Synthesis,characterization, and studies on DNA binding of a new Mg(II) complex with N<Superscript>1</Superscript>,N<Superscript>8</Superscript>-bis(1-methyl-4-nitropyrrole-2-carbonyl)triethylenetetramine

A new Mg(II) complex of MgL(NO3)2 (here L = N(1),N(8)-bis(1-methyl-4-nitropyrrole-2-carbonyl)triethylenetetramine) has been synthesized and characterized. The interactions between the Mg(II) complex and calf thymus DNA has been investigated using UV spectra, fluorescent spectra, viscosity, thermal denaturation, and molecular modeling. The cleavage reaction on plasmid DNA has been monitored by agarose gel electrophoresis. The experimental results show that the mode of binding of the complex to DNA is non-classical electrostatic action and the complex can cleave pBR322 DNA.     

Amelioration of diet-induced nonalcoholic steatohepatitis in rats by Mn-salen complexes via reduction of oxidative stress

Background

Nonalcoholic steatohepatitis (NASH), a progressive stage of nonalcoholic fatty liver disease (NAFLD), is characterized by steatosis (accumulation of triacylglycerols within hepatocytes) along with inflammation and ballooning degeneration. It has been suggested that oxidative stress may play an important role in the progress of NAFLD to NASH. The aim of present study was to determine whether antioxidant supplementations using EUK-8, EUK-134 and vitamin C could improve the biochemical and histological abnormalities associated with diet-induced NASH in rats.

Methods

NASH was induced in male N-Mary rats by feeding a methionine - choline deficient (MCD) diet. The rats were fed either normal chow or MCD diet for 10 weeks. After NASH development, the MCD-fed rats were randomly divided into four groups of six: the NASH group that received MCD diet, the EUK-8 group which was fed MCD diet plus EUK-8, the EUK-134 group which was fed MCD diet plus EUK-134 and the vitamin C group which received MCD diet plus vitamin C. EUK-8, EUK-134 and vitamin C (30 mg/kg body weight/day) were administered by gavage for eight weeks.

Results

Treatment of MCD-fed rats with salens reduced the sera aminotransferases, cholesterol, low density lipoprotein contents, the extent of lipid peroxidation and protein carbonylation whereas the HDL-C cholesterol levels were significantly increased. In addition, EUK-8 and EUK-134 improved steatosis, ballooning degeneration and inflammation in liver of MCD-fed rats.

Conclusion

Antioxidant (EUK-8, EUK-134 and vitamin C) supplementation reduces NASH-induced biochemical and histological abnormalities, pointing out that antioxidant strategy could be beneficial in treatment of NASH.     

Inhibition of sPLA2 enzyme activity by cell-permeable antioxidant EUK-8 and downregulation of p38, Akt,and p65 signals induced by sPLA2 in inflammatory mouse paw edema model

The arachidonic acid (AA) metabolic pathway, plays a vital role in the production of eicosanoids by the action of pro-inflammatory secretory phospholipase A₂ (PLA₂). Release of eicosanoids is known to be involved in many inflammatory diseases. Identification of the inhibitory molecules of this AA pathway enzyme along with the regulation of intracellular signaling cascades may be a finer choice to develop as a powerful anti-inflammatory drug. In this regard, we have screened few cell-permeable antioxidant molecules Tempo, Mito-TEMPO, N,N'-Bis(salicylideneamino)ethane-manganese(II) (EUK)-134, and EUK-8 against pro-inflammatory sPLA₂s. Among these, we found EUK-8 is a potent inhibitor with its IC₅₀ value ranges 0.7–2.0 µM for sPLA₂s isolated from different sources. Furthermore, docking studies confirm the strong binding of EUK-8 towards sPLA₂. In vivo effect of EUK-8 was studied in HSF-sPLA₂-induced edema in mouse paw model. In addition to neutralizing the edema, EUK-8 significantly reduces the phosphorylation level of inflammatory proteins such as p38 member of MAPK pathway, Akt, and p65 along with the suppression of pro-inflammatory cytokine (interleukin-6) and chemokine (CXCL1) in edematous tissue. This shows that EUK-8 not only inhibits the sPLA₂ activity, it also plays an important role in the regulation of sPLA₂-induced cell signaling cascades. Apart from the sPLA₂ inhibition, we also examine the regulatory actions of EUK-8 with other downstream enzymes of AA pathway such as 5-LOX assay in human polymorphonuclear leukocytes (PMNs) and COX-2 expression in carrageenan-λ induced paw edema. Here EUK-8 significantly inhibits 5-LOX enzyme activity and downregulates COX-2 expression. These data indicate that EUK-8 found to be a promising multitargeted inhibitory molecule toward inflammatory pathway. In conclusion, mitochondrial targeted antioxidant EUK-8 is not only the powerful antioxidant, also a potent anti-inflammatory molecule and may be a choice of molecule for pharmacological applications.     

Synthesis, characterization and studies on DNA-binding of a new Cu(II) complex with N1,N8-bis(l-methyl-4-nitropyrrole-2-carbonyl)triethylenetetramine

A new Cu(II) complex of CuLCl(2) (here, L=N(1),N(8)-bis(1-methyl-4-nitropyrrole-2- carbonyl)triethylenetetramine) had been synthesized and characterized. The structure of the complex was investigated with density functional theory (DFT) calculations. DNA-binding of the Cu(II) complex and its effects on tumor cell viability were firstly studied. The interactions between the complex and calf thymus DNA had been investigated using UV spectra, fluorescent spectra, viscosity and CV (cyclic voltammetry). The cleavage reaction on plasmid DNA has been monitored by agarose gel electrophoresis. The experimental results show that the mode of binding of the complex to DNA is classical intercalation and the complex can cleave pBR322 DNA. The effects of the CuL on cell viability were tested using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) dye assay and the results indicate that the CuL had certain effect on cancer cells.     

Cardioprotection by chronic estrogen or superoxide dismutase mimetic treatment in the aged female rat

Aging and estrogen deficiency increase the risk for developing cardiovascular disease (CVD). Oxidative stress has also been implicated in the pathophysiology of CVD and in ischemia-reperfusion (I/R) injury. We tested the hypothesis that chronic in vivo estrogen treatment or superoxide inhibition with the SOD mimetic EUK-8 improves cardiac functional recovery after I/R in the aged female rat. Sprague-Dawley rats (12-14 mo) were used as follows: intact (n = 6), ovariectomized + placebo (OVX, n = 6), OVX + EUK-8 (EUK-8, 3 mg/kg, n = 6), and OVX + estrogen (1.5 mg/pellet, 60 days release, n = 6). Perfused isolated hearts were subjected to global ischemia (25 min) followed by reperfusion (40 min). Functional recovery after I/R and myocardial protein expression of NADPH oxidase (p22, p67, and gp91(phox)), inducible nitric oxide synthase (NOS), endothelial NOS, and SOD1, as well as nitrotyrosine levels (as a marker for peroxynitrite), were assessed. Compared with OVX, EUK-8 and estrogen markedly improved functional recovery after I/R, which was associated with a decrease in NADPH oxidase expression and nitrotyrosine staining. However, estrogen increased inducible NOS expression, whereas EUK-8 had little effect. There were no significant changes in endothelial NOS and SOD1 expression among the groups. These results indicate that EUK-8 and estrogen improved cardiac recovery after I/R. Given the controversy surrounding hormone replacement therapy, EUK-8 may be an alternative to estrogen in protecting those at risk for myocardial ischemia in the aging population.     

Metal-N-saccharide chemistry: synthesis and structure determination of two Cu(II) complexes containing glycosylamines

Two new complexes [Cu(N,N',N"-(D-Glc)3-tren)Cl]Cl (1) and [Cu(N,N',N"-(maltose)-tren)]Cl2.H2O (2), have been synthesized and characterized by elementary analysis, and the IR and UV spectra suggest that complex 1 and complex 2 are arranged in trigonal bipyramidal configuration and square-pyramidal configuration, respectively. The crystal structure of complex 1 has been determined by X-ray diffraction as: a = 9.3476(8), b = 17.4236(13), c = 9.7836(8) angstroms, beta = 91.197 degrees, and V = 1593.1(2) Angstroms3, Z = 2, and R = 0.0325, which shows that three secondary amine groups (N-1, N-2, N-3) of the glycosylamine ligand forms the equatorial plane, and the tertiary amine (N-4) and one Cl- are located at the apical positions.     

Synthesis and properties of 8-azido-1, N6-etheno adenosine triphosphate--a fluorescent and photosensitive ATP analog.

8-Azido-1,N6-etheno-ATP--a fluorescent and photoreactive ATP analog has been synthesized and characterized by elementary analysis, thin layer chromatography, infrared spectroscopy, proton resonance spectroscopy, UV absorption spectroscopy, and fluorescence spectroscopy. The photolytical decomposition upon irradiation at different pH values is tested.     

Orally available Mn porphyrins with superoxide dismutase and catalase activities

Superoxide dismutase/catalase mimetics, such as salen Mn complexes and certain metalloporphyrins, catalytically neutralize reactive oxygen and nitrogen species, which have been implicated in the pathogenesis of many serious diseases. Both classes of mimetic are protective in animal models of oxidative stress. However, only AEOL11207 and EUK-418, two uncharged Mn porphyrins, have been shown to be orally bioavailable. In this study, EUK-418 and several new analogs (the EUK-400 series) were synthesized and shown to exhibit superoxide dismutase, catalase, and peroxidase activities in vitro. Some also protected PC12 cells against staurosporine-induced cell death. All EUK-400 compounds were stable in simulated gastric fluid, and most were substantially more lipophilic than the salen Mn complexes EUK-189 and EUK-207, which lack oral activity. Pharmacokinetics studies demonstrate the presence of all EUK-400 series compounds in the plasma of rats after oral administration. These EUK-400 series compounds are potential oral therapeutic agents for cellular damage caused by oxidative stress. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Stabilization of the non-canonical adenine-adeninium base pair by N(7) coordination of Zn(II)

A new zinc (II) compound with 9-ethyladenine (9-EtA) of formula [Zn(9-EtA-N7)Cl(3)](9-EtAH) has been synthesized and characterized by X-ray diffraction. Its X-structure consists of an Zn(II) anionic complex and 9-ethyladeninium as counteranion. The Zn(II) complex shows a distorted tetrahedral geometry in which three Cl and an 9-EtA coordinates through N(7) position are the ligands. An indirect chelation via intramolecular H-bond between N(6)H and an Cl ligand is present in the complex. The network of [Zn(9-EtA-N7)Cl(3)](9-EtAH) shows interesting features. Thus, self-association of coordinated adenine-adeninium takes place by H-bonding of N(6)-H...N(1) and N(6)-H...N(7), leading to a polymeric ribbon-like 1D supramolecular arrangement. Ab initio calculations have been applied in order to study the stability of the adenine-adeninium interaction due to the coordination of the Zn(II) to the N(7) position and to compare experimental and theoretical structural data.     

Octa-substituted anionic porphyrins: topoisomerase I inhibition and tumor cell apoptosis induction

Beta-octabromo- meso-tetra(4-carboxyl)phenyl porphyrin 6 and beta-octaphenyl- meso-tetra(4-carboxyl)phenyl porphyrin 8 were synthesized and fully characterized by (1)H NMR, UV, and HRMS. Their cytotoxicities to tumor cells were tested using MTT assays. One kind of tumor cell apoptosis induced by these anionic porphyrins under irradiation was examined by flow cytometric analysis. The inhibition of Topo I (Topoisomerase I) indicates that Topo I preferentially binds to the synthesized compounds, thus blocking the interaction between Topo I and DNA. The results implied that compounds 4, 6, and 8 are potential inhibitors to Topo I, which might be one of the important factors inducing apoptosis of tumor cells.     

Synthesis, characterization and DNA-binding properties of La(III) complex of chrysin

A novel La(III) complex of chrysin (5,7-dihydroxyflavone) was synthesized and characterized by UV, IR, 1H NMR, thermogravimetry/differential thermal analysis (TG/DTA) and elementary analyses. The interactions of the La(III) complex and chrysin with calf thymus DNA were investigated by spectrophotometric methods and viscosity measurements. The intrinsic binding constants of La(III) complex and chrysin are 1.29 x 10(6) and 5.44 x 10(5) M(-1), respectively. Experimental results indicated that La(III) complex and chrysin can both bind to DNA by intercalation modes, but the binding affinity of La(III) complex is much higher than that of chrysin. Comparative antitumor activities of La(III) complex and chrysin were tested by MTT and SRB methods. The results show that at the concentration of 10 microM for chrysin and La(III) complex, the inhibitory ratios of La(III) complex against the tested tumor cells were higher than those of chrysin.     

Anti-amyloidogenic and fibril-destabilizing effects of two manganese-salen derivatives against hen egg-white lysozyme aggregation

Amyloid depositions of proteins play crucial roles in a wide variety of degenerative disorders called amyloidosis. In the present study, we used hen egg white lysozyme (HEWL), as an in vitro model system, to induce fibrillation under high temperatures and acidic pH conditions, and investigated the inhibitory and disruptive effects of two salen-manganese complexes, namely EUK-8 and EUK-134, with aromatic structures, against fibrilization. Results of this study showed that EUK-8 and EUK-134 in a dose-dependent manner inhibited the HEWL aggregation. Similar results were obtained when these compounds were added to pre-formed amyloid fibrils. Docking results also demonstrated that the aromatic rings of EUK-8 and EUK-134 interact with the hydrophobic region of lysozyme via Van der Waals interactions. Results of MTT assay indicated that addition of pre-formed fibrils treated with EUK-8 and EUK-134 at doses 1:1 and 5:1 mM; drug to protein, to SK-N-MC cells significantly increased the viability of cells, compared to the fibril sample alone. Based on these results, it might be concluded that in addition to inherent hydrophobicity associated with the ligand section of each of the derivatives, electron density around the central metal ion of the derivatives contributes to lower lysozyme fibril accumulation.     

Synthesis and characterization of a tetracycline-platinum (II) complex active against resistant bacteria

A tetracycline-platinum(II) complex, [PtCl2(C22H24N2O8)], was synthesized and characterized by elemental analysis, conductivity and thermogravimetric analyses, and infrared spectroscopy. The interaction of tetracycline (Tc) with platinum(II) ions was also studied in aqueous solution by 1H NMR and circular dichroism spectroscopies. Tetracycline forms a 1:1 complex with platinum via the oxygen of the hydroxyl group at the A ring and that of the amide group. The complex is as efficient as tetracycline in inhibiting the growth of two Escherichia coli sensitive bacterial strains and six times more potent against E. coli HB101/pBR322, a bacterial strain resistant to tetracycline. This finding is very important because the use of tetracycline to treat bacterial infections has declined due to the emergence of resistant organisms.     

Superoxide dismutase/catalase mimetics are neuroprotective against selective paraquat-mediated dopaminergic neuron death in the substantial nigra: implications for Parkinson disease

Exposure of mice to the herbicide paraquat has been demonstrated to result in the selective loss of dopaminergic neurons of the substantia nigra, pars compacta (SNpc) akin to what is observed in Parkinson disease (PD). In this study, we investigate the efficacy of two synthetic superoxide dismutase/catalase mimetics (EUK-134 and EUK-189) in protecting against paraquat-induced dopaminergic cell death in both the rat dopaminergic cell line 1RB3AN27 (N27) and primary mesencephalic cultures in vitro and in adult mice in vivo. Our data demonstrate that pretreatment with either EUK-134 or EUK-189 significantly attenuates paraquat-induced neurotoxicity in vitro in a concentration-dependent manner. Furthermore, systemic administration of EUK-189 decreases paraquat-mediated SNpc dopaminergic neuronal cell death in vivo. These findings support a role for oxidative stress in paraquat-induced neurotoxicity and suggest novel therapeutic approaches for neurodegenerative disorders associated with oxidative stress such as PD.     

Synthesis, crystal structure and electroluminescent properties of a Schiff base zinc complex

A new complex of zinc with a Schiff base, zinc(N,N′-bis(salicylidene)-3, 6-dioxa-1, 8-diaminooctane monohydrate) (ZnBSO · H₂O), was synthesized and characterized by means of elemental analyses, IR spectra and DTA-TG. Its structure was determined by X-ray single crystal analysis. It was demonstrated that the zinc atom is coordinated by the two oxygen atoms in phenolate and two nitrogen atoms in imine of the ligand in a slightly distorted tetrahedral geometry, while the two oxygen atoms from the oxa-alkyl chain are not coordinated to Zn(II) atom. The energy levels of the HOMO, LUMO and the electrochemical band gap were determined by cyclic voltammeter. The electroluminescent devices with the complex as the emitter showed bright blue emission with a peak at 450 nm, which is same as the fluorescence of the complex in both solution and solid states.     

Polynucleotides. XXXI1. Synthesis of AUG analogs containing 8,2''-S-cycloadenosine, 8,5''-S-cycloadenosine, 8-bromoadenosin, 8-oxyadenosine and formycin in the first position of the codon.

Five AUG analogs having 8,2'-S-cycloadenosine (I), 8,5'-S-cycloadenosine (II), 8-bromoadenosine (III), 8-oxyadenosine (IV) and formycin (V) in the first position of ApUpG W were synthesized. 3'-Phosphates of I, II and V were synthesized by phosphorylation using cyanoethylphosphate and DCC. In the case of II, 2', 3'-cyclic phosphate was directly obtained. 3'-Phosphates, thus obtained, were properly protected on the 2'-OH and/or the N6-amino group and condensed with U(OBz)pGiBu(iBu)2 using DCC to give ApUpG analogs. Some properties on paper chromatography and electrophoresis, and the UV and CD spectra of these trinucleoside diphosphates are reported.     

Synthesis and investigation of antimicrobial activity and spectrophotometric and dyeing properties of some novel azo disperse dyes based on naphthalimides

A series of novel disperse dyes containing azo group were synthesized through a diazotization and coupling process. The 4‐amino‐N‐2‐aminomethylpyridine‐1,8‐naphthalimide was diazotized by nitrosylsulphuric acid and coupled with various aromatic amines such as N,N‐diethylaniline, N,N‐dihydroxyethylaniline, 8‐hydroxyquinoline, and 2‐methylindole. Chemical structures of the synthesized dyes were characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), proton nuclear magnetic resonance (¹H NMR), carbon nuclear magnetic resonance (¹³C NMR), elemental analysis, and ultraviolet–visible (UV–visible) spectroscopy. The spectrophotometric data of all dyes were evaluated in various solvents with different polarity. Eventually, the dyes were applied on polyamide fabrics in order to investigate their dyeing properties. The fastness properties of the dyed fabrics such as wash, light, and rubbing fastness degrees were measured by standard methods. Moreover, the color gamut of the synthesized dyes was measured on polyamide fabrics. Results indicated that some of the synthesized dyes were able to dye polyamide fabrics with deep shades. They had very good wash and rubbing fastness degrees and moderate‐to‐good light fastness on polyamide fabrics. The antibacterial and antifungal activities of the synthesized dyes were evaluated in soluble state and on the dyed fabrics. The results indicated that dye 2 containing N,N‐dihydroxyethylaniline as coupler had the highest activity against all the bacteria and fungi used. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1086–1095, 2015     

Superoxide dismutase/catalase mimetics but not MAP kinase inhibitors are neuroprotective against oxygen/glucose deprivation-induced neuronal death in hippocampus

Although oxygen/glucose deprivation (OGD) has been widely used as a model of ischemic brain damage, the mechanisms underlying acute neuronal death in this model are not yet well understood. We used OGD in acute hippocampal slices to investigate the roles of reactive oxygen species and of the mitogen-activated protein kinases (MAPKs) in neuronal death. In particular, we tested the neuroprotective effects of two synthetic superoxide dismutase/catalase mimetics, EUK-189 and EUK-207. Acute hippocampal slices prepared from 2-month-old or postnatal day 10 rats were exposed to oxygen and glucose deprivation for 2 h followed by 2.5 h reoxygenation. Lactate dehydrogenase (LDH) release in the medium and propidium iodide (PI) uptake were used to evaluate cell viability. EUK-189 or EUK-207 applied during the OGD and reoxygenation periods decreased LDH release and PI uptake in slices from 2-month-old rats. EUK-189 or EUK-207 also partly blocked OGD-induced ATP depletion and extracellular signal-regulated kinases 1 and 2 (ERK1/2) dephosphorylation, and completely eliminated reactive oxygen species generation. The MEK inhibitor U0126 applied together with EUK-189 or EUK-207 completely blocked ERK1/2 activation, but had no effect on their protective effects against OGD-induced LDH release. U0126 alone had no effect on OGD-induced LDH release. EUK-207 had no effect on OGD-induced p38 or c-Jun N-terminal kinase dephosphorylation, and when the p38 inhibitor SB203580 was applied together with EUK-207, it had no effect on the protective effects of EUK-207. SB203580 alone had no effect on OGD-induced LDH release either. In slices from p10 rats, OGD also induced high-LDH release that was partly reversed by EUK-207; however, neither OGD nor EUK-207 produced significant changes in ERK1/2 and p38 phosphorylation. OGD-induced spectrin degradation was not modified by EUK-189 or EUK-207 in slices from p10 or 2-month-old rats, suggesting that their protective effects was not mediated through inhibition of calpain activation. Thus, both EUK-189 and EUK-207 provide neuroprotection in acute ischemic conditions, and this effect is related to elimination of free radical formation and partial reversal of ATP depletion, but not mediated by the activation or inhibition of the MEK/ERK or p38 pathways, or inhibition of calpain activation.     

Superoxide dismutase mimetics elevate superoxide dismutase activity in vivo but do not retard aging in the nematode Caenorhabditis elegans

According to the oxidative damage theory a primary cause of aging is the accrual of molecular damage from reactive oxygen species (ROS), particularly superoxide and its derivatives. This predicts that treatments that reduce ROS levels should retard aging. Using the nematode Caenorhabditis elegans, we tested the effects on stress resistance and life span of treatment with EUK-8 and EUK-134, synthetic mimetics of the antioxidant enzyme superoxide dismutase (SOD), which neutralises superoxide. Treatment with SOD mimetics elevated in vivo SOD activity levels, particularly in mitochondria, where up to 5-fold increases in SOD activity were recorded. Treatment with exogenous SOD mimetics did not affect endogenous protein SOD levels. Where life span was reduced by the superoxide generators paraquat and plumbagin, EUK-8 treatment increased life span in a dose-dependent fashion. Yet in the absence of a superoxide generator, treatment with EUK-8 or EUK-134 did not increase life span, even at doses that were optimal for protection against pro-oxidants. Thus, an elevation of SOD activity levels sufficient to increase life span when it is limited by superoxide generators does not retard aging in the absence of superoxide generators. This suggests that C. elegans life span is not normally limited by levels of superoxide and its derivatives.