The oxidation of N,N′-bis(4-aminophenyl)-N,N′-dimethylethylenediamine (BED) by rat liver

We have examined the oxidation of N,N′-bis(4-aminophenyl)-N,N′-dimethylethylenediamine (BED) by tissue homogenates and fractions of liver homogenates. We find that this agent both gives osmiophilic deposits in tissue blocks and readily increases the uptake of oxygen by hepatic homogenates. The highest activity was in the mitochondrial and, next, in the microsomal fractions. Kinetic evidence indicates that the former represents two enzymatic activities while the latter is only a single site. The activity was greatest in the outer membrane of the mitochondria, in agreement with electron micrographic studies and in the rough microsomal fraction. Further, it was very sensitive to both formaldehyde and detergents. The activity was not well associated with either monamine oxidase (benzylamine substrate) or xanthine oxidase activities. Activity was observed in a large number of tissues.     

Removal of239Pu from mice with 3,4,3 LICAM(C) or N,N′, N″, N‴-tetra-(2,3-dihydroxybenzoyl)-spermine

Summary Male mice SAS/4 were injected i.v. with²³⁹Pu citr(IV) 0.27 µCikg^–1–9.99 kBqkg^–1. After 1 h 30 µmol kg^–1 of 3,4,3 LICAM(C), N, N, N, N-tetra-(2,3-dihydroxybenzoyl)-spermine or Na₃CaDTPA as a reference compound was given intraperitoneally. After 4 days the animals were sacrified and the Pu content in livers, kidneys, femurs and carcasses was determined by the liquid scintillation method. It was found that, as compared with the control, 3,4,3 LICAM(C) removed 83% of the Pu activity deposited in the liver, 71% of that in the femur and 79% of the Pu in the whole body. The Pu content in the kidneys exceeded the control value by about 50%. Na₃CaDTPA removed 96, 86, 40 and 72% of plutonium from the liver, kidneys, femurs and carcasses respectively.Tetra-DHB-spermine caused the excretion of 50, 57 and 39% of Pu from liver, bone and whole body respectively. The retention of Pu in the kidneys was increased to 400% of the control value.     

Dioxo-, oxothio- and dithio-tungsten(VI) and tungsten(V) complexes of the ligand N,N′-Dimethyl-N,N′-bis(2-mercaptophenyl)ethylenediamine

Synthesis of complexes cis,cis-W^VOXL (X=Cl, NCS), cis,trans-W^VOXL (X=Cl, OPh, SPh) and cis,trans-W^VIE₂L (E₂=O₂, OS, S₂) of the title ligand LH₂ are reported. cis,cis-W^VOCIL crystallises in space group P2₁/c with a=13.6541(9) Å, b=7.1555(11) Å, c=18.198(2) Å, β=95.294(6)°, V=1770.4(3) ų and Z=4 while the cis,trans isomer crystallises in space group P2₁/n with a=10.361(3) Å, b=14.141(4) Å, c=12.213(5) Å, β=102.56(3)°, V=1747(2) ų and Z=4. cis,trans-W^VIS₂L crystallises in space group P2₁/n with a=10.645(2) Å, b=13.929(2) Å, c=12.189(2) Å, β=103.14(2)°, V=1760(1) ų and Z=4. A short CH₃···Cl distance of 3.067(7) Å and an acute OWCl angle of 94.1(2)° are seen in cis,cis-W^VOClL, which converts to the cis,trans form on heating in MeCN. The latter isomer features a CH₃···Cl distance of 3.38(2) Å and an OWCl angle of 105.1(8)°. Electrochemical and EPR data are reported. In particular, cis,trans-W^VIE₂L may be reduced to [W^VE₂L]^–. EPR properties of these anions and those of complexes W^VOXL are discussed in the context of W^V centres in tungsten enzymes.     

Antimicrobial efficiency of some N,N′-bis(alkymethyl)-1,2-ethanediamine dioxides and N,N′-bis(alkylmethyl)-1,2-propanediamine dioxides

Ten dioxide species derived from N,N′-bis(alkylmethyl)-1,2-ethanediamine and N,N′-bis(alkylmethyl)-1,2-propanediamine were tested for their activity withStaphylococcus aureus, Escherichia coli andCandida albicans. A relation between the length of the alkylchain, and/or the molecule asymmetry, and the antimicrobial activity was found. Part V of the series Amine Oxides; part IV: Mlynarciket al.: Folia Microbiol. 24, 188 (1979).     

Anti-diabetic Effects of Cesium Aqua (N,N′-ethylene(salicylideneiminato)-5-sulfonato) Oxovanadium (IV) Dihydrate in Streptozotocin-induced Diabetic Rats

The study has been designed to investigate the anti-diabetic effects of cesium aqua (N,N′-ethylene (salicylideneiminato)-5-sulfonato) oxovanadium (IV) dihydrate (VO(salen-SO₃)), an organic vanadium compound, in streptozotocin-induced diabetic rats. VO(salen-SO₃) was orally administrated to diabetic rats at the dose of 0.3 mg/ml through drinking water for 24 days. Blood glucose level was significantly declined, and oral glucose tolerance was improved after VO(salen-SO₃) treatment. Moreover, liver and muscle glycogen concentrations were markedly increased in VO(salen-SO₃)-treated diabetic rats. On the other hand, aspartate amino transferase and blood urea nitrogen in serum were significantly decreased after treatment with VO(salen-SO₃). Take together, these results suggested that VO(salen-SO₃) may be of potential value in the therapy of diabetic symptom and hyperglycemia-induced hepatic and renal dysfunction.     

尿嘧啶N糖基化酶(UNG)的研究进展

尿嘧啶N糖基化酶是碱基切除修复过程中的重要组分。本文从酶的概况、在生物体内的分布范围、人尿嘧啶N糖基化酶的基因结构、基因表达与调控、酶的作用机制等方面进行了介绍,并讨论了进一步研究的意义与方向。     

Binuclear metal complexes. 59. Synthesis and magnetism of dicopper(II) and copper(II)-nickel(II) complexes with N,N′-ethylenedisalicylamidatocuprate(II)

The complexes [Cu(samen)Cu(L)] and [Cu(samen)Ni(L)₂] (Lbpy, phen) have been synthesized by the reaction of sodium N,N′-ethylenedisalicylamidatocuprate(II) pentahydrate (Na₂- [Cu(samen)]·5H₂O), a divalent metal ion, and 2,2′- dipyridyl or 1,10-phenanthroline. Cryomagnetic data for the CuCu complexes did not fit the Bleaney- Bowers equation; but the data did fit a modified Bleaney-Bowers equation

with a large negative J and a significant negative θ, suggesting that a considerable magnetic interaction operates between essentially planar [Cu(samen)Cu(L)] molecules. The magnetisms of the CuNi complexes were well interpreted in terms of the susceptibility equation based on the Heisenberg model. An antiferromagnetic spin-exchange interaction (J= −13∼−14 cm⁻¹) was suggested between the metal ions.     

The Weak Cytokinins N,N′-bis-(1-naphthyl)urea and N,N′-bis-(2-naphthyl)urea may Enhance Rooting in Apple and Mung Bean

The present research investigates the possibility that 2 weak urea-type cytokinins, the N,N′-bis-(1-naphthyl)urea and the N,N′-bis-(2-naphthyl)urea, enhance adventitious root formation. The rooting activity was assessed using the stem slice test, the mung bean rooting test and the rooting of apple microcuttings. The two compounds influenced the adventitious rooting process differently as regards the bioassay used. In the stem slice test, in the presence of exogenous auxin, both compounds enhanced the rooted slice percentage. In mung bean shoots, the N,N′-bis-(1-naphthyl)urea enhanced the root formation at the lowest concentration used (0.01 μM) while the N,N′-bis-(2-naphthyl)urea enhanced rooting at higher concentrations. In the rooting test of apple microcuttings the N,N′-bis-(1-naphthyl)urea and the N,N′-bis-(2-naphthyl)urea slightly enhanced only the mean root number per microcutting.     

Effectiveness of N,N′-Bis(2-hydroxy-5-methylbenzyl) ethylenediamine-N,N′-diacetic acid (HJB) to supply iron to dicot plants

Iron chlorosis is commonly corrected by the application of EDDHA chelates, whose industrial synthesis produces o,oEDDHA together with a mixture of regioisomers and other unknown by-products. HJB, an o,oEDDHA analogous, is a new chelating agent with a purer synthesis pathway than EDDHA. The HJB/Fe³⁺ stability constant is intermediate between the racemic and meso o,oEDDHA/Fe³⁺ stereoisomers. This work studied the efficacy of HJB as a Fe source in plant nutrition. No significant differences between o,oEDDHA/Fe³⁺, HJB/Fe³⁺ and HBED/Fe³⁺ were observed when they are used as substrates of the iron-chelate reductase of mild chlorotic cucumber plants. Chelates prepared with the stable isotope ⁵⁷Fe were used in both soil and hydroponic experiments. In the hydroponic experiment, nutrient solutions with low doses of chelates were renewed weekly. Soybean plants treated with o,oEDDHA/⁵⁷Fe³⁺ recorded the highest results in biomass, SPAD index and Fe nutrition. In the soil experiment, chelates were added once at a rate of 2.5 mg Fe per kg of a calcareous soil. Soybean plants treated with HJB/⁵⁷Fe³⁺ recorded a higher biomass and SPAD index in young leaves than the plants treated with o,oEDDHA/⁵⁷Fe³⁺; however, ⁵⁷Fe and total Fe concentrations in leaves were lower. The results of both pot experiments are associated with a faster ability by o,oEDDHA to provide Fe to the plants and with a more continuous supply of Fe from HJB/Fe³⁺. HJB/⁵⁷Fe³⁺ effectively alleviated the Fe-deficiency chlorosis of soybean with a longer lasting effect than o,oEDDHA/⁵⁷Fe³⁺.     

The presence of N(ε)-(Carboxymethyl) lysine in the human epidermis

It is well known that advanced glycation end products (AGEs) are formed in long-lived dermal proteins such as collagen, and that their formation is related to skin aging. To examine the distribution of AGEs in skin tissue, we performed immunofluorescence studies on the human skin using an anti-AGEs antibody. Interestingly, AGEs signals were observed not only in the dermis but also in the epidermis. The objectives of this study were to confirm the presence of N(ε)-(Carboxymethyl) lysine (CML), an AGE structure, in the epidermis and to characterize the CML-modified proteins. The presence of CML in the stratum corneum (SC) was examined using liquid chromatography-electrospray ionization time-of-flight mass spectrometry. Concordance between the retention times of a compound in the SC hydrolysate and authentic CML, as well as with the specific mass transition of CML, was detected. This result showed that CML is present in the epidermis. In order to characterize the CML-modified proteins in the epidermis, protein samples extracted from the SC were analyzed using two-dimensional electrophoresis followed by an amino acid sequence analysis. The clarified peptide sequences covered approximately 27% of the amino acid sequences of cytokeratin 10 (K10). In the immunoblotting experiment following the two-dimensional electrophoresis, where protein samples extracted from whole epidermis were used, the position of the major CML-positive spots corresponded to those of K10. Taken together these results showed that CML is present in the human epidermis, and suggest that K10 is one of the target molecules for CML modification in the epidermis.     

N′-Isopropylnornicotine in Burley Tobacco (Nicotiana tabacum)

Allyl sulfides such as diallyl sulfide (DAS), diallyl disulfide (DADS), and diallyl trisulfide (DATS), typical flavor components of Allium vegetables, have been shown to inhibit benzo[a]pyrene (B[a]P)-induced carcinogenesis in animal models. As a possible mechanism of this inhibition, the effect of these volatile substances on cytochrome P450 (CYP)1 (CYP1A1, 1A2 and 1B1)-mediated bioactivation of B[a]P was investigated using a human hepatoma cell model (HepG2). DADS and DATS inhibited the B[a]P-induced ethoxyresorufin O-deethylase (EROD) activity, a marker enzyme for CYP1, by 30-90% and 70-95% at 100-1,000 μM concentration, respectively. The cell viability, an indicator of the capacity to inhibit B[a]P bioactivation, was increased by treatments of 100-1,000 μM DADS and 10-100 μM DATS. Immunoblot results indicated that the B[a]P inducible CYP1A2 protein was suppressed by 100-1,000 μM of DADS and 10-100 μM of DATS, but CYP1A1 and 1B1 were not detectable in any microsomes. Analysis of B[a]P metabolites revealed that the level of 7,8-diol formed was significantly reduced in the DADS and DATS treated microsomes as compared to the control. The level of 9,10-diol and 4,5-diol formed was also lowered by the allyl sulfide treatments. These results suggest that the protective mechanism of allyl sulfides on B[a]P-induced carcinogenesis is possibly related with the modulation of CYP1-mediated bioactivation of B[a]P.     

Reduction of N(ω)-hydroxy-L-arginine by the mitochondrial amidoxime reducing component (mARC)

NOSs (nitric oxide synthases) catalyse the oxidation of L-arginine to L-citrulline and nitric oxide via the intermediate NOHA (N(ω)-hydroxy-L-arginine). This intermediate is rapidly converted further, but to a small extent can also be liberated from the active site of NOSs and act as a transportable precursor of nitric oxide or potent physiological inhibitor of arginases. Thus its formation is of enormous importance for the nitric-oxide-generating system. It has also been shown that NOHA is reduced by microsomes and mitochondria to L-arginine. In the present study, we show for the first time that both human isoforms of the newly identified mARC (mitochondrial amidoxime reducing component) enhance the rate of reduction of NOHA, in the presence of NADH cytochrome b? reductase and cytochrome b?, by more than 500-fold. Consequently, these results provide the first hints that mARC might be involved in mitochondrial NOHA reduction and could be of physiological significance in affecting endogenous nitric oxide levels. Possibly, this reduction represents another regulative mechanism in the complex regulation of nitric oxide biosynthesis, considering a mitochondrial NOS has been identified. Moreover, this reduction is not restricted to NOHA since the analogous arginase inhibitor NHAM (N(ω)-hydroxy-N(δ)-methyl-L-arginine) is also reduced by this system.     

The molecular structure and magnetic properties of the dimeric N,N′-ethylenebis(salicylamine)Fe(II)-μ-methoxo-N,N′-ethylene(o-hydroxylphenylglycine)salicylamine Fe(III): A complex with a μ-monodentate acetato bridge

We have prepared and characterized a dimeric complex of the formula Fe₂L(OCH₃)L′·solvent where L = N,N′-ethylenebis(salicylamine) and L′ = N,N′-ethylene(o-hydroxylphenylglycine)salicylamine. Crystals of the methanol solvate were found to be orthorhombic, space group P2nb, with a = 13.748 (5), b = 22.426(9), c = 11.762(6) Å and d_calc = 1.41 g/cm³. Least squares refinement of 966 reflections gave a final R factor of 0.066. The structure shows that the two iron atoms are coordinated to two different ligands and are bridged by a methoxide ion and a μ-monodentate acetate oxygen from the pendant arm of L′. The magnetic susceptibility was measured over the range 2–300 K and gave a spin coupling constant J = −8.3 cm⁻¹. The significance of acetate bridges to the exchange coupling pathway is discussed.     

Detection and quantification of α-keto-δ-(N(G),N(G)-dimethylguanidino)valeric acid: a metabolite of asymmetric dimethylarginine

Nitric oxide is an ubiquitary cell signaling substance. Its enzymatic production rate by nitric oxide synthase is regulated by the concentrations of the substrate L-arginine and the competitive inhibitor asymmetric dimethylarginine (ADMA). A newly recognized elimination pathway for ADMA is the transamination to α-keto-δ-(N(G),N(G)-dimethylguanidino)valeric acid (DMGV) by the enzyme alanine-glyoxylate aminotransferase 2 (AGXT2). This pathway has been proven to be relevant for nitric oxide regulation, but up to now no method exists for the determination of DMGV in biological fluids. We have developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of DMGV. D(6)-DMGV was used as internal standard. Samples were purified online by column switching, and separation was achieved on a porous graphitic carbon column. The calibration was linear over ranges of 10 to 200 nmol/L for plasma and 0.1 to 20 μmol/L for urine. The intra- and interday accuracies and precisions in plasma and urine were better than 10%. In plasma samples, DMGV was present in concentrations between 19.1 and 77.5 nmol/L. In urine samples, concentrations between 0.0114 and 1.03 μmol/mmol creatinine were found. This method can be used as a tool for the scientific investigation of the ADMA conversion to DMGV via the enzyme AGXT2.     

Pt(II) complexes with (N,N′) or (C,N,E)− (E = N,S) ligands: Cytotoxic studies,effect on DNA tertiary structure and structure–activity relationships

The cytotoxic activity of two series of platinum(II) complexes containing the polyfunctional imines R¹–CHN–R² [R¹ = phenyl or ferrocenyl unit and R² = (CH₂)_n–CH₂–NMe₂ where n = 1 or 2) (1 and 2) or C₆H₄-2-SMe (3)] acting as a bidentate (N,N′) (4–7) or terdentate [C(phenyl or ferrocenyl),N,N′]^? (8–10) or [C(ferrocenyl),N,S]^? ligand (11) in front of A549 lung, MDA-MB231 breast and HCT116 colon human adenocarcinoma cell lines is reported. The results reveal that most of the platinum(II) complexes are active against the three assayed lines and compounds 6, 7 and the platinacycles 10 and 11 exhibit a remarkable antiproliferative activity, even greater than cisplatin itself, in the cisplatin resistant HCT116 human cancer cell line. Electrophoretic DNA migration studies showed that most of them modify the DNA tertiary structure in a similar way as the reference cisplatin. Solution studies of a selection of the most relevant complexes have also been performed in order to test: (a) their stability in the aqueous biological medium and/or the formation of biologically active species and (b) their proclivity to react with 9-methylguanine (9-MeG), as a model nucleobase. Computational studies at DFT level have also been performed in order to explain the different solution behaviour of the complexes and their proclivity to react with the nucleobase.     

N,N′-bis-(2,3-methylenedioxyphenyl)urea and N,N′-bis-(3,4-methylenedioxyphenyl)urea interact with auxin in enhancing root formation of M26 apple (Malus pumila Mill.) stem slices

Stem slices cut from micropropagated cuttings of apple rootstock M26 were cultured in the presence of indole-3-butyric acid (IBA) plus N,N-bis-(2,3-methylenedioxyphenyl)urea or N,N-bis-(3,4-methylenedioxyphenyl)urea, to verify if there was an interaction between them in enhancing root formation. The N,N-bis-(methylenedioxyphenyl)ureas were supplemented after, before and in the simultaneous presence of auxin. Our data demonstrate that only the simultaneous presence of auxin and N,N-bis-(methylenedioxyphenyl)ureas in the culture medium enhanced root formation on M26 stem slices. The percentage of rooted slices obtained in the presence of the mixtures was significantly different from that obtained in the presence of low auxin concentration alone (1µM). Moreover both the percentage of rooted slices and the number of roots per slice obtained in these culture conditions was not significantly different to that of the optimal auxinic treatment in which the auxin concentration was threefold higher.     

Comparative growth ecology of Ascophyllum nodosum from Norway (lat. 63°N) and Wales (LAT. 53°N)

Two populations of Ascophyllum nodosum (L.) Le Jol., one from Menai Bridge, Wales, other from Trondheim, Norway, were grown in Trondheim under identical conditions. The two populations showed an equal growth response to light (saturation at 100 Wm⁻² at a day-length > 18 h). Temperature optima were 17–18°C and 16°C for the Menai Bridge and Trondheim populations, respectively.In Menai Bridge, local apical growth during April–August was about twice that in Trondheim. When the two populations were exposed to identical conditions (natural light, variable irradiances, different daylengths, different temperatures), the Menai Bridge population had about a 40% better growth rate than the Trondheim population, irrespective of treatment. It is concluded that the differences in local growth rates are partly due to environmental conditions and partly to different genetic growth capacities.     

Synthesis and spectroscopic studies of platinum(II) complexes of N,N′-dicyclohexylethylenediamine

The platinum(II) complexes of the formula [Pt(DCHEDA)X₂], where DCHEDA is N,N′-dicyclohexylethylenediamine and X⁻ is CL⁻, Br⁻, I⁻, 0.5C₂O₄²⁻ (oxalate), 0.5C₃H₂O₄²⁻ (malonate), 0.5C₉H₄O₆²⁻ (4-carboxyphthalate), 0.5S₂O₃²⁻ or 0.5SO₄²⁻, have been synthesized and characterized by UVVis, IR, and ¹H NMR spectral techniques. All the above complexes are non-electrolytes in DMF/H₂O, except the sulphate complex which becomes a 1:1 electrolyte after incubation for 24 h at 28 °C. The halide complexes were also studied by X-ray photoelectron spectroscopy and these data suggest that there is π-bonding from platinum to halide in these complexes. The oxalate, malonate and sulphate bind in their complexes as bidentate ligands to platinum through two oxygen atoms whereas the thiosulphate in its complex binds as a bidentate ligand to platinum through one oxygen atom and one sulphur atom.     

Adaptation strategies of copepods (superfamily Centropagoidea) in the White Sea (66°N)

Seasonal dynamics of major biochemical features were studied for three abundant egg-diapausing copepods Acartia bifilosa, Centropages hamatus and Temora longicornis, in the White Sea (66°N), between June 2002 and September 2002. Dry weight (DW) and prosome length varied from 0.54 μg ind⁻¹ and 0.163 ± 0.012 mm (A. bifilosa, CI) to 9.58 ± 0.72 μg ind⁻¹ and 1.135 ± 0.167 mm (C. hamatus, females). C_org and N_org content reached up to 5.91 ± 0.44 and 1.23 ± 0.09 μg ind⁻¹ (C. hamatus, females). Protein and lipid content varied greatly from 31.8 to 67.3% DW and from 8.7 to 42.6% DW, respectively. These species show somewhat different biology compared to species at lower latitudes. The copepods use lipid stores to survive during short-term food shortage (e.g. in autumn) and successfully complete their life cycle. In the isolated White Sea during last post-glacial period, species probably evolved some special biochemical features (especially wax esters presence). Food quality demands and long ice coverage are possible factors limiting early development of species in spring.