Agonist Activity Research Articles

Abstract B030: Novel strategy to improve response of high risk HPV+ HNSCC to radiation therapy

Abstract Background: Improving understanding of head and neck squamous cell carcinoma (HNSCC) has led to the discovery of novel molecular markers to stratify risk and guide treatment decisions. Recently, we have identified two subtypes of HPV+ OPSCC – one with good prognosis and one with poor prognosis. The subtypes are distinct in many ways – somatic genes mutated, HPV viral oncogenes expression, the physical state of the viral genome (integrated vs episomal), as well as global mutation and methylation profiles. Intriguingly, all differences converge on intrinsic tumor NF-κB activity with constitutively active NF-κB (usually arising from genetic defects in NF-κB regulators, including TRAF3 and CYLD) driving significantly elevated radiation sensitivity and improved patient survival. NF-κB-based groups define an important clinically actionable prognostic biomarker in HPV+ HNSCC: one important goal is to de-escalate therapy for patients with molecularly low-risk tumors to improve quality of life amongst survivors, while another goal is to improve the cure for of patients with a high risk of treatment failure. Material and methods: We utilized HPV+ head and neck cancer cells, HPV+ HNSCC xenografted mouse model, patient-derived xenografts (PDX), as well as our novel fully immunocompetent mouse model of high risk HPV+ HNSCC; we applied targeted fractionated radiation. To activate NF-κB, we used two clinically applicable drugs with different mechanisms of action: Toll-like receptor 5 (TLR5) agonist and mitochondria-derived activator of caspases (SMAC) mimetic. Custom NF-κB NanoString panel contains our recently developed NF-κB gene signature along with HPV genes and housekeeping genes that are used to normalize the gene expression data. Results: Both drugs activated NF-κB in HPV+ HNSCC and significantly improved response of HPV+ head and neck cancer cells and tumors to radiation. Interestingly, TLR5 agonist alone had a strong tumor suppressing effect in low NF-κB HPV+ HNSCC; this effect was significantly better than 32 Gy focused radiation given in fractions of 4 Gy. Custom NF-κB NanoString panel is robustly prognostic with NF-κB active tumors having improved outcomes after chemoradiation. Conclusions: Because of the average relatively favorable prognosis of HPV+ HNSCC, urgent need for improved therapy for patients with aggressive high risk tumors is greatly undervalued. Here, we present a clinical assay to risk stratify patients with HPV+ HNSCC and begin to explore pharmacological activation of NF-κB as a strategy to sensitize high risk HPV+ HNSCC to radiation therapy. TLR5 agonist is well known for the remarkable normal tissue protective effects against radiation and other damaging conditions; the dual effect of entolimod – sensitization of HPV+ HNSCC to radiation, while simultaneously protecting normal tissues from severe side effects - may be useful for patients with high-risk HPV+ head and neck cancer in combination with radiotherapy. Citation Format: Sri Vemulamanda, Natalia Issaeva1, Aditi Kothari, Travis Schrank, Wendell G. Yarbrough. Novel strategy to improve response of high risk HPV+ HNSCC to radiation therapy. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr B030.

Low-molecular-weight Ligand of the Thyroid-stimulating Hormone Receptor with the Activity of a Partial Agonist and a Negative Allosteric Modulator.

Graves' disease is caused by overactivation of the thyroid-stimulating hormone receptor (TSHR). One approach for its treatment may be the use of negative allosteric modulators (NAM) of TSHR, which normalize TSHR activity and do not cause thyroid hormone (TH) deficiency. The aim of the work was to study the effect of a new compound 5-amino-4-(4-bromophenyl)-2-(methylthio)thieno[2,3-d]pyrimidine-6-carboxylic acid N-tert-butylamide (TPY4) on the basal and TSH-stimulated TH production in cultured FRTL-5 thyrocytes and on basal and thyrotropin-releasing hormone (TRH)-stimulated TH levels in the blood of rats. TPY4 stimulated TH production by thyrocytes and increased TH levels when administered intraperitoneally and orally in rats. It also decreased the TSH-stimulated TH production in thyrocytes and the TRH-stimulated TH levels in rats. Thus, TPY4 is the first known allosteric regulator of TSHR, combining the properties of NAM and a partial agonist, and can be considered as a prototype of drugs for the treatment of Graves' disease.

The safety, tolerability, pharmacokinetics and pharmacodynamics of an optimized dual GLP-1/GIP receptor agonist (BGM0504) in healthy volunteers: A dose-escalation Phase I study.

Previous experiments have demonstrated that BGM0504, a GLP-1R/GIPR dual agonist drug by molecular dynamics-guided optimization, had enhanced agonistic activity compared to tirzepatide. This study aims to investigate its safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) in Chinese healthy volunteers. A randomized, double-blind, placebo-controlled and dose-escalation Phase I study was conducted as follows: a single dose (2.5 mg) and once-weekly administration for 2 weeks to reach target doses (5, 10 and 15 mg) by titration. A total of 40 volunteers received at least one dose of BGM0504 or placebo. The PK profile of BGM0504 was investigated over a wide dose range and supported once-weekly administration. It was observed that Cmax and AUC of BGM0504 were linearly proportional to the dose from 2.5-15 mg. The change in body weight (%) from baseline in BGM0504 groups was greater than that in the placebo group, with -3.24%, -6.26%, -7.09% and - 8.30% in 2.5, 5, 10 and 15 mg groups, respectively, indicating a certain dose correlation. Meanwhile, the potential roles of BGM0504 in glycaemic control were also observed. The most frequent adverse events reported were gastrointestinal (vomiting, nausea, decreased appetite, diarrhoea and abdominal distension). BGM0504 was generally safe and well tolerated with favourable PK profile and potential role in weight loss was also confirmed. These findings support subsequent development of BGM0504 for type 2 diabetes mellitus (T2DM) and obesity.

DOP033 Pre-Clinical Development of SL-325, a High Affinity DR3 Blocking Antibody, for Durable Blockade of the DR3/TL1A Axis in Inflammatory Bowel Disease

Abstract Background TL1A blocking antibodies have demonstrated promising clinical remission rates in patients with inflammatory bowel disease (Sands B et al, NEJM 2024). TL1A promotes inflammation through binding to a single receptor, DR3. There are no known signaling ligands for DR3 aside from TL1A. Whereas TL1A is transiently expressed by antigen presenting and endothelial cells at sites of active inflammation in the small and large intestine, DR3 is constitutively expressed by lymphoid cells in the peripheral blood, and throughout the GI tract at both inflamed and adjacent non-inflamed tissue. Methods A human DR3 blocking antibody, SL-325, was produced from stably transfected CHO cells and purified using an affinity chromatography capture step, followed by two polishing steps. Sequence equivalents of tulisokibart and RO7790121 were produced by transient transfection and affinity purification. The safety, pharmacokinetics (PK), pharmacodynamics (PD), and immunogenicity of SL-325 were evaluated in a GLP toxicology study in cynomolgus macaques over a 6-week in-life period followed by a 4-week recovery at Charles River Laboratories. Results SL-325 binding affinity to human DR3 was measured at 1.3 pM. SL-325 bound to both monomeric and trimeric human DR3 prevented recombinant human TL1A binding with an approximately ~10X improvement in potency in comparison to sequence equivalents of tulisokibart or RO7790121. The DR3 epitope bound by SL-325 did not trigger receptor-mediated endocytosis, and no evidence of SL-325 mediated DR3 agonism was observed in the absence or presence of T cell receptor activation of primary human lymphocytes from healthy donors, or donors with Crohn’s Disease or Ulcerative Colitis. Naïve cynomolgus macaques received 3 doses of intravenous SL-325 (vehicle, 1 mg/kg, 10 mg/kg or 100 mg/kg dose groups), each given two weeks apart, and no evidence of toxicity, organ dysfunction or changes to complete blood counts or metabolic panels were observed. Full and durable DR3 receptor occupancy (RO) was observed in peripheral blood lymphocytes at doses of 1 mg/kg and higher within two hours of infusion and throughout the 14 day inter-dose interval. Serum exposure of free SL-325 increased in a dose proportional manner. No evidence of residual DR3 agonist activity was observed. Conclusion These results indicate SL-325 is a high-affinity DR3 blocking antibody with no evidence of toxicity or residual agonism in cynomolgus macaques, and with an RO/PK profile suggestive of extended dosing intervals that will be studied in an upcoming Phase 1 clinical trial. References Sands BE, Feagan BG, Peyrin-Biroulet L, Danese S, Rubin DT, Laurent O, Luo A, Nguyen DD, Lu J, Yen M, Leszczyszyn J, Kempinski R, McGovern DPB, Ma C, Ritter TE, Targan S. Phase 2 Trial of Anti-TL1A Monoclonal Antobidy Tulisokibart for Ulcerative Colitis. NEJM 2024;391(12):1119-1129

DOP035 Anti-inflammatory potential of novel tethered agonists of the adhesion G protein-coupled receptor F5

Abstract Background An accumulating data suggest that the adhesion G protein-coupled receptor F5 (ADGRF5) is fundamental for human health and diseases1-3. It was noted that ADGRF5 mediates immune response in cancers but its impact on colitis development is still unknown. Moreover, recent findings identified mature tethered agonist of ADGRF5 which corresponds to Stachel sequence of this receptor4. The purpose of this work was to design peptides corresponding to Stachel sequence able to activate ADGRF5 with higher activity than the mature ADGRF5 tethered agonist and evaluate them in colitis model. Methods Single amino acid substitutions in the mature ADGRF5 tethered agonist sequence combined with calcium accumulation and inositol phosphate conversion assays as well as ADGRF5 overexpressing cells were used to identify novel ADGRF5 tethered agonists. The downstream signalling pathway induced by ADGRF5 tethered agonists was estimated using Western blot technique. In vivo studies employing murine model of colitis induced by dextran sulphate sodium salt (DSS) administration were performed. Anti-inflammatory potential of novel ADGRF5 tethered agonists was assessed using macroscopic and microscopic damage score as well as total length of inflamed colon. Results The comparison of mature and modified ADGRF5 tethered agonist activity documented that substitution of the amino acids in position 11 and 13 improves their activity in ADGRF5 overexpressing cells when compared to wild-type cells. In vitro approach using calcium accumulation and inositol phosphate conversion assays revealed that novel ADGRF5 tethered agonists are characterized by 6-fold lower EC50 value than parent ADGRF5 tethered agonist. Moreover, our novel ADGRF5 tethered agonists are able to induce phosphorylation of protein kinase A and B as well as extracellular signal-regulated kinase signalling pathways in time and dose-dependent manner. Finally, administration of novel ADGRF5 tethered agonists in the murine model of colitis led to a significant improvement of macroscopic and microscopic damage score compared to animals treated with mature ADGRF5 tethered agonist. Additionally, the colons of mice treated with novel ADGRF5 tethered agonists but not with mature ADGRF5 tethered agonist were characterized by reduction of total length of inflammation and improvement of colon architecture. Conclusion We found critical positions in the Stachel sequence of ADGRF5 agonists which are required for their activity. New ADGRF5 tethered agonists displayed anti-inflammatory action highlighting that modulation of ADGRF5 activity may serve as an attractive target in colitis treatment.

Thyromimetics and MASLD: Unveiling the Novel Molecules Beyond Resmetirom.

Resmetirom, the first FDA-approved drug for nonalcoholic steatohepatitis (NASH) with fibrosis in obese patients, when combined with lifestyle modifications, improves NASH resolution and reduces fibrosis by at least one stage. Low thyroid hormone (T3) levels are linked to a higher risk of developing metabolic dysfunction-associated steatotic liver disease (MASLD). Epidemiological studies have confirmed the positive correlation between hypothyroidism and MASLD. Unraveling the molecular mechanisms of T3 signaling pathways in MASLD will enhance the prospects of identifying effective and specific targets. Therefore, this review discusses the significant role of thyroid hormones in the homeostasis of fat metabolism and describes the possible molecular mechanisms of thyromimetics in the treatment of MASLD. A comprehensive search in PubMed and EMBASE was conducted using the keywords "thyromimetics and liver diseases," "thyroid hormone and liver diseases," "hypothyroidism and liver diseases," "T3, T4 and liver disease," and "resmetirom and liver disease." Relevant papers published before October 2024 were included. T3 treatment enhances mitochondrial respiration, biogenesis, β-oxidation, and mitophagy, reducing liver lipid accumulation. However, T3 treatment causes cardiotoxicity through thyroid hormone receptor (THR)α agonistic activity. To address this, molecules with high THRβ agonistic but lower THRα activity have been developed. Besides resmetirom, other THRβ agonists like TG68, CS27109, MB07811, and KB-141 show promising results in experimental studies. These molecules upregulate THRβ target genes, activate genes for fatty acid β-oxidation in mitochondria and fatty acid breakdown in peroxisomes, downregulate the genes involved in de novo lipogenesis, reduce inflammation by downregulating NF-κB/JNK/STAT3 signaling pathways, and accelerate fibrosis resolution by downregulating the expressions of fibrosis marker genes in NASH liver tissue. Future clinical studies should thoroughly investigate THRβ agonists, including TG68, CS27109, MB07811, and KB-141.

Effect of a Low-Molecular-Weight Allosteric Agonist of the Thyroid-Stimulating Hormone Receptor on Basal and Thyroliberin-Stimulated Activity of Thyroid System in Diabetic Rats.

The approaches to correct thyroid deficiency include replacement therapy with thyroid hormones (THs), but such therapy causes a number of side effects. A possible alternative is thyroid-stimulating hormone (TSH) receptor activators, including allosteric agonists. The aim of this work was to study the effect of ethyl-2-(4-(4-(5-amino-6-(tert-butylcarbamoyl)-2-(methylthio)thieno[2,3-d]pyrimidin-4-yl)phenyl)-1H-1,2,3-triazol-1-yl) acetate (TPY3m), a TSH receptor allosteric agonist developed by us, on basal and thyroliberin (TRH)-stimulated TH levels and the hypothalamic-pituitary-thyroid (HPT) axis in male rats with high-fat diet/low-dose streptozotocin-induced type 2 diabetes mellitus (T2DM). Single and three-day administration of TPY3m (i.p., 20 mg/kg) was studied, and the effect of TPY3m on the HPT axis was compared with that of levothyroxine. TPY3m increased TH levels when administered to both healthy and diabetic rats, normalizing thyroxine and triiodothyronine levels in T2DM and, unlike levothyroxine, without negatively affecting TSH levels or the expression of hypothalamic and pituitary genes responsible for TSH production. TPY3m pretreatment preserved the stimulatory effects of TRH on TH levels and thyroid gene expression. This indicates the absence of competition between TPY3m and endogenous TSH for TSH receptor activation and is supported by our in vitro results on TPY3m- and TSH-stimulated adenylate cyclase activity in rat thyroid membranes. Morphological analysis of thyroid glands in diabetic rats after three-day TPY3m administration shows an increase in its functional activity without destructive changes. To summarize, TPY3m, with the activity of a partial allosteric agonist of the TSH receptor, was created as a prototype of drugs to correct thyroid insufficiency in T2DM.

Design, Synthesis, and Biological Assessment of Novel Aminobenzidazole Agonists Targeting the Stimulator of Interferon Genes (STING) Receptor Signaling Pathway for Oncology Immunotherapy.

The activation of the STING-mediated signaling pathway leads to the secretion of type I interferon (IFN) and the activation of tumor-specific T cells. STING, a pattern recognition receptor located on the endoplasmic reticulum membrane of immune cells, binds with endogenous cyclic dinucleotides. STING undergoes phosphorylation, triggering the STING-TBK1-IRF3 pathway and NF-κB pathway, resulting in the release of IFN-β and other pro-inflammatory cytokines, ultimately enhancing the activation of tumor-specific T cells. This mechanism serves to complement the limitations of immune checkpoint inhibitors and enhances the efficiency of the immune response. This study selected benzimidazole compounds GSK and SR-717, which exhibit promising potential as patented medicines, as our lead compounds. Aiming to address the challenges associated with the short half-life of benzimidazole compounds and the limited molecular activity of SR-717, we designed and synthesized a series of STING agonists (compounds 6~29). The compound 17 showed excellent agonistic activity on hSTING protein in vitro. The cytotoxicity tests of all the synthesized compounds were performed in vitro. Performed in vivo pharmacokinetic studies on the most promising compounds and conducted molecular docking analyses.

Angelica gigas Nakai (Korean Dang-gui) Root Alcoholic Extracts in Health Promotion and Disease Therapy - active Phytochemicals and In Vivo Molecular Targets.

Angelica gigas Nakai (AGN) root is a medicinal herbal widely used in traditional medicine in Korea. AGN root ethanolic extracts have been marketed as dietary supplements in the United States for memory health and pain management. We have recently reviewed the pharmacokinetics (PK) and first-pass hepatic metabolism of ingested AGN supplements in humans for the signature pyranocoumarins decursin (D, Cmax 1x), decursinol angelate (DA, Cmax ~ 10x) and their common botanical precursor and hepatic metabolite decursinol (DOH, Cmax ~ 1000x). Here we update in vivo medicinal activities of AGN and/or its pyranocoumarins and furanocoumarin nodakenin in cancer, pain, memory loss, cerebral ischemia reperfusion stroke, metabolic syndrome and vascular endothelial dysfunctions, anxiety, sleep disorder, epilepsy, inflammatory bowel disease, osteoporosis and osteoarthritis. Given their polypharmacology nature, the pertinent mechanisms of action are likely misrepresented by many cell culture studies that did not consider the drug metabolism knowledge. We report here Rho-associated protein kinases (ROCK1/2) as novel targets for DA and DOH. Combining with published inhibitory activity of DOH on acetylcholinesterase, agonist activity of DOH and antagonist/degrader activity of DA/D on androgen and estrogen receptors, D/DA promoting activity for glutamic acid decarboxylase (GAD)- gamma-aminobutyric acid (GABA) inhibitory axis and inhibition of glutamate dehydrogenase (GDH), monoamine oxidase-A (MAO-A) and transient receptor potential vanilloid 1 (TRPV1), we postulate their contributions to neuro-cognitive, metabolic, oncologic, vascular and other beneficial bioactivities of AGN extracts. A clinical trial is being planned for an AGN extract to manage side effects of androgen deprivation therapy in prostate cancer patients.

The psychoplastogens ibogaminalog and ibogainalog induce antidepressant-like activity in naïve and depressed mice by mechanisms involving 5-HT2A receptor activation and serotonergic transmission.

The antidepressant-like activity of two psychoplastogens, ibogainalog (IBG) and ibogaminalog (DM506), was studied in naïve mice using the forced swim test (FST) and tail suspension test (TST). The behavioral results showed that a single administration of 25mg/kg DM506 or 10mg/kg IBG induced antidepressant-like activity in naïve mice in a volinanserin-sensitive manner that persisted for 72h. Similar results were observed using the chronic immobilization stress (CIS) test, in which depression symptoms were reduced for 48h. To assess the contribution of serotonergic and/or norepinephrinergic neurotransmission, serotonin (5-HT) and norepinephrine (NE) levels were depleted. The reduction in 5-HT levels, but not NE levels, inhibited the antidepressant-like activity of ibogalogs, suggesting that serotonergic transmission may play a more significant role than norepinephrinergic transmission. Concurrently, DM506, IBG, and TBG (derived from tabernanthine) inhibited monoamine transporters with the following order of selectivity: SERT > NE transporter > dopamine transporter. The IBG exhibited the highest selectivity for SERT. Only TBG inhibited monoamine oxidase A activity, indicating its relatively minor role. Radioligand and functional assays showed that all ibogalogs bind to the 5-HT2 receptor subfamily (DM506>IBG>TBG) and fully activate 5-HT2A/2C receptors with similar potency in the nM range. However, they act as competitive antagonists of the 5-HT2B receptor, with DM506 as an exception, exhibiting partial but potent agonist activity. In conclusion, ibogalogs induce acute and sustained antidepressant-like activity in naïve and depressed mice through mechanisms involving 5-HT2A receptor activation and serotonergic transmission.

Targeting B and T Lymphocyte Attenuator Regulates Lupus Disease Development in NZB/W Mice.

The co-inhibitory receptor B and T Lymphocyte Attenuator (BTLA) negatively regulates B and T cell activation. We have previously shown an altered BTLA expression by regulatory T cells and an impaired capacity of BTLA to inhibit CD4+ T cell activation in lupus patients. In this study, we analyzed BTLA expression and function in the NZB/W lupus-mouse model and examined the therapeutic potential of BTLA targeting. BTLA expression and function were analyzed in young (10-12-week-old) and old-diseased NZB/W mice (>35-week-old with proteinuria) in comparison to age-related BALB/W control mice. 20-22weeks old NZB/W mice (n=10) were injected i.p with 3 mg/kg, twice a week for ten weeks, with the anti-BTLA antibody 6F7 or its isotype control. In old-diseased NZB/W mice, BTLA expression is slightly modified in B cell subsets whereas CD4+ T cells display impaired BTLA functionality. Administration of the 6F7 anti-BTLA antibody into 20-22week-old NZB/W mice resulted in a delayed onset of proteinuria (p<0.01), limited kidney damages (p<0.05) and an increased survival rate (p<0.01) compared to isotype-treated mice. This beneficial effect was associated with a decrease in circulating B cell and spleen follicular B cell numbers. Regarding its mode of action, we demonstrated that the 6F7 antibody is not a depleting antibody and does not block HVEM binding to BTLA, but instead induces BTLA down modulation and exhibits in vivo agonist activity. Overall, our data confirm the involvement of BTLA in lupus pathogenesis and provide the first evidence that BTLA is a potential therapeutic target for the treatment of lupus.

Novel tertiary diarylethylamines as functionally selective agonists of the kappa opioid receptor.

Novel kappa opioid receptor (KOR) agonists that preferentially activate G-protein signaling versus β-arrestin-2 recruitment are described. Starting from a literature-reported phenol-containing diphenethylamine KOR agonist, structure-activity relationship (SAR) studies revealed replacement of the phenol with various non-hydroxylated bicyclic heteroaromatics led to tertiary diarylethylamines which retained KOR agonist activity and improved metabolic stability in human liver microsomes. Further optimizations produced compound 39, a potent activator of G-protein signaling (GTPγS EC50 = 14 nM, 83 % Emax) that did not elicit a β-arrestin-2 recruitment functional response (Emax < 10 %). Compound 39 demonstrated moderate to high intrinsic clearance in human hepatocytes and low potential for Pgp-mediated efflux when evaluated in the MDR1-MDCK permeability assay. Compound 39 exhibited 60- and 810-fold selectivities versus the related mu (MOR) and delta (DOR) opioid receptors in recombinant radioligand binding (Ki) assays. These findings highlight compound 39 and related structures as potential leads toward safe and tolerable therapeutics that target central nervous system (CNS) disorders for which KOR agonism could provide benefit.

Prediction of Potential Risk for Ten Azole and Benzimidazole Fungicides with the Aryl Hydrocarbon Receptor Agonistic Activity to Aquatic Ecosystems.

Azole and benzimidazole fungicides are widely used agrochemicals to prevent and treat fungal growth and are frequently detected in aquatic environments. Here, we aimed to assess the aquatic ecological risks of ten currently used azole and benzimidazole fungicides, which with the aryl hydrocarbon receptor (AhR) agonistic activity, and their transformation products (TPs). We obtained over 400 types of aerobic TPs for ten fungicides. Some fungicides and their TPs (approximately 26.7%) exhibited the potential AhR agonistic activity and toxicity to different aquatic species. Meanwhile, some compounds with the chlorine element and benzene ring structure exhibited environmental persistence and mobile ability. Several of them were frequently detected in aquatic environments, posing potential risks to aquatic ecosystems. These harmful fungicides and their TPs should be given attention. This study provides important insight into the aquatic ecological risks caused by azole and benzimidazole fungicides, which can provide theoretical guidance for their pollution control.

Synthesis and Biological Evaluation of 5'-Deoxy-adenosine Derivatives as A3 Adenosine Receptor Ligands.

The A3 Adenosine Receptor (A3AR) is an important therapeutic target due to its role in inflammation and immune response regulation. Herein, we synthesized and evaluated 5'-deoxy-adenosine derivatives with oxygen at the 4'-position, comparing them to previously studied 4'-thionucleosides. Compound 1h exhibited the highest binding affinity (K i = 5.9 ± 1.1 nM), consistent with the trend observed in the 4'-thionucleosides. Notably, the 5'-deoxy-adenosine derivatives demonstrated enhanced agonistic activity. Docking studies with compound 1h revealed a shift in binding mode when oxygen replaced sulfur at the 4'-position. The compounds retained strong interactions with critical residues, such as Thr94, even without a hydrogen bond donor at the 5'-position. These results explain the increased agonistic effect observed when the ring heteroatom was changed from sulfur to oxygen.

Anthranilic Acid-G-Protein Coupled Receptor109A-Cytosolic Phospholipase A2-Myelin-Cognition Cascade: A New Target for the Treatment/Prevention of Cognitive Impairment in Schizophrenia, Dementia, and Aging.

Cognitive impairment is a core feature of neurodevelopmental (schizophrenia) and aging-associated (mild cognitive impairment and Alzheimer's dementia) neurodegenerative diseases. Limited efficacy of current pharmacological treatments warrants further search for new targets for nootropic interventions. The breakdown of myelin, a phospholipids axonal sheath that protects the conduction of nerve impulse between neurons, was proposed as a neuropathological abnormality that precedes and promotes the deposition of amyloid-β in neuritic plaques. The present review of the recent literature and our own pre- and clinical data suggest (for the first time) that the anthranilic acid (AA)-induced activation of microglial-expressed G-protein coupled receptor (GPR109A) inhibits cytosolic phospholipase A2 (cPLA2), an enzyme that triggers the degradation of myelin and consequently attenuates cognitive impairment. The present review suggests that the up-regulation of AA formation is a sex-specific compensatory (adaptive) reaction aimed to prevent/treat cognitive impairment. The AA-GPR109A-cPLA2-myelin-cognition cascade suggests new nootropic interventions, e.g., the administration of pegylated kynureninase, an enzyme that catalyzes AA formation from Kynurenine (Kyn), a tryptophane catabolite; pegylated interferon-alpha; central and peripheral Kyn aminotransferase inhibitors that increase availability of Kyn as a substrate for AA formation; and vagus nerve stimulation. The cascade predicts nootropic activity of exogenous GPR109A agonists that were designed and underwent clinical trials (unsuccessful) as anti-dyslipidemia agents. The proposed cascade might contribute to the pathogenesis of cognitive impairment. Data on AA in neurodegenerative disorders are scarce, and the proposed cascade needs further exploration in pre- and clinical studies.

CDNA Display Selection of Interacting Peptide Ligands of the Guanylate Cyclase C Receptor.

Guanylate cyclase C (GC-C), a receptor expressed on the apical membrane of intestinal mucosal cells, is activated by heat-stable enterotoxin (STa) produced by enterotoxigenic Escherichia coli, as well as the endogenous ligands guanylin and uroguanylin. In this study, novel peptides that interact with GC-C were generated using the cDNA display method, and their binding affinity and biological activity were evaluated. While the linear peptide library did not yield peptides with sufficient affinity for GC-C, three cyclic peptides (GCC-P1, GCC-P2, and GCC-P3), each containing two cysteine residues within a 15-residue sequence, were obtained from a cyclic peptide library containing nine-residue random sequences. GC-P2 exhibited significant binding affinity in Biacore assays, although the affinity was lower than those reported for known ligands. Notably, GCC-P2 and GCC-P3 demonstrated enhanced cGMP activity when used in combination with linaclotide. However, the agonist activity of these peptides was minimal, indicating that further modifications may be necessary to develop them for clinical applications. This study successfully extracted consensus sequences of peptide motifs that bind to GC-C from a highly diverse nine-residue random sequence library, which provides fundamental insights for the discovery and optimization of novel GC-C ligands.

Two New Diterpenoids Formed by Transannular Diels-Alder Cycloaddition from the Soft Coral Sarcophyton tortuosum, and Their Antibacterial and PPAR-β Agonist Activities.

Two new cembrane-derived tricyclic diterpenes belonging to the sarcophytin family, namely 4a-hydroxy-chatancin (1) and sarcotoroid (2), together with two known related ones (3 and 4), were isolated from the soft coral Sarcophyton tortuosum collected off Ximao Island in the South China Sea. The structures of the new compounds were elucidated by extensive spectroscopic analysis, a quantum mechanical nuclear magnetic resonance (QM-NMR) method, a time-dependent density functional theory electronic circular dichroism (TDDFT-ECD) calculation, X-ray diffraction analysis, and comparison with the reported data in the literature. A plausible biosynthetic pathway of compounds 1-4 was proposed, involving undergoing a transannular Diels-Alder cycloaddition. In the bioassay, the new compound 1 displayed significant inhibitory activities against the fish pathogens Streptococcus parauberis KSP28, oxytetracycline-resistant Streptococcus parauberis SPOF3K, and Photobacterium damselae FP2244, with MIC values of 9.1, 9.1, and 18.2 μg/mL, respectively. Furthermore, by conducting a luciferase reporter assay on rat liver Ac2F cells, compounds 1, 3, and 4 were evaluated for peroxisome proliferator-activated receptor (PPAR) transcriptional activity, and compound 3 showed selective PPAR-β agonist activity at a concentration of 10 μΜ.

Activation of cannabinoid receptor 2 by turmeric oleoresin reduces inflammation and oxidative stress in an osteoarthritis in vitro model

IntroductionOsteoarthritis (OA) is a chronic degenerative joint disease characterized by the progressive degradation of articular cartilage, resulting in pain and reduced mobility. Turmeric (Curcuma longa L.) has been widely recognized for its anti-inflammatory and antioxidant properties, but the molecular mechanisms underlying its therapeutic effects remain inadequately explored. This study investigates the potential of turmeric oleoresin (TUR) to activate Cannabinoid Receptor 2 (CBR2) and its role in mediating anti-inflammatory and antioxidant effects in an in vitro OA model.Material and methodsMolecular docking and cAMP quantification assays were used to evaluate TUR’s agonistic activity on CBR2. Human chondrosarcoma cells (SW-1353) were treated with TUR under oxidative stress induced by menadione or inflammatory conditions simulated with IL-1β and TNF-α. The effects of TUR were assessed in the presence and absence of the CBR2 antagonist SR144528. Outcomes included changes in reactive oxygen species (ROS) production, inflammatory marker expression, oxidative defense markers and endocannabinoid system components and receptors.ResultsTUR was confirmed as a CBR2 agonist and significantly reduced ROS production, downregulated pro-inflammatory cytokines (IL-6, COX-2, metalloproteases), and suppressed signaling pathways such as NFKB1, ERK 1/2, and c-Myc. These effects were reversed upon CBR2 inhibition. TUR also enhanced HMOX-1 expression and modulated endocannabinoid-related enzymes, highlighting its impact on oxidative stress and the endocannabinoid system.DiscussionThese findings suggest that CBR2 activation is central to TUR’s anti-inflammatory and antioxidant effects. By modulating key pathways and endocannabinoid system components, TUR demonstrates potential as a novel therapeutic agent for OA management. Future studies could explore its clinical applications and further validate its molecular mechanisms in vivo.

Pemafibrate Induces a Low Level of PPARα Agonist-Stimulated mRNA Expression of ANGPTL4 in ARPE19 Cell.

To elucidate the unidentified roles of a selective peroxisome proliferator-activated receptor α (PPARα) agonist, pemafibrate (Pema), on the pathogenesis of retinal ischemic diseases (RID)s, the pharmacological effects of Pema on the retinal pigment epithelium (RPE), which is involved in the pathogenesis of RID, were compared with the pharmacological effects of the non-fibrate PPARα agonist GW7647 (GW). For this purpose, the human RPE cell line ARPE19 that was untreated (NT) or treated with Pema or GW was subjected to Seahorse cellular metabolic analysis and RNA sequencing analysis. Real-time cellular metabolic function analysis revealed that pharmacological effects of the PPARα agonist actions on essential metabolic functions in RPE cells were substantially different between Pema-treated cells and GW-treated cells. RNA sequencing analysis revealed the following differentially expressed genes (DEGs): (1) NT vs. Pema-treated cells, 37 substantially upregulated and 72 substantially downregulated DEGs; (2) NT vs. GW-treated cells, 32 substantially upregulated and 54 substantially downregulated DEGs; and (3) Pema vs. GW, 67 substantially upregulated and 51 markedly downregulated DEGs. Gene ontology (GO) analysis and ingenuity pathway analysis (IPA) showed several overlaps or differences in biological functions and pathways estimated by the DEGs between NT and Pema-treated cells and between NT and GW-treated cells, presumably due to common PPARα agonist actions or unspecific off-target effects to each. For further estimation, overlaps of DEGs among different pairs of comparisons (NT vs. Pema, NT vs. GW, and Pema vs. GW) were listed up. Angiopoietin-like 4 (ANGPTL4), which has been shown to cause deterioration of RID, was the only DEG identified as a common significantly upregulated DEG in all three pairs of comparisons, suggesting that ANGPTL4 was upregulated by the PPARα agonist action but that its levels were substantially lower in Pema-treated cells than in GW-treated cells. In qPCR analysis, such lower efficacy for upregulation of the mRNA expression of ANGPTL4 by Pema than by GW was confirmed, in addition to substantial upregulation of the mRNA expression of HIF1α by both agonists. However, different Pema and GW-induced effects on mRNA expression of HIF1α (Pema, no change; GW, significantly downregulated) and mRNA expression of ANGPTL4 (Pema, significantly upregulated; GW, significantly downregulated) were observed in HepG2 cells, a human hepatocyte cell line. The results of this study suggest that actions of the PPARα agonists Pema and GW are significantly organ-specific and that lower upregulation of mRNA expression of the DR-worsening factor ANGPTL4 by Pema than by GW in ARPE19 cells may minimize the risk for development of RID.

Discovery of MT-7117 (Dersimelagon Phosphoric Acid): A Novel, Potent, Selective, and Nonpeptidic Orally Available Melanocortin 1 Receptor Agonist.

Activation of the melanocortin 1 receptor (MC1R) mediates melanogenesis in melanocytes, anti-inflammatory effects in inflammatory cells, and antifibrotic effects in fibroblasts. Thus, MC1R agonists are expected to be beneficial for treating skin, autoimmune, inflammatory, and fibrotic diseases. Afamelanotide, an α-melanocyte-stimulating hormone (α-MSH) analogue MC1R agonist, is used clinically for treating erythropoietic protoporphyria (EPP) as a subcutaneous implant formulation. We explored nonpeptidic small-molecule MC1R agonists with the aim of identifying more convenient oral drugs. By exploring the structure of previously reported compound 5, we discovered compound 11 (MT-7117: dersimelagon phosphoric acid). This compound exhibited strong MC1R agonistic activity, good pharmacokinetic properties, and excellent safety profiles. Furthermore, compound 11 was effective in animal pigmentation evaluation and skin fibrosis model studies. Compound 11 is currently in clinical trials for the treatment of EPP, X-linked protoporphyria (XLP), and systemic sclerosis (SSc). Proof of concept was obtained in phase 2 clinical studies on EPP and XLP.