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⁺.     

Trefoil Factor Family Domains Represent Highly Efficient Conformational Determinants for N-Linked N,N′-di-N-acetyllactosediamine (LacdiNAc) Synthesis

The disaccharide N,N′-di-N-acetyllactose diamine (LacdiNAc, GalNAcβ1–4GlcNAcβ) is found in a limited number of extracellular matrix glycoproteins and neuropeptide hormones indicating a protein-specific transfer of GalNAc by the glycosyltransferases β4GalNAc-T3/T4. Whereas previous studies have revealed evidence for peptide determinants as controlling elements in LacdiNAc biosynthesis, we report here on an entirely independent conformational control of GalNAc transfer by single TFF (Trefoil factor) domains as high stringency determinants. Human TFF2 was recombinantly expressed in HEK-293 cells as a wild type full-length probe (TFF2-Fl, containing TFF domains P1 and P2), as single P1 or P2 domain probes, as a series of Cys/Gly mutant forms with aberrant domain structures, and as a double point-mutated probe (T68Q/F59Q) lacking aromatic residues within a hydrophobic patch. The N-glycosylation probes were analyzed by mass spectrometry for their glycoprofiles. In agreement with natural gastric TFF2, the recombinant full-length and single domain probes expressed nearly exclusively fucosylated LacdiNAc on bi-antennary complex-type chains indicating that a single TFF domain was sufficient to induce transfer of this modification. Contrasting to this, the Cys/Gly mutants showed strongly reduced LacdiNAc levels and instead preponderant LacNAc expression. The probe with point mutations of two highly conserved aromatic residues in loop 3 (T68Q/F59Q) revealed that these are essential determinant components, as the probe lacked LacdiNAc expression. The structural features of the LacdiNAc-inducing determinant on human TFF2 are discussed on the basis of crystal structures of porcine TFF2, and a series of extracellular matrix-related LacdiNAc-positive glycoproteins detected as novel candidate proteins in the secretome of HEK-293 cells.     

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).     

Is Ag(I) an adequate probe for Cu(I) in structural copper–metallothionein studies?

The binding abilities of silver(I) to mammalian MT 1 have been studied and compared with those of copper(I), recently reported [Bofill et al. (2001) J Biol Inorg Chem 6:408–417], with the aim of analyzing the suitability of Ag(I) as a Cu(I) probe in Cu–MT studies. The Zn/Ag replacement in recombinant mouse Zn₇–MT 1 and corresponding Zn₄-MT 1 and Zn₃-MT 1 fragments, as well as the stepwise incorporation of Ag(I) to the corresponding apo-MTs, have been followed in parallel by various spectroscopic techniques including electronic absorption (UV–vis), circular dichroism (CD) and electrospray mass spectrometry coupled to capillary zone electrophoresis (CZE-ESI-MS). A comparative analysis of the sets of data obtained in the titration of Zn₇–MT 1, Zn₄–MT 1 and Zn₃-MT 1 with AgClO₄ at pH 7.5 and 2.5 has led to the reaction pathways followed during the incorporation of silver to these proteins under these specific conditions, disclosing unprecedented stoichiometries and structural features for the species formed. Thus, the Zn/Ag replacement in Zn₇–MT 1 at pH 7.5 has revealed the subsequent formation of Ag₄Zn₅–MT, Ag₇Zn₃–MT, Ag₈Zn₃–MT, Ag₁₀Zn₂–MT, Ag₁₂Zn₁–MT, Ag_x–MT, x=14–19, whose structure consists of two additive domains only if Zn(II) remains coordinated to the protein. A second structural role for Zn(II) has been deduced from the different folding found for the Ag_x–MT species of the same stoichiometry formed at pH 7.5 or 2.5. Comparison of the binding features of Cu(I) and Ag(I) to the entire MT at pH 7.5 shows that, among all the _xZn_y–MT (0y<7) species found, only M^I₄Zn₅–MT [(Zn₄)(₄Zn₁)] and M^I₇Zn₃–MT [(₃Zn₂)(₄Zn₁)], which form during the first stages of the Zn(II)/M(I) metal replacement, show comparable 3D structures; thus, they are the only species where Ag(I) ions can be predicted to be an adequate probe for Cu(I).Electronic Supplementary Material Supplementary material is available in the online version of this article at .     

Syntheses and antitumor activities of N′1,N′3-dialkyl-N′1,N′3-di-(alkylcarbonothioyl) malonohydrazide: The discovery of elesclomol

A series of N′¹,N′³-dialkyl-N′¹,N′³-di(alkylcarbonothioyl) malonohydrazides have been designed and synthesized as anticancer agents by targeting oxidative stress and Hsp70 induction. Structure–activity relationship (SAR) studies lead to the discovery of STA-4783 (elesclomol), a novel small molecule that has been evaluated in a number of clinical trials as an anticancer agent in combination with Taxol.     

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.     

Stoichiometry and products of transmetalation of dimeric copper(I) complexes L2Cu2X2 (L is an N,N,N′,N′-tetraalkylethylenediamine; X = Cl or Br) by M(NS)2 reagents in aprotic solvents

Dimeric copper(I) complexes L₂Cu₂X₂ react with 1 and 2 mol of M(NS)₂ reagents in aprotic solvents to give quantitative yields of products LMX₂ and (NS)M(X,X)M(NS), respectively. Here, L = N,N,N′N′-tetraethylethylenediamine, X = Cl or Br, M = Co, Ni, Cu and Ns = S-methylisopropylidenehydrazinecarbodithioate. Dimers (NS)Cu(X,X)Cu(NS) are oxidatively unstable. LCoCl₂ crystallizes in the monoclinic space group P2₁/c (C_2h⁵): a = 7.345(1), b = 11.801(1), c = 17.478(2) Å, β = 104.98(1)°, Z = 4. The electronic spectra of LMX₂ and (NS)M(X,X)M(NS) complexes are discussed.     

The kinetics of primary events in the reactions of L2Cu2X2 complexes (L is an N,N,N′N′-tetraalkyldiamine; X is Cl or Br) with M(NS)2 reagents

The rate laws for the earliest events in the transmetalation of dimeric copper(I) complexes L₂Cu₂X₂ (L = N,N,N′N′-tetraalkyldiamine; X = Cl or Br) by M(NS)₂ reagents (M = Co, Ni, Cu, Zn; NS is a monoanionic S-methylhydrazinecarbodithioate Schiff base ligand) depend on L, X, M and NS and the aprotic solvent. The kinetic data are compared with those for monotransmetalation of copper(II) complexes (μ₄-O)N₄Cu₄X₆ by M(NS)₂. Different kinetic behavior is particularly marked for cobalt(II) reactants. Unexpectedly high rates of reactions with Cu(NS)₂ are attributed to electron transfer. The results provide a basis for discussion of transmetalation specificity.     

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.     

Efficient synthesis of oligonucleotide conjugates on solid-support using an (aminoethoxycarbonyl)aminohexyl group for 5′-terminal modification

Solid-support conjugation at the 5′-terminal primary amine of oligonucleotides is a convenient and powerful method for introducing various functional groups. However, conventional aliphatic amines do not necessarily provide conjugates with sufficient yields. To improve the modification efficacy, we used the amino-linker (aminoethoxycarbonyl)aminohexyl group (ssH-linker), for solid-support conjugation. In the ssH-linker terminal modification, reactive free amino group could be easily presented onto a solid-support due to rapid removal of the amino-protecting group, and activated amino acids or cholesterol molecules could be covalently connected more efficiently than to typical 6-aminohexyl-linkers. Based on these results, the ssH-linker can be a useful terminal modification for the solid-support conjugation of functional molecules.     

Is the dichogamy ofSalvia verbenaca (Lamiaceae) an effective barrier to self-fertilization?

Though dichogamy is generally interpreted as a means of preventing self-fertilization, the efficiency of this mechanism has been questioned. Little attention has been paid to functional aspects of male/female timing, such as variation over time in pollen germinability and in stigma receptivity. In the present study these aspects of male/female timing were investigated in the protandrous speciesSalvia verbenaca. To evaluate the effects of selfing, fruit set, total seed weight produced and seed/ovule ratio were also determined, (a) following artificial crossing, (b) following selfing (i.e. bagging) and (c) under natural conditions. Both pollen germinability and stigma receptivity peaked on the last day (day 3) of the flower's life, which presumably favours selfing. Neither fruit set nor seed/ovule ratio were significantly affected by pollination regime, but the total seed weight produced by artificially crossed plants was significantly higher than that produced by bagged or untreated plants. Neither fruit set, seed/ovule ratio nor total seed weight differed significantly between the two years of study. Thus, if aS. verbenaca flower receives outcrossing pollen it will produce a greater weight of seeds (with consequent advantages in terms of female reproductive success). However, the peaking of both pollen germinability and stigma receptivity on day 3 of the flower's life means that selfing is likely to occur if outcrossing pollen has not been received over the early part of the flower's life.     

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.     

The reaction of amines with N,N′-ethylenebis(salicylideneiminato)(nitrato)-iron(III) and related complexes

The title compound, Fe(salen)NO₃, was reacted with imidazole, 1-methylimidazole, piperidine, and morpholine in either chloroform or dichloromethane solution. The reactions were monitored with proton NMR and electronic spectra and conductance measurements. The imidazole bases appeared to react with the complex in a 2:1 fashion with displacement of the nitrate, producing a high-spin iron(III) complex. The secondary amines promoted hydrolysis with any trace water present to form [Fe(salen)]₂O. The chloro complex, Fe(salen)Cl, did not react with the imidazole bases, but did form the μ-oxo complex when a large excess of piperidine was present. The N,N′-phenylenebis-(salicylideneimine) complex, Fe-(salphen)NO₃, was found to precipitate from an imidazole (im) chloroform solution as the high-spin complex, Fe(salphen)NO₃·2im.     

Preparation of 2,3′-Anhydropyrimidine Nucleosides using N,N-Diethylaminosulfur Trifluoride (DAST)

Abstract

2,3′-Anhydro-2′-deoxy-5′-0-(triphenyl methyl) and 5′-0-(monomethoxytriphenylmethyl) pyrimidine nucleosides of uracil, thymine, and cytosine were synthesized in a single step from their 2′-deoxy-5′-0-(triphenylmethyl) or 5′-0-(monomethoxytriphenylmethyl) precursors using N,N-diethylaminosulfur trifluoride (DAST). The anhydronucleosides were either isolated or directly converted to their respective 2-deoxy-β-D-threo-pentofuranosyl nucleosides using sodium hydroxide in ethanol.     

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.     

Synthesis,structures and characterization of the dinuclear nickel(II) complexes containing N,N,N′,N′-tetrakis[(1-ethyl-2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane and an azide ion

Two dinuclear nickel(II) complexes, [Ni₂(L-Et)(N₃)(H₂O)₃](NO₃)₂ · 2H₂O (1) and [Ni₂(L-Et)(μ-1,3-N₃)(H₂O)₂](NO₃)₂ · 4H₂O (2) containing (HL-Et = N,N,N′,N′-tetrakis[(1-ethyl-2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane), have been synthesized and characterized by their IR and UV–Vis spectra and magnetic susceptibilities. The crystal structures of [Ni₂(L-Et)(N₃)(H₂O)₃](NO₃)₂ · CH₃OH (1′) and [Ni₂(L-Et)(μ-1,3-N₃)(H₂O)₂](NO₃)₂ · 2C₂H₅OH (2′) similar to 1 and 2 were determined by X-ray crystallography. In 1′, the two nickel(II) ions are bridged by only an alkoxo group of L-Et⁻, while an azido and an alkoxo connect two nickel(II) ions in 2′. Magnetic susceptibility measurements (2–300 K) showed a weak ferromagnetic exchange coupling between the two nickel(II) ions (2J = 10.1 cm⁻¹) for 1. On the other hand, antiferromagnetic interactions were observed for 2 (2J = −15.8 cm⁻¹).