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The synthesis and characterization of [Cu(5-Me-2-tpc)2(4-pyme)2] (I), [Cu(3-Me-2-tpc)2(4-pyme)2] (II), [Cu(2-tpc)2(4-pyme)2] (III), [Cu(2-tpc)2(isonia)2(2-tpcH)] (IV), [Cu(5-Me-2-tpc)2(isonia)2(5-Me-2-tpcH)] (V), [Cu2(2-tpc)4(4-pyme)2] (VI), [Cu2(3-Me-2-tpc)4(isonia)2] (VII) (where 2-tpc is 2-thiophenecarboxylate, 3-Me-2-tpc is 3-methyl-2-thiophenecarboxylate, 5-Me-2-tpc is 5-methyl-2-thiophenecarboxylate and 4-pyme is 4-pyridinemethanol and isonia is isonicotinamide) are reported. The complexes under study were characterized by electronic, IR and EPR spectroscopy, magnetic susceptibility over the temperature range and X-ray structure analysis. Structural studies revealed a distorted tetragonal-bipyramidal environment around the copper ion for monomeric complexes I–V. The structure of dimeric complexes VI and VII consists of units of the known paddle-wheel dicopper(II) tetracarboxylates, which are made up of four thiophene-2-carboxylate ions thus bridging the two copper atoms. The complex molecules of all compounds are connected through H-bonds into supramolecular chains or frameworks. The spectral and magnetic properties are discussed with regard to X-ray data.

Medicinal plants are a significant source of biological active and health protective compounds. Post-harvest treatments can affect, in different ways, the content and biological activity of such compounds. One of the most common post-harvesting methods is drying. In this study, we investigated the effect of drying method on the content of natural pigments (chlorophylls, carotenoids and anthocyanins) and on the antioxidant capacity of two traditionally used herbs, the Melissa officinalis(lemon balm) and the Urtica dioica(stinging nettle) both of them landraces collected from plants grown in Nitra region, West of Slovakia. The freeze-dried samples of both herbs exhibited the highest content of chlorophyll a(7.55 ± 0.13 mg/g dry mass for lemon balm and 9.41 ± 0.17 mg/g dry mass for stinging nettle), chlorophyll b(3.12 ± 0.28 mg/g dry mass for lemon balm and 3.34 ± 0.24 mg/g dry mass for stinging nettle) and carotenoids (2.11 ± 0.24 mg/g dry mass for lemon balm and 2.62 ± 0.06 mg/g dry mass for stinging nettle). The content of chlorophylls and carotenoids correlated with the DPPH antioxidant (radical scavenging) capacity. Higher antioxidant capacity of the lemon balm extracts compared to nettle samples was attributed to the higher content of polyphenol compounds anthocyanins. Despite the higher cost, the freeze drying (lyophilisation) was recommended as the most suitable drying method, mainly for reasons of preserving maximum pigment content and antioxidant capacity.

Nicotinamide was employed as a supramolecular reagent in the synthesis of six new copper(II) bromo-, iodo-, fluoro- and dibromobenzoate complexes. Structures of [Cu(2-Brbz)2(nia)2(H2O)2] (I), [Cu(2-Ibz)2(nia)2(H2O)2] (II), [Cu(2-Fbz)2(nia)2(H2O)2] (III), [Cu(4-Brbz)2(nia)2(H2O)2](IV), [Cu(3,5-Br2 bz)2(nia)2(H2O)2] (V), [Cu(F-Fbz)2(nia)2(H2O)] ·H2O (VI) (nia = nicotinamide, 2-Brbz = 2-bromobenzoate, 4-Brbz = 4-bromobenzoate, 3,5-Br2bz = 3,5-dibromobenzoate, 2-Ibz = 2-iodobenzoate, 2-Fbz = 2-fluorobenzoate, 4-Fbz = 4-fluorobenzoate) were determined using X-ray analysis. Compound [Cu(2-Brbz)2(nia)2] ·2H2O (VII) was prepared by a new method and also characterized by X-ray powder diffraction and EPR spectroscopy. Compounds I–Vare monomeric complexes with a square-bipyramidal coordination sphere around the Cu2+ion. Complex VIis monomeric with coordination environment around the Cu2+ ion of a tetragonal-pyramid. Complexes Iand VIIpresent examples of coordination isomerism. Molecules of all compounds are connected by N—H· · ·O and O—H·· ·O hydrogen bonds from the NH2 groups of nicotinamide and water molecules which create supramolecular hydrogen-bonding-coordination chains and networks.·c 2015 Institute of Chemistry, Slovak Academy of Sciences

Nicotinamide was employed as a supramolecular reagent in the synthesis of six new copper(II) bromo-, iodo-, fluoro- and dibromobenzoate complexes. Structures of [Cu(2-Brbz)2(nia)2(H2O)2] (I), [Cu(2-Ibz)2(nia)2(H2O)2] (II), [Cu(2-Fbz)2(nia)2(H2O)2] (III), [Cu(4-Brbz)2(nia)2(H2O)2] (IV), [Cu(3,5-Br2bz)2(nia)2(H2O)2] (V), [Cu(F-Fbz)2(nia)2(H2O)] · H2O (VI) (nia = nicotinamide, 2-Brbz = 2-bromobenzoate, 4-Brbz = 4-bromobenzoate, 3,5-Br2bz = 3,5-dibromobenzoate, 2-Ibz = 2-iodobenzoate, 2-Fbz = 2-fluorobenzoate, 4-Fbz = 4-fluorobenzoate) were determined using X-ray analysis. Compound [Cu(2-Brbz)2(nia)2] · 2H2O (VII) was prepared by a new method and also characterized by X-ray powder diffraction and EPR spectroscopy. Compounds I–Vare monomeric complexes with a square-bipyramidal coordination sphere around the Cu2+ion. Complex VIis monomeric with coordination environment around the Cu2+ion of a tetragonal-pyramid. Complexes Iand VIIpresent examples of coordination isomerism. Molecules of all compounds are connected by N—H⋯O and O—H⋯O hydrogen bonds from the NH2groups of nicotinamide and water molecules which create supramolecular hydrogen-bonding-coordination chains and networks.

An innovative amperometric immunosensor has been developed to detect antibiotic colistin from the chicken liver. Colistin is a antibacterial peptide that has been barred for human consumption, but it is being commonly used as a veterinary drug, and as a feed additive for livestock. In the present work, an immunosensor was developed by immobilizing an anti-colistin Ab onto the CNF/AuNPs surface of the screen-printed electrode. The sensor records electrochemical response in the chicken liver spiked with colistin with CV. Additionally, the characterization of electrode surface was done with FE-SEM, FTIR, and EIS at each step of fabrication. The lower LOD was 0.89 μgKg−1, with a R2of 0.901 using CV. Further validation of the immunosensor was conducted using commercial chicken liver samples, by comparing the results to those obtained using traditional methods. The fabricated immunosensor showed high specificity towards colistin, which remained stable for 6 months but with a 13% loss in the initial CV current.

Iron is a redox active metal involved in the oxidation-reduction reactions and regulation of cell growth and differentiation. Iron is an integral part of many proteins and enzymes that maintains various physiological functions. Most of the human bodys iron is contained in red blood cells. Despite iron being an abundant trace metal in food, millions of people worldwide suffer from anemia. Iron deficiency results in impaired production of iron-containing proteins and inhibition of cell growth. In contrast, abnormal iron uptake has been related to the most common hereditary disease hemochromatosis, leading to tissue damage derived from free radical toxicity. In addition, disruption of iron regulation plays a key role in the etiology of Alzheimers disease, Parkinsons disease, Huntingtons disease, Friedreichs ataxia and other neurological disorders, cancer (lung cancer, breast cancer, colon cancer), Fanconi anemia, stroke and ageing. Thus the control of this necessary but potentially toxic substance is an important part of many aspects of human health and disease. The most frequent is the toxic role of iron linked with the catalytic decomposition of hydrogen peroxide (Fenton reaction) leading to the formation of reactive oxygen species (ROS) causing damage to biomolecules, including lipids, proteins and DNA. The binding of irondesigned chelators via nitrogen, oxygen or sulphur donor atoms blocks iron’s ability to catalyze the formation of free radicals. Thus the design of various metal chelators to prevent free radical reactions is an important approach in the treatment of many iron-related diseases. The development of effective dual functioning antioxidants, possessing both metal-chelating and free radical-scavenging properties is awaited. The aim of this review is to discuss the role of iron and importance of iron-chelation in human disease and ageing.

Several unsymmetrically substituted salen‐type cobalt(II) Schiff‐base complexes CoL [H2L = 1,6‐bis(2‐hydroxyphenyl)‐3,3‐dimethyl‐2,5‐diaza‐1,5‐hexadiene (1); 1,6‐bis(2‐hydroxyphenyl)‐3,3‐dimethyl‐2,5‐diaza‐1,5‐heptadiene (2); 1‐(3‐tert‐butyl‐2‐hydroxy‐5‐methylphenyl)‐6‐(2‐hydroxyphen‐yl)‐3,3‐dimethyl‐2,5‐diaza‐1,5‐heptadiene (3); 1‐(2‐hydroxyphenyl)‐6‐methyl‐2,5‐diaza‐1,5‐nonadien‐8‐one (4); 1‐(3‐tert‐butyl‐2‐hydroxy‐5‐methylphenyl)‐6‐methyl‐2,5‐di‐aza‐1,5‐nonadien‐8‐one (5); 1‐(2‐hydroxyphenyl)‐3,3,6‐trimethyl‐2,5‐diaza‐1,5‐nonadien‐8‐one (6); 1‐(3‐tert‐butyl‐2‐hydroxy‐5‐methylphenyl)‐3,3,6‐trimethyl‐2,5‐diaza‐1,5‐nonadien‐8‐one (7)] were prepared and characterized by their UV/Vis absorption spectra, magnetic moments, and oxidation potentials. Except for complex 4(irreversible oxidation with t½≈ 3 h), complexes 1–3and 5–7are remarkably resistant against irreversible auto‐oxidation in air‐saturated N,N‐dimethylformamide (DMF) at ambient temperature. To characterize the Lewis acidity of the cobalt center in 1–7, the equilibrium constant Kpywas determined for monoadduct formation with pyridine (CoL + pyCoL·py). An O2‐sensitive optode was used to determine the Henry constant, KH, for the system O2/DMF in the temperature range 298–228 K. The formation of 1:1 adducts of complexes 1–7with O2in DMF, as characterized by the equilibrium constant KO2, was followed spectrophotometrically in the temperature range 298–228 K. The parameters ΔHo, ΔSo, and KO2are reported. At 298 K, KO2ranges from 21.9 M–1(5) to 155 M–1(7). The overall spectroscopic information, including EPR spectra obtained with frozen solutions of 3 and 7in O2‐saturated DMF, confirm that the 1:1 adducts CoL·O2are cobalt(III) superoxo compounds. The symmetrically substituted salen complex8[H2L = 1,6‐bis(3‐tert‐butyl‐2‐hydroxy‐5‐methylphenyl)‐3,3,4,4‐tetramethyl‐2,5‐diaza‐1,5‐hexadiene in 8] is shown to catalyze the oxidation of triphenylphosphane and 2,6‐di‐tert‐butylphenol by O2in DMF at ambient temperature. The correlation of the data obtained for KO2, Kpy, and the oxidation potential E½is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The development of cancer in humans and animals is a multistep process. The complex series of cellular and molecular changes participating in cancer development are mediated by a diversity of endogenous and exogenous stimuli. One type of endogenous damage is that arising from intermediates of oxygen (dioxygen) reduction—oxygen-free radicals (OFR), which attacks not only the bases but also the deoxyribosyl backbone of DNA. Thanks to improvements in analytical techniques, a major achievement in the understanding of carcinogenesis in the past two decades has been the identification and quantification of various adducts of OFR with DNA. OFR are also known to attack other cellular components such as lipids, leaving behind reactive species that in turn can couple to DNA bases. Endogenous DNA lesions are genotoxic and induce mutations. The most extensively studied lesion is the formation of 8-OH-dG. This lesion is important because it is relatively easily formed and is mutagenic and therefore is a potential biomarker of carcinogenesis. Mutations that may arise from formation of 8-OH-dG involve GC → TA transversions. In view of these findings, OFR are considered as an important class of carcinogens. The effect of OFR is balanced by the antioxidant action of non-enzymatic antioxidants as well as antioxidant enzymes. Non-enzymatic antioxidants involve vitamin C, vitamin E, carotenoids (CAR), selenium and others. However, under certain conditions, some antioxidants can also exhibit a pro-oxidant mechanism of action. For example, β-carotene at high concentration and with increased partial pressure of dioxygen is known to behave as a pro-oxidant. Some concerns have also been raised over the potentially deleterious transition metal ion-mediated (iron, copper) pro-oxidant effect of vitamin C. Clinical studies mapping the effect of preventive antioxidants have shown surprisingly little or no effect on cancer incidence. The epidemiological trials together with in vitroexperiments suggest that the optimal approach is to reduce endogenous and exogenous sources of oxidative stress, rather than increase intake of anti-oxidants. In this review, we highlight some major achievements in the study of DNA damage caused by OFR and the role in carcinogenesis played by oxidatively damaged DNA. The protective effect of antioxidants against free radicals is also discussed (Mol Cell Biochem 266:37–56, 2004)