Demethylasterriquinone B1 Research Articles

Coupled small molecules target RNA interference and JAK/STAT signaling to reduce Zika virus infection in Aedes aegypti.

The recent global Zika epidemics have revealed the significant threat that mosquito-borne viruses pose. There are currently no effective vaccines or prophylactics to prevent Zika virus (ZIKV) infection. Limiting exposure to infected mosquitoes is the best way to reduce disease incidence. Recent studies have focused on targeting mosquito reproduction and immune responses to reduce transmission. Previous work has evaluated the effect of insulin signaling on antiviral JAK/STAT and RNAi in vector mosquitoes. Specifically, insulin-fed mosquitoes resulted in reduced virus replication in an RNAi-independent, ERK-mediated JAK/STAT-dependent mechanism. In this work, we demonstrate that targeting insulin signaling through the repurposing of small molecule drugs results in the activation of both RNAi and JAK/STAT antiviral pathways. ZIKV-infected Aedes aegypti were fed blood containing demethylasterriquinone B1 (DMAQ-B1), a potent insulin mimetic, in combination with AKT inhibitor VIII. Activation of this coordinated response additively reduced ZIKV levels in Aedes aegypti. This effect included a quantitatively greater reduction in salivary gland ZIKV levels up to 11 d post-bloodmeal ingestion, relative to single pathway activation. Together, our study indicates the potential for field delivery of these small molecules to substantially reduce virus transmission from mosquito to human. As infections like Zika virus are becoming more burdensome and prevalent, understanding how to control this family of viruses in the insect vector is an important issue in public health.

AKT2 maintains brain endothelial claudin-5 expression and selective activation of IR/AKT2/FOXO1-signaling reverses barrier dysfunction

Inflammation-induced blood–brain barrier (BBB) dysfunction and microvascular leakage are associated with a host of neurological disorders. The tight junction protein claudin-5 (CLDN5) is a crucial protein necessary for BBB integrity and maintenance. CLDN5 is negatively regulated by the transcriptional repressor FOXO1, whose activity increases during impaired insulin/AKT signaling. Owing to an incomplete understanding of the mechanisms that regulate CLDN5 expression in BBB maintenance and dysfunction, therapeutic interventions remain underdeveloped. Here, we show a novel isoform-specific function for AKT2 in maintenance of BBB integrity. We identified that AKT2 during homeostasis specifically regulates CLDN5-dependent barrier integrity in brain microvascular endothelial cells (BMVECs) and that intervention with a selective insulin-receptor (IR) agonist, demethylasterriquinone B1 (DMAQ-B1), rescued IL-1β-induced AKT2 inactivation, FOXO1 nuclear accumulation, and loss of CLDN5-dependent barrier integrity. Moreover, DMAQ-B1 attenuated preclinical CLDN5-dependent BBB dysfunction in mice subjected to experimental autoimmune encephalomyelitis. Taken together, the data suggest a regulatory role for IR/AKT2/FOXO1-signaling in CLDN5 expression and BBB integrity during neuroinflammation.

Dibutyl phthalate exposure aggravates type 2 diabetes by disrupting the insulin-mediated PI3K/AKT signaling pathway

Epidemiological studies suggest a positive relationship between phthalate exposure and diabetes. However, little is known about the impact of dibutyl phthalate (DBP) exposure on the development of diabetes. To determine the role of DBP exposure on the development of type 2 diabetes, mice were orally exposed to DBP dosages of 0.5, 5, 50 mg/kg/day for 7 weeks, combined with a high fat diet and injections of a low dose of streptozotocin (STZ). The results showed that exposure to 50 mg/kg/day DBP alone induced a marked decrease in insulin secretion and glucose intolerance, but had no influence on insulin resistance. However, combined with a high fat diet and STZ treatment, DBP exposure markedly aggravated glucose intolerance, insulin tolerance and insulin resistance and induced lesions in the pancreas and kidney. Investigation of the role of DBP on the insulin signaling pathway, we found that DBP exposure could disrupt the PI3K expression and AKT phosphorylation, and decrease the level of GLUT-2 in the pancreas. Administering demethylasterriquinone B1, significantly increased the level of PI3K, AKT phosphorylation and GLUT-2 expression, effectively inhibiting the aggravation of diabetes. Our results suggested that DBP aggravated type 2 diabetes by disrupting the insulin signaling pathway and impairing insulin secretion.

Abstract 20574: Selective Activation of the PI3K/Akt Pathway With the Insulin Mimetic Demethylasterriquinone B1 Reverses Neuroinflammatory-Mediated Blood-Brain Barrier Dysfunction in Mice

Blood-brain barrier (BBB) dysfunction is a hallmark of neuroinflammation brought on by pathologies such as stroke and amyloid angiopathy. Inflammatory cytokines that act directly on cerebral endothelium can impair tight junction (TJ) stability. We previously identified a mechanism for IL-1β-mediated dysfunction involving inactivation of the PI3K/Akt pathway, activation of the transcription factor FoxO1, and FoxO1-dependent transcriptional repression of the TJ gene claudin-5 (Cldn5). Here we used an insulin mimetic, Demethylasterriquinone B1 (DMAQ-B1), to test the hypotheses that targeted activation of the PI3K/Akt pathway: 1) enhances cerebral endothelial barrier function, 2) reverses IL-1β-mediated dysfunction and 3) attenuates neuroinflammation-induced BBB dysfunction. In Vitro: Primary cerebral microvascular endothelial cells (CMVECs) were grown in collagen-coated dishes, transwell inserts (0.4 μm pores), or ECIS Arrays (Applied Biophysics). Culture media was conditioned with vehicle control, IL-1β (100 ng/mL), and/or DMAQ-B1 (2.5-10 μM). DMAQ-B1 dose-dependently activated Akt (increased pT308), inactivated FoxO1 (decreased nuclear localization), increased Cldn5 expression (WB, ICC), increased transendothelial electrical resistance (TER), and decreased CMVEC monolayer permeability (Ps). Akt silencing (siRNA), PI3K inhibition (LY294002), or IL-1β treatment downregulated Cldn5 and induced CMVEC barrier dysfunction. DMAQ-B1 (5 μM) reversed IL-1β-mediated Akt inactivation, FoxO1 activation, Cldn5 downregulation and CMVEC barrier dysfunction. In Vivo: We used a murine model of neuroinflammation, experimental autoimmune encephalomyelitis (EAE). Cerebral microvascular enriched fractions from EAE-induced mice had less pT308 Akt, increased FoxO1 nuclear accumulation, and decreased Cldn5 expression compared to control. Decreased Cldn5 expression and increased BBB hyperpermeability (sodium fluorescein extravasation) observed in EAE-induced mice was attenuated by 24 hour DMAQ-B1 (5 mg/kg; oral gavage) treatment. These results indicate that promoting PI3K/Akt pathway activation with DMAQ-B1 during neuroinflammatory pathologies may provide a novel therapeutic approach to attenuate BBB dysfunction.

The effect of demethylasterriquinone B-1 on insulin secretion in rat pancreas

A small nonpeptidyl compoud extracted from Pseudomassaria sp. was found to induce the activity of human insulin receptor tyrosine kinase in vitro. The compound was identified as demethylasterriquinone B-1 (DMAQ-B1). DMAQ- B1 also induced an increase in [Ca2+]i and insulin secretion in mice pancreatic beta-cells at low glucose (3 mM) concentration via insulin receptor substrate-1/phosphatidylinositol-3-kinase (PI3 kinase) pathway. By using rat pancreatic perfusion technique, we found that 10 μM DMAQ-B1 directly stimulated insulin secretion up to 240% in normal rat pancreas. In the dosage from 1 to 20 μM, DMAQ-B1 stimulated insulin secretion in a dose dependent manner. Furthermore, DMAQ-B1 enhanced glucose-induced insulin secretion by 17.6% (first stage) and 19.0% (second stage), respectively. The PI3 kinase inhibitors, LY 294002 (3.9 μM) or wortmannin (100 nM), inhibited DMAQ-B1-induced insulin secretion by 46.3% and 57.4%, respectively. LY 294002 or wortmannin also inhibited DMAQ-B1 with10 mMglucose-induced insulin secretion by 70.3% and 79.0%, respectively. All the results suggested that DMAQ-B1 directly stimulated insulin secretion and enhanced glucose-induced insulin secretion. The effect of DMAQ-B1 may mediate through the activation of PI3 kinase pathway to stimulate insulin secretion in normal rat pancreas.

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

BackgroundDiabetes 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.MethodsA 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 ConclusionThis 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.

Glyceraldehyde 3-Phosphate Dehydrogenase Is a Cellular Target of the Insulin Mimic Demethylasterriquinone B1

This study was undertaken to identify cellular proteins that bind an orally active natural product insulin mimic. Phage display cloning was used with a biotinylated derivative of this molecule as bait. Among the proteins identified was glyceraldehyde 3-phosphate dehydrogenase (GAPDH), which has recently been shown to affect insulin receptor signaling. Binding data support a role for human GAPDH as another target of the insulin mimic, which could explain its action as a selective insulin receptor modulator.

Effect of demethylasterriquinone b1 in hypertension associated vascular endothelial dysfunction

Background Activation of Akt stimulates phosphorylation of eNOS, production of nitric oxide and reduces oxidative stress. The study has been designed to investigate the effect of DAQ B1, an activator of Akt, in hypertension associated vascular endothelial dysfunction. Methods Rats were uninephroctomized and DOCA (40 mg kg − 1 , s.c.) was administered to rats to produce hypertension (MABP > 140 mm Hg). Vascular endothelial dysfunction was assessed using isolated aortic ring preparation, electron microscopy of thoracic aorta and serum concentration of nitrite/nitrate. The expression of messenger RNA for p22phox and eNOS was assessed by reverse transcription-polymerase chain reaction. Serum TBARS and aortic superoxide anion were estimated to assess oxidative stress. Results DAQ B1 (5 mg kg − 1 , p.o.) or atorvastatin (30 mg kg − 1 , p.o.) markedly improved acetylcholine induced endothelium dependent relaxation, vascular endothelial lining, expression of mRNA for eNOS and p22phox, serum nitrite/nitrate concentration and serum TBARS in hypertensive rats. However, this ameliorative effect of DAQ B1 has been prevented by l-NAME (25 mg kg − 1 , i.p.), an inhibitor of eNOS. Conclusion Therefore, it may be concluded that DAQ B1 induced activation of Akt may activate eNOS and consequently reduce oxidative stress to improve hypertension associated vascular endothelial dysfunction.

Therapeutic Actions of an Insulin Receptor Activator and a Novel Peroxisome Proliferator-Activated Receptor γ Agonist in the Spontaneously Hypertensive Obese Rat Model of Metabolic Syndrome X

Insulin resistance clusters with hyperlipidemia, impaired glucose tolerance, and hypertension as metabolic syndrome X. We tested a low molecular weight insulin receptor activator, demethylasterriquinone B-1 (DMAQ-B1), and a novel indole peroxisome proliferator-activated receptor gamma agonist, 2-(2-(4-phenoxy-2-propylphenoxy)ethyl)indole-5-acetic acid (PPEIA), in spontaneously hypertensive obese rats (SHROB), a genetic model of syndrome X. Agents were given orally for 19 days. SHROB showed fasting normoglycemia but impaired glucose tolerance after an oral load, as shown by increased glucose area under the curve (AUC) [20,700 mg x min/ml versus 8100 in lean spontaneously hypertensive rats (SHR)]. Insulin resistance was indicated by 20-fold excess fasting insulin and increased insulin AUC (6300 ng x min/ml versus 990 in SHR). DMAQ-B1 did not affect glucose tolerance (glucose AUC = 21,300) but reduced fasting insulin 2-fold and insulin AUC (insulin AUC = 4300). PPEIA normalized glucose tolerance (glucose AUC = 9100) and reduced insulin AUC (to 3180) without affecting fasting insulin. PPEIA also increased food intake, fat mass, and body weight gain (81 +/- 12 versus 45 +/- 8 g in untreated controls), whereas DMAQ-B1 had no effect on body weight but reduced subscapular fat mass. PPEIA but not DMAQ-B1 reduced blood pressure. In skeletal muscle, insulin-stimulated phosphorylation of the insulin receptor and insulin receptor substrate protein 1-associated phosphatidylinositol 3-kinase activity were decreased by 40 to 55% in SHROB relative to lean SHR. PPEIA, but not DMAQ-B1, enhanced both insulin actions. SHROB also showed severe hypertriglyceridemia (355 +/- 42 mg/dl versus 65 +/- 3 in SHR) attenuated by both agents (DMAQ-B1, 228 +/- 18; PPEIA, 79 +/- 3). Both these novel antidiabetic agents attenuate insulin resistance and hypertriglyceridemia associated with metabolic syndrome but via distinct mechanisms.

Methyl Scanning: Total Synthesis of Demethylasterriquinone B1 and Derivatives for Identification of Sites of Interaction with and Isolation of Its Receptor(s)

The principle of methyl scanning is proposed for determination of the sites of interaction between biologically active small molecules and their macromolecular target(s). It involves the systematic preparation of a family of methylated derivatives of a compound and their biological testing. As a functional assay, the method can identify the regions of a molecule that are important (and unimportant) for biological activity against even unknown targets, and thus provides an excellent complement to structural biology. Methyl scanning was applied to demethylasterriquinone B1, a small-molecule mimetic of insulin. A new, optimal total synthesis of this natural product was developed that enables the family of methyl scan derivatives to be concisely prepared for evaluation in a cellular assay. The results of this experiment were used to design a biotin-demethylasterriquinone conjugate for use as an affinity reagent. This compound was prepared in tens of milligram quantities in a four-step synthesis.

Signalling Effects of Demethylasterriquinone B1, a Selective Insulin Receptor Modulator.

Signalling Effects of Demethylasterriquinone B1, a Selective Insulin Receptor Modulator.

Total Syntheses of Demethylasterriquinone B1, an Orally Active Insulin Mimetic, and Demethylasterriquinone A1.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Total syntheses of demethylasterriquinone B1, an orally active insulin mimetic, and demethylasterriquinone A1.

Two total syntheses of the unsymmetrical bis-indolylquinone natural product demethylasterriquinone B1 (also known as L-783,281) have been accomplished. The first exploits a known base-promoted condensation of indoles with bromanil, which stops at monoaddition using the sterically hindered 2-isoprenylindole. This permits addition of the second indole, 7-prenylindole, which gives both meta- and para-substituted bis-indolylquinone products. This regiochemical control problem was solved by extension of a method we recently developed for acid-promoted addition of indoles to 2,5-dichlorobenzoquinone. Under our original mineral acid conditions, reaction of 2-isoprenylindole with dichlorobenzoquinone fails, but it succeeds with 3-bromo-2,5-dichlorobenzoquinone using acetic acid as the promoter. The regiochemistry established in such selectively bromine-substituted quinones can be exploited in Stille couplings. As a model system, the synthesis of demethylasterriquinone A1 was accomplished using as the key step a Stille coupling of a 2,5-dibromobenzoquinone with an (N-isoprenylindol-3-yl)tin, producing the para-substituted bis-indolylquinone exclusively. Use of a (7-prenylindole)tin in coupling with a bromo-2,5-dichloro-4-indolylbenzoquinone gives the demethylasterriquinone B1 precursor. The dihaloquinone products of these indole/quinone coupling processes can be hydrolyzed to the dihydroxyquinone natural products. Demethylasterriquinone B1 is of high recent interest as a small molecule insulin mimetic with oral anti-diabetic activity in mice.

A novel insulin mimetic without a proliferative effect on vascular smooth muscle cells

Background: Insulin induces vascular smooth muscle cell (VSMC) proliferation, which is an important step in the atherosclerotic process. Recently, a nonpeptidyl fungal metabolite originally referred to as L-783,281, but also known as demethylasterriquinone B-1 (DMAQB-1), was found to have hypoglycemic activity in diabetic mice through interaction with the intracellular β subunit of the insulin receptor. This study was designed to determine whether DMAQB-1 has an insulin-like proliferative effect on human infragenicular VSMCs. Methods: Human infragenicular VSMCs were isolated from diabetic patients undergoing amputations. DMAQB-1 cell culture dose response was measured in both serum-free media and media with 1% fetal bovine serum (FBS). A working concentration of DMAQB-1 that ranged from 0.5 to 500 nmol/L was studied in the presence of varying concentrations of glucose and insulin. The ability of DMAQB-1 to stimulate glucose transport at less than or equal to 100 nmol/L was determined by [14C]-2-deoxyglucose uptake. DNA synthesis was used as the marker for proliferative stimulus and detected by [3H]-thymidine uptake measured at 24 hours. Analysis of variance was used to compare the results among the groups; a P value less than.05 was considered significant. Polynomial regression was used to calculate the median lethal dose. Results: In normal glucose media (100 mg/dL), various concentrations of DMAQB-1 demonstrated a small but statistically significant decrease in DNA synthesis at 0.5 nmol/L in serum-free media and at 5 nmol/L in media supplemented with 1% FBS. The corresponding median lethal dose was 107 nmol/L in serum-free media and 650 nmol/L in media supplemented with 1% FBS. A DMAQB-1 concentration of 5 nmol/L induced glucose transport that was equivalent to an insulin concentration of 100 μU/mL. In serum-free, high glucose media (200 mg/dL), DMAQB-1 concentrations up to 500 nmol/L did not cause a statistically significant change in DNA synthesis. When serum-free, high glucose media was combined with mild (100 μU/mL) or moderate (250 μU/mL) concentrations of insulin, DMAQB-1 caused no statistically significant increase in DNA synthesis. Conclusion: Nontoxic doses of DMAQB-1 can induce glucose transport equivalent to insulin in the physiologic range. However, DMAQB-1 does not have an insulin-like proliferative effect on human VSMCs in normal-glucose, high-glucose, or high-insulin environments. (J Vasc Surg 2000;32:1118-26.)