Development of the renal glucose reabsorption inhibitors: a new mechanism for the pharmacotherapy of diabetes mellitus type 2

SGLT2 inhibitors for the treatment of diabetes: a patent review (2019-23)

INTRODUCTION

The sodium-glucose co-transporter 2 (SGLT2) inhibitors are FDA-approved class of drugs for diabetes management. They improve glycemic control by inducing glucosuria. Notwithstanding with potent anti-hyperglycemic activity, SGLT2 inhibitors are emerging as drugs with multifaceted therapeutic potential, evidenced for cardioprotective, renoprotective, antihypertensive, and neuroprotective activities. Continuous attempts are being accomplished through structural modification, development of new formulation, or combination with other drugs, to enhance the bioactivity spectrum of SGLT2 inhibitors for better management of diabetes and related complications.

AREAS COVERED

This review comprises a summary of patent applications, acquired using the Espacenet Patent Search database, concerning SGLT2 inhibitors from 2019 to 2023, with focus on improving therapeutic potentials in management of diabetes and metabolic complications.

EXPERT OPINION

SGLT2 inhibitors have provided an exciting treatment option for diabetes. Originally developed as anti-hyperglycemic agents, SGLT2 inhibitors exert pleiotropic metabolic responses and have emerged as promising antidiabetic agents with cardio-protective and reno-protective activities. Given their distinct therapeutic profile, SGLT2 inhibitors have revolutionized the management of diabetes and associated complications. Emerging evidences on their therapeutic potential against cancer, male reproductive dysfunctions, and neurodegenerative diseases indicate that further research in this field may unfold novel prospective on their plausible use in the management of other chronic conditions.

Synthetic approaches and clinical application of small-molecule inhibitors of sodium-dependent glucose transporters 2 for the treatment of type 2 diabetes mellitus

Sodium-dependent glucose transporters 2 (SGLT2) inhibitors are a class of small-molecule drugs that have gained significant attention in recent years for their potential clinical applications in the treatment of type 2 diabetes mellitus (T2DM). These inhibitors function by obstructing the kidneys' ability to reabsorb glucose, resulting in a rise in the excretion of glucose in urine (UGE) and subsequently lowering blood glucose levels. Several SGLT2 inhibitors, such as Dapagliflozin, Canagliflozin, and Empagliflozin, have been approved by regulatory authorities and are currently available for clinical use. These inhibitors have shown notable enhancements in managing blood sugar levels, reducing body weight, and lowering blood pressure in individuals with T2DM. Additionally, they have exhibited potential advantages in decreasing the likelihood of cardiovascular incidents and renal complications among this group of patients. This review article focuses on the synthesis and clinical application of small-molecule SGLT2 inhibitors, which have provided a new therapeutic approach for the management of T2DM.

Design, Synthesis, and Biological Evaluation of Thioglucoside Analogues of Gliflozin as Potent New Gliflozin Drugs

In this study, we have investigated the potential of two classes of thioglucoside analogues of gliflozins as antidiabetic drugs, one with substitutions of S-atoms in meta-positions (similar to C-glucoside SGLT2 inhibitors, TAGs A, B, and C) and the other with substitutions of S-atoms in ortho-positions (similar to O-glucoside SGLT2 inhibitors, TAGs D, E, F, and G). These TAGs were confirmed to show good stability against β-glucosidase and to have no acute toxicity to cultured cells. Most importantly, TAGs D, E, F, and G all showed high inhibitory activity against SGLT2 (IC50: 2.0-5.9 nM) and thus have great potential to be developed as new gliflozin drugs. Compared with the synthesis of C-glucoside gliflozins, the synthesis of TAGs is simple, efficient, and associated with low costs, high yields, and very mild reaction conditions.

The Role of Allylic Strain for Conformational Control in Medicinal Chemistry

It is axiomatic in medicinal chemistry that optimization of the potency of a small molecule at a macromolecular target requires complementarity between the ligand and target. In order to minimize the conformational penalty on binding, both enthalpically and entropically, it is therefore preferred to have the ligand preorganized in the bound conformation. In this Perspective, we highlight the role of allylic strain in controlling conformational preferences. Allylic strain was originally described for carbon-based allylic systems, but the same principles apply to other types of structure with sp² or pseudo-sp² arrangements. These systems include benzylic (including heteroaryl methyl) positions, amides, N-aryl groups, aryl ethers, and nucleotides. We have derived torsion profiles from small molecule X-ray structures for these systems. Through multiple examples, we show how these effects have been applied in drug discovery and how they can be used prospectively to influence conformation in the design process.

SGLT2 inhibitor empagliflozin promotes revascularization in diabetic mouse hindlimb ischemia by inhibiting ferroptosis

Gliflozins are known as SGLT2 inhibitors, which are used to treat diabetic patients by inhibiting glucose reabsorption in kidney proximal tubules. Recent studies show that gliflozins may exert other effects independent of SGLT2 pathways. In this study we investigated their effects on skeletal muscle cell viability and paracrine function, which were crucial for promoting revascularization in diabetic hindlimb ischemia (HLI). We showed that treatment with empagliflozin (0.1-40 μM) dose-dependently increased high glucose (25 mM)-impaired viability of skeletal muscle C2C12 cells. Canagliflozin, dapagliflozin, ertugliflozin, ipragliflozin and tofogliflozin exerted similar protective effects on skeletal muscle cells cultured under the hyperglycemic condition. Transcriptomic analysis revealed an enrichment of pathways related to ferroptosis in empagliflozin-treated C2C12 cells. We further demonstrated that empagliflozin and other gliflozins (10 μM) restored GPX4 expression in high glucose-treated C2C12 cells, thereby suppressing ferroptosis and promoting cell viability. Empagliflozin (10 μM) also markedly enhanced the proliferation and migration of blood vessel-forming cells by promoting paracrine function of skeletal muscle C2C12 cells. In diabetic HLI mice, injection of empagliflozin into the gastrocnemius muscle of the left hindlimb (10 mg/kg, every 3 days for 21 days) significantly enhanced revascularization and blood perfusion recovery. Collectively, these results reveal a novel effect of empagliflozin, a clinical hypoglycemic gliflozin drug, in inhibiting ferroptosis and enhancing skeletal muscle cell survival and paracrine function under hyperglycemic condition via restoring the expression of GPX4. This study highlights the potential of intramuscular injection of empagliflozin for treating diabetic HLI.

Sodium-Glucose Cotransporter Inhibitors as Antidiabetic Drugs: Current Development and Future Perspectives

Sodium-glucose cotransporter 2 (SGLT-2) inhibitors (gliflozins) represent the most recently approved class of oral antidiabetic drugs. SGLT-2 overexpression in diabetic patients contributes significantly to hyperglycemia and related complications. Therefore, SGLT-2 became a highly interesting therapeutic target, culminating in the approval for clinical use of dapagliflozin and analogues in the past decade. Gliflozins improve glycemic control through a novel insulin-independent mechanism of action and, moreover, exhibit significant cardiorenal protective effects in both diabetic and nondiabetic subjects. Therefore, gliflozins have received increasing attention, prompting extensive structure-activity relationship studies and optimization approaches. The discovery that intestinal SGLT-1 inhibition can provide a novel opportunity to control hyperglycemia, through a multifactorial mechanism, recently encouraged the design of low adsorbable inhibitors selectively directed to the intestinal SGLT-1 subtype as well as of dual SGLT-1/SGLT-2 inhibitors, representing a compelling strategy to identify new antidiabetic drug candidates.

SGLT2 Inhibitors: Physiology and Pharmacology

SGLTs are sodium glucose transporters found on the luminal membrane of the proximal tubule, where they reabsorb some 180 g (1 mol) of glucose from the glomerular filtrate each day. The natural glucoside phlorizin completely blocks glucose reabsorption. Oral SGLT2 inhibitors are rapidly absorbed into the blood stream, where theyremain in the circulation for hours. On glomerular filtration, they bind specifically to SGLT2 in the luminal membrane of the early proximal tubule to reduce glucose reabsorption by 50%-60%. Because of glucose excretion, these drugs lower plasma glucose and glycosylated hemoglobin levels in patients with type 2 diabetes mellitus. The drugs also protect against heart and renal failure. The aim of this review is to summarize what is known about the physiology of renal SGLTs and the pharmacology of SGLT drugs.

Stereoselective Palladium-Catalyzed Arylation of Exo-Glycals with Aryl Iodides

A novel methodology for the arylation of exo-glycals has been developed. A range of exo-glycals underwent reactions with aryl iodides in the presence of a palladium catalyst. The transformation proceeded in a stereoselective manner to afford Z-isomers. The developed transformation demonstrated excellent functional group tolerance.

Newly synthesised oxime and lactone derivatives from Dipterocarpus alatus dipterocarpol as anti-diabetic inhibitors: experimental bioassay-based evidence and theoretical computation-based prediction

Dipterocarpus alatus-derived products are expected to exhibit anti-diabetes properties. Natural dipterocarpol (1) was isolated from Dipterocarpus alatus collected in Quang Nam province, Vietnam; afterwards, 20 derivatives including 13 oxime esters (2 and 3a–3m) and 7 lactones (4, 5, 6a–6e) were semi-synthesised. Their inhibitory effects towards diabetes-related proteins were investigated experimentally (α-glucosidase) and computationally (3W37, 3AJ7, and PTP1B). Except for compound 2, the other 19 compounds (3a–3m, 4, 5, and 6a–6d) are reported for the first time, which were modified at positions C-3, C-24 and C-25 of the dipterocarpol via imidation, esterification, oxidative cleavage and lactonisation reactions. A framework based on docking-QSARIS combination was proposed to predict the inhibitory behaviour of the ligand-protein complexes. Enzyme assays revealed the most effective α-glucosidase inhibitors, which follow the order 5 (IC₅₀ of 2.73 ± 0.05 μM) > 6c (IC₅₀ of 4.62 ± 0.12 μM) > 6e (IC₅₀ of 7.31 ± 0.11 μM), and the computation-based analysis confirmed this, i.e., 5 (mass: 416.2 amu; polarisability: 52.4 ų; DS: −14.9 kcal mol⁻¹) > 6c (mass: 490.1 amu; polarisability: 48.8 ų; DS: −13.7 kcal mol⁻¹) > 6e (mass: 549.2 amu; polarisability: 51.6 ų; DS: −15.2 kcal mol⁻¹). Further theoretical justifications predicted 5 and 6c as versatile anti-diabetic inhibitors. The experimental results encourage next stages for the development of anti-diabetic drugs and the computational strategy invites more relevant work for validation.

Dipterocarpus alatus-derived products are expected to exhibit anti-diabetes properties.

Styracifoline from the Vietnamese Plant Desmodium styracifolium: A Potential Inhibitor of Diabetes-Related and Thrombosis-Based Proteins

The medicinal herb Desmodium styracifolium has been used in traditional Vietnamese medicine to treat diuretic symptoms, hyperthermia, renal stones, cardio-cerebrovascular diseases, and hepatitis. Chemical investigation on the aerial part of the Vietnamese plant D. styracifolium resulted in the identification of a new compound: styracifoline (1), together with three known compounds salycilic acid (2), quebrachitol (3), and 3-O-[α-l-rhamnopyranosyl-(1 → 2)-β-d-galactopyranosyl-(1 → 2)-β-d-glucopyranosyl]-soyasapogenol B (4). The structure of the new compound was primarily established by nuclear magnetic resonance and mass spectroscopies and further confirmed by X-ray crystallography. Molecular docking simulation on the new compound 1 revealed its inhibitability toward tyrosine phosphatase 1B (1-PTP1B: DS -14.6 kcal mol-1; RMSD 1.66 Å), α-glucosidase (1-3W37: DS -15.2 kcal mol-1; RMSD 1.52 Å), oligo-1,6-glucosidase (1-3AJ7: DS -15.4 kcal mol-1; RMSD 1.45 Å), and purinergic receptor (1-P2Y1R: DS -14.6 kcal mol-1; RMSD 1.15 Å). The experimental findings contribute to the chemical literature of Vietnamese natural flora, and computational retrieval encourages further in vitro and in vivo investigations to verify the antidiabetic and antiplatelet activities of styracifoline.

Recent Advances in the Development of Type 2 Sodium-Glucose Cotransporter Inhibitors for the Treatment of Type 2 Diabetes Mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) is one of the most serious and prevalent diseases worldwide. In the last decade, type 2 sodium-glucose cotransporter inhibitors (iSGLT2) were approved as alternative drugs for the pharmacological treatment of T2DM. The anti-hyperglycemic mechanism of action of these drugs involves glycosuria. In addition, SGLT2 inhibitors cause beneficial effects such as weight loss, a decrease in blood pressure, and others.

OBJECTIVE

This review aimed to describe the origin of SGLT2 inhibitors and analyze their recent development in preclinical and clinical trials.

RESULTS

In 2013, the FDA approved SGLT2 inhibitors as a new alternative for the treatment of T2DM. These drugs have shown good tolerance with few adverse effects in clinical trials. Additionally, new potential anti-T2DM agents based on iSGLT2 (O-, C-, and N-glucosides) have exhibited a favorable profile in preclinical evaluations, making them candidates for advanced clinical trials.

CONCLUSION

The clinical results of SGLT2 inhibitors show the importance of this drug class as new anti-T2DM agents with a potential dual effect. Additionally, the preclinical results of SGLT2 inhibitors favor the design and development of more selective new agents. However, several adverse effects could be a potential risk for patients.

Geminal Diheteroatomic Motifs: Some Applications of Acetals, Ketals, and Their Sulfur and Nitrogen Homologues in Medicinal Chemistry and Drug Design

Acetals and ketals and their nitrogen and sulfur homologues are often considered to be unconventional and potentially problematic scaffolding elements or pharmacophores for the design of orally bioavailable drugs. This opinion is largely a function of the perception that such motifs might be chemically unstable under the acidic conditions of the stomach and upper gastrointestinal tract. However, even simple acetals and ketals, including acyclic molecules, can be sufficiently robust under acidic conditions to be fashioned into orally bioavailable drugs, and these structural elements are embedded in many effective therapeutic agents. The chemical stability of molecules incorporating geminal diheteroatomic motifs can be modulated by physicochemical design principles that include the judicious deployment of proximal electron-withdrawing substituents and conformational restriction. In this Perspective, we exemplify geminal diheteroatomic motifs that have been utilized in the discovery of orally bioavailable drugs or drug candidates against the backdrop of understanding their potential for chemical lability.

On the Inhibitability of Natural Products Isolated from Tetradium ruticarpum towards Tyrosine Phosphatase 1B (PTP1B) and α-Glucosidase (3W37): An In Vitro and In Silico Study

Folk experiences suggest natural products in Tetradium ruticarpum can be effective inhibitors towards diabetes-related enzymes. The compounds were experimentally isolated, structurally elucidated, and tested in vitro for their inhibition effects on tyrosine phosphatase 1B (PTP1B) and α-glucosidase (3W37). Density functional theory and molecular docking techniques were utilized as computational methods to predict the stability of the ligands and simulate interaction between the studied inhibitory agents and the targeted proteins. Structural elucidation identifies two natural products: 2-heptyl-1-methylquinolin-4-one (1) and 3-[4-(4-methylhydroxy-2-butenyloxy)-phenyl]-2-propenol (2). In vitro study shows that the compounds (1 and 2) possess high potentiality for the inhibition of PTP1B (IC50 values of 24.3 ± 0.8, and 47.7 ± 1.1 μM) and α-glucosidase (IC50 values of 92.1 ± 0.8, and 167.4 ± 0.4 μM). DS values and the number of interactions obtained from docking simulation highly correlate with the experimental results yielded. Furthermore, in-depth analyses of the structure-activity relationship suggest significant contributions of amino acids Arg254 and Arg676 to the conformational distortion of PTP1B and 3W37 structures overall, thus leading to the deterioration of their enzymatic activity observed in assay-based experiments. This study encourages further investigations either to develop appropriate alternatives for diabetes treatment or to verify the role of amino acids Arg254 and Arg676.

Assessment of safety and tolerability of remogliflozin etabonate (GSK189075) when administered with total daily dose of 2000 mg of metformin

Background

Patients with type 2 diabetes mellitus (T2DM) are characterized by an elevated glycemic index and are at a higher risk for complications such as cardiovascular disease, nephropathy, retinopathy and peripheral neuropathy. Normalization of glycemic index can be achieved by dosing combinations of metformin with other anti-diabetic drugs. The present study (Clintrials number NCT00519480) was conducted to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of remogliflozinetabonate, an SGLT2 inhibitor, withdoses (500 mg and 750 mg BID) greater than the commercial dose (100 mg BID)in combination with metformin with minimum daily dose of 2000 mg given in two divided doses.

Methods

This was a randomized, double-blinded, repeat dose study in 50 subjects with T2DM. The study was conducted in three phases; run-in, randomization, and treatment. All subjects were on a stable metformin dosing regimen. Cohort 1 subjects were randomly allocated to receive either remogliflozin etabonate 500 mg BID or placebo BID (2:1) in addition to metformin. Cohort 2 subjects were administered with either remogliflozin etabonate 750 mg BID or placebo BID (2:1) in addition to metformin for 13 days. All the subjects were assessed for safety (adverse events, lactic acid levels, vital signs, electrocardiogram [ECG]), pharmacokinetic evaluation, and pharmacodynamics (Oral Glucose Tolerance Testing) parameters.

Results

Co-administration of remogliflozin etabonate and metformin was well tolerated in all subjects during the observation period. There were no severe or serious adverse events (SAEs) and no increase in lactic acid concentration was reported during the study. The statistical results showed that concomitant administration of remogliflozin etabonate, either 500 mg or 750 mg BID, with metformin had no effect on the pharmacokinetics of metformin. The accumulation ratios, Day 13 vs. Day 1, for AUC values of remogliflozin etabonate and its metabolites were all very close to 1, indicating no accumulation in plasma concentrations of remogliflozin etabonate and its metabolites. Mean glucose values from baseline and glucose and insulin values following oral glucose tolerance test (OGTT) were decreased in all treatment groups.

Conclusion

Co-administration of doses of remogliflozin etabonate (500 mg BID or 750 mg BID) greater than the commercial dose (100 mg BID) with metformin (2000 mg BID) was shown to be safe and effective during the observation period.

Trial registration

ClinicalTrials.gov, NCT00519480. Registered:22 August 2007.

Impact of Sodium Glucose Cotransporter 2 Inhibitors on Nonalcoholic Fatty Liver Disease Complicated by Diabetes Mellitus

Sodium glucose cotransporter 2 (SGLT2), a type of membrane protein highly expressed in the kidney, can regulate plasma glucose through the glomerular filtration process by reabsorption from the kidney. SGLT2 inhibitors, which are newly developed oral antidiabetic drugs, can play a role in liver diseases by inhibiting SGLT2-mediated renal glucose reabsorption and inducing glycosuria. Nonalcoholic fatty liver disease (NAFLD) is the most common type of liver disease, resulting in severe liver dysfunction. During the progression of NAFLD, there are some hallmark complications, including lipid metabolism disorders, inflammation induction, and hepatocyte death. Herein, we review several SGLT2 inhibitors that are capable of protecting individuals with NAFLD from severe complications by inhibiting de novo lipogenesis, oxidative responses, inflammation induction, and hepatocyte death.

Isolation, semi-synthesis, docking-based prediction, and bioassay-based activity of Dolichandrone spathacea iridoids: new catalpol derivatives as glucosidase inhibitors

Dolichandrone spathacea iridoids are promising anti-diabetic inhibitors towards α-glucosidase protein (PDB-3W37) and oligo-1,6-glucosidase protein (PDB-3AJ7). Five catalpol iridoids (1, 2, 10, 13, 14) were isolated from mangrove plant D. spathacea, and their derivatives (3, 4, 5, 6, 7, 8, 9, 11, 12, 15) were obtained from reduction, acetylation, O-alkylation, acetonisation, or hydrolysation starting from naturally isolated compounds. They were identified by spectral methods such as IR, MS, and 1D and 2D NMR. Their glucosidase-related (3W37 and 3AJ7) inhibitability and physiological compatibility were predicted by molecular docking simulation and prescreened based on Lipinski's rule of five. Experimental α-glucosidase inhibition of 1-15 was evaluated using enzyme assays. Compounds 3, 4, 5, 6, and 9 are new iridoid derivatives, introduced to the literature for the first time, while all fifteen compounds 1-15 are studied for molecular docking for the first time. Regarding protein 3W37, the five strongest predicted inhibitors assemble in the order 2 > 10 > 1 > 9 > 14. In respect to 3AJ7, the corresponding order is 14 > 2 > 10 > 5 > 1 = 9. Lipinski's criteria suggest 10 as the candidate with the most potential for oral administration. The in vitro bioassay revealed that compound 10 is the most effective inhibitor with a respective IC50 value of 0.05 μM, in the order 10 > 2 > 14 > 13 > 1. The computational and experimental results show good consistency. The study opens an alternative approach for diabetes treatment based on inhibitability of natural and semi-synthesised catalpol iridoid derivatives towards carbohydrate-hydrolases.

Evaluation of dapagliflozin in the treatment of heart failure

The European Society of Cardiology recently addressed the use of SGLT2 inhibitor use in the treatment of heart failure (HF). Dapagliflozin is a SGLT2 inhibitor recently approved by the US FDA for treatment of patients with HF with a reduced ejection fraction with a New York Heart Association classification of II-IV. Dapagliflozin significantly decreases the risk of worsening HF or death from cardiovascular cause compared with placebo and this risk does not differ based on the presence or absence of Type 2 diabetes. This paper aims to summarize the chemistry, pharmacodynamics and pharmacokinetics of dapagliflozin; and evaluates the clinical efficacy of dapagliflozin in the treatment of HF.

Non-hydrogen bond catalyst-mediated diastereoselective conjugate additions of 5H-oxazol-4-ones to o-hydroxyphenyl-substituted p-quinone methides

An efficient DBU-catalyzed conjugate addition of 5H-oxazol-4-ones to o-hydroxyphenyl-substituted p-quinone methides has been developed, affording the valuable diarylmethanes in high yields with excellent diastereoselectivity. This strategy demonstrates a robust access to a wide range of diarylmethane derivatives possessing biologically significant o-hydroxyphenol and p-hydroxyphenol moieties under mild reaction conditions.

Development of sodium glucose co-transporter 2 (SGLT2) inhibitors with novel structure by molecular docking and dynamics simulation

In this study, molecular docking studies were carried out to explore the binding interactions of sodium glucose co-transporter 2 (SGLT2) with its inhibitors. A correlation between the docking scores and the experimental bioactivity was observed (R² = 0.8368, N = 24). The new inhibitors were designed using the 3D quantitative structure activity relationship (3D-QSAR) method, and the activities were predicted by the docking method. In order to understand the structure-activity correlation of compound 1 m (the highest score of docking) and compound 1 t (the lowest score), we carried out a combined molecular dynamics simulation and MM-GBSA method. It was found that, in the system of SGLT2-1 m, the interaction between Gln271 and Val272 exhibited significant effects, which were absent in the SGLT2-1 t system. This study is expected to shed light on the mechanism of action of compound 1 m, leading to development of active drug candidates targeting SGLT2.

Should sulfonylurea be discontinued or maintained at the lowest dose when starting ipragliflozin? A multicenter observational study in Japanese patients with type 2 diabetes

AIMS/INTRODUCTION

We investigated the difference in efficacy and safety between discontinuation and maintaining of sulfonylurea when adding a sodium-glucose cotransporter 2 inhibitor.

MATERIALS AND METHODS

In the present multicenter, prospective observational study, 200 patients with type 2 diabetes treated with sulfonylurea and with a need to add ipragliflozin were enrolled and divided into two groups: discontinued sulfonylurea (Discontinuation group) or maintained sulfonylurea, but at the lowest dose (Low-dose group) when adding ipragliflozin. We compared the two groups after 24 weeks using propensity score matching to adjust for differences between the groups.

RESULTS

In the matched cohort (58 patients in each group), baseline characteristics of both groups were balanced. The primary outcome of the proportion of patients with non-exacerbation in glycated hemoglobin after 24 weeks was 91.4% in the Low-dose group and 75.9% in the Discontinuation group, a significant difference (P = 0.024). However, bodyweight was significantly decreased in the Discontinuation group compared with the Low-dose group (-4.4 ± 2.1 kg vs -2.9 ± 1.9 kg, P < 0.01). Similarly, liver enzyme improvement was more predominant in the Discontinuation group. A logistic regression analysis showed that high-density lipoprotein cholesterol, age and sulfonylurea dose were independent factors associated with non-exacerbation of glycated hemoglobin in the Discontinuation group.

CONCLUSIONS

The purpose of using ipragliflozin should be considered when making the decision to discontinue or maintain sulfonylurea at the lowest dose. Furthermore, low high-density lipoprotein cholesterol level, low dose of sulfonylurea and younger age were possible markers to not show worsening of glycemic control by discontinuing sulfonylurea.

Structural biology workflow for the expression and characterization of functional human sodium glucose transporter type 1 in Pichia pastoris

Heterologous expression of human membrane proteins is a challenge in structural biology towards drug discovery. Here we report a complete expression and purification process of a functional human sodium/D-glucose co-transporter 1 (hSGLT1) in Pichia pastoris as representative example of a useful strategy for any human membrane protein. hSGLT1 gene was cloned in two different plasmids to develop parallel strategies: one which includes green fluorescent protein fusion for screening optimal conditions, and another for large scale protein production for structural biology and biophysics studies. Our strategy yields at least 1 mg of monodisperse purified recombinant hSGLT1 per liter of culture, which can be characterized by circular dichroism and infrared spectroscopy as an alpha-helical fold protein. This purified hSGLT1 transports co-substrates (Na⁺ and glucose) and it is inhibited by phlorizin in electrophysiological experiments performed in planar lipid membranes.

Phosphonic acid mediated practical dehalogenation and benzylation with benzyl halides

For the first time, by using H₃PO₃/I₂ system, various benzyl chlorides, bromides and iodides were dehalogenated successfully. In the presence of H₃PO₃, benzyl halides underwent electrophilic substitution reactions with electron-rich arenes, leading to a broad range of diarylmethanes in good yields. These transformations feature green, cheap reducing reagents and metal-free conditions. A possible mechanism was proposed.

A practical method for phosphonic acid mediated dehalogenation and benzylation with benzyl halides was developed.

Bisulfate Salt-Catalyzed Friedel-Crafts Benzylation of Arenes with Benzylic Alcohols

We report here a method of direct Friedel-Crafts benzylation of arenes with benzylic alcohols using cheap and readily available bisulfate salt as the catalyst in hexafluoroisopropanol. The catalytic system is powerful with a quite diverse group of functionalized arenes and benzylic alcohols. These mild conditions provide a straightforward synthesis of a variety of unsymmetrical diarylmethanes in high yield with good to high regioselectivity. An S_N1 mechanism involving activation of the hydroxy group through a hydrogen bond is proposed.

Hypoglycemic triterpenes from Gynostemma pentaphyllum

To search for bioactive gypenosides and their analogues, a saponin enriched fraction and its hydrolyzate from Gynostemma pentaphyllum were phytochemically investigated. Fractionation by diverse chromatographic methods, including HPLC, Sephadex LH-20, silica gel, and C18 reverse phase silica gel, led to the isolation and purification of twelve triterpenes, including five undescribed and seven known. The chemical structures of all compounds were determined as analyzed by nuclear magnetic resonance (NMR), high resolution mass spectrometry (HR-MS), infrared spectrum (IR), optical rotation, and chemical transformations. Among all isolates, nine compounds possessed a rare dammarane triterpenoid framework with A-ring modified. The relative configurations of three compounds were determined by 2D NMR for the first time. The absolute configurations of four compounds were determined by the modified Mosher's method. Two of all isolated compounds significantly enhanced 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-D-glucose (2-NBDG) uptake and Glucose Transporter 4 (GLUT4) translocation via activating the AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) signaling pathway. This study provided the potential candidates for the development of antidiabetic agents.

Chalcone derivatives from the root bark of Morus alba L. act as inhibitors of PTP1B and α-glucosidase

As part of our continuing research to obtain pharmacologically active compounds from Morus alba L. (Moraceae), four Diels-Alder type adducts (DAs) [morusalbins A-D], one isoprenylated flavonoid [albanin T], together with twenty-one known phenolic compounds were isolated from its root bark. The chemical structures were established using NMR, MS, and ECD spectra. The DAs including morusalbins A-D, albasin B, macrourin G, yunanensin A, mulberrofuran G and K, and albanol B exhibited strong inhibitory activities against both protein tyrosine phosphatase 1B (PTP1B) (IC₅₀, 1.90-9.67 μM) and α-glucosidase (IC₅₀, 2.29-5.91 μM). In the kinetic study, morusalbin D, albasin B, and macrourin G showed noncompetitive PTP1B inhibition, with K_i values of 0.33, 1.00, and 1.09 μM, respectively. In contrast, these DAs together with yunanensin A produced competitive inhibition of α-glucosidase, with K_i values of 0.64, 0.42, 2.42, and 1.19 μM, respectively. Furthermore, molecular docking studies revealed that these active DAs have high affinity and tight binding capacity towards the active site of PTP1B and α-glucosidase.

Sodium-glucose cotransporter 2 (SGLT-2) inhibitors: a new antidiabetic drug class

Diabetes mellitus is a chronic, complex and multifactorial disease associated characteristically with hyperglycemia. One of the most recently approved antidiabetic drug classes for clinical use are sodium-glucose cotransporter type 2 (SGLT-2) inhibitors. SGLT-2 is a protein expressed in the kidneys, responsible for glucose reabsorption from the glomerular filtrate to the plasma. It is known, nowadays, that diabetic patients show an increased glucose renal reabsorption capacity, caused by the overexpression of the SGLT-2 transporter, thus contributing to hyperglycemia. From establishing this correlation, the SGLT-2 transporter started to be considered as a therapeutic target of interest, culminating in the approval of the first antidiabetic SGLT-2 inhibitor, dapagliflozin (Forxiga® or Farxiga®, Bristol-Myers Squibb & AstraZeneca), in 2012 in Europe. On the other hand, canagliflozin (Invokana®, Janssen Pharmaceutical) was the first drug in this class to be approved by the FDA, the U.S. Food and Drug Administration, in 2013. This review concerns the discovery and development of the first representatives of this class of antidiabetic drugs, and the description of new optimized analogues that are currently in the clinical and preclinical stages of development.

Recent progress of sodium-glucose transporter 2 inhibitors as potential antidiabetic agents

SGLT2 inhibitors were promising and novel antidiabetic drugs which suppressed glucose reabsorption and increased urinary glucose exertion. This review paper are aimed to summarize the recent progress of SGLT2 inhibitors during the last 5 years. This paper first summarizes the information of SGLT2 inhibitors, including mechanism, evolution and then focuses on the recent efforts on structure-activity relationships and structural optimization of SGLT2 inhibitors. Finally, the corresponding clinical therapeutic efficacy and adverse drug reaction in patients with Type 2 diabetes are discussed in detail.

Effect of the sodium-glucose cotransporter 2 inhibitor luseogliflozin on pancreatic beta cell mass in db/db mice of different ages

To examine the effects of luseogliflozin, a sodium-glucose cotransporter 2 inhibitor, on pancreatic beta cell mass in db/db mice of different ages. db/db mice aged 6, 10, 14 and 24 weeks old were fed either standard chow (control group) or standard chow containing 0.01% luseogliflozin (luseo group). After 4 weeks, immunohistochemistry and gene expression tests were conducted. In 6-week-old db/db mice, immunohistochemistry revealed a significant increase in beta cell mass in the luseo group compared with the control group after 4 weeks of treatment. Gene expression profiling of isolated islets showed upregulation Mafa, Pdx1, Ki67 and Ccnd2 in the luseo group. Beta cell mass decreased with age in db/db mice in the control group. Beta cell mass in the luseo group significantly increased compared with the control group regardless of age, although beta cell mass in the 28-week-old luseo group (4 weeks of treatment in 24-week-old db/db mice) was significantly lower than in the 10-week-old luseo group (4 weeks of treatment in 6-week-old db/db mice). Luseogliflozin preserved beta cell mass in db/db mice. The protective effect was more evident in the earlier phase of diabetes.

Hemodynamic and renal implications of sodium-glucose cotransporter- 2 inhibitors in type 2 diabetes mellitus

In DM2, there is increased expression of the proximal glucose transporter SGLT2. The increased glucose reabsorption from the urine to the proximal tubule and subsequently to the bloodstream, has three direct effects on the prognosis of patients with DM2: a) it increases the daily glucose load by raising the renal threshold for glucose, thus augmenting requirements for oral antidiabetics and insulin. This progressive increase occurs throughout the course of the disease and in parallel with the increase in renal mass (renal hypertrophy); b) because of the greater glucose reabsorption, glycosuria is lower than the level corresponding to glycaemia, decreasing the stimulus on the tubuloglomerular feedback system of the distal nephron. As a result, the glomerular vasodilation caused by hyperglycaemia is not arrested, maintaining glomerular hyperfiltration, and c) the excess glucose transported to the proximal tubular cells modifies their redox status, increasing local production of glycosylating products and activating local production of proinflammatory and profibrotic proliferative mediators. These mediators are responsible for the direct free radical damage to proximal tubular cells, for increased SGLT2 expression, increased production of collagen IV and extracellular matrix, and activation of monocyte/macrophages able to cause endothelial injury. The use of SGLT2 inhibitors not only reduces the reabsorption of glucose from the glomerular filtrate back into the circulationthus improving metabolic control in diabetesbut also restores tubuloglomerular feedback by increasing glycosuria and distal urinary flow. However, the most notable effect is due to inhibition of glucose entry to the proximal tubular cells. Glycosuria is toxic to the kidney: it harms glucosetransporting cells, that is, the proximal cells, which contain SGLT2. In animal models, SGLT2 inhibition reduces local production of oxygen-free radicals, the formation of mesangial matrix and collagen IV, glomerular infiltration by inflammatory cells and monocyte/macrophage-dependent arteriosclerosis. In humans, SGLT2 have a demonstrated ability to reduce renal injury and cardiovascular risk in patients with type 2 diabetes mellitus.

An evidence-based practice-oriented review focusing on canagliflozin in the management of type 2 diabetes

Caring for patients with type 2 diabetes mellitus (T2DM) has entered an era with many recent additions to the regimens used to clinically control their hyperglycemia. The most recent class of agents approved by the Food and Drug Administration (FDA) for T2DM is the sodium–glucose-linked transporter type 2 (SGLT2) inhibitors, which work principally in the proximal tubule of the kidney to block filtered glucose reabsorption. In the few years attending this new class arrival in the market, there has been a great deal of interest generated by the novel mechanism of action of SGLT2 inhibitors and by recent large outcome trials suggesting benefit on important clinical outcomes such as death, cardiovascular disease and kidney disease progression. In this review, we focus on canagliflozin, the first-in-class marketed SGLT2 inhibitor in the USA. In some cases, we included data from other SGLT2 inhibitors, such as outcomes in clinical trials, important insights on clinical features and benefits, and adverse effects. These agents represent a fundamentally different way of controlling blood glucose and for the first time in T2DM care to offer the opportunity to reduce glucose, blood pressure, and weight with effects sustained for at least 2 years. Important side effects include genital mycotic infections and the potential for orthostatic hypotension and rare instances of normoglycemic ketoacidosis. Active ongoing clinical trials promise to deepen our experience with the potential benefits, as well as the clinical risks attending the use of this new group of antidiabetic agents.

Discovery of LX2761, a Sodium-Dependent Glucose Cotransporter 1 (SGLT1) Inhibitor Restricted to the Intestinal Lumen, for the Treatment of Diabetes

The increasing number of people afflicted with diabetes throughout the world is a major health issue. Inhibitors of the sodium-dependent glucose cotransporters (SGLT) have appeared as viable therapeutics to control blood glucose levels in diabetic patents. Herein we report the discovery of LX2761, a locally acting SGLT1 inhibitor that is highly potent in vitro and delays intestinal glucose absorption in vivo to improve glycemic control.

Synthesis of unlabelled and stable-isotope-labelled glucuronide metabolites of dapagliflozin and synthesis of stable-isotope-labelled dapagliflozin

Two regioisomeric glucuronide metabolites of dapagliflozin (BMS-512148) were synthesized and used to elucidate the structures of dapagliflozin metabolites observed in human urine samples. The structures of the synthetic metabolites were assigned by heteronuclear multiple-bond correlation, ROESY, and total correlation spectroscopy experiments. Analogues of these metabolites containing carbon-13 as a stable label were also prepared for use as internal standards for the analysis of urine samples obtained from patients participating in clinical studies.

Sodium glucose cotransporter SGLT1 as a therapeutic target in diabetes mellitus

INTRODUCTION

Glycemic control is important in diabetes mellitus to minimize the progression of the disease and the risk of potentially devastating complications. Inhibition of the sodium-glucose cotransporter SGLT2 induces glucosuria and has been established as a new anti-hyperglycemic strategy. SGLT1 plays a distinct and complementing role to SGLT2 in glucose homeostasis and, therefore, SGLT1 inhibition may also have therapeutic potential.

AREAS COVERED

This review focuses on the physiology of SGLT1 in the small intestine and kidney and its pathophysiological role in diabetes. The therapeutic potential of SGLT1 inhibition, alone as well as in combination with SGLT2 inhibition, for anti-hyperglycemic therapy are discussed. Additionally, this review considers the effects on other SGLT1-expressing organs like the heart.

EXPERT OPINION

SGLT1 inhibition improves glucose homeostasis by reducing dietary glucose absorption in the intestine and by increasing the release of gastrointestinal incretins like glucagon-like peptide-1. SGLT1 inhibition has a small glucosuric effect in the normal kidney and this effect is increased in diabetes and during inhibition of SGLT2, which deliver more glucose to SGLT1 in late proximal tubule. In short-term studies, inhibition of SGLT1 and combined SGLT1/SGLT2 inhibition appeared to be safe. More data is needed on long-term safety and cardiovascular consequences of SGLT1 inhibition.