Discovery of 3-aryl-3-ethoxypropanoic acids as orally active GPR40 agonists

Advances in computer-aided drug design for type 2 diabetes

INTRODUCTION

The number of diabetic patients is increasing, posing a heavy social and economic burden worldwide. Traditional drug development technology is time-consuming and costly, and the emergence of computer-aided drug design (CADD) has changed this situation. This study reviews the applications of CADD in diabetic drug designing.

AREAS COVERED

In this article, the authors focus on the advance in CADD in diabetic drug design by elaborating the discovery, including peroxisome proliferator-activated receptor (PPAR), G protein-coupled receptor 40 (GPR40), dipeptidyl peptidase-IV (DDP-IV), protein tyrosine phosphatase 1B (PTP1B), sodium-dependent glucose transporter 2 (SGLT-2), and glucokinase (GK). Some drug discovery of these targets is related to CADD strategies.

EXPERT OPINION

There is no doubt that CADD has contributed to the discovery of novel anti-diabetic agents. However, there are still many limitations and challenges, such as lack of co-crystal complex, dynamic simulations, water, and metal ion treatment. In the near future, artificial intelligence (AI) may be a promising strategy to accelerate drug discovery and reduce costs by identifying candidates. Moreover, AlphaFold, a deep learning model that predicts the 3D structure of proteins, represents a considerable advancement in the structural prediction of proteins, especially in the absence of homologous templates for protein structures.

Recent Updates on Free Fatty Acid Receptor 1 (GPR-40) Agonists for the Treatment of Type 2 Diabetes Mellitus

BACKGROUND

The global incidence of type 2 diabetes mellitus (T2DM) has enthused the development of new antidiabetic targets with low toxicity and long-term stability. In this respect, free fatty acid receptor 1 (FFAR1), which is also recognized as a G protein-coupled receptor 40 (GPR40), is a novel target for the treatment of T2DM. FFAR1/GPR40 has a high level of expression in β-cells of the pancreas, and the requirement of glucose for stimulating insulin release results in immense stimulation to utilise this target in the medication of T2DM.

METHODS

The data used for this review is based on the search of several scienctific databases as well as various patent databases. The main search terms used were free fatty acid receptor 1, FFAR1, FFAR1 agonists, diabetes mellitus, G protein-coupled receptor 40 (GPR40), GPR40 agonists, GPR40 ligands, type 2 diabetes mellitus and T2DM.

RESULTS

The present review article gives a brief overview of FFAR1, its role in T2DM, recent developments in small molecule FFAR1 (GPR40) agonists reported till now, compounds of natural/plant origin, recent patents published in the last few years, mechanism of FFAR1 activation by the agonists, and clinical status of the FFAR1/GPR40 agonists.

CONCLUSION

The agonists of FFAR1/GRP40 showed considerable potential for the therapeutic control of T2DM. Most of the small molecule FFAR1/GPR40 agonists developed were aryl alkanoic acid derivatives (such as phenylpropionic acids, phenylacetic acids, phenoxyacetic acids, and benzofuran acetic acid derivatives) and thiazolidinediones. Some natural/plant-derived compounds, including fatty acids, sesquiterpenes, phenolic compounds, anthocyanins, isoquinoline, and indole alkaloids, were also reported as potent FFAR1 agonists. The clinical investigations of the FFAR1 agonists demonstrated their probable role in the improvement of glucose control. Though, there are some problems still to be resolved in this field as some FFAR1 agonists terminated in the late phase of clinical studies due to "hepatotoxicity." Currently, PBI-4050 is under clinical investigation by Prometic. Further investigation of pharmacophore scaffolds for FFAR1 full agonists as well as multitargeted modulators and corresponding clinical investigations will be anticipated, which can open up new directions in this area.

Ligand and structure-based computational designing of multi-target molecules directing FFAR-1, FFAR-4 and PPAR-G as modulators of insulin receptor activity

Multi-agent therapies are an important treatment modality in many diseases based on the assumption that combining agents may result in increased therapeutic benefit by overcoming the mechanism of resistance and providing superior efficiency. Extensively validated 3D pharmacophore models for free fatty acid receptor-1 (FFAR-1), free fatty acid receptor-4 (FFAR-4), and peroxisome proliferator-activated receptor-G (PPAR-G) was developed. The pharmacophore model for FFAR-1 (r² = 0.98, q² = 0.90) and PPAR-G (r² = 0.89, q² = 0.88) suggested that one hydrogen bond acceptor, one hydrogen bond donor, three aromatic rings, and two hydrophobic groups arranged in 3D space are essential for the binding affinity of FFAR-1 and PPAR-G inhibitors. Similarly, the pharmacophore model for FFAR-4 (r² = 0.92, q² = 0.87) suggested that the presence of a hydrogen bond acceptor, one negative atom, two aromatic rings, and three hydrophobic groups plays a vital role in the binding of an inhibitor of FFAR-4. These pharmacophore models allowed searches for novel FFAR-1, PPAR-G, and FFAR-4 triple inhibitors from multi-conformer 3D databases (Asinex). Finally, the twenty-five best hits were selected for molecular docking, to study the interaction of their complexes with all the proteins and final binding orientations of these molecules. After molecular docking, ten hits have been predicted to possess good binding affinity as per the Molecular Mechanics Generalized Born Surface Area (MM-GBSA) calculation for FFAR-1, FFAR-4, and PPAR-G which can be further investigated for its experimental in-vitro/in-vivo anti-diabetic activities.Communicated by Ramaswamy H. Sarma.

Discovery of novel potent GPR40 agonists containing imidazo[1,2-a]pyridine core as antidiabetic agents

Free fatty acid receptor 1 (FFA1 or GPR40) has been studied for many years as a target for the treatment of type 2 diabetes mellitus. In order to increase potency and reduce hepatotoxicity, a series of novel compounds containing imidazo[1,2-a]pyridine scaffold as GPR40 agonist were synthesized. Compound I-14 was identified as an effective agonist as shown by the conspicuous drop in blood glucose in normal and diabetic mice. It had no risk of hepatotoxicity compared with TAK-875. Moreover, good pharmacokinetic (PK) properties of I-14 were observed (CL = 27.26 ml/h/kg, t_1/2 = 5.93 h). The results indicate that I-14 could serve as a possible candidate to treat diabetes.

Free fatty acid receptor 1 as a novel therapeutic target for type 2 diabetes mellitus-current status

The incidence of type 2 diabetes mellitus (T2DM) has been on the increase in recent times. Although several oral treatments for T2DM are available, some of them have been found to elicit undesirable side effects. This therefore underscores the need for new treatment options with lesser side effects than the existing ones for people with T2DM. Free fatty acid receptor 1 (FFAR1), also known as GPR40, belongs to a class of G-protein coupled receptors that are encoded by FFAR1 genes in humans. It is expressed in the pancreatic β-cells and it is activated by medium- and long-chain saturated and unsaturated fatty acids. Thus it responds to endogenous medium and long chain unsaturated fatty acids, resulting in enhancement of insulin secretion during increased glucose levels. The glucose dependency of insulin secretion has made this receptor a very good target for developing therapies that could be efficacious with fewer side effects than the existing therapies for the treatment of T2DM. Given that tremendous efforts have been made in recent times in developing novel FFAR1 agonists with antidiabetic potentials, this article provides a current status of knowledge on the efforts made so far in developing novel FFAR1 agonists that would be of relevance in the management of T2DM.

Polymorphic Variation in FFA Receptors: Functions and Consequences

Overfeeding of fat can cause various metabolic disorders including obesity and type 2 diabetes (T2D). Diet provided free fatty acids (FFAs) are not only essential nutrients, but they are also recognized as signaling molecules, which stimulate various important biological functions. Recently, several G protein-coupled receptors (GPCRs), including FFA1-4, have been identified as receptors of FFAs by various physiological and pharmacological studies. FFAs exert physiological functions through these FFA receptors (FFARs) depending on carbon chain length and degree of unsaturation. Functional analyses have revealed that several important metabolic processes, such as peptide hormone secretion, cell maturation and nerve activities, are regulated by FFARs and thereby FFARs contribute to the energy homeostasis through these physiological functions. Hence, FFARs are expected to be promising pharmacological targets for metabolic disorders since imbalances in energy homeostasis lead to metabolic disorders. In human, it is established that different responses of individuals to endogenous ligands and chemical drugs may be due to differences in the ability of such ligands to activate nucleotide polymorphic variants of receptors. However, the clear links between genetic variations that are involved in metabolic disorders and polymorphisms receptors have been relatively difficult to assess. In this review, I summarize current literature describing physiological functions of FFARs and genetic variations of those receptors to discuss the potential of FFARs as drug targets for metabolic disorders.

Free fatty acid receptor agonists for the treatment of type 2 diabetes: drugs in preclinical to phase II clinical development

INTRODUCTION

The alarming prevalence of type 2 diabetes mellitus (T2DM) stimulated the exploitation of new antidiabetic drugs with extended durability and enhanced safety. In this regard, the free fatty acid receptor 1 (FFA1) and FFA4 have emerged as attractive targets in the last decade. FFA1 has prominent advantages in promoting insulin and incretin secretion while FFA4 shows great potential in incretin secretion, insulin sensitization and anti-inflammatory effects.

AREA COVERED

Herein, the authors focus specifically on FFA1 and FFA4 agonists in clinical trials and preclinical development. LY2922470, P11187 and SHR0534 are currently active in clinical trials while the CNX-011-67, SAR1, DS-1558 and BMS-986118 are in preclinical phase. The information for this review is retrieved from Integrity, Scifinder, Espacenet and clinicaltrials.gov databases.

EXPERT OPINION

Current proof-of-concept in clinical trials suggests that FFA1 agonists have a significant improvement for T2DM without the risk of hypoglycemia. However, there are still several challenging problems including the mechanism of the receptor and the efficacy and safety of the ligands.

Ligands at Free Fatty Acid Receptor 1 (GPR40)

FFA1 is a G protein-coupled receptor activated by medium- to long-chain fatty acids. FFA1 plays important roles in various physiological processes such as insulin secretion and energy metabolism. FFA1 expressed on pancreatic β-cells and intestine contributes to insulin and incretin secretion, respectively. These physiological functions of FFA1 are interesting as an attractive drug target for type II diabetes and metabolic disorders. A number of synthetic FFA1 ligands have been developed and they have contributed to our current understanding of the physiological and pathophysiological functions of FFA1 both in in vitro and in vivo studies. In addition, these synthetic ligands also provided information on the structure-activity relationships of FFA1 ligands. Further, FFA1 protein crystallized with one of the high affinity agonist leads provided useful insights for the development of more effective ligands. Among FFA1 ligands, several compounds have been further investigated in the clinical trials. Thus, FFA1 ligands have great potential as drug candidates. In this section, recent progress about FFA1 ligands and the possibility of their clinical use are described.

Discovery of a novel oxime ether scaffold as potent and orally bioavailable free fatty acid receptor 1 agonists

The free fatty acid receptor 1 (FFA1) plays a key role in amplifying glucose-stimulated insulin secretion in pancreatic β-cells.

Discovery of DS-1558: A Potent and Orally Bioavailable GPR40 Agonist

GPR40 is a G protein-coupled receptor that is predominantly expressed in pancreatic β-cells. GPR40 agonists stimulate insulin secretion in the presence of high glucose concentration. On the basis of this mechanism, GPR40 agonists are possible novel insulin secretagogues with reduced or no risk of hypoglycemia. The improvement of in vitro activity and metabolic stability of compound 1 led to the discovery of 13, (3S)-3-ethoxy-3-(4-{[(1R)-4-(trifluoromethyl)-2,3-dihydro-1H-inden-1-yl]oxy}phenyl)propanoic acid, as a potent and orally available GPR40 agonist. Compound 13 (DS-1558) was found to have potent glucose lowering effects during an oral glucose tolerance test in ZDF rats.

Treatment of type 2 diabetes by free Fatty Acid receptor agonists

Dietary free fatty acids (FFAs), such as ω-3 fatty acids, regulate metabolic and anti-inflammatory processes, with many of these effects attributed to FFAs interacting with a family of G protein-coupled receptors. Selective synthetic ligands for free fatty acid receptors (FFA1-4) have consequently been developed as potential treatments for type 2 diabetes (T2D). In particular, clinical studies show that Fasiglifam, an agonist of the long-chain FFA receptor, FFA1, improved glycemic control and reduced HbA1c levels in T2D patients, with a reduced risk of hypoglycemia. However, this ligand was removed from clinical trials due to potential liver toxicity and determining if this is a target or a ligand-specific feature is now of major importance. Pre-clinical studies also show that FFA4 agonism increases insulin sensitivity, induces weight loss, and reduces inflammation and the metabolic and anti-inflammatory effects of short chain fatty acids (SCFAs) are linked with FFA2 and FFA3 activation. In this review, we therefore show that FFA receptor agonism is a potential clinical target for T2D treatment and discuss ongoing drug development programs within industry and academia aimed at improving the safety and effectiveness of these potential treatments.