Discovery of 1,8-naphthyridin-2-one derivative as a potent and selective sphingomyelin synthase 2 inhibitor.

Sphingomyelin synthase 2 (SMS2) has attracted attention as a drug target for the treatment of various cardiovascular and metabolic diseases. The modification of a high throughput screening hit, 2-quinolone 10, enhanced SMS2 inhibition at nanomolar concentrations with good selectivity against SMS1. To improve the pharmaceutical properties such as passive membrane permeability and aqueous solubility, adjustment of lipophilicity was attempted and 1,8-naphthyridin-2-one 37 was identified as a potent and selective SMS2 inhibitor. A significant reduction in hepatic sphingomyelin levels following repeated treatment in mice suggested that compound 37 could be an effective in vivo tool for clarifying the role of SMS2 enzyme and developing the treatment for SMS2-related diseases.

Pharmacological characterization of synthetic serine palmitoyltransferase inhibitors by biochemical and cellular analyses.

Human serine palmitoyltransferase (SPT) is a PLP-dependent enzyme residing in the endoplasmic reticulum. It catalyzes the synthesis of 3-ketodihydrosphingosine (3-KDS) from the substrates palmitoyl-CoA and l-serine. It is a rate-limiting enzyme for sphingolipid synthesis in cells. In the present study, we characterized and pharmacologically profiled a series of tetrahydropyrazolopyridine derivatives that potently inhibit human SPT enzymatic activity, including two cell-active derivatives and one fluorescent-labelled derivative. These SPT inhibitors exhibited dual inhibitory activities against SPT2 and SPT3. We used a fluorescent-labelled probe to molecularly assess the inhibitory mechanism and revealed its binding to the SPT2 or SPT3 subunit in the small subunit (ss) SPTa/SPT1/SPT2/or ssSPTa/SPT1/SPT3 functional complexes. One of the SPT inhibitors exhibited a significantly slow dissociation from the SPT complex. We confirmed that our SPT inhibitors suppressed ceramide content in non-small-cell lung cancer cell line, HCC4006, by performing a target engagement analysis. The potency of ceramide reduction correlated to that observed in a recombinant SPT2 enzyme assay. We thus elucidated and provided a fundamental understanding of the molecular mode of action of SPT inhibitors and developed potent, cell-active SPT inhibitors that can be used to clarify the biological function of SPT.

Discovery of novel serine palmitoyltransferase inhibitors as cancer therapeutic agents.

We pursued serine palmitoyltransferase (SPT) inhibitors as novel cancer therapeutic agents based on a correlation between SPT inhibition and growth suppression of cancer cells. High-throughput screening and medicinal chemistry efforts led to the identification of structurally diverse SPT inhibitors 4 and 5. Both compounds potently inhibited SPT enzyme and decreased intracellular ceramide content. In addition, they suppressed cell growth of human lung adenocarcinoma HCC4006 and acute promyelocytic leukemia PL-21, and displayed good pharmacokinetic profiles. Reduction of 3-ketodihydrosphingosine, the direct downstream product of SPT, was confirmed under in vivo settings after oral administration of compounds 4 and 5. Their anti-tumor efficacy was observed in a PL-21 xenograft mouse model. These results suggested that SPT inhibitors might have potential to be effective cancer therapeutics.

Discovery of a novel prolyl-tRNA synthetase inhibitor and elucidation of its binding mode to the ATP site in complex with l-proline.

Prolyl-tRNA synthetase (PRS) is a member of the aminoacyl-tRNA synthetase family of enzymes and catalyzes the synthesis of prolyl-tRNAPro using ATP, l-proline, and tRNAPro as substrates. An ATP-dependent PRS inhibitor, halofuginone, was shown to suppress autoimmune responses, suggesting that the inhibition of PRS is a potential therapeutic approach for inflammatory diseases. Although a few PRS inhibitors have been derivatized from natural sources or substrate mimetics, small-molecule human PRS inhibitors have not been reported. In this study, we discovered a novel series of pyrazinamide PRS inhibitors from a compound library using pre-transfer editing activity of human PRS enzyme. Steady-state biochemical analysis on the inhibitory mode revealed its distinctive characteristics of inhibition with proline uncompetition and ATP competition. The binding activity of a representative compound was time-dependently potentiated by the presence of l-proline with Kd of 0.76 nM. Thermal shift assays demonstrated the stabilization of PRS in complex with l-proline and pyrazinamide PRS inhibitors. The binding mode of the PRS inhibitor to the ATP site of PRS enzyme was elucidated using the ternary complex crystal structure with l-proline. The results demonstrated the different inhibitory and binding mode of pyrazinamide PRS inhibitors from preceding halofuginone. Furthermore, the PRS inhibitor inhibited intracellular protein synthesis via a different mode than halofuginone. In conclusion, we have identified a novel drug-like PRS inhibitor with a distinctive binding mode. This inhibitor was effective in a cellular context. Thus, the series of PRS inhibitors are considered to be applicable to further development with differentiation from preceding halofuginone.

Antitumor activity of a novel and orally available inhibitor of serine palmitoyltransferase.

Metabolic reprogramming is an essential hallmark of neoplasia. Therefore, targeting cancer metabolism, including lipid synthesis, has attracted much interest in recent years. Serine palmitoyltransferase (SPT) plays a key role in the initial and rate-limiting step of de novo sphingolipid biosynthesis, and inhibiting SPT activity prevents the proliferation of certain cancer cells. Here, we identified a novel and orally available SPT inhibitor, compound-2. Compound-2 showed an anti-proliferative effect in several cancer cell models, reducing the levels of the sphingolipids ceramide and sphingomyelin. In the presence of compound-2, exogenously added S1P partially compensated the intracellular sphingolipid levels through the salvage pathway by partially rescuing compound-2-induced cytotoxicity. This suggested that the mechanism underlying the anti-proliferative effect of compound-2 involved the reduction of sphingolipid levels. Indeed, compound-2 promoted multinuclear formation with reduced endogenous sphingomyelin levels specifically in a compound-2-sensitive cell line, indicating that the effect was induced by sphingolipid reduction. Furthermore, compound-2 showed potent antitumor activity without causing significant body weight loss in the PL-21 acute myeloid leukemia mouse xenograft model. Therefore, SPT may be an attractive therapeutic anti-cancer drug target for which compound-2 may be a promising new drug.

Prolyl-tRNA synthetase inhibition promotes cell death in SK-MEL-2 cells through GCN2-ATF4 pathway activation.

Protein translation is highly activated in cancer tissues through oncogenic mutations and amplifications, and this can support survival and aberrant proliferation. Therefore, blocking translation could be a promising way to block cancer progression. The process of charging a cognate amino acid to tRNA, a crucial step in protein synthesis, is mediated by tRNA synthetases such as prolyl tRNA synthetase (PRS). Interestingly, unlike pan-translation inhibitors, we demonstrated that a novel small molecule PRS inhibitor (T-3861174) induced cell death in several tumor cell lines including SK-MEL-2 without complete suppression of translation. Additionally, our findings indicated that T-3861174-induced cell death was caused by activation of the GCN2-ATF4 pathway. Furthermore, the PRS inhibitor exhibited significant anti-tumor activity in several xenograft models without severe body weight losses. These results indicate that PRS is a druggable target, and suggest that T-3861174 is a potential therapeutic agent for cancer therapy.

Optimization of a novel series of N-phenylindoline-5-sulfonamide-based acyl CoA:monoacylglycerol acyltransferase-2 inhibitors: Mitigation of CYP3A4 time-dependent inhibition and phototoxic liabilities.

Acyl CoA:monoacylglycerol acyltransferase-2 (MGAT2) has emerged as a potential peripheral target for the treatment of obesity and metabolic disorders. We previously identified a novel series of N-phenylindoline-5-sulfonamide derivatives exemplified by 2 as potent and orally bioavailable MGAT2 inhibitors. Despite its attractive potency, further assessment revealed that this compound exhibited time-dependent inhibition (TDI) of cytochrome P450 3A4 (CYP3A4). To remove the undesirable CYP3A4 TDI activity, structural modification was focused on the 2,4-difluoroaniline moiety on the basis of the assumption that this moiety would be involved in mechanism-based inhibition of CYP3A4 via oxidative metabolism. This led to the finding that the introduction of 4-chloro-2,6-difluoroaniline significantly improved CYP3A4 TDI risk. Further optimization resulted in the discovery of N-(4-chloro-2,6-difluorophenyl)-1-{5-[1-methyl-3-(trifluoromethyl)-1H-pyrazol-5-yl]pyrimidin-2-yl}-7-(2-oxopyrrolidin-1-yl)-2,3-dihydro-1H-indole-5-sulfonamide (27c) with potent MGAT2 inhibitory activity (IC50=7.8 nM) and excellent ADME-Tox profiles including metabolic stability, oral bioavailability, and CYP3A4 TDI. In a mouse oral fat tolerance test, compound 27c effectively and dose-dependently suppressed the elevation of plasma triacylglycerol levels after oral administration at doses of 1 and 3mg/kg. We also discuss mitigation of the phototoxic liability of biaryl derivatives on the basis of the HOMO-LUMO gap hypothesis during the course of optimization efforts.

Estimation of the total population moving into and out of the 20 km evacuation zone during the Fukushima NPP accident as calculated using "Auto-GPS" mobile phone data.

The first objective data showing the geographical locations of people in Fukushima after the Fukushima Dai-ichi nuclear power plant accident, obtained by an analysis of GPS (Global Positioning System)-enabled mobile phone logs, are presented. The method of estimation is explained, and the flow of people into and out of the 20 km evacuation zone during the accident is visualized.

Anti-human-TIGIT agonistic antibody ameliorates autoimmune diseases by inhibiting Tfh and Tph cells and enhancing Treg cells.

T cells play important roles in autoimmune diseases, but it remains unclear how to optimally manipulate them. We focused on the T cell immunoreceptor with Ig and ITIM domains (TIGIT), a coinhibitory molecule that regulates and is expressed in T cells. In autoimmune diseases, the association between TIGIT-expressing cells and pathogenesis and the function of human-TIGIT (hu-TIGIT) signalling modification have not been fully elucidated. Here we generated anti-hu-TIGIT agonistic monoclonal antibodies (mAbs) and generated hu-TIGIT knock-in mice to accurately evaluate the efficacy of mAb function. Our mAb suppressed the activation of CD4+ T cells, especially follicular helper T and peripheral helper T cells that highly expressed TIGIT, and enhanced the suppressive function of naïve regulatory T cells. These results indicate that our mAb has advantages in restoring the imbalance of T cells that are activated in autoimmune diseases and suggest potential clinical applications for anti-hu-TIGIT agonistic mAbs as therapeutic agents.

Inhibition of MGAT2 modulates fat-induced gut peptide release and fat intake in normal mice and ameliorates obesity and diabetes in ob/ob mice fed on a high-fat diet.

Monoacylglycerol O-acyltransferase 2 (MGAT2) is one of the key enzymes responsible for triglyceride (TG) re-synthesis in the small intestine. We have previously demonstrated that pharmacological inhibition of MGAT2 has beneficial effects on obesity and metabolic disorders in mice. Here, we further investigate the effects of MGAT2 inhibition on (a) fat-induced gut peptide release and fat intake in normal mice and (b) metabolic disorders in high-fat diet (HFD)-fed ob/ob mice, a model of severe obesity and type 2 diabetes mellitus, using an orally bioavailable MGAT2 inhibitor Compound B (CpdB). CpdB inhibited elevation of plasma TG in mice challenged with an oil-supplemented liquid meal. Oil challenge stimulated the secretion of two gut anorectic hormones (peptide tyrosine-tyrosine and glucagon-like peptide-1) into the bloodstream, and these responses were augmented in mice pretreated with CpdB. In a two-choice test using an HFD and a low-fat diet, CpdB selectively inhibited intake of the HFD in normal mice. Administration of CpdB to HFD-fed ob/ob mice for 5 weeks suppressed food intake and body weight gain and inhibited elevation of glycated hemoglobin. These results indicate that pharmacological MGAT2 inhibition modulates fat-induced gut peptide release and fat intake in normal mice and improves obesity and diabetes in HFD-fed ob/ob mice and thus may have potential for development into a treatment of obesity and its related metabolic diseases.

Discovery of Human Intestinal MGAT Inhibitors Using High-Throughput Mass Spectrometry.

Monoacylglycerol acyltransferase (MGAT) activity catalyzes the synthesis of diacylglycerol (DAG) from fatty acyl-CoA and monoacylglycerol as substrates. It is important for the resynthesis of triacylglycerol (TAG) in the intestine. In the present study, we developed a MGAT enzymatic assay of human intestinal microsomes using a high-throughput mass spectrometry (MS)-based detection system. After screening with small-molecular-weight libraries for compounds exhibiting inhibitions against DAG and the consequent TAG syntheses, we identified multiple compounds that specifically inhibit intestinal MGAT activity. The inhibitory activities of these compounds were correlated to those determined using a recombinant human MGAT2 enzyme. An aryl-sulfonamide compound T1 showed potent inhibitory activity toward human intestinal MGAT and recombinant human MGAT2, with selectivity over MGAT3. This high-throughput MS-based assay provides a novel platform for the discovery of DAG or TAG synthesis inhibitors. The identified aryl-sulfonamide compound T1 is a promising starting compound for optimization studies of inhibitors with selectivity toward MGAT2.

Using a biologically annotated library to analyze the anticancer mechanism of serine palmitoyl transferase (SPT) inhibitors.

Mechanistic understanding is crucial to anticancer drug discovery. Here, we reveal that inhibition of serine palmitoyl transferase (SPT), the rate-limiting enzyme in sphingolipid synthesis, induced death in a lung cancer cell line via a necrosis-dependent pathway. To elucidate the mechanism of cell death induced by SPT inhibition, a biologically annotated library of diverse compounds was screened with an SPT inhibitor. This analysis identified suppressors of SPT inhibitor-mediated cell death. Further analysis using hit compounds from this screening revealed that SPT inhibitors induce COX-2 expression, leading to necrosis-dependent cell death. SPT inhibitors might therefore represent novel candidates for cancer therapy via necrosis pathway regulation. Our data illustrate that compound combination screening of biologically annotated libraries could be used for mechanistic elucidation.

Discovery and pharmacological characterization of a new class of prolyl-tRNA synthetase inhibitor for anti-fibrosis therapy.

Scleroderma has clinical characteristics including skin and other tissue fibrosis, but there is an unmet need for anti-fibrotic therapy. Halofuginone (HF) is a well-known anti-fibrosis agent in preclinical and clinical studies which exerts its effect via inhibition of TGF-ß/Smad3 signaling pathway. Recently, prolyl-tRNA synthetase (PRS) was elucidated as a target protein for HF that binds to the proline binding site of the catalytic domain of PRS. Here, we characterized a new class of PRS inhibitor (T-3833261) that is carefully designed in a way that binds to the ATP site of the catalytic domain and does not disrupt binding of proline. The anti-fibrotic activity and the mechanism of action for T-3833261 on TGF-ß-induced fibrotic assay were compared with those of HF in primary human skin fibroblast. We evaluated in vivo effect of topical application of T-3833261 and HF on TGF-ß-induced fibrotic genes expression in mice. We found that T-3833261 suppressed TGF-ß-induced α-smooth muscle actin (α-SMA) and type I collagen α1 (COL1A1) expression through the Smad3 axis in a similar fashion to HF. In vivo topical application of T-3833261 reduced the increase of fibrotic genes expression such as α-Sma, Col1a1 and Col1a2 by TGF-ß intradermal injection to the ear of a mouse. We revealed that T-3833261 is more effective than HF under the conditions of high proline concentration, as reported in fibrotic tissues. These results suggest the potential of ATP competitive PRS inhibitors for the treatment of fibrotic diseases such as scleroderma.

Discovery and characterization of selective human sphingomyelin synthase 2 inhibitors.

Sphingomyelin synthase (SMS) is a membrane enzyme that catalyzes the synthesis of sphingomyelin, is required for the maintenance of plasma membrane microdomain fluidity, and has two isoforms: SMS1 and SMS2. Although these isoforms exhibit the same SMS activity, they are different enzymes with distinguishable subcellular localizations. It was reported that SMS2 KO mice displayed lower inflammatory responses and anti-atherosclerotic effects, suggesting that inhibition of SMS2 would be a potential therapeutic approach for controlling inflammatory responses and atherosclerosis. This study aimed to discover a novel small-molecule compound that selectively inhibits SMS2 enzymatic activity. We developed a human SMS2 enzyme assay with a high-throughput mass spectrometry-based screening system. We characterized the enzymatic properties of SMS2 and established a high-throughput screening-compatible assay condition. To identify human SMS2 inhibitors, we conducted compound screening using the enzyme assay. We identified a 2-quinolone derivative as a SMS2 selective inhibitor with an IC50 of 950 nM and >100-fold selectivity for SMS2 over SMS1. The 2-quinolone exhibited efficacy in a cell-based engagement assay. We demonstrated that a more potent derivative directly bound to SMS2-expressing membrane fractions in an affinity selection mass spectrometry assay. Mutational analyses revealed that the interaction of the inhibitor with SMS2 required the presence of the amino acids S227 and H229, which are located in the catalytic domain of SMS2. In conclusion, we discovered novel SMS2-selective inhibitors. 2-Quinolone SMS2 inhibitors are considered applicable for leading optimization studies. Further investigations using these SMS2 inhibitors would provide validation tools for SMS2-relevant pathways in vitro and in vivo.

Identification of cytidine-5-triphosphate synthase1-selective inhibitory peptide from random peptide library displayed on T7 phage.

Cytidine triphosphate synthase 1 (CTPS1) is an enzyme expressed in activated lymphocytes that catalyzes the conversion of uridine triphosphate (UTP) to cytidine triphosphate (CTP) with ATP-dependent amination, using either L-glutamine or ammonia as the nitrogen source. Since CTP plays an important role in DNA/RNA synthesis, phospholipid synthesis, and protein sialyation, CTPS1-inhibition is expected to control lymphocyte proliferation and size expansion in inflammatory diseases. In contrast, CTPS2, an isozyme of CTPS1 possessing 74% amino acid sequence homology, is expressed in normal lymphocytes. Thus, CTPS1-selective inhibition is important to avoid undesirable side effects. Here, we report the discovery of CTpep-3: Ac-FRLGLLKAFRRLF-OH from random peptide libraries displayed on T7 phage, which exhibited CTPS1-selective binding with a KD value of 210nM in SPR analysis and CTPS1-selective inhibition with an IC50 value of 110nM in the enzyme assay. Furthermore, two fundamentally different approaches, enzyme inhibition assay and HDX-MS, provided the same conclusion that CTpep-3 acts by binding to the amidoligase (ALase) domain on CTPS1. To our knowledge, CTpep-3 is the first CTPS1-selective inhibitor.

Pharmacological characterization of a series of aryl-sulfonamide derivatives that potently and selectively inhibit monoacylglycerol acyltransferase 2.

Monoacylglycerol acyltransferase (MGAT) 2 is an endoplasmic reticulum membrane enzyme that catalyzes the synthesis of diacylglycerol (DAG) from fatty acyl-CoA and monoacylglycerol as substrates. It is important for the resynthesis of triacylglycerol in the intestine. We have identified a series of aryl-sulfonamide MGAT2 inhibitors and demonstrated pharmacological inhibition of MGAT2 improved hyperlipidemia, obesity, and diabetes in animal models. However, its mechanism of action has not been elucidated in molecular and cellular levels. In the present study, we have characterized a series of aryl-sulfonamide derivatives that potently and selectively inhibit human MGAT2 and determined their pharmacological profiles. Analyses on the molecular mechanism of a representative aryl-sulfonamide MGAT2 inhibitor revealed a reversible inhibitory activity and a binding activity to MGAT2. The aryl-sulfonamide derivatives exhibited potent inhibitory activities against both human and mouse intestinal MGAT activities, which were correlated to those determined using recombinant human and mouse MGAT enzymes. We have developed a cellular assay using Liquid Chromatography-Mass Spectrometry and confirmed that the aryl-sulfonamide derivatives suppressed DAG synthesis in the cellular context. We have thus elucidated their pharmacological profiles and provided the fundamental clues for understanding the molecular and cellular actions of the aryl-sulfonamide MGAT2 inhibitors.

Pharmacological Inhibition of Monoacylglycerol O-Acyltransferase 2 Improves Hyperlipidemia, Obesity, and Diabetes by Change in Intestinal Fat Utilization.

Monoacylglycerol O-acyltransferase 2 (MGAT2) catalyzes the synthesis of diacylglycerol (DG), a triacylglycerol precursor and potential peripheral target for novel anti-obesity therapeutics. High-throughput screening identified lead compounds with MGAT2 inhibitory activity. Through structural modification, a potent, selective, and orally bioavailable MGAT2 inhibitor, compound A (compA), was discovered. CompA dose-dependently inhibited postprandial increases in plasma triglyceride (TG) levels. Metabolic flux analysis revealed that compA inhibited triglyceride/diacylglycerol resynthesis in the small intestine and increased free fatty acid and acyl-carnitine with shorter acyl chains than originally labelled fatty acid. CompA decreased high-fat diet (HFD) intake in C57BL/6J mice. MGAT2-null mice showed a similar phenotype as compA-treated mice and compA did not suppress a food intake in MGAT2 KO mice, indicating that the anorectic effects were dependent on MGAT2 inhibition. Chronic administration of compA significantly prevented body weight gain and fat accumulation in mice fed HFD. MGAT2 inhibition by CompA under severe diabetes ameliorated hyperglycemia and fatty liver in HFD-streptozotocin (STZ)-treated mice. Homeostatic model assessments (HOMA-IR) revealed that compA treatment significantly improved insulin sensitivity. The proximal half of the small intestine displayed weight gain following compA treatment. A similar phenomenon has been observed in Roux-en-Y gastric bypass-treated animals and some studies have reported that this intestinal remodeling is essential to the anti-diabetic effects of bariatric surgery. These results clearly demonstrated that MGAT2 inhibition improved dyslipidemia, obesity, and diabetes, suggesting that compA is an effective therapeutic for obesity-related metabolic disorders.

Enhancement of ligand-dependent vitamin D receptor transactivation by the cardiotonic steroid bufalin.

Bufalin, a bufadienolide type cardiotonic steroid that is one of the major components of the toad venom-prepared traditional Chinese medicine called Ch'an Su or Senso, exhibits a cardiotonic action by inhibiting the membranous Na(+),K(+)-ATPase. Bufalin also induces differentiation of leukemia cells alone or in combination with other differentiation inducers including 1alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)]. In this study, we performed a transient cotransfection assay using a vitamin D receptor (VDR) expression vector and a luciferase reporter and found that although bufalin did not transactivate the VDR, it effectively enhanced VDR activity induced by 1,25(OH)(2)D(3). Bufalin also augmented VDR activation by bile acid ligands, such as lithocholic acid and 3-ketocholanic acid. Other cardiotonic steroids including ouabain, digitoxigenin and cinobufagin did not enhance VDR activation. Bufalin did not bind directly to VDR but did modulate the interaction of VDR and cofactors, such as steroid receptor coactivator-1 and nuclear receptor corepressor. Bufalin treatment significantly increased the expression of an endogenous VDR target gene, CYP24, in kidney- and monocyte-derived cell lines treated with 1,25(OH)(2)D(3). The data indicate that bufalin-mediated cellular mechanisms such as interaction with Na(+), K(+)-ATPase may affect VDR transcriptional activity. Bufalin may be a useful tool in the investigation of VDR regulation by membrane-originating cellular signals and of pathophysiological mechanisms linking VDR to cardiovascular dysfunction.

Structural determinants for vitamin D receptor response to endocrine and xenobiotic signals.

The vitamin D receptor (VDR), initially identified as a nuclear receptor for 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3], regulates calcium metabolism, cellular proliferation and differentiation, immune responses, and other physiological processes. Recently, secondary bile acids such as lithocholic acid (LCA) were identified as endogenous VDR agonists. To identify structural determinants required for VDR activation by 1alpha,25(OH)2D3 and LCA, we generated VDR mutants predicted to modulate ligand response based on sequence homology to pregnane X receptor, another bile acid-responsive nuclear receptor. In both vitamin D response element activation and mammalian two-hybrid assays, we found that VDR-S278V is activated by 1alpha,25(OH)2D3 but not by LCA, whereas VDR-S237M can respond to LCA but not to 1alpha,25(OH)2D3. Competitive ligand binding analysis reveals that LCA, but not 1alpha,25(OH)2D3, effectively binds to VDR-S237M and both 1alpha,25(OH)2D3 and LCA bind to VDR-S278V. We propose a docking model for LCA binding to VDR that is supported by mutagenesis data. Comparative analysis of the VDR-LCA and VDR-1alpha,25(OH)2D3 structure-activity relationships should be useful in the development of bile acid-derived synthetic VDR ligands that selectively target VDR function in cancer and immune disorders without inducing adverse hypercalcemic effects.

Discovery of a Novel Series of N-Phenylindoline-5-sulfonamide Derivatives as Potent, Selective, and Orally Bioavailable Acyl CoA:Monoacylglycerol Acyltransferase-2 Inhibitors.

Acyl CoA:monoacylglycerol acyltransferase-2 (MGAT2) has attracted interest as a novel target for the treatment of obesity and metabolic diseases. Starting from N-phenylbenzenesulfonamide derivative 1 with moderate potency for MGAT2 inhibition, we explored an effective location of the hydrophobic group at the 1-position to enhance MGAT2 inhibitory activity. Shifting the hydrophobic group to the adjacent position followed by introduction of a bicyclic central core to restrict the substituent orientation produced N-phenylindoline-5-sulfonamide derivative 10b, which displayed much improved potency, with an IC50 value of 1.0 nM. This compound also exhibited excellent selectivity (greater than 30,000-fold) against related acyltransferases (MGAT3, DGAT1, DGAT2, and ACAT1). Subsequent optimization efforts were directed toward improving pharmacokinetic profiles, which resulted in the identification of 5-[(2,4-difluorophenyl)sulfamoyl]-7-(2-oxopyrrolidin-1-yl)-N-[4-(trifluoromethyl)phenyl]-2,3-dihydro-1H-indole-1-carboxamide (24d) endowed with potent MGAT2 inhibitory activity (IC50 = 3.4 nM) and high oral bioavailability (F = 52%, mouse). In a mouse oral fat tolerance test, oral administration of this compound effectively suppressed the elevation of plasma triacylglycerol levels.