Vibor Roje

Ecotoxicological effects of aluminum and zinc on growth and antioxidants in Lemna minor L.

The present study aimed at investigating effects of zinc and aluminum (0.15 and 0.3mM) in duckweed (Lemna minor L.) over a 15-day period. High bioaccumulation of both metals was accompanied by an increase in dry weight under higher metal treatments. Antioxidant response was observed under both metal stresses, with large increases in superoxide dismutase and peroxidases. Catalase activity declined only in duckweed exposed to Zn while lipid peroxidation as well as H(2)O(2), proline and ascorbate levels increased. The results suggest induction of oxidative stress under both aluminum and zinc toxicity, and also demonstrate duckweeds capacity to upregulate its antioxidative defense. Additionally, Zn was found to be more toxic than Al to duckweed for the concentrations applied. Due to its high bioaccumulation potential and tolerance via increased antioxidant capacity, duckweed has a potential for phytoremediation of water bodies polluted by low levels of zinc and aluminum.

The first example of coexistence of the ketoamino–enolimino forms of diamine Schiff base naphthaldimine parts: the crystal and molecular structure of N,N′-bis(1-naphthaldimine)-o-phenylenediamine chloroform (1/1) solvate at 200 K

Abstract The N,N′-bis(1-naphthaldimine)-o-phenylenediamine chloroform (1/1) solvate was prepared from 2-hydroxy-1-naphthaldehyde and 1,2-phenylenediamine in a 2:1 molar ratio and characterized in solution and in the solid state using X-ray single crystal diffractometry, IR and NMR spectroscopy. The structure consists of three structural fragments: two planar, but not coplanar naphthaldimine moieties linked by phenyl ring that derived from o-phenylenediamine. The naphthaldimine fragments contain, along with naphthalene rings, six-membered pseudoaromatic chelate rings, formed by O H⋯N or N H⋯O intramolecular hydrogen bonds that retain planarity of the aldimine fragments. This structure is the first example of the coexistence of two different hydrogen bond types within Schiff base molecule, i.e. the one naphthaldimine part exists in the enolimino form (O H⋯N hydrogen bond of 2.5487(17) A), while the other exists in the ketoamino form (N H⋯O hydrogen bond of 2.5706(19) A). The different hydrogen bond types are related to the different π-electron density distribution within two parts. The amino hydrogen atom forms three-center intramolecular hydrogen bond, which includes the N H⋯O hydrogen bond of 2.5706(19) A within the ketoamino part and also the N H⋯N bond of 2.7238(18) A linking two naphthaldimine fragments of the molecule. IR and 1H and 13C NMR spectral data are consistent with revealed molecular structure in the solid state.

OXIDATIVE STRESS AND DNA DAMAGE IN BROAD BEAN (VICIA FABA L.) SEEDLINGS INDUCED BY THALLIUM

Thallium (Tl) is a metal of great toxicological concern because it is highly toxic to all living organisms through mechanisms that are yet poorly understood. Since Tl is accumulated by important crops, the present study aimed to analyze the biological effects induced by bioaccumulation of Tl in broad bean (Vicia faba L.) as well as the plants antioxidative defense mechanisms usually activated by heavy metals. Thallium toxicity was related to production of reactive oxygen species in leaves and roots of broad bean seedlings following short-term (72 h) exposure to thallium (I) acetate (0, 0.5, 1, 5, and 10 mg/L) by evaluating DNA damage and oxidative stress parameters as well as antioxidative response. The possible antagonistic effect of potassium (K) was tested by combined treatment with 5 mg/L of Tl (Tl+) and 10 mg/L of potassium (K+) acetate. Accumulation of Tl+ in roots was 50 to 250 times higher than in broad bean shoots and was accompanied by increase in dry weight and proline. Despite responsive antioxidative defense (increased activities of superoxide dismutase, ascorbate peroxidase, and pyrogallol peroxidase), Tl+ caused oxidative damage to lipids and proteins as evaluated by malondialdehyde and carbonyl group levels, and induced DNA strand breaks. Combined treatment caused no oxidative alternations to lipids and proteins though it induced DNA damage. The difference in Tl-induced genotoxicity following both acellular and cellular exposure implies indirect DNA damage. Results obtained indicate that oxidative stress is involved in the mechanism of Tl toxicity and that the tolerance of broad bean to Tl is achieved, at least in part, through the increased activity of antioxidant enzymes.

Preparation and characterization of the 1:1 adducts of mercury(II) halides with N-benzyl- and N-p-tolyl-2-oxo-1-naphthylideneamine. The crystal and molecular structures of two isostructural di-μ-halo-bis[halo(N-benzyl-2-oxo-1-naphthylideneamine)mercury(II)] adducts (halo=chloro, bromo)

Abstract A series of adducts of the type HgX2(C18H15NO) [X=Cl−, Br−, I−; C18H15NO=N-benzyl-2-oxo-1-naphthylideneamine (bznapH), N-p-tolyl-2-oxo-1-naphthylideneamine (tolnapH)] was obtained by refluxing the solution of the corresponding mercury(II) salt and the related naphthylideneamine in absolute ethanol in a 1:1 molar ratio. The adducts di-μ-chloro-bis[chloro(N-benzyl-2-oxo-1-naphthylideneamine)mercury(II)], HgCl2(bznapH) (1) and di-μ-bromo-bis[bromo(N-benzyl-2-oxo-1-naphthylideneamine)mercury(II)], HgBr2(bznapH) (2) are isostructural with the effective coordination of mercury being 2+2. The HgX2 moieties are retained in the adducts and contain two covalently linked chlorine [2.321(3) and 2.299(3) A in 1] or bromine atoms [2.446(1) and 2.422(1) A in 2]. These moieties are linked mutually by additional contacts of bridging halogen atoms [Hg⋯μX 3.189(2) and 3.298(1) A in 1 and 2, respectively], forming non-planar dimeric Hg2X4 units. Each Schiff-base ligand has a strong contact with mercury through the oxygen atom [Hg⋯O 2.392(5) and 2.410(5) A in 1 and 2, respectively]. The Schiff-base ligand in 1 and 2 exists as the ketoamino (quinoid) tautomeric structure with an intramolecular hydrogen bond of the NH⋯O type [2.58(1) and 2.59(1) A in 1 and 2, respectively]. On the contrary, in DMSO solution, due to dissociation of adducts 1–6, the enolimino (benzenoid) tautomeric form of the Schiff bases was established by NMR spectroscopy.

Fast method of multi-elemental analysis of stream sediment samples by inductively coupled plasma-mass spectrometry (ICP-MS) with prior single-step microwave-assisted digestion

One-step microwave-assisted digestion procedures were investigated with the scope to obtain fast method for multi-elemental analysis of stream sediment samples by sector field inductively coupled plasma-mass spectrometry (SF-ICP-MS). As a model, certified reference material stream sediment (NCS DC 73309), produced by China National Analysis Center for Iron and Steel was used. The reagents whose extraction abilities have been examined were: HNO3, mixture HNO3/HCl (9:1 v/v), mixture HCl/HNO3 (3:1 v/v i.e., aqua regia), and mixture HNO3/HCl/HF (8:1:1 v/v/v). The list of the selected elements is: Ag, Al, As, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, K, Li, Mn, Mo, Na, Ni, Pb, Sb, Sn, Sr, Ti, Tl, V, and Zn. Most of them could be analyzed when only HNO3 for digestion was employed. For the determination of Sb, the use of aqua regia for digestion of stream sediment samples is required. Be, K, Na, Ti, and Tl can be easily and satisfactorily made available for environmental screening when digestion was performed using aqua regia, although the recoveries for these elements were better when the mixture HNO3/HCl/HF (v/v/v 8:1:1) was applied.