Discovery of tofogliflozin, a novel C-arylglucoside with an O-spiroketal ring system, as a highly selective sodium glucose cotransporter 2 (SGLT2) inhibitor for the treatment of type 2 diabetes

Gold(I)-Catalyzed Reactions of exo-Glycals with Propargyl Esters toward C-1 Alkenyl Spirocyclopropyl Carbohydrates

An atom-economic and diazo-free strategy for the construction of novel pseudo anomeric C-1 alkenyl spirocyclopropyl sugars is described. Leveraging the 1,2-migration pathway of propargyl esters under gold(I) catalysis, easily available exo-glycals undergo β-selective alkenylcarbenoid insertion in moderate to excellent yields. Preferential activation of propargyl moieties and concerted [2 + 1] insertion are both favored through ligand choice and electron enrichment of esters. Stereocontrol using conformational bias and rearrangement are also demonstrated.

Exploring novel lead scaffolds for SGLT2 inhibitors: Insights from machine learning and molecular dynamics simulations

Sodium-glucose cotransporter 2 (SGLT2) plays a pivotal role in mediating glucose reabsorption within the renal filtrate, representing a well-known target in type 2 diabetes and heart failure. Recent emphasis has been directed toward designing SGLT2 inhibitors, with C-glycoside inhibitors emerging as front-runners. The architecture of SGLT2 has been successfully resolved using cryo-electron microscopy. However, comprehension of the pharmacophores within the binding site of SGLT2 remains unclear. Here, we use machine learning and molecular dynamics simulations on SGLT2 bound with its inhibitors in preclinical or clinical development to shed light on this issue. Our dataset comprises 1240 SGLT2 inhibitors amalgamated from diverse sources, forming the basis for constructing machine learning models. SHapley Additive exPlanation (SHAP) elucidates the crucial fragments that contribute to inhibitor activity, specifically Morgan_3, 162, 310, 325, 366, 470, 597, 714, 926, and 975. Furthermore, the computed binding free energies and per-residue contributions for SGLT2-inhibitor complexes unveil crucial fragments of inhibitors that interact with residues Asn-75, His-80, Val-95, Phe-98, Val-157, Leu-274, and Phe-453 in the binding site of SGLT2. This comprehensive investigation enhances understanding of the binding mechanism for SGLT2 inhibitors, providing a robust framework for evaluating and discovering novel lead scaffolds within this domain.

Medicinal Chemistry Strategies for the Modification of Bioactive Natural Products

Natural bioactive compounds are valuable resources for drug discovery due to their diverse and unique structures. However, these compounds often lack optimal drug-like properties. Therefore, structural optimization is a crucial step in the drug development process. By employing medicinal chemistry principles, targeted molecular operations can be applied to natural products while considering their size and complexity. Various strategies, including structural fragmentation, elimination of redundant atoms or groups, and exploration of structure-activity relationships, are utilized. Furthermore, improvements in physicochemical properties, chemical and metabolic stability, biophysical properties, and pharmacokinetic properties are sought after. This article provides a concise analysis of the process of modifying a few marketed drugs as illustrative examples.

Solute carrier nutrient transporters in rheumatoid arthritis fibroblast-like synoviocytes

Metabolomic studies show that rheumatoid arthritis (RA) is associated with metabolic disruption. Metabolic changes in fibroblast-like synoviocytes (FLS) likely contribute to FLS abnormal response and strongly contribute to joint destruction. These changes often involve increased expression of nutrient transporters to meet a high demand for energy or biomolecules. The solute carrier (SLC) transporter families are nutrient transporters and serve as 'metabolic gates' for cells by mediating the transport of several different nutrients such as glucose, amino acids, vitamins, neurotransmitters, and inorganic/metal ions. In RA FLS SLC-mediated transmembrane transport was one pathway associated with different epigenetic landscape between RA and osteoarthritis (OA) FLS. These highlight that transporters from the SLC family offer unique targets for further research and offer the promise of future therapeutic targets for RA.

Carbohydrate-based drugs launched during 2000-2021

Carbohydrates are fundamental molecules involved in nearly all aspects of lives, such as being involved in formating the genetic and energy materials, supporting the structure of organisms, constituting invasion and host defense systems, and forming antibiotics secondary metabolites. The naturally occurring carbohydrates and their derivatives have been extensively studied as therapeutic agents for the treatment of various diseases. During 2000 to 2021, totally 54 carbohydrate-based drugs which contain carbohydrate moities as the major structural units have been approved as drugs or diagnostic agents. Here we provide a comprehensive review on the chemical structures, activities, and clinical trial results of these carbohydrate-based drugs, which are categorized by their indications into antiviral drugs, antibacterial/antiparasitic drugs, anticancer drugs, antidiabetics drugs, cardiovascular drugs, nervous system drugs, and other agents.

Unified synthesis of multiply arylated alkanes by catalytic deoxygenative transformation of diarylketones

A deoxygenative transformation of diarylketones leading to multiply arylated alkanes was developed. Diarylketones were reacted with diphenylphosphine oxide resulting in a phospha-Brook rearrangement, followed by palladium-catalyzed cross-couplings or a Friedel-Crafts type alkylation to afford the corresponding multiply arylated alkanes. A variety of diarylketones can be converted to multiply arylated alkanes such as diarylmethanes, tetraarylethanes, and triarylmethanes by reduction, dimerization, and arylation in one pot. Furthermore, a one-pot conversion from arylcarboxylic acids to diarylmethanes and tetraarylethanes, and a synthesis of tetraarylmethane and triphenylethane using sequential coupling reactions are also presented.

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.

Efficient Route to Canagliflozin via Anhydroketopyranose

The development of an efficient route for the synthesis of Canagliflozin is reported. The anhydroketopyranose intermediate was isolated as a novel intermediate, which was used to prepare Canagliflozin API in high purity.

Effects of an SGLT Inhibitor on the Production, Toxicity, and Elimination of Gut-Derived Uremic Toxins: A Call for Additional Evidence

Sodium–glucose cotransporter (SGLT) inhibitors are a class of oral hypoglycemic agents, which, in recent years, have been shown to improve renal and cardiovascular outcomes in patients with diabetic and non-diabetic chronic kidney disease. There remains considerable debate regarding the potential glucose-independent mechanisms by which these benefits are conferred. SGLT inhibitors, to a variable extent, impair small intestinal glucose absorption, facilitating the delivery of glucose into the colon. This suppresses protein fermentation, and thus the generation of uremic toxins such as phenols and indoles. It is acknowledged that such a shift in gut microbial metabolism yields health benefits for the host. SGLT inhibition, in addition, may be hypothesized to foster the renal clearance of protein-bound uremic toxins. Altered generation and elimination of uremic toxins may be in the causal pathway between SGLT inhibition and improved cardiometabolic health. Present review calls for additional research.

Discovery of GCC5694A: A potent and selective sodium glucose co-transporter 2 inhibitor for the treatment of type 2 diabetes

Sodium-dependent glucose co-transporter 2 (SGLT2) has emerged as a promising drug target for the treatment of type 2 diabetes, and recently, several SGLT2 inhibitors have been approved for clinical use. A series of molecules with a C-aryl glucoside scaffold was designed and synthesized for biological evaluation. Among the molecules tested, a dihydrobenzofuran-containing analog, 14g (GCC5694A), exhibited excellentin vitro activity against SGLT2 (IC₅₀ = 0.460 nM), good selectivity for SGLT1, and good metabolic stability. Data from further evaluation of the compound in animal models showed that this molecule is a promising candidate for development as an anti-diabetic agent.

Structural Perspectives and Advancement of SGLT2 Inhibitors for the Treatment of Type 2 Diabetes

Diabetes mellitus is an ailment that affects a large number of individuals worldwide and its pervasiveness has been predicted to increase later on. Every year, billions of dollars are spent globally on diabetes-related health care practices. Contemporary hyperglycemic therapies to rationalize Type 2 Diabetes Mellitus (T2DM) mostly involve pathways that are insulin-dependent and lack effectiveness as the pancreas' β-cell function declines more significantly. Homeostasis via kidneys emerges as a new and future strategy to minimize T2DM complications. This article covers the reabsorption of glucose mechanism in the kidneys, the functional mechanism of various Sodium- Glucose Cotransporter 2 (SGLT2) inhibitors, their structure and driving profile, and a few SGLT2 inhibitors now accessible in the market as well as those in different periods of advancement. The advantages of SGLT2 inhibitors are dose-dependent glycemic regulation changes with a significant reduction both in the concentration of HbA1c and body weight clinically and statistically. A considerable number of SGLT2 inhibitors have been approved by the FDA, while a few others, still in preliminaries, have shown interesting effects.

Diabetic proximal tubulopathy: Can we mimic the disease for in vitro screening of SGLT inhibitors?

Diabetic kidney disease (DKD) is the foremost cause of renal failure. While the glomeruli are severely affected in the course of the disease, the main determinant for disease progression is the tubulointerstitial compartment. DKD does not develop in the absence of hyperglycemia. Since the proximal tubule is the major player in glucose reabsorption, it has been widely studied as a therapeutic target for the development of new therapies. Currently, there are several proximal tubule cell lines available, being the human kidney-2 (HK-2) and human kidney clone-8 (HKC-8) cell lines the ones widely used for studying mechanisms of DKD. Studies in these models have pushed forward the understanding on how DKD unravels, however, these cell culture models possess limitations that hamper research, including lack of transporters and dedifferentiation. The sodium-glucose cotransporters (SGLT) are identified as key players in glucose reabsorption and pharmacological inhibitors have shown to be beneficial for the long-term clinical outcome in DKD. However, their mechanism of action has, as of yet, not been fully elucidated. To comprehend the protective effects of SGLT inhibitors, it is essential to understand the complete functional, structural, and molecular features of the disease, which until now have been difficult to recapitulate. This review addresses the molecular events of diabetic proximal tubulopathy. In addition, we evaluate the protective role of SGLT inhibitors in cardiovascular and renal outcomes, and provide an overview of various in vitro models mimicking diabetic proximal tubulopathy used so far. Finally, new insights on advanced in vitro systems to surpass past limitations are postulated.

Environmentally Benign Synthesis of Quinoline-Spiroquinazolinones by Iron-Catalyzed Dehydrogenative [4 + 2] Cycloaddition of Secondary/Tertiary Anilines and 4-Methylene-quinazolinones

We report an efficient iron-catalyzed cross-dehydrogenative coupling [4 + 2] annulation of secondary/tertiary anilines with quinazolinones to generate quinoline-spiroquinzolinones. The reaction proceeds smoothly with a relatively broad variety of functional groups, a cheap transition metal catalyst (FeCl₃), and environmentally friendly oxidant (H₂O₂/O₂) under mild reaction conditions. Creatively, N-methylanilines are employed for the first time for the cycloaddition as both methyl and methylene sources attached to the N atom of tetrahydroquinolines.

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.

Comprehensive structure–activity relationship (SAR) investigation of C-aryl glycoside derivatives for the development of SGLT1/SGLT2 dual inhibitors

Multi-combined computational approaches were used to explore the SAR and design novel potential SGLT1/SGLT2 dual inhibitors.

Sc(OTf)3 catalyzed [3 + 2]-annulation reaction of donor–acceptor aziridines with methylene exo-glycals: synthesis of chiral carbohydrate-spiro-heterocycles

A Sc(OTf)₃ catalyzed [3 + 2]-annulation reaction between D–A N-tosyl aziridines and methylene exo-glycals was developed for the synthesis of carbohydrate-spiro-heterocycles.

Spirocyclic Scaffolds in Medicinal Chemistry

Spirocyclic scaffolds are incorporated in various approved drugs and drug candidates. The increasing interest in less planar bioactive compounds has given rise to the development of synthetic methodologies for the preparation of spirocyclic scaffolds. In this Perspective, we summarize the diverse synthetic routes to obtain spirocyclic systems. The impact of spirocycles on potency and selectivity, including the aspect of stereochemistry, is discussed. Furthermore, we examine the changes in physicochemical properties as well as in in vitro and in vivo ADME using selected studies that compare spirocyclic compounds to their nonspirocyclic counterparts. In conclusion, the value of spirocyclic scaffolds in medicinal chemistry is discussed.

SGLT2 inhibitors, an accomplished development in field of medicinal chemistry: an extensive review

Diabetes is a chronic progressive metabolic disease caused by insulin deficiency or insulin resistance. In spite of the availability of several antihyperglycaemics, there is a need for the development of safer antidiabetic drugs due to their undesirable effects. Sodium-glucose cotransporter-2 inhibitors are a class of antidiabetics, which hinder the reabsorption of glucose in the kidneys, causing excretion of glucose via urine. Sodium-glucose cotransporter-2 inhibitors are a well-tolerated class with no significant adverse effects and are found to be favorable in certain conditions, which may be rudimentary to cardiovascular and renal diseases. The current advancements in their design and development, their mechanism of action, structure–activity relationship, synthesis and in silico development along with their auxiliary roles have been extensively reviewed.

Opportunities for Tapping into Three-Dimensional Chemical Space through a Quaternary Carbon

A quaternary carbon bears four other carbon substituents or combination of four non-hydrogen substituents at four vertices of a tetrahedron. The spirocyclic quaternary carbon positioned at the center of a bioactive molecule offers conformational rigidity, which in turn reduces the penalty for conformational entropy. The quaternary carbon is a predominant feature of natural product structures and has been associated with more effective and selective binding to target proteins compared to planar compounds with a high sp² count. The presence of a quaternary carbon stereocenter allows the exploration of novel chemical space to obtain new molecules with enhanced three-dimensionality. These characteristics, coupled to an increasing awareness to develop sp³-rich molecules, boosted utility of quaternary carbon stereocenters in bioactive compounds. It is hoped that this Perspective will inspire the chemist to utilize quaternary carbon stereocenters to enhance potency, selectivity, and other drug-like properties.

An exhaustive perspective on structural insights of SGLT2 inhibitors: A novel class of antidiabetic agent

Diabetes mellitus is the global health issue and become an alarming threat in the modern era where human lifestyle gets compromised with modernization. According to the latest statistical report 2020, USA has 9.47% (31 million among 32.72 cr), China has 8.3% (116.4 million among 139.27 cr) and India has 5.6% (77 million among 135.26 cr) of the diabetic people, indicating that diabetes is more prevailing in developed countries as compared to the developing countries. The number of diabetic patients is rising day by day at a tremendous rate and soon it may affect each and every person in a family. So, there is an urgent need to develop novel entities that can meet the scarcity of present antidiabetic agents. In the last few decades, the sodium-glucose co-transporter 2 (SGLT2) has emerged as a prominent target for the treatment of Type 2 diabetes mellitus due to its novel mechanism of action & no involvement in insulin signaling pathway. Most of the inhibitors that target SGLT2 contain three basic moieties: glucose, two benzene rings (one is connected with glucose and the other with methylene), and the methylene bridge which are similar to dapagliflozin. Several SGLT2 inhibitors and their derivatives such as remogliflozin etabonate (phase-II), sotagliflozin (phase-III) and bexagliflozin (phase-III) are under different phases of clinical trial studies and some have been patented. The present review is focused on SGLT2 inhibitors, structure activity relationships (SARs) of dapagliflozin and its several analogues for their binding affinity with SGLT2. We have also presented and summarized the efforts made by various researchers in terms of the synthesis of various dapagliflozin derivatives till date.

Synthesis and Structure-Activity Relationship of C-Phenyl D-Glucitol (TP0454614) Derivatives as Selective Sodium-Dependent Glucose Cotransporter 1 (SGLT1) Inhibitors

Sodium-glucose cotransporter 1 (SGLT1) is the primary transporter for glucose absorption from the gastrointestinal tract. While C-phenyl D-glucitol derivative SGL5213 has been reported to be a potent intestinal SGLT1 inhibitor for use in the treatment of type 2 diabetes, no SGLT1 selectivity was found in vitro (IC₅₀ 29 nM for hSGLT1 and 20 nM for hSGLT2). In this study we found a new method of synthesizing key intermediates 12 by a one-pot three-component condensation reaction and discovered C-phenyl D-glucitol 41j (TP0454614), which has >40-fold SGLT1 selectivity in vitro (IC₅₀ 26 nM for hSGLT1 and 1101 nM for hSGLT2). The results of our study have provided new insights into the structure-activity relationships (SARs) of the SGLT1 selectivity of C-glucitol derivatives.

Safety and effectiveness of tofogliflozin in Japanese patients with type 2 diabetes mellitus: Results of 24-month interim analysis of a long-term post-marketing study (J-STEP/LT)

AIMS/INTRODUCTION

Tofogliflozin is a potent and highly selective sodium-glucose cotransporter 2 inhibitor, and is currently used to treat patients with type 2 diabetes mellitus. We designed a 3-year study of tofogliflozin in patients with type 2 diabetes mellitus to evaluate the safety and effectiveness in routine clinical practice. The 3- and 12-month interim analysis showed tofogliflozin was well-tolerated, safe and clinically effective. Here, we report the results of the 24-month interim analysis.

MATERIALS AND METHODS

This is a 3-year prospective, observational and multicenter post-marketing study (Japanese Study of Tofogliflozin with Type 2 Diabetes Mellitus Patients/Long Term).

RESULTS

Of the 6,897 patients enrolled, 6,712 and 6,461 patients were analyzed for the safety and effectiveness of tofogliflozin, respectively. During the 24-month observation period, the incidence rates of adverse drug reactions (ADRs) and serious adverse drug reactions were 11.25 and 1.21%, respectively. As to adverse drug reactions of special interest, the incidence rates of hypoglycemia, polyuria/pollakiuria, volume depletion-related events, urinary tract infections and genital infection were 0.83, 1.28, 1.46, 1.18 and 1.62%, respectively. Renal disorders, and cardiovascular and cerebrovascular disorders occurred in 0.63 and 0.76% of the patients, respectively. Glycated hemoglobin A1c and bodyweight decreased significantly by -0.70% (P < 0.0001) and -2.95 kg (P < 0.0001), respectively, from baseline to week 104 (last observation carried forward).

CONCLUSIONS

Significant safety concerns have not been observed, and clinical benefit including a long-term reduction in glycated hemoglobin A1c over a 104-week (24 months) observation period with weight loss was suggested in this 24-month interim analysis of the 3-year Japanese Study of Tofogliflozin with Type 2 Diabetes Mellitus Patients/Long Term in routine clinical practice.

A Comprehensive Review on Preclinical Diabetic Models

BACKGROUND

Preclinical experimental models historically play a critical role in the exploration and characterization of disease pathophysiology. Further, these in-vivo and in-vitro preclinical experiments help in target identification, evaluation of novel therapeutic agents and validation of treatments.

INTRODUCTION

Diabetes mellitus (DM) is a multifaceted metabolic disorder of multidimensional aetiologies with the cardinal feature of chronic hyperglycemia. To avoid or minimize late complications of diabetes and related costs, primary prevention and early treatment are therefore necessary. Due to its chronic manifestations, new treatment strategies need to be developed, because of the limited effectiveness of the current therapies.

METHODS

The study included electronic databases such as Pubmed, Web of Science and Scopus. The datasets were searched for entries of studies up to June, 2018.

RESULTS

A large number of in-vivo and in-vitro models have been presented for evaluating the mechanism of anti-hyperglycaemic effect of drugs in hormone-, chemically-, pathogen-induced animal models of diabetes mellitus. The advantages and limitations of each model have also been addressed in this review.

CONCLUSION

This review encompasses the wide pathophysiological and molecular mechanisms associated with diabetes, particularly focusing on the challenges associated with the evaluation and predictive validation of these models as ideal animal models for preclinical assessments and discovering new drugs and therapeutic agents for translational application in humans. This review may further contribute to discover a novel drug to treat diabetes more efficaciously with minimum or no side effects. Furthermore, it also highlights ongoing research and considers the future perspectives in the field of diabetes.

Blue light photoredox-catalysed acetalation of alkynyl bromides

Herein, we report an organo-photoredox-based protocol using 2,2-diethoxyacetic acid as the acetal source to achieve acetalation of alkynyl bromides to afford various alkynyl acetal products. In addition to arylethynyl bromides, substrates bearing heteroaryl rings (thiophene, pyridine, and indole) smoothly gave the corresponding acetalation products. This mild protocol has potential utility for the synthesis of aldehydes by further protonization.

Long-term safety and efficacy of the sodium-glucose cotransporter 2 inhibitor, tofogliflozin, added on glucagon-like peptide-1 receptor agonist in Japanese patients with type 2 diabetes mellitus: A 52-week open-label, multicenter, post-marketing clinical study

AIMS/INTRODUCTION

Tofogliflozin is a potent and highly selective sodium-glucose cotransporter 2 inhibitor that is currently used to treat patients with type 2 diabetes mellitus. The aim of the present study was to evaluate the safety and efficacy of tofogliflozin add-on to glucagon-like peptide-1 (GLP-1) receptor agonist monotherapy.

MATERIALS AND METHODS

In this 52-week, prospective, multicenter, single arm, post-marketing clinical study, Japanese patients who had already been receiving GLP-1 receptor agonist monotherapy for ≥8 weeks, glycated hemoglobin ≥7.0 and <10.5%, and body mass index ≥18.5 and <35.0 kg/m2 were enrolled. Tofogliflozin 20 mg was orally administered once daily for 52 weeks with GLP-1 receptor agonist. Primary end-points were safety and change in glycated hemoglobin from baseline to week 52. Safety was assessed on the basis of the adverse events. Changes from baseline in fasting plasma glucose, bodyweight, blood pressure, uric acid and lipid parameters were assessed as secondary efficacy end-points.

RESULTS

Of the 67 patients enrolled, 63 patients completed the study. Overall, 26 adverse drug reactions occurred in 17 patients (25.4%). Adverse drug reactions with a frequency of two or more patients (3.0%) were constipation, thirst, dehydration and pollakiuria. Hypoglycemia (n = 1) was limited. With the addition of tofogliflozin to GLP-1 receptor agonist, the subsequent mean (standard deviation) reduction in glycated hemoglobin was -0.6% (1.0%; P < 0.0001). Fasting plasma glucose, bodyweight and blood pressure were significantly improved.

CONCLUSIONS

Tofogliflozin add-on to GLP-1 receptor agonist monotherapy is an effective treatment option with an acceptable safety profile.

Glucopyranosylidene-spiro-benzo[ b][1,4]oxazinones and -benzo[ b][1,4]thiazinones: Synthesis and Investigation of Their Effects on Glycogen Phosphorylase and Plant Growth Inhibition

Glucopyranosylidene-spiro-benzo[ b][1,4]oxazinones were obtained via the corresponding 2-nitrophenyl glycosides obtained by two methods: (a) AgOTf-promoted glycosylation of 2-nitrophenol derivatives by O-perbenzoylated methyl (α-d-gluculopyranosyl bromide)heptonate or (b) Mitsunobu-type reactions of O-perbenzoylated methyl (α-d-gluculopyranose)heptonate with bulky 2-nitrophenols in the presence of diethyl azodicarboxylate (DEAD) and PPh₃. Catalytic hydrogenation (H₂-Pd/C) or partial reduction (e.g., H₂-Pd/C, pyridine) of the 2-nitro groups led to spiro-benzo[ b][1,4]oxazinones and spiro-benzo[ b][1,4]-4-hydroxyoxazinones by spontaneous ring closure of the intermediate 2-aminophenyl or 2-hydroxylamino glycosides, respectively. The analogous 2-aminophenyl thioglycosides, prepared by reactions of O-perbenzoylated methyl (α-d-gluculopyranosyl bromide)heptonate with 2-aminothiophenols, were cyclized in m-xylene at reflux temperature to the corresponding spiro-benzo[ b][1,4]thiazinones. O-Debenzoylation was effected by Zemplén transesterification in both series. Spiro-configurations were determined by NMR and electronic circular dichroism time-dependent density functional theory (ECD-TDDFT) methods. Inhibition assays with rabbit muscle glycogen phosphorylase b showed (1' R)-spiro{1',5'-anhydro-d-glucitol-1',2-benzo[ b][1,4]oxazin-3(4 H)-one} and (1' R)-spiro{1',5'-anhydro-d-glucitol-1',2-benzo[ b][1,4]thiazin-3(4 H)-one} to be the most efficient inhibitors (27 and 28% inhibition at 625 μM, respectively). Plant growth tests with white mustard and garden cress indicated no effect except for (1' R)-4-hydroxyspiro{1',5'-anhydro-d-glucitol-1',2-benzo[ b][1,4]oxazin-3(4 H)-one} with the latter plant to show modest inhibition of germination (95% relative to control).

In the Search of Glycoside-Based Molecules as Antidiabetic Agents

This review is an effort to summarize recent developments in synthesis of O-glycosides and N-, C-glycosyl molecules with promising antidiabetic potential. Articles published after 2000 are included. First, the O-glycosides used in the treatment of diabetes are presented, followed by the N-glycosides and finally the C-glycosides constituting the largest group of antidiabetic drugs are described. Within each group of glycosides, we presented how the structure of compounds representing potential drugs changes and when discussing chemical compounds of a similar structure, achievements are presented in the chronological order. C-Glycosyl compounds mimicking O-glycosides structure, exhibit the best features in terms of pharmacodynamics and pharmacokinetics. Therefore, the largest part of the article is concerned with the description of the synthesis and biological studies of various C-glycosides. Also N-glycosides such as N-(β-d-glucopyranosyl)-amides, N-(β-d-glucopyranosyl)-ureas, and 1,2,3-triazolyl derivatives belong to the most potent classes of antidiabetic agents. In order to indicate which of the compounds presented in the given sections have the best inhibitory properties, a list of the best inhibitors is presented at the end of each section. In summary, the best inhibitors were selected from each of the summarizing figures and the results of the ranking were placed. In this way, the reader can learn about the structure of the compounds having the best antidiabetic activity. The compounds, whose synthesis was described in the article but did not appear on the figures presenting the structures of the most active inhibitors, did not show proper activity as inhibitors. Thus, the article also presents studies that have not yielded the desired results and show directions of research that should not be followed. In order to show the directions of the latest research, articles from 2018 to 2019 are described in a separate Sect. 5. In Sect. 6, biological mechanisms of action of the glycosides and patents of marketed drugs are described.

Enantioselective Synthesis of Cyclohexadienone Containing Spiroketals via DyKat Ketalization/oxa-Michael Addition Cascade

An oxidative dearomatization of phenol followed by a dynamic kinetic (DyKat) ketalization/oxa-Michael addition cascade using cinchona alkaloid-based chiral bifunctional amino-squaramide catalysts is reported. A broad array of sterically hindered [5,5]-spiroketals attached to a cyclohexadienone moiety in spiro-fashion is synthesized in an enantiopure form. Further, the methodology was optimized and extended to the corresponding benzannulated [5,5]-spiroketals attached to a cyclohexadienone moiety in spiro-fashion. In general, good yields and excellent diastereoselectivies and enantioselectivities (up to 20:1 dr and up to 99% ee) were obtained.

What does sodium-glucose co-transporter 1 inhibition add: Prospects for dual inhibition

Epithelial glucose transport is accomplished by Na+ -glucose co-transporters, SGLT1 and SGLT2. In the intestine, uptake of dietary glucose is for its majority mediated by SGLT1, and humans with mutations in the SGLT1 gene show glucose/galactose malabsorption. In the kidney, both transporters, SGLT1 and SGLT2, are expressed and recent studies identified that SGLT2 mediates up to 97% of glucose reabsorption. Humans with mutations in the SGLT2 gene show familial renal glucosuria. In the last three decades, significant progress was made in understanding the physiology of these transporters and their potential as therapeutic targets. Based on the structure of phlorizin, a natural compound acting as a SGLT1/2 inhibitor, initially several SGLT2, and later SGLT1 and dual SGLT1/2 inhibitors have been developed. Interestingly, SGLT2 knockout or treatment with SGLT2 selective inhibitors only causes a fractional glucose excretion in the magnitude of ∼60%, an effect mediated by up-regulation of renal SGLT1. Based on these findings the hypothesis was brought forward that dual SGLT1/2 inhibition might further improve glycaemic control via targeting two distinct organs that express SGLT1: the intestine and the kidney. Of note, SGLT1/2 double knockout mice completely lack renal glucose reabsorption. This review will address the rationale for the development of SGLT1 and dual SGLT1/2 inhibitors and potential benefits compared to sole SGLT2 inhibition.

A New Synthetic Spiroketal: Studies on Antitumor Activity on Murine Melanoma Model In Vivo and Mechanism of Action In Vitro

BACKGROUND

In a previous study, we synthesised a new spiroketal derivative, inspired to natural products, that has shown high antiproliferative activity, potent telomerase inhibition and proapoptotic activity on several human cell lines.

OBJECTIVE

This work focused on the study of in vivo antitumor effect of this synthetic spiroketal on a murine melanoma model. In order to shed additional light on the origin of the antitumor effect, in vitro studies were performed.

METHODS

Spiroketal was administered to B16F10 melanoma mice at a dose of 5 mg/Kg body weight via intraperitoneum at alternate days for 15 days. Tumor volume measures were made every 2 days starting after 12 days from cells injection. The effects of the spiroketal on tumor growth inhibition, apoptosis induction, and cell cycle modification were investigated in vitro on B16 cells. HIF1α gene expression, the inhibition of cells migration and the changes induced in cytoskeleton conformation were evaluated.

RESULTS

Spiroketal displayed proapoptotic activity and high antitumor activity in B16 cells with nanomolar IC50. Moreover it has shown to inhibit cell migration, to strongly reduce the HIF1α expression and to induce strongly deterioration of cytoskeleton structure. A potent dose-dependent antitumor efficacy in syngenic B16/C57BL/6J murine model of melanoma was observed with the suppression of tumor growth by an average of 90% at a dose of 5 mg/kg.

CONCLUSION

The synthesized spiroketal shows high antitumor activity in the B16 cells in vitro at nM concentration and a dose-dependent antitumor efficacy in syngenic B16/C57BL/6J mice. The results suggest that this natural product inspired spiroketal may have a potential application in melanoma therapy.

Bicyclic acetals: biological relevance, scaffold analysis, and applications in diversity-oriented synthesis

The chemoinformatics analysis of fused, spiro, and bridged bicyclic acetals is instrumental for the DOS of natural product-inspired molecular collections.

Tofogliflozin Salt Cocrystals with Sodium Acetate and Potassium Acetate

We investigated the salt cocrystals formed by tofogliflozin with sodium acetate and potassium acetate by determining the crystal structures of the salt cocrystals and characterizing the solid states. The salt cocrystal screening using the slurry method and the liquid-assisted grinding method resulted in the formation of tofogliflozin-sodium acetate 1 : 1 and tofogliflozin-potassium acetate 1 : 1 salt cocrystals. Single-crystal X-ray diffraction revealed that, although each salt cocrystal belongs to a different space group, both of the salt cocrystals have almost similar structural features, including the conformation of tofogliflozin molecules, the coordination to Na⁺/K⁺ ions, and hydrogen bonds. The salt cocrystals exhibited extreme hygroscopicity with deliquescence, which is also a property of sodium acetate and potassium acetate. In addition, tofogliflozin-potassium acetate salt cocrystal had two polymorphs, which were enantiotropically related.

Discovery of a potent, low-absorbable sodium-dependent glucose cotransporter 1 (SGLT1) inhibitor (TP0438836) for the treatment of type 2 diabetes

The design and synthesis of a novel class of low-absorbable SGLT1 inhibitors are described. To achieve low absorption in the new series, we performed an optimization study based on a strategy to increase TPSA. Fortunately, the optimization of an aglycon moiety and a side chain of the distal aglycon moiety led to the identification of compound 30b as a potent and low-absorbable SGLT1 inhibitor. Compound 30b showed a desirable PK profile in Sprague-Dawley (SD) rats and a favorable glucose-lowering effect in diabetic rats.

There is a Close Association Between the Recovery of Liver Injury and Glycemic Control after SGLT2 Inhibitor Treatment in Japanese Subjects with Type 2 Diabetes: A Retrospective Clinical Study

INTRODUCTION

Sodium-glucose co-transporter 2 (SGLT2) inhibitors function not only to reduce hyperglycemia but also to ameliorate liver injury and reduce body weight. The aim of this study was to examine in which subjects SGLT2 inhibitors are more effective for glycemic control, liver injury, and obesity in Japanese subjects with type 2 diabetes mellitus.

METHODS

We enrolled a total of 156 subjects with type 2 diabetes who initiated SGLT2 inhibitor treatment after September 1, 2014 in Kawasaki Medical School (Protocol No. 2375). We evaluated the alteration of glycemic control, liver injury, body mass composition, and various clinical parameters.

RESULTS

SGLT2 inhibitors significantly ameliorated glycemic control and improved liver injury in Japanese subjects with type 2 diabetes. SGLT2 inhibitors were more effective for liver injury when glycemic control was improved with SGLT2 inhibitors. In multivariate analyses, the amelioration of glycemic control was an independent determinant factor for the improvement of liver damage in Japanese subjects with type 2 diabetes. The reverse was also correct; the improvement of liver damage was an independent determinant factor for the amelioration of glycemic control.

CONCLUSION

Recovery of liver injury with SGLT2 inhibitor treatment was closely associated with their effects on glycemic control in Japanese subjects with type 2 diabetes.

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

Hypervalent iodine reagents have been developed as highly valuable reagents in synthetic organic chemistry during the past few decades. These reagents have been identified as key replacements of various toxic heavy metals in organic synthesis. Various synthetically and biologically important scaffolds have been developed using hypervalent iodine reagents either in stoichiometric or catalytic amounts. In addition, hypervalent iodine reagents have been employed for the synthesis of spirocyclic scaffolds via dearomatization processes. In this review, various approaches for the synthesis of spirocyclic scaffolds using hypervalent iodine reagents are covered including their stereoselective synthesis. Additionally, the applications of these reagents in natural product synthesis are also covered.

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.