G-protein-coupled receptor

G-protein-coupled receptors signal through cognate G proteins. Despite the widespread importance of these receptors, their regulatory mechanisms for G-protein selectivity are not fully understood. Here we present a native mass spectrometry-based approach to interrogate both biased signalling and allosteric modulation of the β1-adrenergic receptor in response to various ligands. By simultaneously capturing the effects of ligand binding and receptor coupling to different G proteins, we probed the relative importance of specific interactions with the receptor through systematic changes in 14 ligands, including isoprenaline derivatives, full and partial agonists, and antagonists. We observed enhanced dynamics of the intracellular loop 3 in the presence of isoprenaline, which is capable of acting as a biased agonist. We also show here that endogenous zinc ions augment the binding in receptor–Gs complexes and propose a zinc ion-binding hotspot at the TM5/TM6 intracellular interface of the receptor–Gs complex. Further interrogation led us to propose a mechanism in which zinc ions facilitate a structural transition of the intermediate complex towards the stable state.

CGP42112: the full AT2 receptor agonist and its role in the renin-angiotensin-aldosterone system: no longer misunderstood.

For years, the AT2R-selective ligand CGP42112 has been erroneously characterized as a partial agonist, partly due to its ability to also interact with the AT1R at high concentrations. As late as 2009, it was still being characterized as an antagonist as well. In this perspective/opinion piece, we try to resolve the ambiguity that surrounds the efficacy of this compound by extensively reviewing the literature, tracing its beginnings to 1989, showing that CGP42112 has never been convincingly shown to be a partial agonist or an antagonist at the AT2R. While CGP42112 is now routinely characterized as an AT2R agonist, regrettably, there is a paucity of studies that can validate its efficacy as a full agonist at the AT2R, leaving the door open for continuing speculation regarding the extent of its efficacy. Hopefully, the information presented in this perspective/opinion piece will firmly establish CGP42112 as a full agonist at the AT2R such that it can once again be used as a tool to study the AT2R.

Signaling underlying kappa opioid receptor-mediated behaviors in rodents.

Kappa opioid receptor (KOR) agonists are potentially useful as analgesic and anti-pruritic agents, for prevention and treatment of substance use disorders, and for treatment of demyelinating diseases. However, side effects of KOR agonists, including psychotomimesis, dysphoria, and sedation, have caused early termination of clinical trials. Understanding the signaling mechanisms underlying the beneficial therapeutic effects and the adverse side effects may help in the development of KOR agonist compounds. In this review, we summarize the current knowledge in this regard in five sections. First, studies conducted on mutant mouse lines (GRK3-/-, p38alpha MAPK-/-, β-arrestin2-/-, phosphorylation-deficient KOR) are summarized. In addition, the abilities of four distinct KOR agonists, which have analgesic and anti-pruritic effects with different side effect profiles, to cause KOR phosphorylation are discussed. Second, investigations on the KOR agonist nalfurafine, both in vitro and in vivo are reviewed. Nalfurafine was the first KOR full agonist approved for clinical use and in the therapeutic dose range it did not produce significant side effects associated with typical KOR agonists. Third, large-scale high-throughput phosphoproteomic studies without a priori hypotheses are described. These studies have revealed that KOR-mediated side effects are associated with many signaling pathways. Fourth, several novel G protein-biased KOR agonists that have been characterized for in vitro biochemical properties and agonist biases and in vivo behavior effects are described. Lastly, possible mechanisms underlying KOR-mediated CPA, hypolocomotion and motor incoordination are discussed. Overall, it is agreed upon that the analgesic and anti-pruritic effects of KOR agonists are mediated via G protein signaling. However, there is no consensus on the mechanisms underlying their side effects. GRK3, p38 MAPK, β-arrestin2, mTOR pathway, CB1 cannabinoid receptor and protein kinase C have been implicated in one side effect or another. For drug discovery, after initial in vitro characterization, in vivo pharmacological characterizations in various behavior tests are still the most crucial steps and dose separation between beneficial therapeutic effects and adverse side effects are the critical determinant for the compounds to be moved forward for clinical development.

Pharmacological characterization of 5-iodo-A-85380, a β2-selective nicotinic receptor agonist, in mice.

Because of their implications in several pathological conditions, α4β2* nicotinic acetylcholine receptors (nAChRs) are potential targets for the treatment of nicotine dependence, pain, and many psychiatric and neurodegenerative diseases. However, they exist in various subtypes, and finding selective tools to investigate them has proved challenging. The nicotinic receptor agonist, 5-iodo-A-85380 (5IA), has helped in delineating the function of β2-containing subtypes in vitro; however, much is still unknown about its behavioral effects. Furthermore, its effectiveness on α6-containing subtypes is limited. To investigate the effects of 5IA on nociception (formalin, hot-plate, and tail-flick tests), locomotion, hypothermia, and conditioned reward after acute and repeated administration, and to examine the potential role of β2 and α6 nAChR subunits in these effects. Lastly, its selectivity for expressed low sensitivity (LS) and high sensitivity (HS) α4β2 receptors is investigated. 5IA dose-dependently induced hypothermia, locomotion suppression, conditioned place preference, and antinociception (only in the formalin test but not in the hot-plate or tail-flick tests). Furthermore, these effects were mediated by β2 but not α6 nicotinic subunits. Finally, we show that 5-iodo-A-85380 potently activates both stoichiometries of α4β2 nAChRs with differential efficacies, being a full agonist on HS α4(2)β2(3) nAChRs, and a partial agonist on LS α4(3)β2(2) nAChRs and α6-containing subtypes as well.

RF04 | PSUN233 Design of an Ultra-Stable Insulin/Glucagon Fusion Protein

Abstract Insulin replacement therapy is lifesaving for insulin-dependent diabetic patients, but it comes with an ever-present threat of hypoglycemia, which can eventually cause ischemic events, arrhythmias, neurological damage, coma, or even death. Consequently, the risk of hypoglycemia remains the most significant obstacle that prevents insulin-dependent patients from attaining adequate metabolic control. One approach to solve this issue involves the co-injection of insulin and glucagon at a fixed ratio, which has been shown to improve glycemic control with prevention of hypoglycemia. The co-administration of both hormones is based on two known physiological processes: first, insulin is a potent inhibitor of glucagon activity, especially under hyperglycemic conditions, and second, glucagon overpowers insulin and stimulates hepatic glucose production under hypoglycemic circumstances. In this work, we took this concept further into developing an insulin/glucagon fusion protein that will provide glycemic control (by the insulin portion) while preventing hypoglycemia (through the glucagon portion). Because both hormones are known to be unstable and form amyloid-like fibrils, our approach consists of using a fibrillation-resistant single-chain insulin (SCI) analog fused to a novel fibrillation-resistant glucagon analog. These molecules were independently synthesized by Solid-Phase Peptide Synthesis (SPPS) and linked together from the C-Terminus of the glucagon analog to the N-Terminus of the SCI analog by trypsin-mediated ligation. By themselves or when fused, these ultra-stable analogs didn't form fibrils after one month of agitation at 37°C in PBS (pH 7.4). By contrast, native insulin started fibrillation at 12.14 ± 3.65 hours, and native glucagon at time 0. The glucagon analog was designed to be less potent than the native molecule to allow unopposed insulin activity while in hyperglycemia but maintaining full agonism to prevent hypoglycemia. The in vitro glucagon activity was measured by cAMP production in HEK293 expressing the glucagon receptor. The glucagon analog was determined to be a full agonist with an EC50 of 125.7 nM, a ∼58-fold potency difference to the native molecule (2.175 nM). The fusion protein was tested in vitro and in vivo to determine the activities of both moieties when fused. The in vitro insulin activity of the fusion protein measured by traditional and in-cell western blot was comparable to the SCI alone. The in vitro glucagon activity of the fusion protein was also similar to the glucagon analog alone (EC50 151.2 nM), therefore validating our fusion approach. The in vivo insulin and glucagon activities are currently being tested by subcutaneous injection in diabetic (STZ) and normal rats. So far, both insulin and glucagon moieties have shown to be fully active, and hypoglycemia has not been observed in rats. Increasing doses studies are underway. We believe that this approach will allow the design of next-generation insulin treatments protected against hypoglycemia, ultra-stable, and amenable for multiplatform delivery. Presentation: Saturday, June 11, 2022 1:54 p.m. - 1:59 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

PMON14 Estrogen Activity of Supplements Targeted for Post-Menopausal Women

Abstract A wide variety of dietary supplements are available for the treatment of post-menopausal symptoms in women. Many women choose these supplements to avoid the potential unwanted side effects and long-term complications associated with traditional hormone therapy. In this study, we evaluated the in vitro estrogen activity of extracts from eleven supplements targeted for post-menopausal women to test the hypothesis that some of these supplements will induce estrogen activity in human breast cancer cell bioassays. Ethanol extracts (1 g: 1 mL) were prepared from the supplements: Amberen, Nature's Bounty Black Cohosh, Nature's Bounty St. John's Wort, Swanson Chasteberry Fruit, Nature's Way Red Clover, Promensil Real Health, Estroven, Relizen, Remifemin, and Equelle. Black cohosh, St. John's Wort, Chasteberry fruit, and red clover are standalone products that are not sold under a brand name. Promensil, Estroven, and Equelle contain isoflavones that have been reported to be estrogenic. Estroven and Remifemin contain black cohosh. Relizen contains a purified Swedish flower pollen extract and Amberen contains succinates, amino acids, minerals, and vitamin E. The estrogen activity of each extract was measured using both the T47D-kb-Luc estrogen responsive reporter gene and MCF-7 E3 proliferation estrogen bio-assays. The extracts from Nature's Way Red Clover, Promensil Real Health, and Equelle induced full estrogen agonist efficacy in the MCF-7 proliferation assay and more than full efficacy in the T47D-kb-Luc assay compared to estradiol. The agonist activity of these extracts in both bio-assays was inhibited by fulvestrant. Extracts from Nature's Bounty Black Cohosh, Nature's Bounty St. John's Wort, Swanson Chasteberry Fruit and Relizen induced less than full agonist estrogen activity only in the MCF-7 proliferation assay that was not, or not completely inhibited by fulvestrant. Thus, some supplements in this study likely target the estrogen receptor as agonists while others may be only weak estrogens that may also activate other proliferative pathways. While estrogen therapy is known to provide relief of some post-menopausal symptoms, estrogen use is associated with increased breast cancer risk. Consumers may benefit from information about the estrogen activity of supplements targeted for post-menopausal women. The results of this study may allow women to make more informed decisions about the use of these supplements. This study may be a prototype for evaluating the estrogen activity of dietary supplements for the purpose of informing consumers. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Suboxone: History, controversy, and open questions.

There are more than 200 opioid overdose deaths each day in the US. In combating this epidemic we look to available treatment tools. Here, we find only three medications approved by the Food and Drug Administration (FDA) for the treatment of opioid use disorder. Of the three, buprenorphine is of particular importance due to its reduced overdose potential as a partial opioid agonist. Evidence supports its clinical equivalence to its full agonist cousin methadone, and suggests that it is better slated for long-term treatment of opioid use disorder compared to the non-selective opioid antagonist naltrexone. Buprenorphine is most popularized within Suboxone, a medication which also contains the non-selective opioid antagonist naloxone. The naloxone has no additional effect when the drug is taken as instructed, as it is intended to prevent diversion in those that would attempt to inject the medication. While Suboxone is regarded by some as the future of medical treatment, others have expressed concerns. This review aims to explore the history, controversy, and open questions that surround buprenorphine and its most prescribed variation, Suboxone. These include its pharmacological, legislative, and social history, alternative indications, efficacy as a treatment of opioid use disorder, and more. Armed with this information, the reader will have a more in-depth and holistic understanding of the medication's place in their community.

Mechanistic basis of GPCR activation explored by ensemble refinement of crystallographic structures.

G protein‐coupled receptors (GPCRs) are important drug targets characterized by a canonical seven transmembrane (TM) helix architecture. Recent advances in X‐ray crystallography and cryo‐EM have resulted in a wealth of GPCR structures that have been used in drug design and formed the basis for mechanistic activation hypotheses. Here, ensemble refinement (ER) of crystallographic structures is applied to explore the impact of binding of agonists and antagonist/inverse agonists to selected structures of cannabinoid receptor 1 (CB1R), β2 adrenergic receptor (β2AR), and A2A adenosine receptor (A2AAR). To assess the conformational flexibility and its role in GPCR activation, hydrogen bond (H‐bond) networks are analyzed by calculating and comparing H‐bond propensities. Mapping pairwise propensity differences between agonist‐ and inverse agonist/antagonist‐bound structures for CB1R and β2AR shows that agonist binding destabilizes H‐bonds in the intracellular parts of TM 5–7, forming the G protein binding cavity, while H‐bonds of the extracellular segment of TMs surrounding the orthosteric site are conversely stabilized. Certain class A GPCRs, for example, A2AAR, bind an allosteric sodium ion that negatively modulates agonist binding. The impact of sodium‐excluding mutants (D522.50N, S913.39A) of A2AAR on agonist binding is examined by applying ER analysis to structures of wildtype and the two mutants in complex with a full agonist. While S913.39A exhibits normal activity, D522.50N quenches the downstream signaling. The mainchain H‐bond pattern of the latter is stabilized in the intracellular part of TM 7 containing the NPxxY motif, indicating that an induced rigidity of the mutation prevents conformational selection of G proteins resulting in receptor inactivation.

Identification of Selective PPAR-γ Modulators by Combining Pharmacophore Modeling, Molecular Docking, and Adipogenesis Assay.

The clinically used glitazones (rosiglitazone and pioglitazone) for type 2 diabetes mellitus therapy have been linked to serious side effects such as fluid retention, congestive heart failure, weight gain, bone loss, and an increased risk of bladder cancer. The complete activation of PPAR-γ receptors in target tissues is linked to these effects. Many studies have demonstrated that partial PPAR-γ activators (GW0072, PAT5A, GQ16) give equivalent therapeutic benefits to full PPAR-γ agonists without the associated side effects. These breakthroughs cleared the path for the development of partial agonists or selective PPAR-γ modulators (SPPARγMs). This study combined pharmacophore modeling, molecular docking, and an adipogenesis experiment to identify thiazolidine analogs as SPPARMs/partial agonists. A custom library of 220 molecules was created and virtual screened to discover 90 compounds as SPPARγMs/ partial agonists. The chosen eight compounds were synthesized and tested for adipogenesis using 3T3L1 cell lines. These compounds' partial agonistic activity was evaluated in 3T3L1 cell lines by comparing their capacity to stimulate PPAR-γ mediated adipogenesis to that of a full agonist, rosiglitazone. The findings of the adipogenesis experiment demonstrate that all eight compounds examined had a partial potential to stimulate adipogenesis when compared to the full agonist, rosiglitazone. The current investigation identified eight possible PPAR-γ partial agonists or SPPARγMs that may be effective in the treatment of type 2 diabetes mellitus.