Development of Novel Alkene Oxindole Derivatives As Orally Efficacious AMP-Activated Protein Kinase Activators

A General and Highly Versatile Heterogeneous Pd-Catalyzed Oxidative Aminocarbonylation of Alkynes with Aromatic and Aliphatic Amines

An efficient heterogeneous catalytic system for the oxidative aminocarbonylation of alkynes and amines in the presence of CO/O2 to afford substituted propiolamides has been developed. The active nanocatalyst, [Pd/Mg3Al-LDH]-300(D), is composed by Pd nanoaggregates (2-3 nm average particle size) stabilized over a partially dehydrated [Mg3Al-LDH] matrix. The methodology has resulted widely applicable, being the first catalytic system, either homogeneous or heterogeneous, able to activate not only aliphatic amines but also poorly-nucleophilic aromatic amines. In fact, >60 substituted propiolamides have been synthesized in good to excellent isolated yields through this methodology, being 27 novel compounds. An important characterization effort (XRD, 27Al MAS NMR, TGA, TPD-CO2, BET area, XPS, HAADF-HRSTEM and HRTEM) and optimization of the synthesis conditions of the optimal catalyst has been performed. This study, together with a series of kinetic and mechanistic essays, indicates that the optimal catalyst is composed by Pd(0) species stabilized in a partially dehydrated/dehydroxylated LDH material with a Mg/Al molar ratio of 3 and a small crystallite size. All the experimental data indicates that the in situ formation of [PdI2] active species in the material surface together with the presence of a matrix with the optimal acid/base properties are key aspects of this process.

Blue LED-Mediated Synthesis of 3-Arylidene Oxindoles

Blue LED-promoted cross-coupling olefination of symmetrical and unsymmetrical 3-arylidene oxindoles has been described from diazoindolones and diphenylmethanethiones. Thermal olefin isomerization and stereoselective synthesis of 3-arylidene oxindoles were also demonstrated in good yield.

Steric-Hindrance-Induced Diastereoselective Radical Nitration of 3-Alkylidene-2-oxindoles Followed by Tosylhydrazine-Mediated Sulfonation

Metal-free radical nitration of the β C-H bond of 3-alkylidene-2-oxindoles with tert-butyl nitrite (TBN) has been explored. Interestingly, (E)-3-(2-(aryl)-2-oxoethylidene)oxindole and (E)-3-ylidene oxindole give different diastereomers on nitration. The mechanistic investigation revealed that the diastereoselectivity was controlled by the size of the functional group. Another transformation of 3-(nitroalkylidene) oxindole into 3-(tosylalkylidene) oxindole was performed through metal and oxidant-free tosylhydrazine-mediated sulfonation. Both methods have the advantages of readily available starting materials and operational simplicity.

Physicochemical Properties, Drug Likeness, ADMET, DFT Studies and in vitro antioxidant activity of Oxindole Derivatives

Poor pharmacokinetic and safety profiles create significant hurdles in the drug development process. This work focuses on a detailed understanding of drug discovery interplay among physicochemical, pharmacokinetic, toxicity endpoints, and antioxidant properties of oxindole derivatives. DFT compıutations were also performed at B3LYP/6-311G** level to evaluate the physicochemical properties, global reactivity features, and intramolecular interactions. The BOILED-Egg pharmacokinetic model envisaged gastrointestinal absorption, blood-brain barrier penetration, and no interaction with p-glycoprotein for compounds C1 and C2. The physicochemical evaluation revealed that C1 possesses superior drug-like properties fit for oral absorption. Both derivatives were predicted to have high plasma protein binding, efficient distribution, and inhibiting CYP 450 major isoforms but serve as substrates only for a few of them. Both molecules have mild to moderate clearance rates. Out of ten toxicity parameters, only hepatotoxicity was predicted. DFT results implied that the meta position of the -OH group made the possibility of charge transfer greater than -para positioned -OH, due to the ΔN_max (eV) values of molecules C1 and C2 being calculated at 2.596 and 2.477, respectively. Both C1 and C2 exhibited a concentration dependant DPPH and ABTS radical scavenging activity. The chemical structure-physicochemical-pharmacokinetic relationship identified the meta position as the favorite for the electron-withdrawing hydroxyl group. This provides useful insight to medicinal chemists to design 6-chlorooxindole derivatives with an acceptable drug-like and pharmacokinetic property.

Cryptotanshinone attenuates LPS-induced acute lung injury by regulating metabolic reprogramming of macrophage

Background

Acute lung injury (ALI) is a life-threatening inflammatory disease without effective therapeutic regimen. Macrophage polarization plays a key role in the initiation and resolution of pulmonary inflammation. Therefore, modulating macrophage phenotype is a potentially effective way for acute lung injury. Cryptotanshinone (CTS) is a lipophilic bioactive compound extracted from the root of Salvia miltiorrhiza with a variety of pharmacological effects, especially the anti-inflammatory role. In this study, we investigated the therapeutic and immunomodulatory effects of CTS on ALI.

Materials and methods

The rat model of ALI was established by intratracheal instillation of LPS (5 mg/kg) to evaluate the lung protective effect of CTS in vivo and to explore the regulation of CTS on the phenotype of lung macrophage polarization. LPS (1 μg/mL) was used to stimulate RAW264.7 macrophages in vitro to further explore the effect of CTS on the polarization and metabolic reprogramming of RAW264.7 macrophages and to clarify the potential mechanism of CTS anti-ALI.

Results

CTS significantly improved lung function, reduced pulmonary edema, effectively inhibited pulmonary inflammatory infiltration, and alleviated ALI. Both in vivo and in vitro results revealed that CTS inhibited the differentiation of macrophage into the M1 phenotype and promoted polarization into M2 phenotype during ALI. Further in vitro studies indicated that CTS significantly suppressed LPS-induced metabolic transition from aerobic oxidation to glycolysis in macrophages. Mechanistically, CTS blocked LPS-induced metabolic transformation of macrophages by activating AMPK.

Conclusion

These findings demonstrated that CTS regulates macrophage metabolism by activating AMPK, and then induced M1-type macrophages to transform into M2-type macrophages, thereby alleviating the inflammatory response of ALI, suggesting that CTS might be a potential anti-ALI agent.

Non-Palladium-Catalyzed Approach to the Synthesis of (E)-3-(1,3-Diarylallylidene)Oxindoles

Two novel synthetic approaches for synthesizing (E)-3-(1,3-diarylallylidene)oxindoles from oxindole were developed. All previously reported methods for synthesizing 3-(1,3-diarylallylidene)oxindoles utilized palladium-catalyzed reactions as a key step to form this unique skeleton. Despite high efficiency, palladium-catalyzed reactions have limitations in terms of substrate scope. Especially, an iodoaryl moiety cannot be introduced by the previous methods due to its high reactivity toward the palladium catalyst. Our Knoevenagel/allylic oxidation/Wittig and Knoevenagel/aldol/dehydration strategies complement each other and show broad substrate scope, including substrates with iodoaryl groups. The current methods utilized acetophenones, benzylidene phosphonium ylides, and benzaldehydes that are commercially available or easily accessible. Thus, the current synthetic approaches to (E)-3-(1,3-diarylallyldiene)oxindoles are readily amendable for variety of oxindole derivatives.

Synthesis of alkynamides through reaction of alkyl- or aryl-substituted alkynylaluminums with isocyanates

An efficient and facile method for the preparation of alkynamides through Et₃N-catalyzed alumination of alkyl- or aryl-substituted terminal alkynes with AlMe₃ and sequential nucleophilic addition of in situ generated alkynylaluminums to isocyanates is described. This method has the merits of using readily available isocyanates and monosubstituted alkynes, easy access to organoaluminums, short reaction times, and high efficiency. A gram-scale synthesis of the desired alkynamide and its application to the formation of α-methylene-β-lactams demonstrates the synthetic utility of this method.

Towards multi-target antidiabetic agents: In vitro and in vivo evaluation of 3,5-disubstituted indolin-2-one derivatives as novel α-glucosidase inhibitors

Type 2 diabetes mellitus is a chronic progressive disease that usually requires polypharmacological treatment approaches. Previously we have described a series of 2-oxindole derivatives as GSK3β inhibitors with in vivo antihyperglycemic activity. α-Glucosidase is another antidiabetic target that prevents postprandial hyperglycemia and corresponding hyperinsulinemic response. Herein we report a study of 3,5-disubstituted indolin-2-one derivatives as potent α-glucosidase inhibitors. These inhibitors were identified via efficient synthesis, in vitro screening, and biological evaluation. The most active compound 5f inhibits yeast α-glucosidase with IC₅₀ of 6.78 µM and prevents postprandial hyperglycemia in rats after maltose and sucrose challenge at 5.0 mg/kg dose. Two lead glucosidase inhibitors, 5f and 5m, are also GSK3β inhibitors with submicromolar potency. Hence, structure-activity studies elucidate foundation for development of dual GSK3β/α-glucosidase inhibitors for treatment of type 2 diabetes.

High serum high-density lipoprotein and low serum triglycerides in Kratom users: A study of Kratom users in Thailand

Objective

The present study aims to examine the association between Kratom use and serum lipid level.

Method

This study compared the serum lipid profile of Kratom users and non-users living in Nam Phu Subdistrict, a special area that allows the traditional use of Kratom. The study subjects consisted of 581 individuals aged 18 and above. Binary logistic regression was used to determine an association between Kratom use and serum lipid level.

Results

The findings revealed an association between Kratom use and an elevated HDL level (≥60 mg/dL) with an adjusted OR of 1.82 (95% CI, 1.17-2.8), and an association between Kratom use and a triglyceride level <90 mg/dL with an adjusted OR of 1.75 (95% CI; 1.17-2.63). There were no associations between Kratom use and LDL as well as total cholesterol level.

Discussion and conclusions

This study provided additional evidence of Kratom use and a favorable lipid profile. Prevention of coronary heart disease or cerebrovascular disease via an improvement in the lipid profile may be a future pharmaceutical application of Kratom.

AMPK activator C24 inhibits hepatic lipogenesis and ameliorates dyslipidemia in HFHC diet-induced animal models

Dyslipidemia is a chronic metabolic disease characterized by elevated levels of lipids in plasma. Recently, various studies demonstrate that the increased activity of adenosine 5'-monophosphate-activated protein kinase (AMPK) causes health benefits in energy regulation. Thus, great efforts have been made to develop AMPK activators as a metabolic syndrome treatment. In the present study, we investigated the effects of the AMPK activator C24 on dyslipidemia and the potential mechanisms. We showed that C24 (5-40 μM) dose-dependently increased the phosphorylation of AMPKα and acetyl-CoA carboxylase (ACC), and inhibited lipogenesis in HepG2 cells. Using compound C, an AMPK inhibitor, or hepatocytes isolated from liver tissue-specific AMPK knockout AMPKα1α2fl/fl;Alb-cre mice (AMPK LKO), we demonstrated that the lipogenesis inhibition of C24 was dependent on hepatic AMPK activation. In rabbits with high-fat and high-cholesterol diet-induced dyslipidemia, administration of C24 (20, 40, and 60 mg · kg-1· d-1, ig, for 4 weeks) dose-dependently decreased the content of TG, total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) in plasma and played a role in protecting against hepatic dysfunction by decreasing lipid accumulation. A lipid-lowering effect was also observed in high-fat and high-cholesterol diet-fed hamsters. In conclusion, our results demonstrate that the small molecular AMPK activator C24 alleviates hyperlipidemia and represents a promising compound for the development of a lipid-lowering drug.

AMP-independent activator of AMPK for treatment of mitochondrial disorders

Mitochondrial diseases are a clinically heterogenous group of disorders caused by respiratory chain dysfunction and associated with progressive, multi-systemic phenotype. There is no effective treatment or cure, and no FDA-approved drug for treating mitochondrial disease. To identify and characterize potential therapeutic compounds, we developed an in vitro screening assay and identified a group of direct AMP-activated protein kinase (AMPK) activators originally developed for the treatment of diabetes and metabolic syndrome. Unlike previously investigated AMPK agonists such as AICAR, these compounds allosterically activate AMPK in an AMP-independent manner, thereby increasing specificity and decreasing pleiotropic effects. The direct AMPK activator PT1 significantly improved mitochondrial function in assays of cellular respiration, energy status, and cellular redox. PT1 also protected against retinal degeneration in a mouse model of photoreceptor degeneration associated with mitochondrial dysfunction and oxidative stress, further supporting the therapeutic potential of AMP-independent AMPK agonists in the treatment of mitochondrial disease.

Palladium Nanoparticle-Catalyzed Stereoselective Domino Synthesis of 3-Allylidene-2(3H)-oxindoles and 3-Allylidene-2(3H)-benzofuranones

A single-step, stereoselective protocol for the synthesis of unsymmetrically substituted (E)-3-allylideneoxindole and (E)-3-allylidenebenzofuran from readily accessible starting materials using palladium binaphthyl nanoparticles (Pd-BNPs) has been developed. Pd-BNP showing a wide range of functional group tolerance and an immense array of substrate scope have been explored with the successful synthesis of the drug molecule "tubulin polymerization inhibitor" free from trace metal impurities. The model reaction is extended to a gram-scale synthesis, and one of the products is utilized for derivatization. The Pd-BNP has been recycled up to 5 catalytic cycles without any loss in reaction yields and particle size of nanoparticles.

Synthesis and structure-activity relationships of pyrazolo-[3,4-b]pyridine derivatives as adenosine 5'-monophosphate-activated protein kinase activators

A series of pyrazolo[3,4-b]pyridine derivatives were designed, synthesized, and evaluated for their activation activity toward adenosine 5'-monophosphate-activated protein kinase (AMPK). According to the enzyme activity, the pyrazole N-H exposure and para substitution on the diphenyl group were proved to be essential for the activation potency. Compound 17f showed equal activation compared with A-769662. In the molecular modeling study, compound 17f exhibited important hydrogen bond interaction with Lys29, Asp88, and Arg83. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays on the NRK-49F cell line showed that potent enzyme activators could effectively inhibit cell proliferation, especially for 17f (EC₅₀ [AMPKα1γ1β1] = 0.42 μM, efficacy = 79%; IC₅₀ [NRK-49F cell line] = 0.78 μM). These results might provide new insights to explore novel AMPK activators.

Identification and structural insight of an effective PPARγ modulator with improved therapeutic index for anti-diabetic drug discovery

Peroxisome proliferator-activated receptor γ (PPARγ) is a key regulator of glucose homeostasis and lipid metabolism, and an important target for the development of modern anti-diabetic drugs. However, current PPARγ-targeting anti-diabetic drugs such as classical thiazolidinediones (TZDs) are associated with undesirable side effects. To address this concern, we here describe the structure-based design, synthesis, identification and detailed in vitro and in vivo characterization of a novel, decanoic acid (DA)-based and selective PPARγ modulator (SPPARγM), VSP-77, especially (S)-VSP-77, as the potential "hit" for the development of improved and safer anti-diabetic therapeutics. We have also determined the co-crystal structure of the PPARγ ligand-binding domain (LBD) in complex with two molecules of (S)-VSP-77, which reveal a previously undisclosed allosteric binding mode. Overall, these findings not only demonstrate the therapeutic advantage of (S)-VSP-77 over current TZD drugs and representative partial agonist INT131, but also provide a rational basis for the development of future SPPARγMs as safe and highly efficacious anti-diabetic drugs.

Divergent synthesis of oxindole derivatives via controllable reactions of isatin-derived para-quinone methides with sulfur ylides

A catalyst-free and controllable reaction of isatin-derived para-quinone methides with sulfur ylides was developed, and it enables the divergent synthesis of two valuable oxindoles.

Triazolopyrimidine and triazolopyridine scaffolds as TDP2 inhibitors

Tyrosyl-DNA phosphodiesterase 2 (TDP2) repairs topoisomerase II (TOP2) mediated DNA damages and causes cellular resistance to clinically used TOP2 poisons. Inhibiting TDP2 can potentially sensitize cancer cells toward TOP2 poisons. Commercial compound P10A10, to which the structure was assigned as 7-phenyl triazolopyrimidine analogue 6a, was previously identified as a TDP2 inhibitor hit in our virtual and fluorescence-based biochemical screening campaign. We report herein that the hit validation through resynthesis and structure elucidation revealed the correct structure of P10A10 (Chembridge ID 7236827) to be the 5-phenyl triazolopyrimidine regioisomer 7a. Subsequent structure-activity relationship (SAR) via the synthesis of a total of 47 analogues of both the 5-phenyl triazolopyrimidine scaffold (7) and its bioisosteric triazolopyridine scaffold (17) identified four derivatives (7a, 17a, 17e, and 17z) with significant TDP2 inhibition (IC₅₀ < 50 µM), with 17z showing excellent cell permeability and no cytotoxicity.

Novel substituted pyrazolone derivatives as AMP-activated protein kinase activators to inhibit lipid synthesis and reduce lipid accumulation in ob/ob mice

Non-alcoholic fatty liver disease (NAFLD) is a clinical syndrome characterized by hepatic steatosis. NAFLD is closely linked to obesity, insulin resistance and dyslipidemia. AMP-activated protein kinase (AMPK) functions as an energy sensor and plays a central role in regulating lipid metabolism. In this study, we identified a series of novel pyrazolone AMPK activators using a homogeneous time-resolved fluorescence assay (HTRF) based on the AMPKα2β1γ1 complex. Compound 29 (C29) is a candidate compound that directly activated the kinase domain of AMPK with an EC50 value of 2.1-0.2 μmol/L and acted as a non-selective activator of AMPK complexes. Treatment of HepG2 cells with C29 (20, 40 μmol/L) dose-dependently inhibited triglyceride accumulation. Chronic administration of C29 (10, 30 mg/kg every day, po, for 5 weeks) significantly improved lipid metabolism in both the liver and the plasma of ob/ob mice. These results demonstrate that the AMPK activators could be part of a novel treatment approach for NAFLD and associated metabolic disorders.

Enantioselective Synthesis of All-Carbon Quaternary Centers Structurally Related to Amaryllidaceae Alkaloids

Enantioselective synthesis of all-carbon quaternary centers remains a considerable challenge for synthetic organic chemists. Here, we report a two-step protocol to synthesize such centers including tandem cyclization/Suzuki cross-coupling followed by halocarbocyclization. During this process, two rings, three new C-C bonds and a stereochemically defined all-carbon quaternary center are formed. The absolute configuration of this center is controlled by the stereochemistry of the adjacent stereocenter, which derives from an appropriate enantioenriched starting material. Using this method, we synthesized polycyclic compounds structurally similar to Amaryllidaceae alkaloids in high enantiomeric excesses. Because these products resemble naturally occurring compounds, our protocol can be used to synthesize various potentially bioactive compounds.

Identification of a novel 2-oxindole fluorinated derivative as in vivo antitumor agent for prostate cancer acting via AMPK activation

The key metabolic sensor adenosine monophosphate-dependent kinase (AMPK) has emerged as a promising therapeutic target for cancer prevention and treatment. Besides its role in energy homeostasis, AMPK blocks cell cycle, regulates autophagy and suppresses the anabolic processes required for rapid cell growth. AMPK is especially relevant in prostate cancer in which activation of lipogenic pathways correlate with tumor progression and aggressiveness. This study reports the discovery of a new series of 2-oxindole derivatives whose AMPK modulatory ability, as well as the antitumoral profile in prostate cancer cells, was evaluated. One of the assayed compounds, compound 8c, notably activated AMPK in cultured PC-3, DU145 and LNCaP prostate cancer cells. Likewise, compound 8c caused PC-3, DU145 and LNCaP cells viability inhibition. Selective knocking down of α1 or α2 isoforms as well as in vitro assays using human recombinant α1β1γ1 or α2β1γ1 AMPK isoforms revealed that compound 8c exhibit preference for AMPKα1. Consistent with efficacy at the cellular level, compound 8c was potent in suppressing the growth of PC-3 xenograft tumors. In conclusion, our results show that a new 2-oxindole fluorinated derivative exerts potent in vivo antitumor actions against prostate cancer cells, indicating a promising clinical therapeutic strategy for the treatment of androgen-independent prostate cancer.

Efficient synthesis of N-butadiene substituted oxindole derivatives

A novel rhodium(iii)-catalyzed amide carbonyl group directed alkenylation reaction between oxindoles and alkenes has been reported, which provides an efficient method for the synthesis of valuable and versatile functionalized N-(2E,4Z)-butadiene substituted oxindole derivatives.

Advanced palladium free approach to the synthesis of substituted alkene oxindoles via aluminum-promoted Knoevenagel reaction

A synthetic route for the synthesis of C24, as well as for the design of focused libraries of direct AMPK activators was developed based on a convergent strategy. The proposed scheme corresponds to the current trends in C–H bond functionalization. The use of aluminum isopropoxide for the Knoevenagel condensation of oxindole with benzophenones is a noticeable point of this work.

A synthetic route for the synthesis of C24, as well as for the design of focused libraries of direct AMPK activators was developed based on a convergent strategy.

Synthesis and evaluation of oxindoles as promising inhibitors of the immunosuppressive enzyme indoleamine 2,3-dioxygenase 1

Indoleamine 2,3-dioxygenase 1 (IDO1) is considered as an important therapeutic target for the treatment of cancer, chronic infections and other diseases that are associated with immune suppression. Recent developments in understanding the catalytic mechanism of the IDO1 enzyme revealed that conversion of l-tryptophan (l-Trp) to N-formylkynurenine proceeded through an epoxide intermediate state. Accordingly, we synthesized a series of 3-substituted oxindoles from l-Trp, tryptamine and isatin. Compounds with C3-substituted oxindole moieties showed moderate inhibitory activity against the purified human IDO1 enzyme. Their optimization led to the identification of potent compounds, 6, 22, 23 and 25 (IC₅₀ = 0.19 to 0.62 μM), which are competitive inhibitors of IDO1 with respect to l-Trp. These potent compounds also showed IDO1 inhibition potencies in the low-micromolar range (IC₅₀ = 0.33-0.49 μM) in MDA-MB-231 cells. The cytotoxicity of these potent compounds was trivial in different model cancer (MDA-MB-231, A549 and HeLa) cells and macrophage (J774A.1) cells. Stronger selectivity for the IDO1 enzyme (124 to 210-fold) over the tryptophan 2,3-dioxygenase (TDO) enzyme was also observed for these compounds. These results suggest that the oxindole moiety of the compounds could mimic the epoxide intermediate state of l-Trp. Therefore, the structural simplicity and low-micromolar inhibition potencies of these 3-substituted oxindoles make them quite attractive for further investigation of IDO1 function and immunotherapeutic applications.

Structure and Regulation of AMPK

AMP-activated protein kinase is a family of heterotrimeric serine/threonine protein kinases that come in twelve different flavors. They serve an essential function in all eukaryotes of conserving cellular energy levels. AMPK complexes are regulated by changes in cellular AMP:ATP or ADP:ATP ratios and by a number of neutraceuticals and some of the widely-used diabetes medications such as metformin and thiazolinonediones. Moreover, biochemical activities of AMPK are tightly regulated by phosphorylation or dephosphorylation by upstream kinases and phosphatases respectively. Efforts are underway in many pharmaceutical companies to discover direct AMPK activators for the treatment of cardiovascular and metabolic diseases such as diabetes, non-alcoholic steatohepatitis (NASH) and diabetic nephropathy. Many advances have been made in the AMPK structural biology arena over the last few years that are beginning to provide detailed molecular insights into the overall topology of these fascinating enzymes and how binding of small molecules elicit subtle conformational changes leading to their activation and protection from dephosphorylation. In the brief review below on AMPK structure and function, we have focused on the recent crystallographic results especially on specific molecular interactions of direct synthetic AMPK activators which lead to biased activation of a sub-family of AMPK isoforms.

Down-regulation of adenosine monophosphate–activated protein kinase activity: A driver of cancer

Adenosine monophosphate–activated protein kinase (AMPK), a serine/threonine protein kinase, is known as “intracellular energy sensor and regulator.” AMPK regulates multiple cellular processes including protein and lipid synthesis, cell proliferation, invasion, migration, and apoptosis. Moreover, AMPK plays a key role in the regulation of “Warburg effect” in cancer cells. AMPK activity is down-regulated in most tumor tissues compared with the corresponding adjacent paracancerous or normal tissues, indicating that the decline in AMPK activity is closely associated with the development and progression of cancer. Therefore, understanding the mechanism of AMPK deactivation during cancer progression is of pivotal importance as it may identify AMPK as a valid therapeutic target for cancer treatment. Here, we review the mechanisms by which AMPK is down-regulated in cancer.

Consecutive One-Pot versus Domino Multicomponent Approaches to 3-(Diarylmethylene)oxindoles

Based on consecutive one-pot conditions combining three palladium-catalyzed reactions (Sonogashira, Heck and Suzuki-Miyaura reactions), a more efficient domino multicomponent method has been successfully developed to access a wide variety of 3-(diarylmethylene)oxindoles. Microwave irradiation and use of a silver salt were the most important factors to achieve high yields and stereoselectivity.

Stereoselective Synthesis of 3-(1,3-Diarylallylidene)oxindoles via a Palladium-Catalyzed Tandem Reaction

We have developed an efficient three-component tandem reaction for the synthesis of 3-(1,3-diarylallylidene)oxindoles combining three palladium-catalyzed reactions: the Sonogashira, Heck, and Suzuki-Miyaura reactions. This method allows a stereoselective approach to each (E)- and (Z)-isomer by ligand change and controlling the reaction temperature.

Fused Heterocyclic Compounds as Potent Indoleamine-2,3-dioxygenase 1 Inhibitors

Uncontrolled metabolism of l-tryptophan (l-Trp) in the immune system has been recognized as a critical cellular process in immune tolerance. Indoleamine 2,3-dioxygenase 1 (IDO1) enzyme plays an important role in the metabolism of a local l-Trp through the kynurenine pathway in the immune systems. In this regard, IDO1 has emerged as a therapeutic target for the treatment of diseases that are associated with immune suppression like chronic infections, cancer, and others. In this study, we synthesized a series of pyridopyrimidine, pyrazolopyranopyrimidine, and dipyrazolopyran derivatives. Further lead optimizations directed to the identification of potent compounds, 4j and 4l (IC₅₀ = 260 and 151 nM, respectively). These compounds also exhibited IDO1 inhibitory activities in the low nanomolar range in MDA-MB-231 cells with very low cytotoxicity. Stronger selectivity for the IDO1 enzyme (>300-fold) over tryptophan 2,3-dioxygenase (TDO) enzyme was also observed for these compounds. Hence, these fused heterocyclic compounds are attractive candidates for the advanced study of IDO1-dependent cellular function and immunotherapeutic applications.

Protein kinases: mechanisms and downstream targets in inflammation-mediated obesity and insulin resistance

Obesity-induced low-grade inflammation (metaflammation) impairs insulin receptor signaling. This has been implicated in the development of insulin resistance. Insulin signaling in the target tissues is mediated by stress kinases such as p38 mitogen-activated protein kinase, c-Jun NH2-terminal kinase, inhibitor of NF-kB kinase complex β (IKKβ), AMP-activated protein kinase, protein kinase C, Rho-associated coiled-coil containing protein kinase, and RNA-activated protein kinase. Most of these kinases phosphorylate several key regulators in glucose homeostasis. The phosphorylation of serine residues in the insulin receptor and IRS-1 molecule results in diminished enzymatic activity in the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. This has been one of the key mechanisms observed in the tissues that are implicated in insulin resistance especially in type 2 diabetes mellitus (T2-DM). Identifying the specific protein kinases involved in obesity-induced chronic inflammation may help in developing the targeted drug therapies to minimize the insulin resistance. This review is focused on the protein kinases involved in the inflammatory cascade and molecular mechanisms and their downstream targets with special reference to obesity-induced T2-DM.

Recent progress in the identification of adenosine monophosphate-activated protein kinase (AMPK) activators

Adenosine monophosphate-activated protein kinase (AMPK), a serine/threonine heterotrimeric protein kinase, is a critical regulator of cellular and whole body energy homeostasis. There are twelve known AMPK isoforms that are differentially expressed in tissues and species. Dysregulation of AMPK signaling is associated with a multitude of human pathologies. Hence isoform-selective activators of AMPK are actively being sought for the treatment of cardiovascular and metabolic diseases. The present review summarizes the status of direct AMPK activators from the patent and published literature.

Oxindole: A chemical prism carrying plethora of therapeutic benefits

Oxindole has emerged as a valuable scaffold in medicinal chemistry possessing diverse range of pharmacological activities. Its value has further been increased by its natural occurrence as alkaloids in variety of plants. It was first extracted from the cat claw's plant Uncaria tomentosa found in the Amazon rainforest and other tropical areas of South and Central America. Traditionally as well as present emerging therapeutic potential of oxindole nucleus has captured the interest of medicinal chemists to synthesize novel oxindole derivatives. In the present review the authors have integrated its chemistry and synthetic strategies developed after 1945. Also the information of naturally occurring oxindole alkaloids has been incorporated. The detailed pharmacological activities including anti-cancer, anti-HIV, antidiabetic, antibacterial, antioxidant, kinase inhibitory, AChE inhibitory, anti-leishmanial, β3 adrenergic receptor agonistic, phosphatase inhibitory, analgesic, spermicidal, vasopressin antagonists, progesterone antagonists, neuroprotection, and NMDA blocker activities of oxindole derivatives alongwith their SAR has also been discussed in detail. Additionally, information regarding the oxindole derivatives in clinical trials has been incorporated. Thus, this review will provide insights for the synthetic as well as medicinal chemist for the designing and synthesis of novel oxindole derivatives with novel improved range of pharmacological implications.

Nitrobenzofurazan derivatives of N'-hydroxyamidines as potent inhibitors of indoleamine-2,3-dioxygenase 1

Tryptophan metabolism through the kynurenine pathway is considered as a crucial mechanism in immune tolerance. Indoleamine 2,3-dioxygenase 1 (IDO1) plays a key role in tryptophan catabolism in the immune system and it is also considered as an important therapeutic target for the treatment of cancer and other diseases that are linked with kynurenine pathway. In this study, a series of nitrobenzofurazan derivatives of N'-hydroxybenzimidamides (1) and N'-hydroxy-2-phenylacetimidamides (2) were synthesized and their inhibitory activities against human IDO1 enzyme were tested using in-vitro and cellular enzyme activity assay. The optimization leads to the identification of potent compounds, 1d, 2i and 2k (IC50 = 39-80 nM), which are either competitive or uncompetitive inhibitors of IDO1 enzyme. These compounds also showed IDO1 inhibition potencies in the nanomolar range (IC50 = 50-71 nM) in MDA-MB-231 cells with no/negligible amount of cytotoxicity. The stronger selectivity of the potent compounds for IDO1 enzyme over tryptophan 2,3-dioxygenase (TDO) enzyme (312-1593-fold) also makes them very attractive for further immunotherapeutic applications.

Identification of novel pyrazole–rhodanine hybrid scaffolds as potent inhibitors of aldose reductase: design, synthesis, biological evaluation and molecular docking analysis

A series of novel pyrazole–rhodanine derivatives was designed, synthesized, and biologically evaluated for their potential inhibitory effect on both aldehyde reductase (ALR1) and aldose reductase (ALR2).

AMP-activated protein kinase: structure, function, and role in pathological processes

Recently, AMP-activated protein kinase (AMPK) has emerged as a key regulator of energy balance at cellular and whole-body levels. Due to the involvement in multiple signaling pathways, AMPK efficiently controls ATP-consuming/ATP-generating processes to maintain energy homeostasis under stress conditions. Loss of the kinase activity or attenuation of its expression leads to a variety of metabolic disorders and increases cancer risk. In this review, we discuss recent findings on the structure of AMPK, its activation mechanisms, as well as the consequences of its targets in regulation of metabolism. Particular attention is given to low-molecular-weight compounds that activate or inhibit AMPK; the perspective of therapeutic use of such modulators in treatment of several common diseases is discussed.

Pharmacological Targeting of AMP-Activated Protein Kinase and Opportunities for Computer-Aided Drug Design

As a central regulator of metabolism, the AMP-activated protein kinase (AMPK) is an established therapeutic target for metabolic diseases. Beyond the metabolic area, the number of medical fields that involve AMPK grows continuously, expanding the potential applications for AMPK modulators. Even though indirect AMPK activators are used in the clinics for their beneficial metabolic outcome, the few described direct agonists all failed to reach the market to date, which leaves options open for novel targeting methods. As AMPK is not actually a single molecule and has different roles depending on its isoform composition, the opportunity for isoform-specific targeting has notably come forward, but the currently available modulators fall short of expectations. In this review, we argue that with the amount of available structural and ligand data, computer-based drug design offers a number of opportunities to undertake novel and isoform-specific targeting of AMPK.

Development of Potent Adenosine Monophosphate Activated Protein Kinase (AMPK) Activators

Previously, we reported the identification of a thiazolidinedione-based adenosine monophosphate activated protein kinase (AMPK) activator, compound 1 (N-[4-({3-[(1-methylcyclohexyl)methyl]-2,4-dioxothiazolidin-5-ylidene}methyl)phenyl]-4-nitro-3-(trifluoromethyl)benzenesulfonamide), which provided a proof of concept to delineate the intricate role of AMPK in regulating oncogenic signaling pathways associated with cell proliferation and epithelial-mesenchymal transition (EMT) in cancer cells. In this study, we used 1 as a scaffold to conduct lead optimization, which generated a series of derivatives. Analysis of the antiproliferative and AMPK-activating activities of individual derivatives revealed a distinct structure-activity relationship and identified 59 (N-(3-nitrophenyl)-N'-{4-[(3-{[3,5-bis(trifluoromethyl)phenyl]methyl}-2,4-dioxothiazolidin-5-ylidene)methyl]phenyl}urea) as the optimal agent. Relative to 1, compound 59 exhibits multifold higher potency in upregulating AMPK phosphorylation in various cell lines irrespective of their liver kinase B1 (LKB1) functional status, accompanied by parallel changes in the phosphorylation/expression levels of p70S6K, Akt, Foxo3a, and EMT-associated markers. Consistent with its predicted activity against tumors with activated Akt status, orally administered 59 was efficacious in suppressing the growth of phosphatase and tensin homologue (PTEN)-null PC-3 xenograft tumors in nude mice. Together, these findings suggest that 59 has clinical value in therapeutic strategies for PTEN-negative cancer and warrants continued investigation in this regard.

Palladium-Catalyzed One-Pot Approach to 3-(Diarylmethylene)oxindoles from Propiolamidoaryl Triflate

3-(Diarylmethylene)oxindoles have been synthesized from propiolamidoaryl triflate utilizing a palladium-catalyzed one-pot reaction consisting of three successive reactions: Sonogashira, Heck, and Suzuki-Miyaura. This method allows for the production of a complex skeleton of 3-(diarylmethylene)oxindole from propiolamidoaryl triflate using a commercially available aryl iodide and arylboronic acid in a simple and efficient way with moderate yield and stereoselectivity.

PT-1 selectively activates AMPK-γ1 complexes in mouse skeletal muscle, but activates all three γ subunit complexes in cultured human cells by inhibiting the respiratory chain

AMP-activated protein kinase (AMPK) occurs as heterotrimeric complexes in which a catalytic subunit (α1/α2) is bound to one of two β subunits (β1/β2) and one of three γ subunits (γ1/γ2/γ3). The ability to selectively activate specific isoforms would be a useful research tool and a promising strategy to combat diseases such as cancer and Type 2 diabetes. We report that the AMPK activator PT-1 selectively increased the activity of γ1- but not γ3-containing complexes in incubated mouse muscle. PT-1 increased the AMPK-dependent phosphorylation of the autophagy-regulating kinase ULK1 (unc-51-like autophagy-activating kinase 1) on Ser555, but not proposed AMPK-γ3 substrates such as Ser231 on TBC1 (tre-2/USP6, BUB2, cdc16) domain family, member 1 (TBC1D1) or Ser212 on acetyl-CoA carboxylase subunit 2 (ACC2), nor did it stimulate glucose transport. Surprisingly, however, in human embryonic kidney (HEK) 293 cells expressing human γ1, γ2 or γ3, PT-1 activated all three complexes equally. We were unable to reproduce previous findings suggesting that PT-1 activates AMPK by direct binding between the kinase and auto-inhibitory domains (AIDs) of the α subunit. We show instead that PT-1 activates AMPK indirectly by inhibiting the respiratory chain and increasing cellular AMP:ATP and/or ADP:ATP ratios. Consistent with this mechanism, PT-1 failed to activate AMPK in HEK293 cells expressing an AMP-insensitive R299G mutant of AMPK-γ1. We propose that the failure of PT-1 to activate γ3-containing complexes in muscle is not an intrinsic feature of such complexes, but is because PT-1 does not increase cellular AMP:ATP ratios in the specific subcellular compartment(s) in which γ3 complexes are located.

Antiplatelet effect of a newly developed AMP-activated protein kinase activator YLF-466D

AMP-activated protein kinase (AMPK) acts as a major regulator of cellular energy homeostasis. In platelets, AMPK activation stimulates endothelial nitric oxide synthase (eNOS) and its downstream signaling, and thereby inhibits platelet aggregation. In this study, a newly developed AMPK activator 3-[[(3E)-3-[(4-chlorophenyl)phenylmethylene]-2,3-dihydro-2-oxo-1H-indol-1-yl]methyl]-benzoic acid (YLF-466D) was tested for its antiplatelet activity. Treatment of isolated platelets with YLF-466D resulted in AMPK activation in a concentration-dependent manner in a range of 50-150 μM. Under the same experimental condition, YLF-466D effectively inhibited aggregation induced by platelet agonists including thrombin, ADP and collagen. Such AMPK activation and aggregation inhibition were abolished by pretreatment with the AMPK inhibitors compound C (CC) and ara-A, indicating that antiaggregatory effect of YLF-466D is mediated by AMPK. YLF-466D induced an activation-dependent eNOS phosphorylation at Ser1177, an elevation of cyclic nucleotides cGMP and cAMP, and subsequent phosphorylation of vasodilator-stimulated phosphoprotein (VASP) at Ser239 and Ser157. All these events were prevented by CC and ara-A. In addition to isolated platelets, YLF-466D attenuated whole blood aggregation induced by collagen. Taken together, YLF-466D is capable of inhibiting platelet aggregation by activating AMPK and its downstream eNOS-cGMP-PKG signaling axis. This study reconfirms the antiplatelet activity of AMPK activators and suggests the potential application of YLF-466D to antiplatelet therapy, although the in vivo and clinical validation remains to be assessed.