The basal SAR of a novel insulin receptor activator

One-Pot Mechanochemical Synthesis of Mono- and Bis-Indolylquinones via Solvent-Free Multiple Bond-Forming Processes

Bis-indolylquinones are fungal natural products endowed with interesting pharmacological properties. Most of the previously described methodologies in solution for the construction of the bis-indolylquinone framework show disadvantages associated with long reaction times and difficult, waste-generating purifications. A one-pot mechanochemical methodology for the synthesis of indolylquinones was developed, starting from indoles and dihaloquinones in the presence of FeCl₃ or p-TsOH as catalysts and Fetizon's reagent as an oxidant. In contrast to solution chemistry, mechanochemical activation allowed the double addition of indole to a quinone substrate in one pot, leading to symmetrical or non-symmetrical bis-indolylquinones via a domino processes comprising up to six steps. In terms of sustainability, the method has several advantages over the solution protocol, including much shorter reaction times, no external heating, one-pot operation, and the absence of chromatography, leading to a drastically better performance in green metrics and demonstrating the application of several principles of green chemistry, in particular principles 2, 3, and 5.

Developing Insulin and BDNF Mimetics for Diabetes Therapy

Diabetes is a global public health concern nowadays. The majority of diabetes mellitus (DM) patients belong to type 2 diabetes mellitus (T2DM), which is highly associated with obesity. The general principle of current therapeutic strategies for patients with T2DM mainly focuses on restoring cellular insulin response by potentiating the insulin-induced signaling pathway. In late-stage T2DM, impaired insulin production requires the patients to receive insulin replacement therapy for maintaining their glucose homeostasis. T2DM patients also demonstrate a drop of brain-derived neurotrophic factor (BDNF) in their circulation, which suggests that replenishing BDNF or enhancing its downstream signaling pathway may be beneficial. Because of their protein nature, recombinant insulin or BDNF possess several limitations that hinder their clinical application in T2DM treatment. Thus, developing orally active "insulin pill" or "BDNF pill" is essential to provide a more convenient and effective therapy. This article reviews the current development of non-peptidyl chemicals that mimic insulin or BDNF and their potential as anti-diabetic agents.

[Low molecular weight regulators of the intracellular insulin signal transduction as a correction method of the insulin resistance in the treatment of type 2 diabetes]

Insulin resistance is the characteristic feature of type 2 diabetes. This condition is manifested in the reduction of peripheral tissues sensitivity to the biological action of insulin and is expressed in the inhibition of cellular glucose absorption and metabolism in response to hormonal stimulation. At the cellular level, disorders which are realized both at the receptor and the postreceptor levels can serve a prerequisite to the formation of insulin resistance and are associated with a change in the amount or dysfunction of major molecular signaling cascade. Thus, the insulin receptor, as well as the other related signaling molecules can be considered as ideal therapeutic targets for the correction of insulin resistance and thus low molecular weight effectors which act on the individual links of insulin signaling cascade may be positioned as a new generation of anti-diabetic agents. This report provides information on the regulators of insulin receptor cascade, main advantages and disadvantages of their impact on biological targets and prospects for their therapeutic use as anti-diabetic drugs.

Identification of a small molecular insulin receptor agonist with potent antidiabetes activity

Insulin replacement therapy is a widely adopted treatment for all patients with type 1 diabetes and some with type 2 diabetes. However, injection of insulin has suffered from problems such as tissue irritation, abscesses, discomfort, and inconvenience. The use of orally bioactive insulin mimetics thus represents an ideal treatment alternative. Here we show that a chaetochromin derivative (4548-G05) acts as a new nonpeptidyl insulin mimetic. 4548-G05 selectively activates an insulin receptor (IR) but not insulin-like growth factor receptor-I or other receptor tyrosine kinases. Through binding to the extracellular domain of the IR, 4548-G05 induces activation of the receptor and initiates the downstream Akt and extracellular signal-related kinase pathways to trigger glucose uptake in C2C12 myotubes. Moreover, it displays a potent blood glucose-lowering effect when administrated orally in normal, type 1 diabetic, and type 2 diabetic mice models. Therefore, 4548-G05 may represent a novel pharmacological agent for antidiabetes drug development.

A novel hydroxyfuroic acid compound as an insulin receptor activator. Structure and activity relationship of a prenylindole moiety to insulin receptor activation

Background

Diabetes Mellitus is a chronic disease and many patients of which require frequent subcutaneous insulin injection to maintain proper blood glucose levels. Due to the inconvenience of insulin administration, an orally active insulin replacement has long been a prime target for many pharmaceutical companies. Demethylasterriquinone (DMAQ) B1, extracted from tropical fungus, Pseudomassaria sp., has been reported to be an orally effective agent at lowering circulating glucose levels in diabetic (db/db) mice; however, the cytotoxicity associated with the quinone moiety has not been addressed thus far.

Methods

A series of hydroxyfuroic acid compounds were synthesized and tested for their efficacies at activating human insulin receptor. Cytotoxicity to Chinese hamster ovary cells, selectivities over insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF), and fibroblast growth factor (FGF) receptors were examined in this study.

Result and Conclusion

This study reports a new non-quinone DMAQ B1 derivative, a hydroxyfuroic acid compound (D-410639), which is 128 fold less cytotoxic as DMAQ B1 and as potent as compound 2, a DMAQ B1 synthetic derivative from Merck, at activating human insulin receptor. D-410639 has little activation potential on IGF-1 receptor but is a moderate inhibitor to EGF receptor. Structure and activity relationship of the prenylindole moiety to insulin receptor activation is discussed.

Design, synthesis, and structure-activity relationships of novel insulin receptor tyrosine kinase activators

A novel series of symmetrical ureas of [(7-amino(2-naphthyl))sulfonyl]phenylamines were designed, synthesized, and tested for their ability to increase glucose transport in mouse 3T3-L1 adipocytes, a surrogate readout for activation of the insulin receptor (IR) tyrosine kinase (IRTK). A structure-activity relationship was established that indicated glucose transport activity was dependent on the presence of two acidic functionalities, two sulfonamide linkages, and a central urea or 2-imidazolidinone core. Compound 30 was identified as a potent and selective IRTK activator. At low concentrations, 30 was able to increase the tyrosine phosphorylation of the IR stimulated by submaximal insulin. At higher concentrations, 30 was able to increase tyrosine the phosphorylation levels of the IR in the absence of insulin. When administered intraperitoneally (ip) and orally (po), 30 improved glucose tolerance in hypoinsulinemic, streptozotocin-treated rats. These data provide pharmacological validation that small molecule IRTK activators represent a potential new class of antidiabetic agents.

Identification of novel orally available small molecule insulin mimetics

Oral hypoglycemic agents have great potential for the treatment of both type 1 and type 2 diabetes. Here we report the identification of novel, small-molecule, insulin mimetics that activate the insulin receptor (IR) in vivo and in vitro, stimulate the Akt and extracellular signal-regulated kinase pathways downstream of the IR, and mimic the ability of insulin to stimulate glucose uptake, glycogen synthesis, and lipid synthesis in 3T3-L1 adipocytes. However, the compounds do not mimic the mitogenic effect of insulin. In animals, these compounds have oral hypoglycemic effects in both normal C57BL6 mice and diabetic db/db mice. Quantitative structure activity relationship modeling on data from a library of 60 compounds has highlighted structural features that are important for IR agonist activity that can be used to guide design of second and third generation compounds with greater potency and specificity.

Fluorescent indicators for imaging protein phosphorylation in single living cells

To visualize signal transduction based on protein phosphorylation in living cells, we have developed genetically encoded fluorescent indicators, named phocuses. Two different color mutants of green fluorescent protein (GFP) were joined by a tandem fusion domain composed of a substrate domain for the protein kinase of interest, a flexible linker sequence, and a phosphorylation recognition domain that binds with the phosphorylated substrate domain. Intramolecular interaction of the substrate domain and the adjacent phosphorylation recognition domain within a phocus was dependent upon phosphorylation of the substrate domain by protein kinase, which influenced the efficiency of fluorescence resonance energy transfer (FRET) between the GFPs within a phocus. In the present study, we employed phocuses composed of insulin signaling proteins to visualize protein phosphorylation by the insulin receptor. This method may provide a general approach for studying the dynamics of protein phosphorylation-based signal transduction in living cells.