Syntheses and characterization of new tetraazamacrocyclic copper(II) complexes as a dual functional mimic enzyme (catalase and superoxide dismutase)

A series of macrocyclic complexes, [Cu(TAAP)]X₂, X?=?ClO₄ and CH₃COO; [Cu(TAAP)X]X, X?=?NO₃, Cl, and Br, have been synthesized by self-condensation of 5-amino-3-methyl-l-phenylpyrazole-4-carbaldehyde (AMPC) in the presence of copper(II). Elemental analyses and conductivity measurements confirm the stoichiometry of the ligand and complexes, while the characteristic absorption bands in IR spectra confirmed the formation of ligand framework around copper. Square-pyramidal and square-planar stereochemistries have been proposed for the five-coordinate (nitrato and halogeno) and four-coordinate (perchlorate and acetate) complexes. The electrochemical properties and thermal behaviors have been studied by cyclic voltammetry and TGA. Mimetics of antioxidant enzymes such as superoxide dismutase (SOD) and catalase demonstrated that there is a correlation between the observed redox properties and the SOD and catalase biomimetic catalytic activities of the copper(II) complexes.     

Metabonomics research of diabetic nephropathy and type 2 diabetes mellitus based on UPLC-oaTOF-MS system

Ultra performance liquid chromatography (UPLC) coupled with orthogonal acceleration time-of-flight (oaTOF) mass spectrometry has showed great potential in diabetes research. In this paper, a UPLC-oaTOF-MS system was employed to distinguish the global serum profiles of 8 diabetic nephropathy (DN) patients, 33 type 2 diabetes mellitus (T2DM) patients and 25 healthy volunteers, and tried to find potential biomarkers. The UPLC system produced information-rich chromatograms with typical measured peak widths of 4 s, generating peak capacities of 225 in 15 min. Furthermore, principal component analysis (PCA) was used for group differentiation and marker selection. As shown in the scores plot, the distinct clustering between the patients and controls was observed, and DN and T2DM patients were also separated into two individual groups. Several compounds were tentatively identified based on accurate mass, isotopic pattern and MS/MS information. In addition, significant changes in the serum level of leucine, dihydrosphingosine and phytoshpingosine were noted, indicating the perturbations of amino acid metabolism and phospholipid metabolism in diabetic diseases, which having implications in clinical diagnosis and treatment.     

Association of lipoprotein lipase (LPL) single nucleotide polymorphisms with type 2 diabetes mellitus

The etiology and pathogenesis of type 2 diabetes mellitus (T2DM) are not completely understood although it is often associated with other conditions such as obesity, hypertension, and dyslipidemia. Lipoprotein lipase (LPL) is a key enzyme in human lipid metabolism that facilitates the removal of triglyceride-rich lipoproteins from the bloodstream. LPL hydrolyzes the core of triglyceride-rich lipoproteins (chylomicrons and very low density lipoprotein) into free fatty acids and monoacylglycerol. To gain insight into the possible role of LPL in T2DM, nine single nucleotide polymorphisms (SNPs) of LPL were analyzed for the association with T2DM using 944 unrelated Koreans, including 474 T2DM subjects and 470 normal healthy controls. Of the nine LPL SNPs we analyzed, a significant association with multiple tests by the false discovery rate (FDR) was observed between T2DM and SNP rs343 (+13836C>A in intron 3). SNP rs343 was also marginally associated with some of T2DM-related phenotypes including total cholesterol, high density lipoprotein cholesterol (HDLc), and log transformed glycosylated hemoglobin in 470 normal controls, although no significant association was detected by multiple tests. In total, our results suggest that the control of lipid level by LPL in the bloodstream might be an important factor in T2DM pathogenesis in the Korean population.     

A novel catalase mutation detected by polymerase chain reaction-single strand conformation polymorphism, nucleotide sequencing, and western blot analyses is responsible for the type C of Hungarian acatalasemia

Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) screening was used for searching mutations of the catalase gene in two Hungarian hypocatalasemic families. A syndrome-causing mutation was found in a PCR product containing exon 7 and its boundaries. Nucleotide sequence analyses detected a G to T substitution at position 5 of intron 7. The effect of this splice site mutation was confirmed by Western blot analyses demonstrating a decreased catalase protein level in these patients. These findings represent a novel type (C) of catalase mutations in the Hungarian acatalasemic/hypocatalasemic patients.     

Self-assembled biomimetic catalysts: studies of the catalase and peroxidase activities of Mn(III)-Schiff base complexes

Five Mn(III) nitrate complexes have been synthesized from dianionic hexadentate Schiff bases obtained by the condensation of 3-ethoxy-2-hydroxybenzaldehyde with different diamines. The complexes have been characterized by elemental analysis, ESI mass spectrometry, IR and ¹H NMR spectroscopy, r. t. magnetic, and molar conductivity measurements. Parallel-mode EPR spectroscopy of 1 is also reported. Ligand H₂L³ and complexes [MnL¹(H₂O)₂](NO₃)(CH₃OH) (1), [MnL³(H₂O)₂]₂(NO₃)₂(CH₃OH)(H₂O) (3), and [MnL⁴(H₂O)₂](NO₃)(H₂O)₂ (4) were crystallographically characterized. The X-ray structures show the self-assembly of the Mn(III)–Schiff base complexes through µ-aquo bridges between neighboring axial water molecules and also by π–π stacking interactions, establishing dimeric and polymeric structures. The peroxidase and catalase activities of the complexes have been studied. Complexes with the shorter spacer between the imine groups (1–2) behave as better peroxidase and catalase mimics, probably due to their ability to coordinate the hydrogen peroxide substrate to manganese.     

Synthesis and catalase-like activity of a dimanganese(II) complex with a pentadentate L-prolin-based ligand

The preparation, spectroscopic properties, and catalase-like activity of the dimanganese(II) complex [Mn₂L(OAc)(H₂O)₂](H₂O)₂ (H₃L: 2,6-bis[(prolin-1-yl)methyl]4-t-butylphenol) are reported. The title compound was a suitable catalyst for the disproportionation of H₂O₂ into water and dioxygen under ambient conditions. Kinetic measurements resulted in the bimolecular rate law of d[O₂]/dt = k[H₂O₂][Mn₂L(OAc)(H₂O)₂](H₂O)₂].     

Biomimetic complexes of Mn(II), Fe(III), Co(II), and Ni(II) with 1,10-phenanthroline and a salen type ligand: tailored synthesis,characterization, DFT,enzyme kinetics,and antibacterial screening

Abstract

A symmetrical tetradentate Schiff base, o-HACPHENEN, was prepared by condensation of 1,2-bis(ethylenediamine) with o-hydroxyacetophenone in 1:2 molar ratio. The Schiff base ligand and 1,10-phenanthroline were used for the tailored synthesis of four mixed-ligand complexes, [Mn(o-HACPHENEN)(1,10-phen)] (1), [Fe(o-HACPHENEN)(1,10-phen)]Cl (2), [Co(o-HACPHENEN)(1,10-phen)] (3), and [Ni(o-HACPHENEN)(1,10-phen)] (4). The ligand and complexes were characterized on the basis of elemental analyses, ESI-MS, molar conductance, electronic, FT-IR, ¹H-NMR, and ¹³C-NMR spectra. DFT study was used to optimize the geometry of the investigated compounds. Using Gaussian09 molecular modeling, HOMO-LUMO study, bond lengths, bond angles, molecular electrostatic potential map (MEP), and Mulliken charge were also evaluated. Complexes displayed remarkable catalase-like activity in the disproportion reactions of hydrogen peroxide. The kinetics of the activity were investigated and data are fitted in Lineweaver Burk plot, revealing Michaelis Menten behavior. The catalase activity of ligand and complexes were found in the order 1 > 2 > 4 > 3 > o-HACPHENEN. Compounds were screened for their antibacterial activity against gram-negative bacteria Escherichia coli in comparison to standard drugs. Complexes were more potent than Schiff base. The MIC of complexes was also studied.     

Catalase mimics of a manganese(II) complex: The effect of axial ligands and pH

The mononuclear [Mn(indH)Cl₂](CH₃OH) (indH: 1,3-bis(2′-pyridylimino)-isoindoline) complex has been prepared and characterized by various techniques such as elemental analysis, IR, UV–vis, ESR spectroscopy and X-ray diffraction. The title compound in the presence of a base such as 1-methylimidazole, imidazole or pyridine is efficient catalyst for the disproportionation of H₂O₂ in CH₃CN. Among the various nitrogenous bases investigated in this study imidazole and substituted imidazoles with strong π-donating ability show better co-catalytic effect.

In case of aqueous solution the complex [Mn(indH)Cl₂](CH₃OH) shows much higher catalytic activity, and the initial rate of the disproportionation of H₂O₂ increases with increasing pH and goes through a maximum, which was found at pH  9.6. In this pH value the reaction shows first-order dependence on the catalyst, and saturation kinetics on [H₂O₂] with V_max = 8.1 × 10⁻³ Ms⁻¹, K_M = 489 mM, k_cat = 38 ± 2 s⁻¹ and k₂(k_cat/K_M) = 79 ± 4 M⁻¹s⁻¹.     

Synthesis,Crystal Structure,Cryomagnetic Properties and Catalytic Activity for H2O2 Disproportionation of New Dinuclear and Polynuclear Bis(2,4-pentanedionate)manganese(II) Complexes with Diazine Ligands

The structures, magnetic properties, and catalytic activity for H₂O₂ disproportionation are reported for three new complexes [Mn₂(acac),(pydz)] ( 1 ), [Mn(acac)₂(pym)] ( 2 ), and (Mn(acac)₂(pyz)] ( 3 ) (acac = 2,4-pentanedionate, pydz = pyridazine, pym = pyrimidine, pyz = pyrazine). The X-ray crystal structures of 1 and 3 have been determined. Complex 1 crystallizes as a binuclear complex with η²-pyridazine and acac bridging ligands 3 crystallizes as a linear polymeric chain with bridging pyrazine molecule. Cryomagnetic investigations (4-300 K) reveal a weak intramolecular antiferromagnetic spin exchange with J = ?2.05, ?0.04, and ?0.05 cm^?1 for the complexes of 1, 2 , and 3 , respectively. The complexes 1–3 showed two-step catalytic activity for H₂O₂ disproportionation in pyridine solution at 0 °C.     

Beyond blood sugar: the potential of NMR-based metabonomics for type 2 human diabetes,and the horse as a possible model

Metabonomic analysis is a powerful tool for identifying and characterizing metabolic disorders, for example type 2 diabetes and the metabolic syndrome. Nuclear magnetic resonance (NMR) spectroscopy is an essential tool for such analysis, with special benefits. The review assesses the current status and potential of NMR-based metabonomics of type 2 diabetes. The horse is proposed as a possible model for studying this condition and disease. Some examples are shown of horse blood analyses by NMR.     

Synthesis and cell uptake of a novel dualmodality (188)Re-HGRGD (D) F-CdTe QDs probe

A novel dualmodality probe was prepared by linking ¹⁸⁸Re-HGRGD (D) F with CdTe QDs, which was monitored using radio-thin layer chromatography (TLC) and -high performance liquid chromatography (HPLC). The ¹⁸⁸Re-HGRGD (D) F-CdTe QDs probe possesses a radiochemistry yield of 92.1% and strong photoluminescence (PL) stability. However, the radiochemical purity of ¹⁸⁸Re-HGRGD (D) F-QDs would reduce to 74.8%, which should be further improved, after incubation with newborn calf serum (NCF) for 24 h. Human glioblastoma U87MG cells, known to express a high-affinity to RGD, were used to assess the in vitro cell binding of probe. The results showed that the radio-signal was in accord with the change of PL intensity, which meant the successful integration of ¹⁸⁸Re and QDs.     

Cytotoxic activity and molecular docking of a novel biflavonoid isolated from Jacaranda acutifolia (Bignoniaceae)

A novel biflavonoid [kaempferol (6→8″) apigenin] was isolated from the leaves of Jacaranda acutifolia. The structure was elucidated based on chemical evidence, 1D and 2D spectroscopic analyses as well as spectrometric techniques. The compound showed promising cytotoxic activity against breast cancer cell line MCF-7. The anticancer activity was explained via virtual docking of the isolated compound to the main sites in the human cyclin-dependent kinase2 (CDK2) crystal structure.     

Preparation,characterization and antioxidant activity of a novel polysaccharide-iron (III) from Flammulina velutipes scraps

In the present study, a novel polysaccharide from Flammulina velutipes scraps (FVSP) was extracted and purified from Flammulina velutipes scraps. FVSP was chemically chelated to synthesize FVSP-iron (III) complex. Based on single factor experiments, preparation process of FVSP- iron (III) was optimized by response surface methodology. The characterization and antioxidant activity of FVSP-iron (III) were investigated. The results showed that the optimal preparation process of FVSP-iron (III) was reaction temperature of 50 °C, reaction time of 4.7 h and the mass ratio of FVSP/sodium citrate - of 2:1. The relative molecular weight of FVSP-iron (III) was 36.25 kDa. FVSP-Iron (III) was composed of glucose, galactose, mannose and xylose in a molar ratio of 65.1:20.5:5.2:9.2.The results of UV–vis absorption spectrum, FI-IR spectrum and X-ray diffraction showed that both hydroxyl and carboxyl groups in FVSP participated in the coordination reaction and the iron core of FVSP-Iron(III) was a polymerized β-FeOOH structure. FVSP-iron (III) had better thermal stability and stronger antioxidant activities than FVSP. The results indicated that FVSP-iron (III) could be potentially used in food industry as a new food additive and iron supplement.     

A novel approach for LC-MS/MS-based chiral metabolomics fingerprinting and chiral metabolomics extraction using a pair of enantiomers of chiral derivatization reagents

Chiral metabolites are found in a wide variety of living organisms and some of them are understood to be physiologically active compounds and biomarkers. However, the overall analysis of chiral metabolomics is quite difficult due to the high number of metabolites, the significant diversity in their physicochemical properties, and concentration range from metabolite-to-metabolite. To solve this difficulty, we developed a novel approach for chiral metabolomics fingerprinting and chiral metabolomics extraction, which is based on the labeling of a pair of enantiomers of chiral derivatization reagents (i.e., DMT-(S,R)-Pro-OSu and DMT-3(S,R)-Apy) and precursor ion scan chromatography of the derivatives. The multivariate statistics is also required for this strategy. The proposed procedures were evaluated by the detection of a diagnostic marker (i.e., d-lactic acid) using the saliva of diabetic patients. This method was used for the determination of biomarker candidates of chiral amines and carboxyls in Alzheimer's disease (AD) brain homogenates. As the results, l-phenylalanine (L-Phe) and l-lactic acid (L-LA) were identified as the decreased and increased biomarker candidates in the AD brain, respectively. Therefore, the proposed approach seems to be helpful for the determination of non-target chiral metabolomics possessing amines and carboxyls.     

Synthesis,structure, and catalase-like activity of a novel manganese(II) complex: Dichloro[1,3-bis(2′-benzimidazolylimino)isoindoline]manganese(II)

Reaction of the ligand 1,3-bis(2′-benzimidazolylimino)isoindoline with manganese(II) chloride in acetonitrile/methanol leads to the novel mononuclear manganese(II) complex 1,3-bis(2′-benzimidazolylimino)isoindolinedichloro manganese(II) [Mn(bimindH)Cl₂], which has been characterized by various techniques such as elemental analysis, IR, UV–Vis, ESR spectroscopy, and X-ray diffraction. The ligand bimindH was synthesized by fusing phthalonitrile and 2-aminobenzimidazole at high temperature until ammonia evolution ceased. The catalase-like activity of the complex was tested in propionitrile, and it proved to be active in the dihydrogen peroxide dismutation. Based on kinetic studies the reaction is first-order in relation to both the complex and hydrogen peroxide.     

Development of a method for urine bikunin/urinary trypsin inhibitor (UTI) quantitation and structural characterization: Application to type 1 and type 2 diabetes

Bikunin is a plasma proteinase inhibitor often associated with inflammatory conditions. It has a half‐life of few minutes and it is rapidly excreted into urine as urinary trypsin inhibitor (UTI). UTI levels are usually low in healthy individuals but they can increase up to tenfold in both acute and chronic inflammatory diseases. This article describes a sensitive method for both direct UTI quantitation and structural characterization. UTI purification was performed by anion exchange micro‐chromatography followed by SDS‐PAGE. A calibration curve for protein quantitation was set up by using a purified UTI fraction. UTI identification and structural characterization was performed by Nano‐LC‐MS/MS analysis. The method was applied on urine samples from 9 patients with type 1 diabetes, 11 patients with type 2 diabetes, and 28 healthy controls, matched for age and sex with patients, evidencing higher UTI levels in both groups of patients with respect to controls (p < 0.001 and p = 0.001, respectively). Spearman's correlation tests highlighted no association between UTI levels and age in each group tested. Owing to the elevated sensitivity and specificity, the described method allows UTI quantitation from very low quantities of specimen. Furthermore, as UTI concentration is normalized for creatinine level, the analysis could be also performed on randomly collected urine samples. Finally, MS/MS analysis prospects the possibility of characterizing PTM sites potentially able to affect UTI localization, function, and pathophysiological activity. Preliminary results suggest that UTI levels could represent a useful marker of chronic inflammatory condition in type 1 and 2 diabetes.     

High-performance liquid chromatographic method for the determination of a novel leukotriene D4 antagonist (MK-0571) in biological specimens

A rapid, sensitive and selective liquid chromatographic procedure was developed to quantitate the levels of a novel leukotriene D4 antagonist, MK-0571 (I), in biological samples. The method involves the addition of an internal standard, an analogue of I, and methanol to the biological matrix. Following centrifugation the supernatant is chromatographed isocratically on a C18 reversed-phase column and the acids are detected with an ultraviolet detector. The sensitivity of the method is such that 50 ng of drug can be quantitated per aliquot of sample. Assays were linear over a 0.06-40.0 micrograms range and exhibited a recovery of 100.5 +/- 7.0% (mean +/- S.D.) over this range. This procedure was utilized to monitor plasma, liver and urinary levels of I in chronic and acute toxicity studies in several animal species.     

Protective effect of total aralosides of Aralia elata (Miq) Seem (TASAES) against diabetic cardiomyopathy in rats during the early stage, and possible mechanisms

Total aralosides of Aralia elata (Miq) Seem (TASAES) from Chinese traditional herb Longya Aralia chinensis L was found to improve cardiac function. The present study was to determine the protective effects of TASAES on diabetic cardiomyopathy, and the possible mechanisms. Therefore, a single dose of streptozotocin was used to induce diabetes in Wister rats. Diabetic rats were immediately treated with low, medium and high doses of TASAES at 4.9, 9.8 mg/kg and 19.6 mg/kg body weight by gavage, respectively, for eight weeks. Cardiac function was evaluated by in situ hemodynamic measurements, and patch clamp for the L-type Ca²⁺ channel current (I_Ca²⁺-L) and transient outward K⁺ channel current (I_to). Histopathological changes were observed under light and electron microscope. The expression of pro-fibrotic factor, connective tissue growth factor (CTGF) was monitored using immunohistochemistry staining. Compared with diabetic group, medium and high doses, but not low dose, of TASAES showed a significant protection against diabetes-induced cardiac dysfunction, shown by increased absolute value of left ventricular systolic pressure (LVSP) and maximum rates of pressure development (±dp/dt_max), and enhanced amplitude of I_Ca²⁺-L (P < 0.05). Histological staining indicated a significant inhibition of diabetes-caused pathological changes and up-regulation of CTGF expression (P < 0.05). The results suggest that TASAES prevents diabetes-induced cardiac dysfunction and pathological damage through up-regulating I_Ca²⁺-L in cardiac cells and decreasing CTGF expression.     

Synthesis and antimicrobial activities of novel quinazolin-4(3H)-one derivatives containing a 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole moiety

A series of novel quinazolin-4(3H)-one derivatives (6a–6y) containing a 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole moiety were designed and synthesized, and their structures were fully characterized by ¹H NMR, ¹³C NMR, HRMS and IR spectra. Among them, the structure of compound 6u was unambiguously confirmed via single crystal X-ray diffraction analysis. The obtained bioassay results showed that compounds 6h, 6k, 6l and 6y had the EC₅₀ (half-maximal effective concentration) values of 34.8, 28.2, 41.5 and 42.5 μg/mL against the phytopathogenic bacterium Xanthomonas oryzae pv. oryzae (Xoo), respectively, which were significantly better than commercial bactericide Bismerthiazol (EC₅₀ = 95.8 μg/mL). Additionally, compounds 6a and 6b exhibited the strong inhibition activity against the pathogen Xanthomonas axonopodis pv. citri (Xac).     

Electrochemical Characterization of Nickel Electrodes in Phosphate and Carbonate Electrolytes in View of Assessing a Medical Diagnostic Device for the Detection of Early Diabetes

In view of optimizing a multi‐electrode device using proprietary technology for noninvasive assessment of eccrine sweat gland activity and thus the early detection of diabetes, we thoroughly explored the electrochemical behavior of a nickel electrode in a three‐electrode set up combining a nickel counter electrode and a nickel pseudo‐reference electrode in synthetic buffered phosphate and carbonate solutions in presence of chloride, lactate and urea that mimic the composition of physiological sweat. This approach provides insight into the origin of the onset of responses measured upon the application of low voltage potential with variable amplitudes to Ni electrodes on the skin. For low voltage amplitude of ca. ΔE=0.6 V, the electrochemical reactions measured at the electrodes are those related to the oxidation of Ni leading to the formation of a passive layer, as well as the reduction of this passive layer. For voltage amplitude higher than 1 V, or current densities higher than 1 mA/cm², the breakdown of the passive layer becomes the main electrochemical anodic reaction, while its reduction and the electrolytic solution govern the cathode reactions. This brings explanation of the nonlinear current‐voltage features measured during the clinic tests. Finally, the obtained results make possible the definition of the experimental electrochemical conditions where the Ni electrodes can be renewed.