Monoacylglycerol Acyltransferase 2 (MGAT2) Inhibitors for the Treatment of Metabolic Diseases and Nonalcoholic Steatohepatitis (NASH)

Discovery of (BMS-986172) as a Highly Potent MGAT2 Inhibitor that Achieved Targeted Efficacious Exposures at a Low Human Dose for the Treatment of Metabolic Disorders

A series of dihydropyridinone (DHP) compounds was prepared and evaluated for MGAT2 activity. The efforts led to the identification of novel tetrazolones with potent MGAT2 inhibitory activity and favorable in vitro profiles. Further tests of select analogues in mouse models revealed significant reduction in food intake and body weight. Subsequent studies in MGAT2 knockout mice with the lead candidate 12 (BMS-986172) showed on-target- and mechanism-based pharmacology. Moreover, its favorable pharmacokinetic (PK) profile and the lack of species variability in the glucuronidation potential resulted in a greater confidence level in the projection of a low dose for achieving targeted efficacious exposures in humans. Consistent with these projections, PK data from a phase 1 trial confirmed that targeted efficacious exposures could be achieved at a low dose in humans, which supported compound 12 as our second and potentially superior development candidate for the treatment of various metabolic disorders.

Discovery of novel pyridinones as MGAT2 inhibitors for the treatment of metabolic disorders

Inhibition of monoacylglycerol transferase 2 (MGAT2) has recently emerged as a potential therapeutic strategy for the treatment of metabolic diseases such as obesity, diabetes and non-alcoholic steatohepatitis (NASH). Metabolism studies with our clinical lead (1) suggested variability in in vitro glucuronidation rates in liver microsomes across species, which made projection of human doses challenging. In addition, the observation of deconjugation of the C3-C4 double bond in the dihydropyridinone ring of 1 in solution had the potential to complicate its clinical development. This report describes our lead optimization efforts in a novel pyridinone series, exemplified by compound 33, which successfully addressed both of these potential issues.

New insights into the role of dietary triglyceride absorption in obesity and metabolic diseases

The incidence of obesity and associated metabolic diseases is increasing globally, adversely affecting human health. Dietary fats, especially triglycerides, are an important source of energy for the body, and the intestine absorbs lipids through a series of orderly and complex steps. A long-term high-fat diet leads to intestinal dysfunction, inducing obesity and metabolic disorders. Therefore, regulating dietary triglycerides absorption is a promising therapeutic strategy. In this review, we will discuss diverse aspects of the dietary triglycerides hydrolysis, fatty acid uptake, triglycerides resynthesis, chylomicron assembly, trafficking, and secretion processes in intestinal epithelial cells, as well as potential targets in this process that may influence dietary fat-induced obesity and metabolic diseases. We also mention the possible shortcomings and deficiencies in modulating dietary lipid absorption targets to provide a better understanding of their administrability as drugs in obesity and related metabolic disorders.

Comprehensive molecular mechanisms and clinical therapy in nonalcoholic steatohepatitis: An overview and current perspectives

Our understanding of nonalcoholic steatohepatitis (NASH) pathophysiology continues to advance rapidly. Given the complexity of the pathogenesis of NASH, the field has moved from describing the single pathogenesis of NASH to deeply phenotyping with a description of the multi-mechanism and multi-target pathogenesis that includes glucose, lipid and cholesterol metabolism, fibrotic progression, inflammation, immune reaction and apoptosis. To make the picture more complex, the pathogenesis of NASH involves pathological connections between the liver and several organs such as the adipose, pancreas, kidney and gut. Numerous pharmacologic candidates have been tested in clinical trials and have generated some positive results. Importantly, PPAR as triglyceride synthesis inhibitor and FXR as bile acids synthesis inhibitor have displayed beneficial effects on candidates for lipid and cholesterol metabolism. Although the efficacy of these drugs has been affirmed, serious side effects hinder their further development. It is a particularly important task to carry out the in-depth long-term research. Additionally, drug combination increases response rate and reduces side effects of a single drug. Mastering the advantages and limitations of clinical candidate drugs and continuous improvement and innovation are necessary to formulate a new strategy for the future treatment of NASH.

Structure-Based Ligand Design Targeting Pseudomonas aeruginosa LpxA in Lipid A Biosynthesis

Enzymes involved in lipid A biosynthesis are promising antibacterial drug targets in Gram-negative bacteria. In this study, we use a structure-based design approach to develop a series of novel tetrazole ligands with low μM affinity for LpxA, the first enzyme in the lipid A pathway. Aided by previous structural data, X-ray crystallography, and surface plasmon resonance bioanalysis, we identify 17 hit compounds. Two of these hits were subsequently modified to optimize interactions with three regions of the LpxA active site. This strategy ultimately led to the discovery of ligand L13, which had a K_D of 3.0 μM. The results reveal new chemical scaffolds as potential LpxA inhibitors, important binding features for ligand optimization, and protein conformational changes in response to ligand binding. Specifically, they show that a tetrazole ring is well-accommodated in a small cleft formed between Met169, the "hydrophobic-ruler" and His156, both of which demonstrate significant conformational flexibility. Furthermore, we find that the acyl-chain binding pocket is the most tractable region of the active site for realizing affinity gains and, along with a neighboring patch of hydrophobic residues, preferentially binds aliphatic and aromatic groups. The results presented herein provide valuable chemical and structural information for future inhibitor discovery against this important antibacterial drug target.

Mechanisms of intestinal triacylglycerol synthesis

Triacylglycerols are a major source of stored energy that are obtained either from the diet or can be synthesized to some extent by most tissues. Alterations in pathways of triacylglycerol metabolism can result in their excessive accumulation leading to obesity, insulin resistance, cardiovascular disease and nonalcoholic fatty liver disease. Most tissues in mammals synthesize triacylglycerols via the glycerol 3-phosphate pathway. However, in the small intestine the monoacylglycerol acyltransferase pathway is the predominant pathway for triacylglycerol biosynthesis where it participates in the absorption of dietary triacylglycerol. In this review, the enzymes that are part of both the glycerol 3-phosphate and monoacylglycerol acyltransferase pathways and their contributions to intestinal triacylglycerol metabolism are reviewed. The potential of some of the enzymes involved in triacylglycerol synthesis in the small intestine as possible therapeutic targets for treating metabolic disorders associated with elevated triacylglycerol is briefly discussed.

Bioactive lipids and metabolic syndrome-a symposium report

Recent research has shed light on the cellular and molecular functions of bioactive lipids that go far beyond what was known about their role as dietary lipids. Bioactive lipids regulate inflammation and its resolution as signaling molecules. Genetic studies have identified key factors that can increase the risk of cardiovascular diseases and metabolic syndrome through their effects on lipogenesis. Lipid scientists have explored how these signaling pathways affect lipid metabolism in the liver, adipose tissue, and macrophages by utilizing a variety of techniques in both humans and animal models, including novel lipidomics approaches and molecular dynamics models. Dissecting out these lipid pathways can help identify mechanisms that can be targeted to prevent or treat cardiometabolic conditions. Continued investigation of the multitude of functions mediated by bioactive lipids may reveal additional components of these pathways that can provide a greater understanding of metabolic homeostasis.

DGAT2-MOGAT2 SNPs and Gene-Environment Interactions on Serum Lipid Profiles and the Risk of Ischemic Stroke

Background: The genetic susceptibility to ischemic stroke (IS) is still not well-understood. Recent genome-wide association studies (GWASes) found that several single nucleotide polymorphisms (SNPs) in the Diacylglycerol acyltransferase 2 gene (DGAT2) and monoacylglycerol O-acyltransferase 2 (MOGAT2) cluster were associated with serum lipid levels. However, the association between the DGAT2-MOGAT2 SNPs and serum lipid phenotypes has not yet been verified in the Chinese people. Therefore, the present study was to determine the DGAT2-MOGAT2 SNPs and gene-environment interactions on serum lipid profiles and the risk of IS. Methods: Genotyping of 5 SNPs (DGAT2 rs11236530, DGAT2 rs3060, MOGAT2 rs600626, MOGAT2 rs609379, and MOGAT2 rs10899104) in 544 IS patients and 561 healthy controls was performed by the next-generation sequencing technologies. The association between genotypes and serum lipid data was determined by analysis of covariance, and a corrected P-value was adopted after Bonferroni correction. Unconditional logistic regression analysis was performed to assess the association between genotypes and the risk of IS after adjustment of potential confounders. Results: The rs11236530A allele was associated with increased risk of IS (CA/AA vs. CC, OR = 1.45, 95%CI = 1.12-1.88, P = 0.0044), whereas the rs600626G-rs609379A-rs10899104G haplotype was associated with decreased risk of IS (adjusted OR = 0.67, 95% CI = 0.48-0.93, P = 0.018). The rs11236530A allele carriers had lower high-density lipoprotein cholesterol (HDL-C) concentrations than the rs11236530A allele non-carriers (P < 0.001). The interactions of rs11236530-smoking, rs3060-smoking and rs10899104-smoking influenced serum apolipoprotein B levels, whereas the interactions of rs11236530- and rs3060-alcohol affected serum HDL-C levels (P _I < 0.004-0.001). The interaction of rs600626G-rs609379A-rs10899104G-alcohol (OR = 0.41, 95% CI = 0.22-0.76) and rs600626G-rs609379C-rs10899104T-alcohol (OR = 0.12, 95% CI = 0.04-0.36) decreased the risk of IS (P _I < 0.0001). Conclusions: The rs11236530A allele was associated with decreased serum HDL-C levels in controls and increased risk of IS in patient group. The rs600626G-rs609379A-rs10899104G haplotype, the rs600626G-rs 609379A-rs10899104G-alcohol and rs600626G-rs609379C-rs10899104T-alcohol interactions were associated with decreased risk of IS. The rs11236530 SNP may be a genetic marker for IS in our study populations.

Screening Hit to Clinical Candidate: Discovery of BMS-963272, a Potent, Selective MGAT2 Inhibitor for the Treatment of Metabolic Disorders

MGAT2 inhibition is a potential therapeutic approach for the treatment of metabolic disorders. High-throughput screening of the BMS internal compound collection identified the aryl dihydropyridinone compound 1 (hMGAT2 IC₅₀ = 175 nM) as a hit. Compound 1 had moderate potency against human MGAT2, was inactive vs mouse MGAT2 and had poor microsomal metabolic stability. A novel chemistry route was developed to synthesize aryl dihydropyridinone analogs to explore structure-activity relationship around this hit, leading to the discovery of potent and selective MGAT2 inhibitors 21f, 21s, and 28e that are stable to liver microsomal metabolism. After triaging out 21f due to its inferior in vivo potency, pharmacokinetics, and structure-based liabilities and tetrazole 28e due to its inferior channel liability profile, 21s (BMS-963272) was selected as the clinical candidate following demonstration of on-target weight loss efficacy in the diet-induced obese mouse model and an acceptable safety and tolerability profile in multiple preclinical species.

Novel Cell-Based Assay to Investigate Monoacylglycerol Acyltransferase 2 Inhibitory Activity Using HIEC-6 Cell Line

The dietary triacylglycerol (TAG) gets absorbed and accumulated in the body through the monoacylglycerol (MAG) pathway, which plays a major role in obesity and related disorders. The main enzyme of this pathway, monoacylglycerol acyltransferase 2 (MGAT2), is considered as a potential target for developing antiobesity compounds. Hence, there is a need for in vitro cell-based assays for screening the potential leads for MGAT2 inhibitors. Because of synthetic inhibitor's side effects, there is an increased interest in natural extracts as potential leads. Hence, we have optimized a 2-MAG-induced TAG accumulation inhibitory cell-based assay to screen natural extracts using the HIEC-6 cell line. A concentration-dependent TAG accumulation was observed when the HIEC-6 cells were fed with exogenous 2-MAG. The TAG accumulation was confirmed by in situ BODIPY staining and was quantified. However, no TAG accumulation was seen when the cells were fed with exogenous DAG or TAG, suggesting MGAT2-mediated MAG uptake and its conversion to TAG. We demonstrated the utility of this assay by screening five different plant-based aqueous extracts. These extracts showed various inhibition levels (25% to 30%) of 2-MAG-induced TAG accumulation in the HIEC-6. The MGAT2 inhibitory potential of these extracts was confirmed by an in vitro MGAT2 assay. This cell-based assay adds a new methodology for screening, developing, and evaluating MGAT2 inhibitors for addressing obesity and related disorders.

Patent landscape for discovery of promising acyltransferase DGAT and MGAT inhibitors

INTRODUCTION

DGAT and MGAT enzymes play an important role in triacylglycerol (TGA) biosynthesis. Overexpression of these enzymes may lead to accumulation of TGA in adipose tissues causing development of diseases such as obesity and diabetes. High triglyceride levels increase risk factors for atherosclerosis, and increase the risk of heart attack, stroke and other heart diseases. DGAT and MGAT inhibitors are used for the treatment of such metabolic diseases. A number of DGAT and MGAT inhibitors entered into clinical and preclinical stages. However, some adverse effects are associated with them. Thus there is need to develop new, potent and safe DGAT and MGAT inhibitors.

AREA COVERED

In this review, the authors carefully searched patent literature and reviewed recent advances since the year 2014. Diverse chemical classes reported in the patents belonging to the category DGAT and MGAT inhibitors have been highlighted.

EXPERT OPINION

DGAT and MGAT inhibitors are now gaining significant importance in the treatment of metabolic diseases. Fused heterocycles with a combination of aromatic and aliphatic hydrophobic substituents could offer more potent DGAT and MGAT inhibitors. Previously reported chemical scaffolds and their DGAT and MGAT inhibitory activity could be employed as an input for some in silico studies to discover novel, potent and safe DGAT and MGAT inhibitors.

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.

Metabolomics combined with network pharmacology exploration reveals the modulatory properties of Astragali Radix extract in the treatment of liver fibrosis

Background

Astragali Radix (AR) is widely-used for improving liver fibrosis, but, the mechanism of action has not been systematically explained. This study aims to investigate the mechanism of AR intervention in liver fibrosis based on comprehensive metabolomics combined with network pharmacology approach.

Materials and methods

UPLC–Q-TOF/MS based metabolomics technique was used to explore the specific metabolites and possible pathways of AR affecting the pathological process of liver fibrosis. Network pharmacology analysis was introduced to explore the key targets of AR regarding the mechanisms on liver fibrosis.

Results

AR significantly reduced the levels of ALT, AST and AKP in serum, and improved pathological characteristics. Metabolomics analysis showed that the therapeutic effect of AR was mainly related to the regulation of nine metabolites, including sphingosine, 6-keto-prostaglandin F1a, LysoPC (O-18:0), 3-dehydrosphinganine, 5,6-epoxy-8,11,14-eicosatrienoic acid, leukotriene C4, taurochenodesoxycholic acid, LysoPC (18:1 (9Z)) and 2-acetyl-1-alkyl-sn-glycero-3-phosphocholine. Pathway analysis indicated that the treatment of AR on liver fibrosis was related to arachidonic acid metabolism, ether lipid metabolism, sphingolipid metabolism, glycerophospholipid metabolism and primary bile acid biosynthesis. Validation of the key targets by network pharmacology analysis of potential metabolic markers showed that AR significantly down-regulated the expression of CYP1B1 and up-regulated the expression of CYP1A2 and PCYT1A.

Conclusion

Metabolomics combined with network pharmacology was used for the first time to clarify that the treatment of AR on liver fibrosis, which is related to the regulation of arachidonic acid metabolism and ether lipid metabolism by modulating the expression of CYP1A2, CYP1B1 and PCYT1A. And the integrated approach can provide new strategies and ideas for the study of molecular mechanisms of traditional Chinese medicines in the treatment of liver fibrosis.