This study elucidated the structure-activity relationships (SAR) of three distinct opioid ligand series at the μ-opioid receptor (μ-OR) and investigated the ligand-dependent role of arrestin in downstream signaling. Radioligand binding assays across 13 compounds revealed that high-affinity μ-OR binding is not restricted to a single chemical scaffold. For fentanyl analogs, SAR analysis identified four key structural determinants: the N-phenethyl group (R1) is essential for μ-OR binding, the piperidine 4-position (R2) is sterically constrained and tolerates only small substituents such as carbomethoxy, the acyl side chain (R3) tolerates diverse chemical modifications including alkyl, alkoxy, and heteroaryl groups without substantial loss of affinity, and para-substitution on the phenethyl ring (R4) with electron-withdrawing groups like fluorine is well-tolerated. Analysis of non-fentanyl scaffolds (2-Methyl AP-237, W-15, and brorphine) demonstrated that specific side-chain functionalization, rather than core scaffold architecture, primarily determines binding potency. Comparison of classical opioids further revealed that structural flexibility, exemplified by methadone, can confer superior binding affinity compared to the rigid morphine scaffold. Consistent with this structural diversity, the contribution of arrestins to ERK activation varied substantially across compounds, suggesting that μ-OR-biased signaling is not dictated exclusively by intrinsic receptor properties but emerges from the interplay between receptor conformation and ligandspecific structural features. Collectively, our results provide a molecular framework for understanding opioid pharmacology with important implications for rational drug design aimed at minimizing adverse effects while maintaining analgesic efficacy.

The N-methyl-D-aspartate receptor (NMDA-R) subunit GluN2B is abundantly expressed in brain regions critical for synaptic plasticity and cognitive processes. This study investigated the structure-activity relationships (SAR) of NMDA-R ligands using GluN2B as a molecular target. Thirty potential NMDA-R antagonists were categorized into two structural classes: 1-(1-phenylcyclohexyl) amines (series A) and α-amino-2-phenylcyclohexanone derivatives (series B). In series A compounds, the phenyl ring and R1 substituents were positioned at the carbon center of the cyclohexyl ring, with R2 substituents at the para- or meta-positions of the phenyl ring. SAR analysis revealed optimal binding affinity when R1 was carbonyl (C=O) and R2 was 4-methoxy (4-OMe). Series B compounds featured a cyclohexanone scaffold with NH-R1 at the α-position and a phenyl ring bearing R2 substituents at ortho-, meta-, or para-positions. Maximum binding affinity was achieved with R1 as hydrogen (H) and R2 as hydroxyl (OH). Compounds were assessed for GluN2B-mediated ERK activation to evaluate potential metabotropic signaling properties. Approximately 50% of the compounds demonstrated ERK activation through a non-ionotropic signaling cascade involving Src, phosphatidylinositol 3-kinase, and protein kinase C. This study elucidated key structural determinants for NMDA-R binding and characterized a novel metabotropic signaling pathway. Notably, our findings suggest that compounds acting as antagonists at the ionotropic site may simultaneously function as agonists through non-ionotropic mechanisms.

Although histone deacetylase 6 (HDAC6) is considered a therapeutic target for Alzheimer’s disease (AD), its role in cholinergic dysfunction in AD patients remains unclear. This study investigated the effects of (E)-3-(2-(4-fluorostyryl)thiazol-4-yl)-N-hydroxypropanamide (4-FHA), a new synthetic HDAC6 inhibitor, on cognitive and memory impairments in a scopolamine-induced-AD mouse model. Behaviorally, 4-FHA improved scopolamine-induced memory impairments in the Y-maze, passive avoidance, and Morris water maze tests. In addition, 4-FHA ameliorated scopolamine-induced cognitive impairments in the novel object recognition and place recognition tests. Furthermore, 4-FHA increased acetylation of α-tubulin (a major HDAC6 substrate); the expression of BDNF; and the phosphorylation of ERK 1/2, CREB, and ChAT in the hippocampus of scopolamine-treated mice. In summary, according to our data 4-FHA, an HDAC6 inhibitor, improved the cognitive and memory deficits of the AD mouse model by normalizing BDNF signaling and synaptic transmission, suggesting that 4-FHA might be a potential therapeutic candidate for AD.

The N-methyl-D-aspartate receptor (NMDA-R) subunit GluN2B is abundantly expressed in brain regions critical for synaptic plasticity and cognitive processes. This study investigated the structure-activity relationships (SAR) of NMDA-R ligands using GluN2B as a molecular target. Thirty potential NMDA-R antagonists were categorized into two structural classes: 1-(1-phenylcyclohexyl) amines (series A) and α-amino-2-phenylcyclohexanone derivatives (series B). In series A compounds, the phenyl ring and R1 substituents were positioned at the carbon center of the cyclohexyl ring, with R2 substituents at the para- or meta-positions of the phenyl ring. SAR analysis revealed optimal binding affinity when R1 was carbonyl (C=O) and R2 was 4-methoxy (4-OMe). Series B compounds featured a cyclohexanone scaffold with NH-R1 at the α-position and a phenyl ring bearing R2 substituents at ortho-, meta-, or para-positions. Maximum binding affinity was achieved with R1 as hydrogen (H) and R2 as hydroxyl (OH). Compounds were assessed for GluN2B-mediated ERK activation to evaluate potential metabotropic signaling properties. Approximately 50% of the compounds demonstrated ERK activation through a non-ionotropic signaling cascade involving Src, phosphatidylinositol 3-kinase, and protein kinase C. This study elucidated key structural determinants for NMDA-R binding and characterized a novel metabotropic signaling pathway. Notably, our findings suggest that compounds acting as antagonists at the ionotropic site may simultaneously function as agonists through non-ionotropic mechanisms.

Although histone deacetylase 6 (HDAC6) is considered a therapeutic target for Alzheimer’s disease (AD), its role in cholinergic dysfunction in AD patients remains unclear. This study investigated the effects of (E)-3-(2-(4-fluorostyryl)thiazol-4-yl)-N-hydroxypropanamide (4-FHA), a new synthetic HDAC6 inhibitor, on cognitive and memory impairments in a scopolamine-induced-AD mouse model. Behaviorally, 4-FHA improved scopolamine-induced memory impairments in the Y-maze, passive avoidance, and Morris water maze tests. In addition, 4-FHA ameliorated scopolamine-induced cognitive impairments in the novel object recognition and place recognition tests. Furthermore, 4-FHA increased acetylation of α-tubulin (a major HDAC6 substrate); the expression of BDNF; and the phosphorylation of ERK 1/2, CREB, and ChAT in the hippocampus of scopolamine-treated mice. In summary, according to our data 4-FHA, an HDAC6 inhibitor, improved the cognitive and memory deficits of the AD mouse model by normalizing BDNF signaling and synaptic transmission, suggesting that 4-FHA might be a potential therapeutic candidate for AD.

The N-methyl-D-aspartate receptor (NMDA-R) subunit GluN2B is abundantly expressed in brain regions critical for synaptic plasticity and cognitive processes. This study investigated the structure-activity relationships (SAR) of NMDA-R ligands using GluN2B as a molecular target. Thirty potential NMDA-R antagonists were categorized into two structural classes: 1-(1-phenylcyclohexyl) amines (series A) and α-amino-2-phenylcyclohexanone derivatives (series B). In series A compounds, the phenyl ring and R1 substituents were positioned at the carbon center of the cyclohexyl ring, with R2 substituents at the para- or meta-positions of the phenyl ring. SAR analysis revealed optimal binding affinity when R1 was carbonyl (C=O) and R2 was 4-methoxy (4-OMe). Series B compounds featured a cyclohexanone scaffold with NH-R1 at the α-position and a phenyl ring bearing R2 substituents at ortho-, meta-, or para-positions. Maximum binding affinity was achieved with R1 as hydrogen (H) and R2 as hydroxyl (OH). Compounds were assessed for GluN2B-mediated ERK activation to evaluate potential metabotropic signaling properties. Approximately 50% of the compounds demonstrated ERK activation through a non-ionotropic signaling cascade involving Src, phosphatidylinositol 3-kinase, and protein kinase C. This study elucidated key structural determinants for NMDA-R binding and characterized a novel metabotropic signaling pathway. Notably, our findings suggest that compounds acting as antagonists at the ionotropic site may simultaneously function as agonists through non-ionotropic mechanisms.

Although histone deacetylase 6 (HDAC6) is considered a therapeutic target for Alzheimer’s disease (AD), its role in cholinergic dysfunction in AD patients remains unclear. This study investigated the effects of (E)-3-(2-(4-fluorostyryl)thiazol-4-yl)-N-hydroxypropanamide (4-FHA), a new synthetic HDAC6 inhibitor, on cognitive and memory impairments in a scopolamine-induced-AD mouse model. Behaviorally, 4-FHA improved scopolamine-induced memory impairments in the Y-maze, passive avoidance, and Morris water maze tests. In addition, 4-FHA ameliorated scopolamine-induced cognitive impairments in the novel object recognition and place recognition tests. Furthermore, 4-FHA increased acetylation of α-tubulin (a major HDAC6 substrate); the expression of BDNF; and the phosphorylation of ERK 1/2, CREB, and ChAT in the hippocampus of scopolamine-treated mice. In summary, according to our data 4-FHA, an HDAC6 inhibitor, improved the cognitive and memory deficits of the AD mouse model by normalizing BDNF signaling and synaptic transmission, suggesting that 4-FHA might be a potential therapeutic candidate for AD.

The type-1 cannabinoid receptor (CB 1R) is a potential therapeutic target in several pathological conditions, including neuropsychological disorders and neurodegenerative diseases. Owing to their structural diversity, it is not easy to derive general structure–activity relationships (SARs) for CB 1R ligands. In this study, CB 1R ligands were classified into six structural families, and the corresponding SAR was determined for their affinities for CB 1R. In addition, we determined their functional activities for the activation of extracellular signal-regulated kinases (ERKs). Among derivatives of indol-3-yl-methanone, the highest ligand affinity was observed when a pentyl and a naphthalenyl group were attached to the N1 position of the indole ring and the carbon site of the methanone moiety, respectively. In the case of adamantane indazole-3-carboxamide derivatives, the presence of fluorine in the pentyl group, the substituent at the N1 position of the indazole ring, strongly increased the affinity for CB 1R. For (naphthalen-1-yl) methanone derivatives, the presence of 4-alkoxynaphthalene in the methanone moiety was more beneficial for the affinity to CB 1R than that of a heterocyclic ring. The functional activities of the tested compounds, evaluated through ERK assay, were correlated with their affinity for CB 1R, suggesting their agonistic nature. In conclusion, this study provides valuable insight for designing novel ligands for CB 1R, which can be used to control psychiatric disorders and drug abuse.

Background: It is well known that a large number of patients with diabetes also have dyslipidemia, which significantly increases the risk of cardiovascular disease (CVD). This study aimed to evaluate the efficacy and safety of combination drugs consisting of metformin and atorvastatin, widely used as therapeutic agents for diabetes and dyslipidemia. Methods: This randomized, double-blind, placebo-controlled, parallel-group and phase III multicenter study included adults with glycosylated hemoglobin (HbA1c) levels >7.0% and <10.0%, low-density lipoprotein cholesterol (LDL-C) >100 and <250 mg/dL. One hundred eighty-five eligible subjects were randomized to the combination group (metformin+atorvastatin), metformin group (metformin+atorvastatin placebo), and atorvastatin group (atorvastatin+metformin placebo). The primary efficacy endpoints were the percent changes in HbA1c and LDL-C levels from baseline at the end of the treatment. Results: After 16 weeks of treatment compared to baseline, HbA1c showed a significant difference of 0.94% compared to the atorvastatin group in the combination group (0.35% vs. −0.58%, respectively; P<0.0001), whereas the proportion of patients with increased HbA1c was also 62% and 15%, respectively, showing a significant difference (P<0.001). The combination group also showed a significant decrease in LDL-C levels compared to the metformin group (−55.20% vs. −7.69%, P<0.001) without previously unknown adverse drug events. Conclusion The addition of atorvastatin to metformin improved HbA1c and LDL-C levels to a significant extent compared to metformin or atorvastatin alone in diabetes and dyslipidemia patients. This study also suggested metformin’s preventive effect on the glucose-elevating potential of atorvastatin in patients with type 2 diabetes mellitus and dyslipidemia, insufficiently controlled with exercise and diet. Metformin and atorvastatin combination might be an effective treatment in reducing the CVD risk in patients with both diabetes and dyslipidemia because of its lowering effect on LDL-C and glucose.

Background: Atherogenic dyslipidemia, which is frequently associated with type 2 diabetes (T2D) and insulin resistance, contributes to the development of vascular complications. Statin therapy is the primary approach to dyslipidemia management in T2D, however, the role of non-statin therapy remains unclear. Ezetimibe reduces cholesterol burden by inhibiting intestinal cholesterol absorption. Fibrates lower triglyceride levels and increase high-density lipoprotein cholesterol (HDL-C) levels via peroxisome proliferator- activated receptor alpha agonism. Therefore, when combined, these drugs effectively lower non-HDL-C levels. Despite this, few clinical trials have specifically targeted non-HDL-C, and the efficacy of triple combination therapies, including statins, ezetimibe, and fibrates, has yet to be determined. Methods: This is a multicenter, prospective, randomized, open-label, active-comparator controlled trial involving 3,958 eligible participants with T2D, cardiovascular risk factors, and elevated non-HDL-C (≥100 mg/dL). Participants, already on moderate-intensity statins, will be randomly assigned to either Ezefeno (ezetimibe/fenofibrate) addition or statin dose-escalation. The primary end point is the development of a composite of major adverse cardiovascular and diabetic microvascular events over 48 months. Conclusion This trial aims to assess whether combining statins, ezetimibe, and fenofibrate is as effective as, or possibly superior to, statin monotherapy intensification in lowering cardiovascular and microvascular disease risk for patients with T2D. This could propose a novel therapeutic approach for managing dyslipidemia in T2D.