The amide-type phytoalexin activity of carnation extracts is partly due to an artifact

The relative distribution of phytoalexins induced by Fusarium oxysporum fsp. dianthi in carnation and localized by pyrolysis-mass spectrometry in the xylem differs from that found by HPLC in acetone extracts. In situ, in the xylem, there is a predominance of 2-aryl-1,3-benzoxazin-4H-ones over the more fungitoxic N-aroylanthranilates. At least part of the dianthramides in the extracts has to be ascribed to artifacts apparently due to hydrolysis of benzoxazinones.     

Esters and amides of 2,3-dimethoxy-8,9-methylenedioxy-benzo[i]phenanthridine-12-carboxylic acid: potent cytotoxic and topoisomerase I-targeting agents

The exceptional topoisomerase I-targeting activity and antitumor activity of 5-(2-N,N-dimethylamino)ethyl-8,9-dimethoxy-2,3-methylenedioxy-5H-dibenzo[c,h][1,6]naphthyridin-6-one (ARC-111, topovale) prompted studies on similarly substituted benzo[i]phenanthridine-12-carboxylic ester and amide derivatives. Among the benzo[i]phenanthridine-12-carboxylic esters evaluated, the 2-(N,N-dimethylamino)ethyl, 2-(N,N-dimethylamino)-1-methylethyl, and 2-(N,N-dimethylamino)-1,1-dimethylethyl esters possessed similar cytotoxicity, ranging from 30 to 55 nM in RPMI8402 and KB3-1 cells. Several of the carboxamide derivatives possess potent topoisomerase I-targeting activity and cytotoxicity. The 2-(N,N-dimethylamino)ethyl, 2-(N,N-diethylamino)ethyl, and 2-(pyrrolidin-1-yl)ethyl amides were among the more cytotoxic benzo[i]phenanthridine-12-carboxylic derivatives, with IC₅₀ values ranging from 0.4 to 5.0 nM in RPMI8402 and KB3-1 cells.     

H NMR study of the interaction of N,N′,N″-triacetyl chitotriose with Ac-AMP2, a sugar binding antimicrobial protein isolated from Amaranthus caudatus

The interaction between Ac-AMP2, a lectin-like small protein with antimicrobial and antifungal activity isolated from Amaranthus caudatus, and N,N′,N″-triacetyl chitotriose was studied using ¹H NMR spectroscopy. Changes in chemical shift and line width upon increasing concentration of N,N′,N″-triacetyl chitotriose to Ac-AMP2 solutions at pH 6.9 and 2.4 were used to determine the interaction site and the association constant K_a. The most pronounced shifts occur mainly in the C-terminal half of the sequence. They involve the aromatic residues Phe¹⁸, Tyr²⁰ and Tyr²⁷ together with their surrounding residues, as well as the N-terminal Val-Gly-Glu segment. Several NOEs between Ac-AMP2 and the N,N′,N″-triacetyl chitotriose resonances are reported.     

Biohydroxylation of N,N-dialkylarylamines by the isolated topsoil bacterium Bacillus megaterium

Topsoil microorganisms were screened for their acceptability of the standard substrate N,N-dimethylaniline in bacterial ‘whole-cell’ incubations. One bacterium converted N,N-dimethylaniline and was identified as Bacillus megaterium by 16S rDNA analysis and DNA/DNA-hybridization. In contrast to the well-known C-hydroxylation by liver microsomes, leading to p-hydroxylation, B. megaterium formed o- and p-monohydroxylated products, i.e. N,N-dimethyl-2-aminophenol and N,N-dimethyl-4-aminophenol, both identified by gas chromatography–mass spectrometry (GC–MS) using synthesized reference compounds. The observed hydroxylation showed slight regioselectivity in favour of the o-hydroxylated product. Two further substrates, N,N-diethylaniline and N-ethyl-N-methylaniline, were also successfully biohydroxylated by B. megaterium with corresponding regioselectivity. Interestingly, aniline, known to be transformed easily by cytochrome P-450meg into p-aminophenol, was not accepted as substrate.     

Redox state of the partially reduced cytochrome aa3-cyanide complex

The low-spin ferric cyanide complex of beef heart cytochrome aa₃ can be partially reduced by stoichiometric additions of ferrous cytochrome c or by similar additions of N,N,N′,N′-tetramethyl-p-phenylene diamine. In both cases the initial ratio of cytochrome c oxidized: cytochrome a reduced or Wurster's Blue: cytochrome a reduced approximates the value 2. It is concluded that the binding of a single HCN prevents the reduction of both cytochrome a₃ and its associated EPR-invisible Cu atom.     

Estimation of absorption efficiency in polychaetes using nitrogen content of food

From 14 values reported for nine species of polychaetes, a highly significant (P < 0.0005) multiple correlation (r = 0.987) between the nitrogen content of food (N) and absorption efficiency (Ae) is observed and is adequately fitted by the polynomial cubic equation: Ae = 11.744−13.353 N+6.510 N²−0.458 N³.     

Dinuclear silver(I) complexes of 24-membered bibracchial tetraimine Schiff base macrocycles derived from 2,5-diformylthiophene

The cyclocondensation of 2,5-diformylthiophene and the amines N,N-bis-(2-aminoethyl)-2-phenylethylamine, N,N-bis-(2aminoethyl)-t-butyl-amine and N,N-bis-(2-aminoethyl)-t-butyl-amine in the presence of silver(I) salts yields homodinuclear bibracchial tetraimine Schiff base macrocyclic complexes. The structures of two such complexes are also reported. The complex Ag₂L⁴(NO₃)(PF₆) (2) crystallises in the triclinic space group , No. 2) and has unit-cell dimensions a = 12.834(6), B = 13.183(6), C = 14.588(7) Å, = 64.86(4), β = 79.77(4), γ = 69.44(3)° with Z = 2; there is a monodentate and singly bridging nitrate anion present and the Ag---Ag separation is 4.161 Å. The complex Ag₂L⁴(CH₃CN)₂(BF₄)₂·CH₃CN (9) crystallises in the triclinic space group , No. 2) and has unit-cell dimensions a = 9.297(4), B = 12.985(3), C = 21.770(5) Å, = 91.570(10), β = 92.33(3), γ = 97.92(3) ° with Z = 2; there is a strongly bonded acetonitrile molecule coordinated to each silver atom and the Ag---Ag separation is 4.920 Å.     

枫香叶斑病病原菌

从福建多地采集了55份感染叶斑病的枫香植物病样,包含叶片、叶柄、枝条和树皮。通过分离纯化得到了12个类拟盘多毛孢属真菌菌株,综合形态特征以及3个基因(ITS、β-tubulin和tef1)的分子系统发育分析结果,分别鉴定为Neopestalotiopsis cocoes、N. chrysea、Pestalotiopsis neglecta和P. neolitseae,均为枫香上首次报道,其中N. cocoes在国内首次被发现。通过柯赫氏法则验证,发现N. cocoes能够侵染叶片、叶柄和枝条,N. chrysea能侵染叶片和枝条,P. neglecta能侵染叶柄和枝条,而P. neolitseae不能侵染枫香植物组织。     

Aromatase activity, serum oestradiol and their correlation with demographic indices

Peripheral aromatase activity was measured in 24 postmenopausal women suffering from advanced breast cancer. The % conversion of androstenedione to oestrone was then assessed for a significant correlation with age, weight, height, Quetelets index (weight/height², Q.I.) and length of menopause. Serum oestradiol (E₂) levels were measured in 22 of the subjects and compared with the same indices. There was no correlation between E₂ or aromatase activity with the length of menopause (P = 0.3 and P = 0.5, respectively). In our data aromatase activity did not correlate with age (P > 0.5, N = 22). Serum E₂ levels (P = 0.07, N = 20) expressed a negative correlation (i.e. decreased) with age. There was also a poor correlation between aromatase activity and weight of Quetelets index (P = 0.3, N = 20 for both). Serum E₂ levels showed a statistically significant correlation with weight (P = 0.01, N = 21), but the relationship with Quetelets index just failed to attain statistical significance (P = 0.07, N = 20). In both cases the regression line was positive. When aromatase activity was correlated with serum E₂ levels the regression line was positive but not statistically significant (P = 0.4, N = 22). The data indicate that aromatase activity is only one factor determining the differences in serum E₂ levels between postmenopausal women.     

A novel one-pot three-component reaction: synthesis of triheterocyclic 4H-pyrimido[2,1-b]benzazoles ring systems

A novel one-pot three-component condensation reaction of an aldehyde, β-ketoester and 2-aminobenzimidazole or 2-aminobenzothiazole in 1,1,3,3-N,N,N′,N′-tetramethylguanidinium trifluoroacetate as an ionic liquid is described. During the course of this reaction 4H-pyrimido[2,1-b]benzimidazoles or 4H-pyrimido[2,1-b]benzothiazoles are formed in high yields at 100 °C. The ionic liquid can be recovered conveniently and reused efficiently.     

1,10-Phenanthroline-5,6-dione as a building block for the synthesis of homo- and heterometallic complexes

1,10-Phenanthroline-5,6-dione (C₁₂H₆N₂O₂ (1)) reacts with V(η⁶-mesitylene)₂ and Ti(η⁶-toluene)₂ affording coordination compounds of general formula M(O,O′---C₁₂H₆N₂O₂)₃ (M=Ti (2); M=V (3)) which further react with TiCl₄ or TiCp₂(CO)₂ yielding the tetrametallic species M(O,O′---C₁₂H₆N₂O₂---N,N′)₃(M′L_n)₃ (M=V, M′L_n=TiCl₄ (4); M=Ti, M′L_n=TiCp₂ (5); M=V, M′L_n=TiCp₂ (6)). The complex salt [Fe(N,N′---C₁₂H₆N₂O₂)₃][PF₆]₂ (7) has been obtained from iron(II) chloride tetrahydrate and 1 in the presence of NH₄PF₆. The reaction of 7 with TiCp₂(CO)₂ affords the tetrametallic derivative [Fe(N,N′---C₁₂H₆N₂O₂---O,O′)₃(TiCp₂)₃][PF₆]₂ (8). TiCl₂(THF)₂ reacts with MCp₂(O,O′---C₁₂H₆N₂O₂) to give MCp₂(O,O′---C₁₂H₆N₂O₂---N,N′)TiCl₂ (M=Ti (9); M=V (10)). By reaction of TiCp₂(O,O′---C₁₂H₆N₂O₂---N,N′)TiCl₂ (9) with C₁₂H₆N₂O₂, the bimetallic derivative TiCp₂(O,O′---C₁₂H₆N₂O₂---N,N′)TiCl₂(O,O′---C₁₂H₆N₂O₂) (11) has been prepared, which readily adds to TiCl₄, to give the trimetallic titanium derivative TiCp₂(O,O′---C₁₂H₆N₂O₂---N,N′)TiCl₂(O,O′---C₁₂H₆N₂O₂---N,N′)TiCl₄ (12). VCp₂(O,O′---C₁₂H₆N₂O₂---N,N′)TiCl₂ (10) reacts with the tris-chelate iron(II) cation 7 affording the heptametallic cationic complex [Fe(N,N′---C₁₂H₆N₂O₂---O,O′)TiCl₂(N,N′---C₁₂H₆N₂O₂---O,O′)VCp₂]₃ ⁺² isolated as the hexafluorophosphate 13.     

X-ray crystal structure of Cu2(medpco-2H)Cl2, (medpco = N,N′-bis(2-N,N-dimethylaminoethyl)pyridine-2,6-dicarboxamide 1-oxide. Copper(II) complexes of a deprotonated binucleating pyridine N-oxide ligand

The X-ray structure is reported for the complex Cu₂(medpco-2H)Cl₂, (medpco = N,N′-bis-N,N-dimethylaminoethyl)pyridine-2,6-dicarboxamide 1-oxide. The complex is triclinic, , a=8.313(4), B=11.403(5), C=11.611(3) Å, =91.66(3), β=108.99(4), γ=109.60(3)° and Z=2. The deprotonated ligand (medpco-2H)²⁻ acts as a binulceating ligand, producing an N-oxide-bridged complex. Each copper in Cu₂(medpco-2H)Cl₂ is five-coordinate, being coordinated by a bridging N-oxide oxygen, a deprotonated amide nitrogen, a tertiary amine nitrogen and two bridging chlorides. The complex does not exhibit significant magnetic interaction, and this may be the result of distortion of the bridging geometry from planarity. A range of other, apparently N-oxide-bridged, complexes of the type Cu₂(medpco-2H)X₂ is reported. The complex Cu₂(medpco-2H)Br₂·H₂O is strongly antiferromagnetic, with magnetic data closely fitting the expected binuclear structure.     

Induction of lacI mutations in Big Blue Rat-2 cells treated with 1-(2-hydroxyethyl)-1-nitrosourea: a model system for the analysis of mutagenic potential of the hydroxyethyl adducts produced by 1,3-bis (2-chloroethyl)-1-nitrosourea.

We have investigated the genotoxic effects of 1-(2-hydroxyethyl)-1-nitrosourea (HENU). We have chosen this agent because of its demonstrated ability to produce N7-(2-hydroxyethyl) guanine (N7-HOEtG) and O⁶-(2-hydroxyethyl) 2′-deoxyguanosine (O⁶-HOEtdG); two of the DNA alkylation products produced by 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU). For these studies, we have used the Big Blue Rat-2 cell line that contains a lambda/lacI shuttle vector. Treatment of these cells with HENU produced a dose dependent increase in the levels of N7-HOEtG and O⁶-HOEtdG as quantified by HPLC with electrochemical detection. Treatment of Big Blue Rat-2 cells with either 0, 1 or 5 mM HENU resulted in mutation frequencies of 7.2±2.2×10⁻⁵, 45.2±2.9×10⁻⁵ and 120.3±24.4×10⁻⁵, respectively. Comparison of the mutation frequencies demonstrates that 1 and 5 mM HENU treatments have increased the mutation frequency by 6- and 16-fold, respectively. This increase in mutation frequency was statistically significant (P<0.001). Sequence analysis of HENU-induced mutations have revealed primarily G:C→A:T transitions (52%) and a significant number of A:T→T:A transversions (16%). We propose that the observed G:C→A:T transitions are produced by the DNA alkylation product O⁶-HOEtdG. These results suggest that the formation of O⁶-HOEtdG by BCNU treatment contributes to its observed mutagenic properties.     

Plant regeneration from mesophyll protoplasts of Solanum commersonii dun

Somatic fusion of Solanum commersonii, a frost tolerant wild potato species not crossable with Solanum tuberosum, relies on the possibility to isolate and culture protoplasts. This study was conducted to determine whether protoplasts could be isolated and plants regenerated in three S. commersonii accessions. Shoot cultures for protoplast isolation were maintained on Murashige and Skoog medium. Mesophyll protoplasts were isolated and cultured using a protocol originally described for S. tuberosum with some modifications. Differences were evident among the three accessions for protoplast yield, plating efficiency and regeneration frequency. Protoplast yield ranged from 3.0 to 8.5 × 10⁶ protoplasts per g of fresh tissue. At 1–2 × 10⁴ protoplasts ml⁻¹, which was the optimal plating density, 10–20% of plated protoplasts gave multicellular colonies. Regeneration of shoots was observed in two accessions only, the maximum regeneration frequency being 66%. In one of these accessions the reduction of sucrose concentration in regeneration media improved the regeneration frequency from 14 to 35%. About three hundred plants were rooted in vitro and successfully transferred to soil.     

亚热带人工林乔灌草根际土壤氮矿化特征

为了探讨人工林内优势乔木和林下灌草根际土壤氮矿化特征, 明确乔灌草根际土壤氮转化差异, 该研究以江西泰和千烟洲站区典型人工杉木(Cunninghamia lanceolata)、马尾松(Pinus massoniana)和湿地松(Pinus elliottii)林为对象, 在植被生长季初期(4月)和旺盛期(7月)分析3种人工林内乔木、优势灌木(檵木(Loropetalum chinense)、杨桐(Adinandra millettii)、格药柃(Eurya muricata))和草本(狗脊蕨(Woodwardia japonica)、暗鳞鳞毛蕨(Dryopteris atrata))根际土壤的净氮矿化速率、土壤化学性质及土壤微生物特征。结果发现: 1)物种、林型和取样季节显著影响了根际土壤净氮矿化速率(N_min)、净铵化速率(N_amm)和净硝化速率(N_nit)。马尾松和湿地松林内林下灌草根际土壤净氮矿化的季节敏感性高于乔木: 4月乔木根际土壤N_min和N_amm显著高于大多数林下灌草, 而7月林下灌草根际土壤N_min和N_amm显著提高, 与乔木不再具有显著差异, 与主成分综合得分方差分析的结果一致。一般情况下, 杉木林N_min和N_nit显著高于马尾松林和湿地松林。7月净氮矿化显著高于4月。2)土壤铵态氮、硝态氮、全氮及土壤微生物量氮含量是影响根际土壤净氮矿化的主要因素。土壤化学性质对人工林根际土壤净氮矿化变异的贡献率为29.2%, 显著高于土壤微生物的解释率。充分考虑不同季节林下植被根际土壤的净氮矿化及其关键影响因素可为准确评估人工林生态系统养分循环状况提供重要支撑。     

Studies of the cation complexing ability of crowns Part I. Synthesis, characterization and crystal structure of diazacrowns and their barium complexes

A number of N,N′-bis(4-substituted phenyl)-1,7-diaza-12-crown-4 and N,N′-bis(4-substituted phenyl)-1, 10-diaza-18-crown-6 (where the substituents are OCH₃, CH₃, H, Cl, respectively) have been prepared by cyclization reaction of a ditosylate with the appropriately substituted diol. These new macrocyclic ligands have been characterized by means of elemental analysis, IR, ¹H NMR and MS spectra. The crystal structures of N,N′-bis(4-chlorophenyl)-1,10-diaza-18-crown-6 (21) and its complex with barium thiocyanate Ba(SCN)₂ (22) have been determined by single crystal X-ray diffraction. The crystallographic data are as follows: 21: C₂₄H₃₂Cl₂N₂O₄, orthorhombic, P2₁2₁2₁, A=4.852(1), B=11.989(2), C=41.231(8) Å, V=2398.7(8) ų, Z=4; 22: C₂₆H₃₂Cl₂N₄O₄S₂Ba, monoclinic, P2₁/c, A=8.801(2), B=11.653(9), C=15.756(6) Å, ß=105.96(3)°, V=1553.7(14) ų, Z=2. In the complex, the Ba atom is eight-coordinate (O(1), O(2), O(1)′, O(2)′, N(1), N(1)′, N(21), N(21)′) to form a distorted D_6h geometry with the Ba atom at the center of crystallographic symmetry.     

Post functionalization of carboxymethylated starch and acrylonitrile based networks through amidoximation for use as ion sorbents

Carboxymethylation of starch provided carboxymethyl starch (CMS) and the modification was followed by grafting CMS with acrylonitrile (AN) using ammonium per sulphate-N,N,N,N-tetramethylethylene diamine as initiator–accelerator system. Crosslinked networks of CMS and AN were obtained using two crosslinkers, viz., N,N-methylenebisacrylamide and ethyleneglycoldimethacrylate. The networks were further reacted with hydroxylamine to generate metal ion active amidoxime groups. The synthesized hydrogels were characterized by FTIR, SEM, nitrogen analysis and swelling studies to evaluate water uptake and the candidate polymers were used as matrices for the sorption of Fe²⁺ ions, as a model metal ion, as a function of time, temperature, pH and ionic strength. An attempt was made to investigate the thermodynamics of its sorption behaviour.     

Characteristics of soil nitrogen mineralization in the rhizosphere of trees,shrubs, and herbs in subtropical forest plantations

为了探讨人工林内优势乔木和林下灌草根际土壤氮矿化特征, 明确乔灌草根际土壤氮转化差异, 该研究以江西泰和千烟洲站区典型人工杉木(Cunninghamia lanceolata)、马尾松(Pinus massoniana)和湿地松(Pinus elliottii)林为对象, 在植被生长季初期(4月)和旺盛期(7月)分析3种人工林内乔木、优势灌木(檵木(Loropetalum chinense)、杨桐(Adinandra millettii)、格药柃(Eurya muricata))和草本(狗脊蕨(Woodwardia japonica)、暗鳞鳞毛蕨(Dryopteris atrata))根际土壤的净氮矿化速率、土壤化学性质及土壤微生物特征。结果发现: 1)物种、林型和取样季节显著影响了根际土壤净氮矿化速率(N_min)、净铵化速率(N_amm)和净硝化速率(N_nit)。马尾松和湿地松林内林下灌草根际土壤净氮矿化的季节敏感性高于乔木: 4月乔木根际土壤N_min和N_amm显著高于大多数林下灌草, 而7月林下灌草根际土壤N_min和N_amm显著提高, 与乔木不再具有显著差异, 与主成分综合得分方差分析的结果一致。一般情况下, 杉木林N_min和N_nit显著高于马尾松林和湿地松林。7月净氮矿化显著高于4月。2)土壤铵态氮、硝态氮、全氮及土壤微生物量氮含量是影响根际土壤净氮矿化的主要因素。土壤化学性质对人工林根际土壤净氮矿化变异的贡献率为29.2%, 显著高于土壤微生物的解释率。充分考虑不同季节林下植被根际土壤的净氮矿化及其关键影响因素可为准确评估人工林生态系统养分循环状况提供重要支撑。     

Preparation, spectral characterization, cytotoxic and thermal studies of platinum (IV) thiohydrazone complexes

Platinum (IV) complexes of type [Pt(L)₂Cl₂] [where, L=benzaldehyde-N,N-diphenyl-N-thiohydrazone (L¹), salicylaldehyde-N,N-diphenyl-N-thiohydrazone (L²), acetaphenone-N,N-diphenyl-N-thiohydrazone (L³) and cyclohexanone-N,N-diphenyl-N-thiohydrazone (L⁴)] have been synthesized. The thiohydrazones can exist as thione–thiol tautomer and coordinates as a bidentate N–S ligand. The ligands found to act in monobasic bidentate fashion. Analytical data reveals that metal to ligand stoichiometry is 1:2. The complexes have been characterized by elemental analysis, IR, mass, electronic, ¹H NMR spectroscopic studies, and TG/DTA study. Various kinetic and thermodynamic parameters like order of reaction (n), activation energy (E_a), apparent activation entropy (S^#) and heat of reaction (ΔH) have also been carried out for one complex. Cytotoxic study has also been carried out for one complex.     

A new dinuclear unsymmetric copper(II) complex as model for the active site of catechol oxidase

The crystal structure, magnetic, redox and spectroscopic properties of a novel unsymmetrical dinuclear copper(II) complex, prepared by the reaction between copper(II) perchlorate, sodium acetate and the unsymmetrical, binucleating ligand HTPPNOL, where HTPPNOL is N,N,N′-tris-(2-pyridylmethyl)-1,3-diaminopropan-2-ol, is reported. HTPPNOL (1 equiv.) reacted with 1 equiv. of copper(II) ion, in methanol, and produced the mononuclear copper complex [Cu(TPPNOL)](ClO₄)(BPh₄) (1). On the other hand, the reaction of 1 equiv. of HTPPNOL with 2 equiv. each of copper (II) ion and acetate, in methanol, produced the dinuclear complex [Cu₂(TPPNOL)(OOCCH₃)](ClO₄)₂ (2), whose structure has been determined by X-ray diffraction. In complex 2, as a result of the inherent asymmetry of the ligand HTPPNOL, one copper ion is five-coordinated (distorted trigonal-bipyramidal) while the other copper is four-coordinated (distorted square-planar). Then, as a result of the presence of distinct geometries for the metal centres, complex 2 exhibits a ferromagnetic coupling (J=+25.41 cm⁻¹). Titration experiments carried out on the dinuclear complex suggest a pK_a=8.0, which was related to the aquo/hydroxo equilibrium. Complex 2 is able to oxidise 3,5-di-tert-butylcatechol to the respective o-quinone. The oxidation reaction was studied by following the appearance of the quinone spectrophotometrically, at pH 8.0 and 25 °C.