Zoltán May

Catalytic activation of dioxygen by oximatocobalt(II) and oximatoiron(II) complexes for catecholase-mimetic oxidations of o-substituted phenols

Bis(dimethylglyoximato)cobalt(II) and -iron(II) complexes, referred to as cobaloxime(II) and ferroxime(II), respectively, containing rigid equatorial macrocycles stabilized by hydrogen bonding, are functional catecholase and phenoxazinone synthase models, but show no catechol dioxygenase type activity. We have studied the oxidation of 3,5-di-tert-butylcatechol (DBCatH2) and 2-aminophenol (AP) as model substrates with the objective of elucidating the mechanisms of these reactions, using a combination of techniques including identification of free-radical intermediates by ESR spectroscopy and UV–vis spectrophotometry of semiquinone anion radical adducts of cobaloxime and ferroxime species. Detailed kinetic studies of the catecholase-mimetic oxidations reveal a general mechanistic pattern involving reversible formation of ternary catalyst–substrate–dioxygen complexes, which are key intermediates capable of H-atom abstraction from the substrates. The resulting semiquinone anion-radical intermediate and its adducts with the catalyst complexes have been detected by ESR spectroscopy. They contain a unidentate catecholato ligand as shown by the adduct of cobaloxime(II), which has been isolated and characterized by X-ray diffraction. Our work has led to the conclusion that the lack of catechol dioxygenase activity in the case of ferroxime(II) is due to the rigid equatorial macrocycle, which prevents bidentate catechol coordination. To further test this hypothesis, we have synthesized and studied analogous iron(II) complexes with flexible quadridentate and quinquedentate dioximato Schiff-base ligands. In line with expectations, these new complexes exhibit both catecholase and catechol dioxygenase activity.

Hydrogen atom vs electron transfer in catecholase-mimetic oxidations by superoxometal complexes. Deuterium kinetic isotope effects

Dioximato-cobalt(II), -iron(II) and -manganese(II) complexes (1)-(6), acting as functional catecholase and phenoxazinone synthase models, exhibit a deuterium kinetic isotope effect predicted by theory (k4H/k4D < or = 3) in the catalytic oxidative dehydrogenation of 3,5-di-tert-butylcatechol and 2-aminophenol by O2. KIEs in the range of (k4H/k4D approximately 1.79-3.51) are observed with (1) and (2) as catalysts, pointing to hydrogen atom transfer in the rate-determining step from the substrate hydroxy group to the metal-bound superoxo ligand. Less significant KIEs (1.06-1.20) are exhibited by catalysts systems (3)-(6), indicating that proton-coupled electron transfer is the preferred route in those cases.

Cisplatin administration influences on toxic and non-essential element metabolism in rats

Nowadays several papers deal with the effectiveness and side effects of metal complexes, especially cisplatin, in cancer therapy. The excretion of essential metal elements from the body is a serious problem in the treatment, but there are no data concerning the distribution and metabolism of toxic and nonessential elements. Therefore our aim was to study the concentration of some of these elements after treatment with cisplatin. Male Wistar rats (n=20, 175-190 g) were randomly divided into 2 groups (n=10/group). The control group received 1% (w/v) methyl cellulose at 10 mL/kg body weight, p.o. by gastric gavage twice daily for 14 days, while cisplatin was injected i.p. in a single dose of 6.5 mg/kg body weight. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used for measuring Al, B, Ba, Cr, Li, Ni, Pb, Pt, Sb, Si, Sn, Sr and V content in plasma, liver and kidney. Liver total scavenger capacity, diene conjugate content and malondialdehyde concentration were also determined. Cisplatin elevated the free radical reactions in the liver, although redox balance did not change significantly. According to the study it seems that the metabolism of Al, Ba, Cr, Ni, Pb, Sr were changed by the effect of cisplatin, and the most notable alterations were found for Al and Pb. Therefore, besides the toxic effect of and free radical induction by Pt, the side effects of increased levels of other toxic and non-essential elements have to be taken into consideration.

Polystyrene films as barrier layers for corrosion protection of copper and copper alloys

Dip-coated polystyrene layers of sub-micrometre thickness (85-500nm) have been applied on copper and copper alloys (aluminium brass, copper-nickel 70/30), as well as on stainless steel 304, and produced an effective barrier against corrosion and adhesion of corrosion-relevant microorganisms. According to the dynamic wettability measurements, the coatings exhibited high advancing (103°), receding (79°) and equilibrium (87°) contact angles, low contact angle hysteresis (6°) and surface free energy (31mJ/m(2)). The corrosion rate of copper-nickel 70/30 alloy samples in 3.5% NaCl was as low as 3.2μm/a (44% of that of the uncoated samples), and in artificial seawater was only 0.9μm/a (29% of that of the uncoated samples). Cell adhesion was studied by fluorescence microscopy, using monoculture of Desulfovibrio alaskensis. The coatings not only decreased the corrosion rate but also markedly reduced the number of bacterial cells adhered to the coated surfaces. The PS coating on copper gave the best result, 2×10(3)cells/cm(2) (1% of that of the uncoated control).

Wacker-Oxidation of Ethylene Over Pillared Layered Material Catalysts

This paper concerns the Wacker oxidation of ethylene by oxygen in the presence of water over supported Pd/VOx catalysts. High surface area porous supports were obtained from layer-structured materials, such as, montmorillonite (MT), laponite (smectites), and hydrotalcite (layered double hydroxide, LDH) by pillaring. Before introduction of Pd, supports MT and LDH were pillared by vanadia. The laponite was used in titania-pillared form (TiO2–LAP) as support of Pd/VOx active component. Acetaldehyde, acetic acid and CO2 were the products with yields and selectivities, depending on the reaction conditions and the properties of the applied catalyst. Under comparable conditions the pillared smectite catalysts gave higher AcH yield than the pillared LDH catalyst. UV–Vis spectroscopic examination suggested that the pillared smectites contained polymeric chains of VO4, whereas only isolated monomeric VO4 species were present in the pillared LDH. The higher catalytic activity in the Wacker oxidation was attributed to the more favorable redox property of the polymeric than of the monomeric vanadia. The V3+ ions in the polymeric species can reduce O2 to O2− ions, whereas the obtained V5+ ions are ready to pass over O to Pd0 to generate PdO whereon the oxidation of the ethylene proceeds.Graphical Abstract

Remineralization of demineralized bone matrix in critical size cranial defects in rats: A 6-month follow-up study.

The key drawback of using demineralized bone matrix (DBM) is its low initial mechanical stability due to the severe depletion of mineral content. In the present study, we investigated the long-term regeneration of DBM in a critical size bone defect model and investigated the remineralization after 6 months. Bone defects were created in the cranium of male Wistar rats which were filled with DBM or left empty as negative control. In vivo bone formation was monitored with computed tomography after 11, 19, and 26 weeks postoperatively. After 6 months, parietal bones were subjected to micro-CT. Mineral content was determined with spectrophotometric analysis. After 11 weeks the DBM-filled bone defects were completely closed, while empty defects were still open. Density of the DBM-treated group increased significantly while the controls remained unchanged. Quantitative analysis by micro-CT confirmed the in vivo results, bone volume/tissue volume was significantly lower in the controls than in the DBM group. The demineralization procedure depleted the key minerals of the bone to a very low level. Six months after implantation Ca, P, Na, Mg, Zn, and Cr contents were completely restored to the normal level, while K, Sr, and Mn were only partially restored. The remineralization process of DBM is largely complete by the 6th month after implantation in terms of bone density, structure, and key mineral levels. Although DBM does not provide sufficient sources for any of these minerals, it induces a faster and more complete regeneration process.

Mineral element content of some herbs with antiinflammatory effect used in gastrointestinal diseases

Bevezetes: A gasztrointestinalis rendszer megbetegedeseiben a nepgyogyaszat gyakran ajanl gyulladascsokkentő hatassal rendelkező gyogynovenyeket. Az orvosi gyakorlatban ma is kedvelt a stomaticumok adjuvans terapiaban tortenő alkalmazasa. Cel: Az emesztőrendszeri betegsegek kialakulasaban, ill. kezeleseben az asvanyi elemek is fontosak lehetnek, tovabba szoros osszefugges talalhato a femek jelenlete, ill. hianya es a gyulladasos mediatorok kozott, ezert a szerzők celul tűztek ki nehany novenyi drog asvanyi elemtartalmanak vizsgalatat. Modszer: A Trigonellae foenugraeci semen, Farfarae folium et flos, Taraxaci radix, Cichoriae radix, es a belőluk keszult tea asvanyielem-tartalmat induktiven csatolt plazma optikai emisszios spektrometriaval hataroztak meg. Az eredmenyeket taplalkozasi es orvosbiologiai megkozelitesből is ertekeltek. Eredmenyek: Megallapitottak, hogy a Farfarae folium et flos tea taplalkozasi szempontbol jelentős kalcium-, krom-, mangan- es molibdenforrasnak tekinthető, mig a Trigonellae foenugraeci semen, Taraxaci radix es Cichoriae radix teakban kedvező a kalcium:magnezium arany (1-1,5) es az immunvedekezesben fontos femelemeket is tartalmaznak (mangan, vas, rez es cink). Kovetkeztetes: A vizsgalt gyogynovenyek kedvező terapias hatasa osszefugghet azok asvanyielem-tartalmaval.INTRODUCTION In gastrointestinal diseases folk medicine usually recommends herbs and teas with antiinflammatory activities, especially mucilage and bitter agent containing plants. The use of stomatics as adjuvant therapy in medical practice is frequent. AIM The authors explored the mineral element content of some herbs, because mineral elements may have significant role in the development and treatment of gastrointestinal diseases, and a close connection between the presence or absence of mineral elements and inflammatory mediators was noted. METHODS The mineral content in Trigonellae foenugraeci semen, Farfarae folium et flos, Taraxaci radix and Cichorii radix and teas prepared from these herbs was determined using inductively coupled plasma optical emission spectrometry. The results were evaluated from nutritional and biomedical points of view. RESULTS Farfarae folium et flos tea was found to be a rich source of calcium, chromium, manganese and molybdenum. Trigonellae foenugraeci semen, Taraxaci radix and Cichorii radix displayed favourable calcium to magnesium ratio (1-1.5) and they contained other elements (manganese, iron, copper, zinc) which may have significant role in the immune defence system. CONCLUSION The beneficial therapeutic effect of the studied herbs may be related to their mineral element content.

[Effects of magnesium supplementation on calcium and magnesium levels, and redox homeostasis in normolipidemic and food-induced hyperlipidemic rats].

UNLABELLED Magnesium supplementation is quite popular because of intention of health and healthy lifestyle. However, there is no information on the metabolic effects of magnesium supplementation in healthy people and in different diseases. AIMS Authors examined the effects of magnesium-malate on calcium, magnesium levels, and antioxidant parameters in normolipidemic and hyperlipidemic rats. METHODS Male Wistar rats (n = 40; 150-200 g) were divided into 4 groups (control, control-treated, hyperlipidemic, hyperlipidemic-treated). Rats in the control and control-treated groups were fed with normal diet, while hyperlipidemic and hyperlipidemic-treated groups were fed with fat rich diet (2% cholesterol, 20% sunflower oil, 0.5% cholic acid). After the 9-day-long diet the following parameters were measured: routine laboratory parameters with automatic analysator, metal content using ICP-OES, and redox-parameters using spectrophotometric and luminometric methods. RESULTS Magnesium-malate failed to produce significant changes in the measured parameters in control animals in most cases. Magnesium-malate decreased significantly serum glucose concentration, alkaline phosphatase and amylase activities in the hyperlipidemic group. Significantly low induced chemiluminescent activity was measured in the plasma and erythrocytes of hyperlipidemic group. The magnesium supplementation did not increase significantly magnesium concentration in different organs although the calcium/magnesium concentration ratio was decreased. CONCLUSIONS In control animals there was no significant change in the measured parameters in most cases after dietary supplementation with a large amount of magnesium for a short period of time, but magnesium supplementation affected the metal homeostasis, routine laboratory parameters and redox system in hyperlipidemic animals. Although several changes were favorable, it should be emphasized that magnesium supplementation must be applied watchfully particularly in metabolic diseases.

Direct immobilization of manganese chelates on silica nanospheres for MRI applications

The development of tissue specific magnetic resonance imaging (MRI) contrast agents (CAs) is very desirable to achieve high contrast ratio combined with excellent anatomical details. To this end, we introduce a highly effective manganese(II) containing silica material, with the aim to shorten the longitudinal (T1) relaxation time. The microporous silica nanospheres (MSNSs) with enlarged porosity and specific surface area were prepared by a surfactant assisted aqueous method. Subsequently, the surface silanol groups were amino-functionalized, reacted with diethylenetriaminepentaacetic (DTPA) dianhydride and finally deposited with Mn2+. After comprehensive characterization, the MRI properties of functionalized MSNSs were investigated. The resulting nanospheres demonstrated substantial contrast enhancement during the in vitro MRI investigations, which was also evidenced by significant contrast enhancement on T1-weighted MR images in vivo. Moreover, in vitro cytotoxicity assay of functionalized MSNSs on hepatocyte mono- and hepatocyte-Kuppfer cell co-cultures showed no significant decrease in cell viability. Our findings confirmed our hypothesis, that Mn2+-chelating MSNSs are appropriate candidates for liver-specific T1-weighted MRI CAs with high relaxivities (r1=7.18mM-1s-1).

Archaeometric investigation of the hoard from Bodrogolaszi, Hungary

Abstract The hoard from Bodrogolaszi is a very significant find, dating back to the 15th-16th centuries. Unfortunately only 73 coins have survived from the original 135. In our study we would like to present the site, the circumstances of finding the hoard, and also a short numismatic introduction to these coins. We used stereomicroscopy to investigate the surface of coins, searching for additional artificial interventions (breaking, cutting, and fillip). We discovered darker reddish brown spots on several coins. We applied Raman spectroscopy to determine the origin of the spots. The results revealed they are part of a lepidocrocitegoethite cover layer caused by exposure to the soil. XRF measurements were used to prove that the purity of the coins differs from historical data.