Covalent and noncovalent interactions of coordination compounds with DNA: An overview.

Deoxyribonucleic acid plays a central role in crucial cellular processes, and many drugs exert their effects through binding to DNA. Since the discovery of cisplatin and its derivatives considerable attention of researchers has been focused on the development of novel anticancer metal-based drugs. Transition metal complexes, due to their great diversity in size and structure, have a big potential to modify DNA through diverse types of interactions, making them the prominent class of compounds for DNA targeted therapy. In this review we describe various binding modes of metal complexes to duplex DNA based on covalent and noncovalent interactions or combination of both. Specific examples of each binding mode as well as possible cytotoxic effects of metal complexes in tumor cells are presented.

Oxidative Stress Markers and Their Dynamic Changes in Patients after Acute Ischemic Stroke.

We have focused on determining the range of oxidative stress biomarkers and their dynamic changes in patients at different time points after the acute ischemic stroke (AIS). 82 patients with AIS were involved in our study and were tested: within 24 h from the onset of the attack (group A); at 7-day follow-up (group B); and at 3-month follow-up (group C). 81 gender and age matched volunteers were used as controls. Stroke patients in group A had significantly higher concentrations of plasma lipid peroxides and urine 8-isoprostanes when compared with controls. Protein carbonyls were not significantly different in any experimental group compared to controls. Antioxidant capacity of plasma was increased only in experimental group C. Activities of superoxide dismutase and catalase were elevated in all three experimental AIS groups compared to controls. Paraoxonase activity was reduced in groups A and B and unchanged in group C when compared to controls. Glutathione peroxide activity was elevated only in group A. Our results suggest that free radical damage is the highest within 24 h after the attack. During the next 3 months oxidative damage to lipids caused by free radicals is reduced due to activated antioxidant system.

Autophagy in MCF-7 cancer cells induced by copper complexes.

BACKGROUND: Autophagy plays an important role in cancer cells. Targeting autophagy in cancer can provide new opportunities for drug development. METHODS: In this study we tested four Schiff base Cu(II) complexes against human breast cancer cells (MCF-7) and human non-cancerous cells (HEK-293T). We have tested their cytotoxic effect by evaluating IC50 using MTT test. To detect morphological changes of the actin fibers we have used fluorescent microscopy. To determine the type of cell death we used electrophoretic analysis and western blot analysis (protein LC3). RESULTS: IC50 values of the complexes increased with time of their influence, indicating acquired resistance of MCF-7 to the complexes. Healthy cells HEK-293T were not sensitive to the Cu(II) complexes. Compared with the control cells (cells without Cu(II) complexes) which were without morphological changes of actin fibers, Cu(II) complexes induced condensation and asymmetric conformational changes in actin filaments. To examine the type of cell death induced by the Cu(II) complexes we treated MCF-7 cells with Cu(II) complexes (1, 10, 50 and 100µmol/L) during a 72h incubation period. By electrophoresis we have not detected any DNA fragmentation. To determine whether Cu(II) complexes induced autophagy or necrotic cell death we used the western blot analysis. MCF-7 cells influenced with tested Cu(II) complexes produced LC3 protein after their 72h incubation indicating autophagy in MCF-7 cancer cells. CONCLUSIONS: Tested Schiff base copper (II) complexes have antiproliferative activity against cancer cells but not against healthy cells. They have induced autophagy in the cancer cell line MCF-7.

Effect of Schiff base Cu(II) complexes on signaling pathways in HT-29 cells.

Schiff base copper (II) complexes are known for their anticancer, antifungal, antiviral and anti­inflammatory activities. The aim of the current study was to investigate biological effects of Schiff base Cu (II) complexes (0.001­100 µmol/l)­[Cu2(sal­D, L­glu)2(isoquinoline)2]·2C2H5OH (1), [Cu(sal­5­met­L­glu)(H2O)].H2O (2), [Cu(ethanol)2(imidazole)4][Cu2(sal­D, L-glu)2(imidazole)2] (3), [Cu(sal­D,L­glu)(2­methylimidazole)] (4) on the human colon carcinoma cells HT­29, the mouse noncancerous cell line NIH­3T3 and the human noncancerous fibroblast cell line VH10. The results suggested that Cu (II) complexes exhibit cytotoxic effects against the HT­29 cell line, while complexes 3 and 4 were the most effective. Subsequent to 72 h of incubation, apoptosis was observed in the HT­29 cells induced by Cu (II) complexes 1 (0.1, 1, 10 and 50 µmol/l), 2 (1, 10, 50 and 100 µmol/l), 3 (0.01, 1, 10 and 50 µmol/l) and 4 (0.01, 0.1, 1 and 10 µmol/l). The apoptotic pathways activated by the Cu (II) complexes were identified. The results indicated that complexes 2, 3 and 4 were able to induce the mitochondria­dependent pathway of apoptosis in HT­29 cells, while complex 1 was obsered to activate the extrinsic pathway of apoptosis. The levels of the anti­apoptotic protein Bcl­2 were reduced and those of the pro­apoptotic protein Bax increased following treatment with complexes 2, 3 and 4. Complex 1 had no effect on Bax protein expression. Complexes 2 and 3 induced elevation of cytochrome c (cyt c), while complex 4 induced a time­dependent elevation of cyt c levels. No cyt c was detected in HT­29 cells exposed to complex 1, suggesting that Cu (II) complexes activated the extrinsic pathway of apoptosis. The results from the current study in addition to previous studies suggest that Schiff base Cu (II) complexes have potential as novel anticancer drugs.

High density lipoprotein subfractions and paraoxonase 1 in children.

The Lipoprint system (Quantimetrix Corp., CA, USA), enables the determination of 10 high density lipoprotein (HDL) subfractions in contrast to the 5 HDL subfractions that can be determined by ultracentrifuge analysis. HDL subfractions, and their relationships to the arylesterase (PON1-A) and lactonase (PON1-L) activities of paraoxonase 1 (PON1), together with total-, very low density lipoprotein- and low density lipoprotein (LDL)-cholesterol and LDL subfractions were investigated in the serum of 27 mildly hypercholesterolemic children and 21 healthy controls. Our results suggest the antiatherogenity of large HDL (L-HDL) subfractions and the atherogenity of small HDL (S-HDL) subfractions in the study groups. However, the relationship between the intermediate HDL (I-HDL) subfractions with the LDL subfractions and other lipoproteins did not suggest that I-HDL subfractions are antiatherogenic. No significant association between PON1-A and the HDL subfractions was found. In contrast, PON1-L activity positively correlated with the antiatherogenic large HDL1 subfraction and negatively with intermediate HDL subfractions 4, 5 and 6. Our results contribute to the knowledge of the roles of total HDL and ten individual HDL subfractions in children and adolescents.

Influence of oak wood polyphenols on cysteine, homocysteine and glutathione total levels and PON1 activities in human adult volunteers - a pilot study.

Oxidative stress reflects an imbalance between antioxidants and pro-oxidants. Many diseases like atherosclerosis or heart failure are involved in oxidative stress. Increased oxidative stress is one of the potential contributing factors to aging. The aim of this study was to monitor the total thiol levels as markers of oxidative stress in 20 healthy volunteers after polyphenols intake (extract from the French oak wood Quercus robur - Robuvit® (300 mg/day)). Polyphenols are known as biomodulators with antioxidant activities. Homocysteine, cysteine and glutathione total levels were determined by using HPLC with electrochemical detection. The activity of the antioxidant enzyme paraoxonase-1 toward two substrates was determined by spectrophotometry. The level of thiol compounds and paraoxonase-1 activities were controlled after run-in (week 0), intervention (week 4) and washout (week 6) period. After the intervention period the results showed that Robuvit® had no significant influence on glutathione level (p = 0.382) and paraoxonase activities towards both, arylester and lactone substrates. On the other hand, homocysteine and cysteine levels decreased significantly (p = 0.029; p < 0.001, respectively). The negative correlation between paraoxonase lactonase activity and homocysteine level was noticed. This confirms that paraoxonase might play an important role in homocysteine-thiolactone metabolism.

Paraoxonase 1 and HDL subfractions in hypercholesterolemic children and adolescents.

BACKGROUND: Assessment of the cardiovascular disease (CVD) risk factors in children can predict clinical manifestations of atherosclerosis in adulthood. The arylesterase (PON1-A) and lactonase (PON1-L) activities of paraoxonase 1 (PON1) and lipid parameters (Total cholesterol (TCH), VLDL-cholesterol (VLDL), triacylglycerols (TAG), HDL-cholesterol (HDL), LDL-cholesterol (LDL) and LDL- and HDL-subfractions and their mutual associations in 27 hypercholesterolemic children and adolescents were investigated. METHODS: Serum levels of TCH and TAG were determined using a Hitachi 911 analyser (Roche Diagnostics, Switzerland). LDL- and HDL-subfractions were determined by Lipoprint® system (Quantimetrix, Corp., USA). PON1-A and PON1-L activities were determined according to Gan et al. (1991) and Aviram and Rosenblat (2008). RESULTS: PON1-A activity was higher compared to healthy children (134.1±26.2 vs. 118.16±7.05 U/ml) and PON1-L was not different from healthy controls. Increased levels of atherogenic risk factors TCH, VLDL, IDL1 subfraction and decreased levels of the antiatherogenic IDL3 and LDL1 subfractions were observed in the hypercholesterolemic children compared to reference values. Increased levels of large HDL subfractions, comparable levels of intermediate HDL and lower levels of small HDL subfractions were observed in hypercholesterolemic children compared to healthy adults (in absence of data available for healthy children). No significant correlation between PON1-A and HDL subfractions was found. PON1-L activity positively correlated with antiatherogenic large HDL1 subfraction and negatively correlated with intermediate HDL4, 5 and 6 subfractions. CONCLUSIONS: The findings suggest that the PON1-L activity rather than PON1-A activity play a protective role in atherosclerosis. We confirmed atheroprotective effect of large and atherogenic properties of small HDL subfractions. The intermediate HDL subfractions probably play no atheroprotective role.

Effect of the Schiff base complex diaqua-(N-salicylidene-l-glutamato)copper(II) monohydrate on human tumor cells.

The aim of our study was to estimate cytostatic/cytotoxic activity of the copper(II) Schiff base complex of the composition [Cu(N-salicylidene-l-glutamato)(H2O)2]·H2O, further Cu(SG-L)H2O, against human colon carcinoma cell line HT-29, as well as to determine type of cell death and to find out the molecular mechanism of apoptosis induced by this complex. Two highest concentrations (50, 100 µmol/l) of the complex showed a strong cytotoxic activity against human colon carcinoma cells HT-29 after 72 h of influence. Other concentrations had a cytostatic activity. Unchelated copper(II) ions and free ligands had no effect on the cell growth. Cu(SG-L)H2O preferentially reduced cancer cell viability compared to healthy cells (NIH-3T3). Cu(SG-L)H2O induced apoptosis of cells HT-29 at all concentrations used (1-100 µmol/l) after 48 h of influence. Apoptosis was carried out by the mitochondrial pathway with active caspases 3 and 9. By the spin-trapping technique combined with electron paramagnetic resonance we found that our complex is photochemically stable in aqueous systems and does not exhibit radical-scavenging activity when 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) cation radical was used as an oxidant. The complex exhibits a strong prooxidant property in the initial stages of thermal decomposition of K2S2O8 in water solutions leading to the massive production of (·)OH radicals. Therefore, this complex could strongly participate in anticancer action via a free radical mechanism.

DNA damage induction and antiproliferative activity of vanadium(V) oxido monoperoxido complex containing two bidentate heteroligands.

Several peroxidovanadium(V) complexes have been shown as a potent anticancer agents. The aim of this study was to investigate the interaction of monoperoxidovanadium(V) complex Pr(4)N[VO(O(2))(ox)(phen)], (Vphen), [phen=1,10-phenantroline, ox=oxalate(2-) and Pr(4)N=tetra(n-propyl)ammonium(1+)] with DNA. UV-Vis spectrophotometry and the alkaline single-cell gel electrophoresis (SCGE, the comet assay) were used to examine the possibility of the vanadium(V) complex to induce changes in DNA. The interaction of Vphen with calf thymus DNA resulted in absorption hyperchromicity in DNA spectrum and shift of the absorption band of DNA to longer wavelengths for the [complex]/[DNA] concentration ratio equals to 4 and after 60 min of incubation. The rise in DNA absorption (by 34%) and bathochromic shift (Δλ(max)=6 nm) are indicative of the interaction between DNA and the complex molecules. DNA strand breaks in cellular DNA were investigated using the comet assay. The human lymphocytes were exposed to various concentrations of Vphen for 30 min. The results revealed that Vphen contributed to the DNA damage expressed as DNA strand breaks in concentration dependent manner. The used concentrations of Vphen (ranging from 0.1 to 100 µmol/L) caused higher DNA damage in lymphocytes compared to untreated cells (from 1.2 times for 0.1 µmol/L to 1.8 times for 100 µmol/L). Vphen was screened for its potential antitumor activity towards murine leukemia cell line L1210. Vphen exhibited significant antiproliferative activity depending on its concentration and time of exposure. The IC(50) values were 0.247 µg/mL (0.45 µmol/L) for 24h, 0.671 µg/mL (1.21 µmol/L) for 48 h and 0.627 µg/mL (1.13 µmol/L) for 72 h.

X-ray and DFT studies of a mono- and binuclear copper(II) ionic compound containing a Schiff base.

In the structure of trans-bis(ethanol-κO)tetrakis(1H-imidazole-κN(3))copper(II) bis[µ-N-(2-oxidobenzylidene)-D,L-glutamato]-κ(4)O(1),N,O(2'):O(2');κ(4)O(2'):O(1),N,O(2')-bis[(1H-imidazole-κN(3))cuprate(II)], [Cu(C(3)H(4)N(2))(4)(C(2)H(6)O)(2)][Cu(2)(C(15)H(14)N(3)O(5))(2)], both ions are located on centres of inversion. The cation is mononuclear, showing a distorted octahedral coordination, while the anion is a binuclear centrosymmetric dimer with a square-pyramidal copper(II) coordination. An extensive three-dimensional hydrogen-bonding network is formed between the ions. According to B3LYP/6-31G* calculations, the two equivalent components of the anion are in doublet states (spin density located mostly on Cu(II) ions) and are coupled as a triplet, with only marginal preference over an open-shell singlet.

Oxidative stress in women with perimenopausal symptoms.

OBJECTIVE: In this study, we examined the relationships between perimenopausal symptoms, biochemical parameters, and markers of oxidative stress in women in perimenopause and compared them with those of premenopausal women. METHODS: Sixty-two women (age, 53.2 ± 5.7 y) with perimenopausal symptoms were recruited to participate in our study. The control group consisted of 18 women without perimenopausal symptoms (age, 40 ± 5 y).Clinical perimenopausal symptoms were evaluated via the questionnaire of the Menopausal Rating Scale. Our participants were checked for basic biochemical parameters. The oxidative status of our samples was determined through the examination of lipoperoxides, 8-oxoguanine (8-oxoG) levels, and the total antioxidant status (TAS). RESULTS: Perimenopausal women had higher total cholesterol values and lower paraoxonase-1 (PON1) activity compared to reference values. Other biochemical parameters as well as 8-oxoG levels were unchanged compared with those of healthy control women. Lipoperoxide levels were significantly increased compared with those of premenopausal women. We found an indirect correlation between PON1 arylesterase (PON1 A) activity and lipoperoxide levels, between PON1 A activity and atherogenic index, between age and TAS, and between age and 8-oxoG levels. DNA repair ability and the total antioxidant status of women in perimenopause were significantly increased compared with women in premenopause. Hypercholesterolemic women had significantly increased low-density lipoprotein cholesterol levels when compared with normocholesterolemic individuals, but these values were still within the reference range. Normocholesterolemic women had significantly decreased high-density lipoprotein cholesterol levels, below the reference range. We found no correlations between perimenopausal symptoms and biochemical parameters or oxidative stress markers. CONCLUSIONS: We found that women in perimenopause are under increased oxidative stress manifested by reduced PON1 A activity and elevated lipoperoxidation, DNA repair ability, and TAS. Nutritional antioxidant supplementation may be an effective approach in improving menopausal symptoms.