Richness and diversity of Pontic flora on serpentine of Serbia

Serpentine substrate in Serbia covers wide areas mainly in Kosovo and in central, western and south-western part of the country. On the serpentines of Serbia, particularly on the skeleton soils of hills and on lower elevation mountain slopes, there are some xerophilous and steppe-like vegetations. These xerophilous grasslands include mostly Pontic, Pontic-Submediterranean and/or Mediterranean-Submediterranean-Pontic plants. The distribution of 161 taxa of Pontic, Pontic-Submediterranean and Mediterranean-Submediterranean-Pontic areal — types on serpentinites of Serbia was analyzed in order to distinguish centers of richness and diversity. The distribution of taxa was analyzed with respect to geographic, ecological and climatic factors. The qualitative composition of Pontic flora on the serpentine areas was also compared. The greatest floristic richness and the center of diversity of Pontic flora on serpentine of Serbia was recorded in central part of the area investigated.     

Differential Regulation of CuZnSOD Expression in Rat Brain by Acute and/or Chronic Stress

Neuroendocrine stress (NES) causes increase of glucocorticoids and alters physiological levels of reactive oxygen species production in cells, which might involve modifications in the antioxidant defense system. We investigated the hypothesis that acute, chronic, or combined stress alters copper–zinc superoxide dismutase (CuZnSOD) expression pattern at both, mRNA and subcellular protein level in the cerebral cortex and hippocampus of rats and that there may be a relationship between stress-induced corticosterone and CuZnSOD expression. The most effective stress model which led to the most pronounced changes in CuZnSOD expression patterns was also investigated. Our results demonstrated that acute stress immobilization up-regulates mRNA expression of hippocampal CuZnSOD, while cytosolic protein expression of this enzyme was increased in both brain structures. Chronic stress isolation had no effect on either mRNA and protein expression level and caused a lack of significant up-regulation to a novel acute stressors. The presence of this protein in nuclear fractions of both brain structures was also confirmed. The elevated cytosolic CuZnSOD protein levels following acute immobilization might reflect on the defense system against oxidative stress. Chronic isolation compromises CuZnSOD protein expression, which may lead to the inefficient defense against reactive oxygen species (ROS). The stress-triggered CuZnSOD protein expression was not correlated by the corresponding mRNA. The results suggest that different stress models exert a different degree of influence on mRNA and protein level of CuZnSOD in both brain structures as well as serum corticosterone.     

Synthesis, structure and characterization of novel Cd(II) and Zn(II) complexes with the condensation product of 2-formylpyridine and selenosemicarbazide: Antiproliferative activity of the synthesized complexes and related selenosemicarbazone complexes

Two novel Cd(II) and Zn(II) complexes with the condensation product of 2-formylpyridine and selenosemicarbazide were synthesized. The structure of Cd(II) complex was determined by X-ray crystallography. The ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms and the selenium donor. The cadmium ion completes its five-coordination by two chloride ligands, forming a square-pyramidal geometry. The structure of Zn(II) complex was established by analysis of spectroscopic data, which indicated coordination of the ligand as a bidentate via the selenium and the azomethine nitrogen atoms. The cytotoxic activity of the newly synthesized complexes, as well as if five structurally related complexes and the ligand evaluated against eight tumor cell lines. The new Cd(II) complex showed the highest activity similar to cisplatin with IC50 less than 10 μM for all cell lines. Cell cycle distribution and apoptosis study showed that Cd(II) complex and cisplatin might have some similarity in anticancer activity, which was not the case for cisplatin and other studied complexes. Effects of the complexes on matrix metalloproteinases (MMPs) MMP-9 and MMP-2 was also studied. Cd(II) and Zn(II) complexes and cisplatin increased MMP-2 activity in supernatants of tested cells, while Ni(II) complex with the same ligand decreased the activity, implying a possible activity in preventing tumor invasion and metastasis processes.     

Recurrent somatic embryogenesis and plant regeneration from immature zygotic embryos of cabbage (Brassica oleracea var. capitata) and cauliflower (Brassica oleracea var. botrytis)

A simple and rapid protocol was established for repetitive somatic embryogenesis and subsequent plant regeneration in two important Brassica oleracea varieties, cabbage and cauliflower. Direct regeneration of somatic embryos (SEs) was achieved from immature zygotic embryos cultured on B5 plant growth regulator (PGR)-free (B5-0) induction medium and on B5 medium supplemented with 1 mg l^?1 2,4-dichlorophenoxyacetic acid (2,4-D) (B5-D). Zygotic embryos of both cabbage and cauliflower at the cotyledonary (C) stage (1.8 mm long) incubated on B5-0 medium displayed the highest embryo-forming capacities (EFCs) of 11.84 and 11.95, respectively. Secondary somatic embryos (SSEs) appeared on the cabbage and cauliflower’s primary embryos at a high frequency (83.3 and 87.5 %, respectively), and this process continued in a repetitive way on PGR-free Murashige and Skoog (MS-0) medium. The embryogenic potential of the cultures with a gradual diminution was maintained for 10 months (ten cycles). A total of 20 % of the mature SSEs from cabbage and 55 % from cauliflower spontaneously regenerated plantlets on MS-0 medium. The addition of 1 mg l^?1 6-benzyladenine (BA) or 6-furfurylaminopurine (Kin) in the regeneration medium significantly improved somatic embryo conversion into plantlets by up to 56 % in cabbage and 79 % in cauliflower. Regenerated plants acclimated successfully to ex vitro conditions and displayed morphological and reproductive characteristics similar to seed-derived plants. Effective recurrent somatic embryogenesis may be an appropriate practical solution for clonal propagation and genetic modifications of cabbage and cauliflower.     

Age-Dependent Effects of ELF-MF on Oxidative Stress in the Brain of Mongolian Gerbils

The aim of study was to investigate the effects of extremely low frequency magnetic field (ELF-MF; 50 Hz; 0.1, 0.25 and 0.5 mT) on oxidative stress in the brain of 3- (adult) and 10-month-old (middle-aged) gerbils. Nitric oxide (NO) level, superoxide (O₂ ^?) production, superoxide dismutase (SOD) activity, and index of lipid peroxidation (ILP) were measured in the forebrain cortex, striatum, hippocampus, and cerebellum immediately and 3 days after cessation of 7-day exposure. In all gerbils, ELF-MF significantly increased oxidative stress in all tested brain regions. This effect was correlated with the value of magnetic induction and was higher in middle-aged gerbils. Three days after cessation of exposure, the values of examined parameters were closer to control levels. In adult gerbils, the effect of ELF-MF of 0.1 mT on NO level, O₂ ^? production and SOD activity was almost fully disappeared, and ILP was at the control level regardless of the value of magnetic induction. In middle-aged gerbils, the effect of ELF-MF was still present but to a lesser degree than those observed immediately after cessation of exposure. These findings pointed out the ability of ELF-MF to induce age- and magnetic induction-dependent modification of oxidative stress in the brain.     

The phenanthridine biguanides efficiently differentiate between dGdC, dAdT and rArU sequences by two independent, sensitive spectroscopic methods

At submicromolar concentrations two novel phenanthridine biguanides exhibit distinctly different spectroscopic signals for dGdC and dAdT sequences, respectively, by opposite fluorimetric changes (quenching for dGdC and increase for dAdT) and especially the bis-biguanide derivative gives an opposite ICD response (negative ICD for dGC and strong positive for dAdT). This specific signalling was explained by the ability of compounds to switch the binding mode from intercalation into dGdC to minor groove binding into dAdT sequences. Both compounds bind to rArU by intercalation, yielding different fluorimetric and CD response in comparison to any of aforementioned ds-DNA. Moreover, both compounds revealed significantly higher affinity toward ds-polynucleotides in comparison to previously studied alkylamine- and urea-analogues. Furthermore, DNA/RNA binding properties of novel compounds could be controlled by pH, due to the protonation of heterocyclic nitrogen. Low in vitro cytotoxicity of both compounds against human cell lines makes them interesting spectrophotometric probes.     

Seasonal dynamics of allelopathically significant phenolic compounds in globally successful invader Conyza canadensis L. plants and associated sandy soil

The seasonal dynamics of total phenolics and phenolic acids in the stems of the global invader Conyza canadensis, from March (young plants in the form of rosettes) to September (fruit abscission and the beginning of plant decline), and in sandy soil were monitored monthly in non-native areas. The highest amount of total free phenolics was found in its tissues (31,000 μg g⁻¹) during the flowering and fruiting time (August). Bound phenolics peaked (up to 8443 μg g⁻¹) during shoot elongation and intensive plant growth (May–June) and in September. In the stems, bound phenolic acids (p-coumaric, ferulic, p-hydroxybenzoic, vanillic and syringic) have a maximum twice, in May and in August, with ferulic acid predominating (up to 951.6 μg g⁻¹). Free phenolic acids in the plant's tissue peaked in May (plant elongation). In the soil under C. canadensis, the amount of bound phenolics decreased between March and June, before increasing up to the full bloom phase of the plants (August). The amount of bound phenolic acids was several times greater than that of free ones, with maximum values in August. C. canadensis is a highly important source of phenolics in the ruderal phytocoenosis in new areas. In order to better explain the mechanisms of the spread and domination of invasive plants in non-native areas, in which allelopathy plays a decisive role, it is necessary to measure the production of allelochemicals in tissue and their accumulation in soil at the shortest possible intervals and link this with the phases of plant development.     

In vivo antigenotoxic potential and possible mechanism of action of selected 4-hydroxy-2H-chromen-2-one derivatives

The in vivo sex‐linked recessive lethal test was carried out in Drosophila melanogaster to investigate whether or not five substituted 4‐hydroxy‐2H‐chromen‐2‐ones can modulate the genotoxicity of the well‐established mutagenic agent ethyl methanesulfonate (EMS). For this purpose, 3 days old Canton S males were treated with the potent mutagen EMS alone in concentration of 0.75 ppm, as well as in combination with one of the five 4‐hydroxycoumarins, namely diethyl 2‐(1‐(4‐hydroxy‐2‐oxo‐2H‐chromen‐3‐yl)ethylidene)malonate ( 2b ), 3‐(1‐(4‐hydroxy‐2‐oxo‐2H‐chromen‐3‐yl)ethylidene)pentane‐2,4‐dione ( 6b ), 4‐(4‐(4‐hydroxy‐2‐oxo‐2H‐chromen‐3‐yl)thiazol‐2‐ylamino) benzenesulfonic acid ( 4c ), 4‐hydroxy‐3‐(2‐(2‐nitropheny lamino)thiazol‐4‐yl)‐2H‐chromen‐2‐one ( 9c ), and (E)‐4‐hydroxy‐3‐(1‐(m‐tolylimino)ethyl)‐2H‐chromen‐2‐one ( 5d ), in concentration of 70 ppm. The frequency of germinative mutations increased significantly after the treatment with EMS and decreased after treatments with coumarins. The maximum reduction was observed after treatments with 2b , 6b , 4c , and 5d . By the formation of hydrogen bonds or electrostatic interactions with O⁶ of DNA guanine, tested coumarins prevent EMS‐induced alkylation. The results indicate a protective role of five 4‐hydroxycoumarins under the action of a strong mutagen. © 2012 Wiley Periodicals, Inc. J Biochem Mol Toxicol 26:322–330, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/jbt.21426     

Very strong metal ligand aromatic cation-π interactions in transition metal complexes: intermolecular interaction in tetraphenylborate salts

Strong intermolecular interactions between ligands in cationic metal complexes and aromatic rings of tetraphenylborate anion, so-called metal ligand aromatic cation-π (MLACπ) interactions, were found by screening Cambridge Structural Database. Distances between phenyl ring and ligand are shorter in these structures than in previously reported MLACπ interactions by 0.2 Å.     

Cytotoxic and Antimicrobial Activity of Dehydrozingerone based Cyclopropyl Derivatives

A small series of 1‐acetyl‐2‐(4‐alkoxy‐3‐methoxyphenyl)cyclopropanes was prepared, starting from dehydrozingerone (4‐(4‐hydroxy‐3‐methoxyphenyl)‐3‐buten‐2‐one) and its O‐alkyl derivatives. Their microbiological activities toward some strains of bacteria and fungi were tested, as well as their in vitro cytotoxic activity against some cancer cell lines (HeLa, LS174 and A549). All synthesized compounds showed significant antimicrobial activity and expressed cytotoxic activity against tested carcinoma cell lines, but they showed no significant influence on normal cell line (MRC5). Butyl derivative is the most active on HeLa cells (IC₅₀ = 8.63 μm ), while benzyl one is active against LS174 and A549 cell lines (IC₅₀ = 10.17 and 12.15 μm , respectively).