The role of apoptosis and autophagy in the insulin-enhancing activity of oxovanadium(IV) bipyridine complex in streptozotocin-induced diabetic mice.

Metal-based therapies (e.g. Vanadium) possess an attractive proposition in medicinal treatment of diabetes mellitus. Defective insulin secretion can result from impaired ß-cell function which is mediated by many process including apoptosis and autophagy. In this study. diabetes was induced by administration of streptozotocin then treatment was performed by vanadyl sulfate and [VO(bpy)2 Cl] Cl.H2O complex. Blood glucose level, AST, ALT, BUN, CR, TCHO, TG and total protein were determined in serum. MDA, NO, erythrocyte GSH and SOD were estimated. LC3 and Caspase 3 levels in pancreatic cells were assessed by flow cytometer. Histopathological investigation of pancreatic tissue was performed. Results of Diabetic group showed a significant increase in transaminases activities, TCHO, TG, MDA, NO and Caspase 3 levels and significant decrease in TP, GSH, SOD and LC3 levels. Oral administration of vanadium complex resulted in normoglycemia, significant increase in blood GSH, SOD, TP and LC3 levels, significant decrease in ALT, AST, BUN, TCHO, TG, MDA and NO and Caspase 3 levels. In addition, proliferative effect of complex prevents islet atrophy. From previous results, the insulin-enhancing effect induced by this complex indicated that this new complex can be a valuable candidate as insulin-enhancing and antioxidant compound than inorganic vanadyl sulfate.

Anti-inflammatory and antinociceptive effects of 2,2`-dipyridyl diselenide through reduction of inducible nitric oxide synthase, nuclear factor-kappa B and c-Jun N-terminal kinase phosphorylation levels in the mouse spinal cord.

Appropriate treatment of pain requires analgesics and anti-inflammatory drugs generally associated with undesirable side effects and not fully effective in a significant proportion of patients. Organoselenium compounds elicit a plenty of pharmacological effects in different animal models. Among these compounds, the 2,2`-dipyridyl diselenide (DPD) has a potent antioxidant effect and low toxicity. In this way, the aim of this study was to investigate the possible DPD antinociceptive effect and its mechanism of action, as well as the safety of the compound. Female Swiss mice were treated with vehicle or DPD (0.01-50 mg/kg) intragastrically. Dose-response curve and time-course of the antinociceptive effect of DPD were performed on formalin and tail immersion tests. Morphine (2.5 mg/kg, subcutaneous, 15 min earlier) was used as a positive control in behavioral tests. The results showed that DPD presents a rapid antinociceptive effect in low doses, without changing the spontaneous locomotor activity and parameters of toxicity in mice. The DPD antinociceptive effect was also confirmed in male Swiss mice in both formalin and tail immersion tests. In addition, DPD reduced the paw edema induced by 2.5% formalin and ear edema induced by 2.5% croton oil. l-arginine (600 mg/kg, intraperitoneally) reduced the DPD antinociceptive effect in the first phase of the formalin test. Moreover, DPD attenuated the increase in iNOS, NF-κB and JNK phosphorylation in the spinal cord of mice injected with formalin. These results showed that DPD exerts peripheral and central nociceptive actions associated with anti-inflammatory effect and this organoselenium compound could be an interesting alternative therapy for pain treatment.

The Discovery of Novel Antimalarial Aminoxadiazoles as a Promising Nonendoperoxide Scaffold.

Since the appearance of resistance to the current front-line antimalarial treatments, ACTs (artemisinin combination therapies), the discovery of novel chemical entities to treat the disease is recognized as a major global health priority. From the GSK antimalarial set, we identified an aminoxadiazole with an antiparasitic profile comparable with artemisinin (1), with no cross-resistance in a resistant strains panel and a potential new mode of action. A medicinal chemistry program allowed delivery of compounds such as 19 with high solubility in aqueous media, an acceptable toxicological profile, and oral efficacy. Further evaluation of the lead compounds showed that in vivo genotoxic degradants might be generated. The compounds generated during this medicinal chemistry program and others from the GSK collection were used to build a pharmacophore model which could be used in the virtual screening of compound collections and potentially identify new chemotypes that could deliver the same antiparasitic profile.

2,2'-dipyridyl induces pexophagy.

Pexophagy is the selective degradation of peroxisomes for maintaining peroxisome homeostasis within cells. Peroxisome dynamics and pexophagy are important events required to maintain the quality control of peroxisomes, thereby preventing peroxisome-associated diseases. To identify novel pexophagy modulators, we developed a cell-based screening system and selected 2,2'-dipyridyl (2,2-DP) as a candidate molecule. 2,2-DP treatment induced peroxisome degradation as evidenced by an increased number of low-pH autolysosomes originating from peroxisomes and a decrease in the expression of peroxisomal proteins such as catalase, Pex14, and PMP70. The phenotype was defined as pexophagy, because 2,2-DP induced autophagy and inhibition of autophagy significantly reduced the degree of peroxisome degradation. Mechanistically, 2,2-DP-dependent pexophagy seemed to be mediated by iron chelation, since another iron chelator displayed a similar effect on pexophagy, but a copper chelator did not. Notably, iron replenishment prevented 2,2-DP-mediated pexophagy. Taken together, our results suggest that 2,2-DP treatment disrupts peroxisome dynamics and promotes pexophagy through iron depletion.

Gd-Al co-doped mesoporous silica nanoparticles loaded with Ru(bpy)3²âº as a dual-modality probe for fluorescence and magnetic resonance imaging.

Mesoporous silica nanoparticles (MSNs) were co-doped with Gd(3+) and Al(3+) and then loaded with Ru(bpy)3(2+) by ion-exchange to prepare Ru/Gd-Al@MSNs. The as-prepared Ru/Gd-Al@MSNs were applied as contrast agents for in vivo fluorescence and magnetic resonance (MR) dual-modality imaging with a mouse as a model. The effects of Al(3+) and MSNs on longitudinal relaxivity (r1) and fluorescence were investigated using a series of Gd-containing silica nanoparticles, including Gd@MSNs, Gd-Al@MSNs, and Ru/Gd-Al@nonporous silica nanoparticles. Co-doping with Al(3+) improved the loading of Gd(3+); the mesoporous structure improved the water exchange rate. The improvement enhanced the MR imaging efficiency of the Ru/Gd-Al@MSN probe. A higher relaxivity (19.2 mM(-1) s(-1)) was observed compared to that from a commercial contrast agent, Gd-diethylene triamine pentaacetic acid (Gd-DTPA). Importantly, the mesoporous structure provided a large specific surface area for the loading of Ru(bpy)3(2+) by a simple ion-exchange procedure. Intense red fluorescence was observed from Ru/Gd-Al@MSN probes. The versatility of Ru/Gd-Al@MSNs for dual-modality imaging was demonstrated using in vivo fluorescence imaging and T1-weighted MR imaging with a mouse model. The nanoparticles are biocompatible and may be attractive for clinical applications.

Bipyridine, an iron chelator, does not lessen intracerebral iron-induced damage or improve outcome after intracerebral hemorrhagic stroke in rats.

Iron chelators, such as the intracellular ferrous chelator 2,2'-bipyridine, are a potential means of ameliorating iron-induced injury after intracerebral hemorrhage (ICH). We evaluated bipyridine against the collagenase and whole-blood ICH models and a simplified model of iron-induced damage involving a striatal injection of FeCl2 in adult rats. First, we assessed whether bipyridine (25 mg/kg beginning 12 h post-ICH and every 12 h for 3 days) would attenuate non-heme iron levels in the brain and lessen behavioral impairments (neurological deficit scale, corner turn test, and horizontal ladder) 7 days after collagenase-induced ICH. Second, we evaluated bipyridine (20 mg/kg beginning 6 h post-ICH and then every 24 h) on edema 3 days after collagenase infusion. Body temperature was continually recorded in a subset of these rats beginning 24 h prior to ICH until euthanasia. Third, bipyridine was administered (as per experiment 2) after whole-blood infusion to examine tissue loss, neuronal degeneration, and behavioral impairments at 7 days post-stroke, as well as body temperature for 3 days post-stroke. Finally, we evaluated whether bipyridine (25 mg/kg given 2 h prior to surgery and then every 12 h for 3 days) lessens tissue loss, neuronal death, and behavioral deficits after striatal FeCl2 injection. Bipyridine caused a significant hypothermic effect (maximum drop to 34.6 °C for 2-5 h after each injection) in both ICH models; however, in all experiments bipyridine-treated rats were indistinguishable from vehicle controls on all other measures (e.g., tissue loss, behavioral impairments, etc.). These results do not support the use of bipyridine against ICH.

A new strategy for neurochemical photodelivery: metal-ligand heterolytic cleavage.

A new strategy to build caged-compounds is presented. The approach is based on heterolytic photocleavage of a metal-ligand bond in a coordination compound. A ruthenium polypyridine complex, containing the neurocompound 4-amino pyridine (4AP) is used as the core of the phototrigger. The biomolecule is released by irradiation with visible light (>480 nm). The liberated 4AP promotes the activation of a leech neuron by means of blocking its K+ channels. The syntesis, characterization, and the inherent advantages of this method are discussed.

Amelioration of cerulein-induced acute pancreatitis by 2,2'-dipyridyl in rats.

We studied the effect of iron chelators, 2,2'-dipyridyl and desferrioxamine, on cerulein-induced pancreatitis in rats. Acute pancreatitis was induced by a single subcutaneous injection of 100 micrograms/kg body weight of cerulein, which caused hyperamylasemia and edematous pancreatitis with neutrophilic infiltration. Blood samples were collected for determination of serum amylase values and the pancreas was removed for the histological examination 6 h after the cerulein injection. Intraperitoneal administration of a ferrous iron chelator, 2,2'-dipyridyl, prior to the cerulein injection resulted in amelioration of hyperamylasemia and histological abnormalities such as edema and inflammation but not of acinar cell vacuolization. In contrast, administration of a ferric iron chelator, desferrioxamine, did not show any beneficial effects. These results indicate that administration of 2,2'-dipyridyl ameliorates the pancreatitis induced by the supramaximal dose of cerulein.

Development of novel dye-doped silica nanoparticles for biomarker application.

We report the development of novel luminescent nanoparticles composed of inorganic luminescent dye, Tris(2,2'-bipyridyl) dichlororuthenium (II) hexahydrate, doped inside a silica network. These dye doped silica (DDS) nanoparticles have been synthesized using a water-in-oil microemulsion technique in which controlled hydrolysis of the tetraethyl orthosilicate leads to the formation of monodispersed nanoparticles. They are prepared with a variety of sizes: small (5+/-1 nm), medium (63+/-4 nm), and large (400+/-10 nm), which shows the efficiency of the microemulsion technique for the synthesis of uniform nanoparticles. All these nanoparticles are suitable for biomarker application since they are much smaller than cellular dimension. These nanoparticles are highly photostable in comparison to most commonly used organic dyes. These nanoparticles have been characterized by various microscopic and spectroscopic techniques. The amount of dye content in these nanoparticles has been optimized to eliminate self-quenching. It has been observed that maximum luminescence intensity is achieved when the dye content is around 20 wt%. Silica surface of DDS nanoparticles is available for surface modification and bioconjunction. For demonstration as a biomarker, the DDS nanoparticle's surface has been biochemically modified to attach membrane-anchoring groups and applied successfully to stain human leukemia cells.

N-Acetylaspartate, a marker of both cellular dysfunction and neuronal loss: its relevance to studies of acute brain injury.

To evaluate the contribution of cellular dysfunction and neuronal loss to brain N-acetylaspartate (NAA) depletion, NAA was measured in brain tissue by HPLC and UV detection in rats subjected to cerebral injury, associated or not with cell death. When lesion was induced by intracarotid injection of microspheres, the fall in NAA was related to the degree of embolization and to the severity of brain oedema. When striatal lesion was induced by local injection of malonate, the larger the lesion volume, the higher the NAA depletion. However, reduction of brain oedema and striatal lesion by treatment with the lipophilic iron chelator dipyridyl (20 mg/kg, 1 h before and every 8 h after embolization) and the inducible nitric oxide synthase inhibitor aminoguanidine (100 mg/kg given 1 h before malonate and then every 9 h), respectively, failed to ameliorate the fall in NAA. Moreover, after systemic administration of 3-nitropropionic acid, a marked reversible fall in NAA striatal content was observed despite the lack of tissue necrosis. Overall results show that cellular dysfunction can cause higher reductions in NAA level than neuronal loss, thus making of NAA quantification a potential tool for visualizing the penumbra area in stroke patients.

Elimination of basal lamina and the collagen "scar" after spinal cord injury fails to augment corticospinal tract regeneration.

The production of specific extracellular matrix molecules is upregulated following injury to the adult CNS, and some of these molecules have been postulated to inhibit axonal regeneration. In particular, the deposition of collagen in conjunction with basal lamina formation has been correlated with the failure of CNS axons to extend beyond sites of injury. In the present experiment, the spatial and temporal distribution of fibrillar collagen type III and the main constituents of basal lamina (collagen type IV and laminin) were characterized after defined lesions of the adult spinal cord at cervical and thoracic levels. The deposition of collagen was then blocked in animals undergoing defined mid-thoracic spinal cord lesions by administration of the iron chelator 2,2'-bipyridine, and subsequent effects on corticospinal axonal growth were examined. At time points from 1 to 6 weeks postinjury, collagen and laminin were deposited at spinal cord lesion sites as a dense matrix at the host-lesion interface that extended for short distances into the surrounding spinal cord parenchyma. The failure of corticospinal axons to grow beyond the lesioned region correlated spatially and temporally with collagen III formation and basal lamina production. However, successful blockade of collagen and basal lamina formation with 2,2'-bipyridine injections failed to enhance corticospinal axon regeneration or sprouting. These results suggest either that collagen and basal lamina formation after CNS injury do not contribute to corticospinal axonal growth failure or, more likely, that molecules in addition to collagen and basal lamina contribute to axonal growth failure and must be collectively blocked to promote corticospinal regeneration.

[The role of the maternal genotype in the realization of the embryotoxic activity of teratogens]. / Rol' genotipa materi v realizatsii émbriotoksicheskoi aktivnosti nekotorykh teratogenov.

Against the background of the induced iron deficit ethanol (6.4 g/kg) causes aggravation of the embryolethal effect and anomalies in 15% of embryos in 14-day pregnant rats. Changes in the genome of rat males and females after the injection of the plasmid with a foreign gene at the stage of two pronuclei and the subsequent crossing with intact animals account for the increase in sensitivity of embryos to subteratogenic doses of sodium salicilate. The maternal organism disturbances have a more pronounced effect than the paternal ones.

Implications and problems in analysing cytotoxic activity of hydroxyurea in combination with a potential inhibitor of ribonucleotide reductase.

The cytotoxicity of hydroxyurea in combination with 2.2'-bipyridyl-6-carbothioamide (a potential inhibitor of ribonucleotide reductase) on P388 murine leukemia is reported. Synergistic activity was studied using various interpretations of the isobologram method and the combination index method. We evaluated the pros and cons of these methods and their overall usefulness. In our opinion, to obtain all possible information from a compound association, it is important to choose a formally correct method that (a) can quantitatively evaluate synergism or antagonism, (b) may offer the possibility of averaging final results, (c) needs a minimal amount of experimental data, and (d) is rapid. Moreover, we emphasize both the utility of testing at least three molar ratios of compound association and the importance of carefully choosing the fractional inhibition used in calculating the combination effect. Such evaluation of drug combinations gives information essential to the preparation of new anticancer drug regimens and to the early assessment of biochemical interactions.

Comparative study of different iron-chelating agents in cold-induced brain edema.

Increasing numbers of reports demonstrate the importance of iron and oxygen free radicals in brain injury and brain edema. We investigated the protective effects of three different ferric and ferrous iron-chelating agents on cold-induced brain edema. Vasogenic brain edema was produced by a cortical freezing lesion. Thirty-eight cats were separated into five groups: Group 1 (N = 8): normal control group without lesion; Group 2 (N = 8): untreated group; Group 3 (N = 8): deferoxamine (extracellular and intracellular ferric iron chelator)-treated group; Group 4 (N = 8): 2,3-dihydroxybenzoic acid (extracellular ferric iron chelator)-treated group; and Group 5 (N = 6): 2,2-bipyridine (intracellular ferrous iron chelator)-treated group. In Groups 3, 4, and 5, each agent was administered intravenously 15 minutes before lesion production and 60 minutes later. Animals in Groups 2, 3, 4, and 5 were killed 6 hours after lesion production. Brain water content in 8 sampling areas was measured by the specific gravity method. Blood-brain barrier disruption was assessed by the spread of Evans blue dye measured by planimetry. Brain water contents and Evans blue dye extravasated areas were significantly reduced in Groups 3 and 5 in comparison to Groups 2 and 4. These data suggest that both ferrous and ferric iron-chelating agents, which can penetrate the cell membrane and, presumably, act intracellularly, are effective in reducing cold-induced brain edema.

In vitro cytotoxicity of caracemide alone and in combination with hydroxyurea or iron-chelating agents in human chronic myeloid leukemia cells and murine tumors.

The cytotoxic effect of caracemide and hydroxyurea was compared in human chronic myeloid leukemia cells. Caracemide was found to be about twelve times more effective than hydroxyurea. The combined effect of caracemide, hydroxyurea and hydrophobic iron-chelating agents at relatively nontoxic concentrations was studied. Hydroxyurea, 2,2'-bipyridine and 1,10-phenanthroline combined with caracemide synergistically inhibited DNA synthesis, while Desferal did not show any such effect. Fe++ partially reversed the cytotoxicity of caracemide in combination with 2,2'-bipyridine, while it had no effect on the cytotoxicity of caracemide alone. Caracemide was found to have a stronger inhibitory effect on DNA synthesis in P388 lymphocytic leukemia and Ehrlich ascites carcinoma cells than hydroxyurea. However, bipyridine, phenanthroline and Desferal in combination with caracemide did not induce any synergistic inhibition. These data indicate the value of human tumor cells to predict drug responsiveness and suggest the further evaluation of caracemide and its combination with hydroxyurea and iron-chelating agents in the treatment of human leukemias.

Determination of some pyridinium aldoxime compounds by means of ion-pair reversed-phase high-performance liquid chromatography: application in biological material.

Two reversed-phase high-performance liquid chromatographic systems are presented for the separation and assay of the pyridinium aldoximes benzyl-P2A, HI-6 and obidoxime in aqueous solutions and biological samples. The systems involve a 5-micrometer C18 silica gel stationary phase. The eluent consists of methanol, acetic acid buffer (pH 4.80), a counter ion (per-chlorate or n-octanesulphonate) and a surfactant. The compounds were detected spectrophotometrically at 304 nm. In the concentration range used, linear plots of concentration versus extinction were obtained, both in blood and in water. Detection limits plots of concentration versus extinction were obtained, both in blood and in water. Detection limits, even in blood are satisfactory (0.5-1 microM). Evidence of presented that, at least for HI-6, the addition of counter ions to the system does not lead to the formation of ion pairs to be retained by partition, but rather to a mechanism based on adsorption chromatography.