DNA Hydrolysis by Homo- and Heteronuclear Cu(II)–Ni(II) Complexes of Two Diester-type Ligands

Nucleolytic activities of novel mononuclear Cu(II), homo- and heterodinuclear Cu(II)–Ni(II) complexes with two diester-type ligands were investigated on pCYTEXP by neutral agarose gel electrophoresis. The analyses of the cleavage products obtained electrophoretically indicate that the examined complexes induce very similar conformational changes on supercoiled DNA by converting supercoiled form to nicked form. At concentrations greater than 100M, the complexes possessed effective nucleolytic activities for 10min of incubation time. However, their nucleolytic activities did not increase significantly with longer periods of incubation. The pH-nucleolytic activity profiles of the complexes differed significantly. Metal complex induced DNA cleavage was also tested for inhibition by various radical scavengers. It could be proposed from the data that diffusible intermediate oxidants are not involved in these reactions or they are not necessary for DNA cleavage since none of antioxidants inhibited DNA cleaving activities of the complexes.     

Synthesis and structural studies of (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}pyridin-2-yl)imino]butan-2-one oxime, ligand and its mono-, di- and trinuclear copper(II) complexes

A new dioxime ligand, (2E,3E)-3-[(6-{[(1E,2E)-2-(hydroxyimino)-1-methylpropylidene]amino}-pyridin-2-yl)imino]butan-2-one oxime, (H₂Pymdo) (3) has been synthesized in H₂O by reacting 2,3-butenedione monoxime (2) with 2,6-diaminopyridine. Mono-, di- and tri-nuclear copper(II) complexes of the dioxime ligand (H₂Pymdo) and/or 1,10-phenanthroline have been prepared. The dioxime ligand (H₂Pymdo) and its copper(II) complexes were characterized by ¹H-n.m.r., ¹³C-n.m.r. and elemental analyses, magnetic moments, i.r. and mass spectral studies. The mononuclear copper(II) complex of H₂Pymdo was found to have a 1:1 metal:ligand ratio. Elemental analyses, stoichiometric and spectroscopic data of the metal complexes indicated that the metal ions are coordinated to the oxime and imine nitrogen atoms (C=N). In the dinuclear complexes, in which the first Cu(II) ion was complexed with nitrogen atoms of the oxime and imine groups, the second Cu(II) ion is ligated with dianionic oxygen atoms of the oxime groups and are linked to the 1,10-phenanthroline nitrogen atoms. The trinuclear copper(II) complex (6) was formed by coordination of the third Cu(II) ion with dianionic oxygen atoms of each of two molecules of the mononuclear copper(II) complexes. The data support the proposed structure of H₂Pymdo and its Cu(II) complexes.     

Phenolic compounds from the aerial parts of Clematis viticella L. and their in vitro anti-inflammatory activities*

Phytochemical investigations on the EtOH extract of Clematis viticella led to the isolation of six flavonoid glycosides, isoorientin (1), isoorientin 3′-O-methyl ether (2), quercetin 7-O-α-L-rhamnopyranoside (3), quercetin 3,7-di-O-α-L-rhamnopyranoside (4), manghaslin (5) and chrysoeriol 7-O-β-D-glucopyranoside (6), one phenylethanol derivative, hydroxytyrosol (7), along with three phenolic acids, caffeic acid (8), (E)-p-coumaric acid (9) and p-hydroxybenzoic acid (10). The structures of the isolates were elucidated on the basis of NMR and HR-MS data. All compounds were isolated from C. viticella for the first time. Compounds 7 and 8 showed significant anti-inflammatory activity at 100 μM by reducing the release of NO in LPS-stimulated macrophages comparable to positive control indomethacin. Compounds 3 and 7 exhibited anti-inflammatory activity through lowering the levels of TNF-α while 1, 3 and 5 decreased the levels of neopterin better than the positive controls.     

Synthesis and characterization of SPE membrane based on sulfonated FEP‐g‐acrylic acid by radiation induced graft copolymerization for PEM fuel cell

A Novel solid polymer electrolyte (SPE) membrane containing both ? COOH and ? SO₃H group has been prepared by simultaneous method of radiation grafting of acrylic acid onto FEP followed by sulfonation. The presence of weakly acidic acrylic acid controls the swelling in water while ? SO₃H group provides conductivity due to its strongly ionic characteristic. FEP‐g‐acrylic acid and its sulfonated derivatives were characterized by their properties. While the mechanical properties decreased, other properties such as ion exchange capacity (IEC), water uptake and ionic conductivity increased with increase in graft content. These properties further changed on sulfonation. Acrylic acid being weakly acidic in nature, conductivity values of the grafted membrane were quite low. However, introduction of strong ? SO₃H group resulted in conductivity closer to Nafion 117. Few sulfonated membranes have been tested with respect to H₂/O₂ fuel cell performance. Short‐term fuel cell test for 100 hr gave a stable performance. These membranes are less expensive compared to Nafion. Copyright © 2004 John Wiley & Sons, Ltd.     

Polymeric copper(II) and nickel(II) complexes of a tetraoxime containing a binucleating macrocycle ligand

Polymeric copper(II) and nickel(II) complexes of a binucleating tetraoxime macrocycle, 6,6-methylene-bis[1,12-di(hydroximino)- 2,3;9,10-dibenzo-1,11-diaza-4,8-dithiacyclotridecane] (H4L), have been prepared and characterised by elemental analysis, magnetic moments, i.r., uv/vis., and e.p.r. spectral studies. I.r. spectra show that the ligand acts in a tetradentate manner and coordinates via N, S and O donor atoms. The geometry of the resulting metal chelates is discussed with the help of magnetic and spectroscopic measurements. The elemental analyses, stoichiometry and the spectroscopic data of the complexes indicate that the copper(II) and nickel(II) ions are coordinated by the coordination environment of the ligand. The spectral data suggest a distorted tetragonal geometry for polymeric copper(II), and nickel(II) ions in the complexes. The stoichiometry of the metal-to- H4L ratio of complexes (2) and (3), prepared from CuCl2 and NiCl2 respectively, was 3:1, suggesting the formation of polymeric species.     

Microencapsulated oleic–capric acid/hexadecane mixture as phase change material for thermal energy storage

Journal of Thermal Analysis and Calorimetry - Thermal energy storage systems provide efficiency in order to have better utilization of energy sources while protecting the environment. Thermal...     

Facile syntheses of (−)-montagnetol and (−)-erythrin

A novel synthetic method is introduced to prepare the biologically important montagnetol and erythrin compounds starting from a 1,3-benzodioxin-4-one, synthesized from commercially available orsellinic acid and erythritol.     

Development of a validated high-performance thin-layer chromatography method for the standardization of an Ayurvedic formulation using berberine and ursolic acid

Giloy Tulsi tablet is an Ayurvedic preparation containing Tinospora cordifolia (Giloy) and Ocimum sanctum (Tulsi) and it is recommended for boosting the body’s immune response. This research work is about the marker-based standardization of this Ayurvedic preparation using high-performance thin-layer chromatography method. Standardization is based on the determination and quantification of the phytoconstituents berberine and ursolic acid present in Giloy Tulsi tablets. Separation was performed on pre-coated silica gel 60 F₂₅₄ plate as the stationary phase, with chloroform‒acetone‒formic acid (6:3.5:0.5, V/V) as the mobile phase. Identification and quantification were conducted densitometrically at 330 nm. The developed method resulted in good quality peak shape and enabled high-quality resolution of biomarkers. The R_F value for berberine (0.46 ± 0.02) and for ursolic acid (0.68 ± 0.02) in both reference standard and formulation were found to be comparable. The method was validated for specificity, linearity, limit of detection, limit of quantification, intra-day and inter-day precisions, accuracy, and robustness. The limit of detection values were 91 and 153 ng/band for berberine and ursolic acid, respectively. The limit of quantification values were 175 and 465 ng/band for berberine and ursolic acid, respectively. Regression analysis of the calibration data revealed a good linear relationship between peak area response and concentration in the range 200‒1000 ng/band for berberine (r² = 0.995) and 500‒2500 ng/band for ursolic acid (r² = 0.9968). The accuracy of the method, determined by measurement of recovery at three different levels, was in the range 98‒102% for both markers. These results are indication of reliability, reproducibility, accuracy, and precision of the method.