N-Indolylglycosides bearing modifications at the glucose C6-position as sodium-dependent glucose co-transporter 2 inhibitors

Suppression of glucose reabsorption through the inhibition of sodium-dependent glucose co-transporter 2 (SGLT2) is a promising therapeutic approach for the treatment of type 2 diabetes. To investigate the effect of C6-substitution on inhibition of SGLT2 by N-indolylglucosides, a small library of 6-triazole, 6-amide, 6-urea, and 6-thiourea N-indolylglycosides were synthesized and tested. A detailed structure–activity relationship (SAR) study culminated in the identification of 6-amide derivatives 6a and 6o as potent SGLT2 inhibitors, which were further tested for inhibitory activity against SGLT1. The data obtained indicated that 6a and 6o are mildly to moderately selective for SGLT2 over SGLT1. Both compounds were also evaluated in a urinary glucose excretion test and pharmacokinetic study; 6a was found capable of inducing urinary glucose excretion in normal SD rats.     

The design and synthesis of novel SGLT2 inhibitors: C-glycosides with benzyltriazolopyridinone and phenylhydantoin as the aglycone moieties

The sodium glucose co-transporter 2 (SGLT2) has received considerable attention in recent years as a target for the treatment of type 2 diabetes mellitus. This report describes the design, synthesis and structure–activity relationship (SAR) of C-glycosides with benzyltriazolopyridinone and phenylhydantoin as the aglycone moieties as novel SGLT2 inhibitors. Compounds 5p and 33b demonstrated high potency in inhibiting SGLT2 and high selectivity against SGLT1. The in vitro ADMET properties of these compounds will also be discussed.     

Synthesis and biological evaluation of benzocyclobutane-C-glycosides as potent and orally active SGLT1/SGLT2 dual inhibitors

Synthesis and biological evaluation of benzocyclobutane-C-glycosides as potent and orally active SGLT1/SGLT2 dual inhibitors are described. Compound 19 showed high inhibitory potency at SGLT1 (IC₅₀?=?45?nM), and excellent potency at SGLT2 (IC₅₀?=?1?nM). It also displayed excellent PK profiles in mice, rats, dogs and monkeys (F?=?78–107%). In SD rats, compound 19 treatments significantly reduced blood glucose levels in a dose-dependent manner. In ZDF rats, compound 19 displayed anti-hyperglycemic effect up to 24?h. Therefore, compound 19 may serve as valuable pharmacological tool, and potential use as a treatment for metabolic syndrome.     

Synthesis of novel l-rhamnose derived acyclic C-nucleosides with substituted 1,2,3-triazole core as potent sodium-glucose co-transporter (SGLT) inhibitors

Sodium-glucose co-transporter (SGLT) inhibitors are a novel class of therapeutic agents for the treatment of type 2 diabetes by preventing renal glucose reabsorption. In our efforts to identify novel inhibitors of SGLT, we synthesized a series of l-rhamnose derived acyclic C-nucleosides with 1,2,3-triazole core. The key β-ketoester building block 4 prepared from l-rhamnose in five steps, was reacted with various aryl azides to produce the respective 1,2,3-triazole derivatives in excellent yields. Deprotection of acetonide group gave the desired acyclic C-nucleosides 7a–o. All the new compounds were screened for their sodium-glucose co-transporters (SGLT1 and SGLT2) inhibition activity using recently developed cell-based nonradioactive fluorescence glucose uptake assay. Among them, 7m with IC₅₀: 125.9 nM emerged as the most potent SGLT2 inhibitor. On the other hand compound 7d exhibited best selectivity for inhibition of SGLT2 (IC₅₀: 149.1 nM) over SGLT1 (IC₅₀: 693.2 nM). The results presented here demonstrated the utility of acyclic C-nucleosides as novel SGLT inhibitors for future investigations.     

Identification of novel uracil derivatives incorporating benzoic acid moieties as highly potent Dipeptidyl Peptidase-IV inhibitors

Dipeptidyl Peptidase-IV (DPP-4) is a validated therapeutic target for type 2 diabetes. Aiming to interact with both residues Try629 and Lys554 in S₂′ site, a series of novel uracil derivatives 1a–l and 2a–i incorporating benzoic acid moieties at the N₃ position were designed and evaluated for their DPP-4 inhibitory activity. Structure-activity relationships (SAR) study led to the identification of the optimal compound 2b as a potent and selective DPP-4 inhibitor (IC₅₀?=?1.7?nM). Docking study revealed the additional salt bridge formed between the carboxylic acid and primary amine of Lys554 has a key role in the enhancement of the activity. Furthermore, compound 2b exhibited no cytotoxicity in human hepatocyte LO2 cells up to 50?μM. Subsequent in vivo evaluations revealed that the ester of 2b robustly improves the glucose tolerance in normal mice. The overall results have shown that compound 2b has the potential to a safe and efficacious treatment for T2DM.     

Design,synthesis and evaluation of 2-(indolylmethylidene)-2,3-dihydro-1-benzofuran-3-one and 2-(indolyl)-4H-chromen-4-one derivatives as novel monoamine oxidases inhibitors

A series of 2-(indolylmethylidene)-2,3-dihydro-1-benzofuran-3-ones (aurone-indole hybrids) and 2-(indolyl)-4H-chromen-4-ones (flavone-indole hybrids) were designed, synthesized, and their monoamine oxidase (MAO) A and B inhibitory activities were evaluated. Compounds 5b and 11b showed potent inhibitory activities against MAO-A, comparable to that of pargyline used as a positive control, and most of the compounds, except for 2a and 10b, showed potent inhibitory activities against MAO-B. Compound 9a was the most potent and highly selective inhibitor of MAO-B (IC₅₀ value for MAO-B: 0.0026 μM, and MAO-A: >100 μM). Comparison of the inhibitory activities of 1a vs. 9a vs. 13a and 1b vs. 7b vs. 11b suggested that methoxy substitution at R¹ on the A-rings of flavonoids increases MAO-A inhibition whereas methoxy substitution at R² increased MAO-B inhibition. Comparison of 4a vs. 10a, 6a vs. 11a, 3b vs. 8b and 4b vs. 9b showed incremental increases in MAO-B inhibitory activity by R² substitution on the A ring. Comparison of the MAO-B inhibitory effects of the flavone-indole hybrids and aurone-indole hybrids showed that most of the aurone-indole hybrids were stronger inhibitors than the corresponding flavone-indole hybrids. Molecular docking analysis of compounds 1a and 9a with MAO-B further supported the above structural effects of these compounds on MAO-B inhibitory activity.This is the first report identifying aurone-indole hybrids as potent MAO-B inhibitors. The results reported here suggest that 2-(1H-indol-1-ylmethylene)-6-methoxy-3(2H)-benzofuranone (9a) might be a useful lead for the design and development of novel MAO-B inhibitors     

Synthesis and biological evaluation of pyrrolidine-2-carbonitrile and 4-fluoropyrrolidine-2-carbonitrile derivatives as dipeptidyl peptidase-4 inhibitors for the treatment of type 2 diabetes

A novel series of pyrrolidine-2-carbonitrile and 4-fluoropyrrolidine-2-carbonitrile derivatives was designed, synthesized, and found to act as dipeptidyl peptidase-4 (DPP-4) inhibitors. From this series of compounds, compound 17a was identified as an efficacious, safe, and selective inhibitor of DPP-4. In vivo studies in ICR and KKAy mice showed that administration of this compound resulted in decreased blood glucose in these mice after an oral glucose challenge. Compound 17a showed high DPP-4 inhibitory activity (IC₅₀ = 0.017 μM), moderate selectivity against DPP-4 (selective ratio: DPP-8/DPP-4 = 1324; DPP-9/DPP-4 = 1164), and good efficacy in oral glucose tolerance tests in ICR and KKAy mice. These in vivo anti-diabetic properties and its desirable pharmacokinetic profile in Sprague–Dawley rats demonstrate that compound 17a is a promising candidate for development as an anti-diabetic agent.     

Design,synthesis and biological evaluation of (2S,3R,4R,5S,6R)-5-fluoro-6-(hydroxymethyl)-2-aryltetrahydro-2H-pyran-3,4-diols as potent and orally active SGLT dual inhibitors

A new series of (2S,3R,4R,5S,6R)-5-fluoro-6-(hydroxymethyl)-2-aryltetrahydro-2H-pyran-3,4-diols as dual inhibitors of sodium glucose co-transporter proteins (SGLTs) were disclosed. Two methods were developed to efficiently synthesize C₅-fluoro-lactones 3 and 4, which are key intermediates to the C₅-fluoro-hexose based C-aryl glucosides. Compound 2b demonstrated potent hSGLT1 and hSGLT2 inhibition (IC₅₀?=?43?nM for SGLT1 and IC₅₀?=?9?nM for SGLT2). It showed robust inhibition of blood glucose excursion in oral glucose tolerance test (OGTT) in Sprague Dawley (SD) rats and exerted pronounced antihyperglycemic effects in db/db mice and high-fat diet-fed ZDF rats when dosed orally at 10?mg/kg.     

C-Glucosides with heteroaryl thiophene as novel sodium-dependent glucose cotransporter 2 inhibitors

Canagliflozin (1), a novel inhibitor for sodium-dependent glucose cotransporter 2 (SGLT2), has been developed for the treatment of type 2 diabetes. To investigate the effect of replacement of the phenyl ring in 1 with heteroaromatics, C-glucosides 2 were designed, synthesized, and evaluated for their inhibitory activities against SGLT2. Of these, 3-pyridyl, 2-pyrimidyl or 5-membered heteroaryl substituted derivatives showed highly potent inhibitory activity against SGLT2, while 5-pyrimidyl substitution was associated with slightly reduced activity. In particular, 2g (TA-3404) had remarkable anti-hyperglycemic effects in high-fat diet fed KK (HF-KK) mice.     

Design,synthesis and biological evaluation of novel pyrimidinedione derivatives as DPP-4 inhibitors

A series of novel pyrimidinedione derivatives were designed and evaluated for in vitro dipeptidyl peptidase-4 (DPP-4) inhibitory activity and in vivo anti-hyperglycemic efficacy. Among them, the representative compounds 11, 15 and 16 showed excellent inhibitory activity of DPP-4 with IC₅₀ values of 64.47?nM, 188.7?nM and 65.36?nM, respectively. Further studies revealed that compound 11 was potent in vivo hypoglycemic effect. The structure–activity relationships of these pyrimidinedione derivatives had been discussed, which would be useful for developing novel DPP-4 inhibitors as treating type 2 diabetes.     

Synthesis and biological evaluation of N-glucosyl indole derivatives as sodium-dependent glucose co-transporter 2 inhibitors

Sodium-dependent glucose co-transporter 2 (SGLT2) inhibition has been demonstrated to efficiently control hyperglycemia via an insulin secretion-independent pathway. The unique mode of action eliminates the risk of hypoglycemia and makes SGLT2 inhibitors an attractive option for the treatment of type 2 diabetes. In a continuation of our previous studies on SGLT2 inhibitors bearing different sugar moieties, sixteen new N-glucosyl indole derivatives were designed, synthesized, and evaluated for their inhibitory activity against hSGLT2. Of these sixteen, acethydrazide-containing N-glucosyl indole 9d was found to be the most potent SGLT2 inhibitor, and caused a significant elevation in urine glucose excretion in rats at 50 mg/kg, relative to the vehicle control.     

Synthesis and biological evaluations of new nitric oxide-anti-inflammatory drug hybrids

Three novel series of nitroso derivatives (11–15), isoxazolopyrazoles (17a–c) and isoxazolo[3,4-d]pyridazines (18a–c) were prepared from the hydroxyimoyl chloride 10. In vitro COX1?2 inhibition activities were evaluated, both of 17b and 18a proved a promising inhibitory activity with IC₅₀ = 1.12, 0.78 μM in sequent. Carrageenan induced Paw edema, ulcer liability, nitric oxide (NO) release and histopathological study were determined. Most of the prepared compounds showed excellent activities. Reactions of 2-aminopyridine and enaminone with hydroxyimoyl chloride 10 were investigated and proved by 2D NMR. Molecular docking for most active compounds was operated giving a hint for compound–receptor interactions.     

Discovery of novel selective Janus kinase 2 (JAK2) inhibitors bearing a 1H-pyrazolo[3,4-d]pyrimidin-4-amino scaffold

Janus kinases (JAKs) regulate various cancers and immune responses and are targets for the treatment of cancers and immune diseases. A new series of 1H-pyrazolo[3,4-d]pyrimidin-4-amino derivatives were synthesized and optimized by introducing a functional 3,5-disubstituted-1H-pyrazole moiety into the C-3 moiety of pyrazole template, and then were biologically evaluated as potent Janus kinase 2 (JAK2) inhibitors. Among these molecules, inhibitors 11f, 11g, 11h and 11k displayed strong activity and selectivity against the JAK2 kinase, with IC₅₀ values of 7.2?nM, 6.5?nM, 8.0?nM and 9.7?nM, respectively. In particular, the cellular inhibitory assay and western blot analysis further support the JAK2 selectivity of compound 11g also in cells. Furthermore, compound 11g also exhibited potent inhibitory activity in lymphocytes proliferation assay and delayed hypersensitivity assay. Taken together, the novel JAK2 selective inhibitors discovered in this study may be potential lead compounds for new drug discovery via further development of more potent and selective JAK2 inhibitors.     

Synthesis,biological evaluation and molecular modeling of novel selective COX-2 inhibitors: sulfide,sulfoxide, and sulfone derivatives of 1,5-diarylpyrrol-3-substituted scaffold

A novel series of 1,5-diarylpyrrol-3-sulfur derivatives (10–12) was synthesized and characterized by NMR and mass spectroscopy and x-ray diffraction. The biological activity of these compounds was evaluated in in vitro and in vivo tests to assess their COX-2 inhibitory activity along with anti-inflammatory and antinociceptive effect.Results showed that the bioisosteric transformation of previously reported alkoxyethyl ethers (9a-c) into the corresponding alkyl thioethers (10a-c) still leads to selective and active compounds being the COX-2 inhibitory activity for most of them in the low nanomolar range. The oxidation products of 10a,b were also investigated and both couple of sulfoxides (11a,b) and sulfones (12a,b) showed an appreciable COX-2 inhibitory activity. Molecular modeling studies were performed to investigate the binding mode of the representative compounds 10b, 11b, and 12b into COX-2 enzyme and to explore the potential site of metabolism of 10a and 10b due to the different in vivo efficacy. Among the developed compounds, compound 10b showed a significant in vivo anti-inflammatory and antinociceptive activity paving the way to develop novel anti-inflammatory drugs.     

Surrogating and redirection of pyrazolo[1,5-a]pyrimidin-7(4H)-one core,a novel class of potent and selective DPP-4 inhibitors

The initial focus on characterizing novel pyrazolo[1,5-a]pyrimidin-7(4H)-one derivatives as DPP-4 inhibitors, led to a potent and selective inhibitor compound b2. This ligand exhibits potent in vitro DPP-4 inhibitory activity (IC₅₀: 80?nM), while maintaining other key cellular parameters such as high selectivity, low cytotoxicity and good cell viability. Subsequent optimization of b2 based on docking analysis and structure-based drug design knowledge resulted in d1. Compound d1 has nearly 2-fold increase of inhibitory activity (IC₅₀: 49?nM) and over 1000-fold selectivity against DPP-8 and DPP-9. Further in vivo IPGTT assays showed that compound b2 effectively reduce glucose excursion by 34% at the dose of 10?mg/kg in diabetic mice. Herein we report the optimization and design of a potent and highly selective series of pyrazolo[1,5-a]pyrimidin-7(4H)-one DPP-4 inhibitors.     

Alstiphyllanines E–H,picraline and ajmaline-type alkaloids from Alstonia macrophylla inhibiting sodium glucose cotransporter

Three new picraline-type alkaloids, alstiphyllanines E–G (1–3) and a new ajmaline-type alkaloid, alstiphyllanine H (4) were isolated from the leaves of Alstonia macrophylla together with 16 related alkaloids (5–20). Structures and stereochemistry of 1–4 were fully elucidated and characterized by 2D NMR analysis. Alstiphyllanines E and F (1 and 2) showed moderate Na⁺-glucose cotransporter (SGLT1 and SGLT2) inhibitory activity. A series of a hydroxy substituted derivatives 21–28 at C-17 of the picraline-type alkaloids have been derived as having potent SGLT inhibitory activity. 10-Methoxy-N(1)-methylburnamine-17-O-veratrate (6) exhibited potent inhibitory activity, suggesting that the presence of an ester side chain at C-17 may be important to show SGLT inhibitory activity. Structure activity relationship of alstiphyllanines on inhibitory activity of SGLT was discussed.     

Role of the side chain stereochemistry in the α-glucosidase inhibitory activity of kotalanol,a potent natural α-glucosidase inhibitor. Part 2

To examine the role of the side chain of kotalanol (2), a potent natural α-glucosidase inhibitor isolated from Salacia reticulata, on inhibitory activity, four diastereomers (11a–11d) with reversed configuration (S) at the C-4′ position in the side chain were synthesized and evaluated. Two of the four (11b and 11d) significantly lost their inhibitory activity against both maltase and sucrase, while the other two (11a and 11c) sustained the inhibitory activity to a considerable extent, showing distinct activity in response to the change of stereochemistry of the hydroxyls at the 5′and 6′ positions. Different activities were rationalized with reference to in silico docking studies on these inhibitors with hNtMGAM. Against isomaltase, all four analogs showed potent inhibitory activity as well as 2, and 11b and 11d exhibited enzyme selectivity.     

Synthesis and biological evaluation of novel tryptoline derivatives as indoleamine 2,3-dioxygenase (IDO) inhibitors

Indoleamine 2,3-dioxygenase (IDO) plays a significant role in several disorders such as Alzheimer’s disease, age-related cataracts and tumors. A series of novel tryptoline derivatives were synthesized and evaluated for their inhibitory activity against IDO. Substituted tryptoline derivatives (11a, 11c, 11e, 12b and 12c) were demonstrated to be more potent than known inhibitor MTH-Trp. Suzuki–Miyaura cross-coupling reaction of 11a–d with phenylboronic acid proceeded in high yields. In most cases, C5 and C6 substitutions on the corresponding indole ring were well tolerated. The tryptoline derivative 11c is a promising chemical lead for the discovery of novel IDO inhibitors.     

Multifunctional 5,6-dimethoxybenzo[d]isothiazol-3(2H)-one-N-alkylbenzylamine derivatives with acetylcholinesterase,monoamine oxidases and β-amyloid aggregation inhibitory activities as potential agents against Alzheimer’s disease

A series of 5,6-dimethoxybenzo[d]isothiazol-3(2H)-one-N-alkylbenzylamine derivatives were designed, synthesized and evaluated as potential multifunctional agents for the treatment of Alzheimer’s disease (AD). The in vitro assays indicated that most of these derivatives were selective AChE inhibitors with good multifunctional properties. Among them, compounds 11b and 11d displayed comprehensive advantages, with good AChE (IC₅₀?=?0.29?±?0.01?μM and 0.46?±?0.02?μM, respectively), MAO-A (IC₅₀?=?8.2?±?0.08?μM and 7.9?±?0.07?μM, respectively) and MAO-B (IC₅₀?=?20.1?±?0.16?μM and 43.8?±?2.0% at 10?μM, respectively) inhibitory activities, moderate self-induced Aβ_1–42 aggregation inhibitory potency (35.4?±?0.42% and 48.0?±?1.53% at 25?μM, respectively) and potential antioxidant activity. In addition, the two representative compounds displayed high BBB permeability in vitro. Taken together, these multifunctional properties make 11b and 11d as a promising candidate for the development of efficient drugs against AD.     

Discovery of novel selective GPR120 agonists with potent anti-diabetic activity by hybrid design

GPR120 is an attractive target for the treatment of type 2 diabetes. In this study, a series of biphenyl derivatives were designed, synthesized by hybrid design. The selected compound 6a exhibited potent GPR120 agonist activity (EC₅₀?=?93?nM) and high selectivity over GPR40. The results of oral glucose tolerance test (OGTT) demonstrated that 6a exhibited significant glucose-lowering effect in glucose-loaded ICR male mice. Analysis of the structure–activity relationship is also presented. Compound 6a deserves further biological evaluation and structural modifications.