Structure Studies of the Extracellular Polysaccharide from <Emphasis Type="Italic">Trichoderma</Emphasis> sp. KK19L1 and Its Antitumor Effect via Cell Cycle Arrest and Apoptosis

An extracellular polysaccharide TP1A was purified from the fermented broth of Trichoderma sp. KK19L1 by combination of Q Sepharose fast flow and Sephacryl S-300 chromatography. TP1A was composed of Man, Gal, and Glc in a molar ratio of about 3.0:5.1:8.1. The molar mass of TP1A was about 40.0 kDa. Methylation and NMR analysis indicated that the probable structure of TP1A was [→4,6)-α-D-Glcp(1→6)-β-D-Galf(1→6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-β-D-Galf(1→2,6)-α-D-Manp(1→2,6)-α-D-Manp(1→] with [α-D-Glcp(1→] and [α-D-Manp(1→6)-α-D-Glcp(1→6)-α-D-Glcp(1→] as branches. The antitumor study showed that TP1A was able to inhibit the cell viability of HeLa and MCF-7 cells. TP1A could arrest HeLa cells in G2/M phase and induce HeLa cell apoptosis. These findings suggest that fungal polysaccharides could be a potential source for antitumor agents.     

Concise synthesis of two natural steroidal glycosides isolated from <Emphasis Type="Italic">Allium schoenoprasum</Emphasis>

Two natural steroidal glycosides, diosgenin 3-O-α-l-rhamnopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→4)]-β-d-glucopyranoside (1) and laxogenin 3-O-α-l-rhamnopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→4)]-β-d-glucopyranoside (2) with important cytotoxic activity against the HCT 116 and HT-29 human colon cancer cell lines have been efficiently synthesized via straightforward sequential glycosylation reaction with the combined use of N-phenyltrifluoroacetimidates and trichloroacetimidates donors at room temperature. All structures of the synthesized new compounds were identified by ¹H NMR, ¹³C NMR and HRMS spectra.     

Structure of the N-acetylpseudaminic acid-containing capsular polysaccharide of Acinetobacter baumannii NIPH67

Capsular polysaccharide (CPS) was isolated from a nosocomial pathogen Acinetobacter baumannii (A. baumannii) NIPH67 and studied by sugar analysis, Smith degradation, and ¹H and ¹³C NMR spectroscopy. The CPS was found to contain 5,7-diacetamido-3,5,7,9-tetradeoxy-l-glycero-l-manno-non-2-ulosonic acid (di-N-acetylpseudaminic acid, Pse5Ac7Ac), and the structure of the linear trisaccharide repeating unit of the CPS was established as →4)-α-Psep5Ac7Ac-(2→6)-β-d-Galp-(1→3)-α-d-GalpNAc-(1→. The genetic content of the capsule biosynthesis cluster of A. baumannii NIPH67, designated KL33, is consistent with the established CPS structure, and thus the capsule of the investigated strain was assigned to K33 group. Functions of proteins including two glycosyltransferases encoded by the genes of the K33 locus were assigned based on the structure of CPS and by the comparison with related proteins of other capsular types of A. baumannii.     

NMR characteristics of α-D-Man-(1→2)-D-Man and α-D-Man-(1→3)-D-Man mannobioses related to <Emphasis Type="Italic">Candida albicans</Emphasis> yeast mannan structures

Candida albicans mannans are highly perspective polysaccharides for pharmaceutical and biomedical industry. However, they have not been fully characterized. Generally, the larger, acid-stable part of these complex polymers mostly contain α- (and a few β-) linked mannoses. According to this statement all ¹H–¹³C NMR crosspeaks of α-(1→2) and α-(1→3) mannobioses in d₂-water as model disaccharides were assigned (and in d₆-DMSO—partial assignment). It is clearly shown that it is possible to differentiate the type, configuration and position of the glycosidic linkage i.e. α-(1→2) or α-(1→3) by one bond heteronuclear correlated spectroscopy methodology. Subsequently we compared the reference NMR data and isolated dimer fraction from Candida albicans and concluded that it is exclusively composed of α-(1→2) mannobiose. Notably α-(1→2) linkages as the branching points in the mannan polysaccharide structure imply rather spatially rigid orientation of its sidechains.     

Reaction of transsilylation of <Emphasis Type="Italic">N</Emphasis>-methyl-<Emphasis Type="Italic">N</Emphasis>-trimethylsilylacetamide with silanes ClCH<Subscript>2</Subscript>SiR<Superscript>1</Superscript>R<Superscript>2</Superscript>Cl

The reaction of N-methyl-N-trimethylsilylacetamide with silanes ClCH₂SiR¹R²Cl (R¹, R² = H, Me; H, Ph; Ph₂) leads to the formation of (O→Si) chelate compounds with pentacoordinate silicon: N-[chloro(methyl)-silyl]methyl-, N-[chloro(phenyl)silyl]methyl-, and N-[chloro(diphenyl)silyl]methyl-N-methylacetamides. From the data of multinuclear NMR spectroscopy, the intermediates of the reaction of N-methyl-N-trimethylsilylacetamide with ClCH₂SiPhHCl and ClCH₂SiPh²Cl are stable in CDCl₃ solution at room temperature during several days and slowly rearrange to the final (O–Si) chelate compounds.     

Synthesis of bifunctional thieno[3,2-c]pyrazole,pyrazolothieno[2,3-d]pyrimidin derivatives and their antimicrobial activities

A simple and convenient route was performed for the synthesis of some new heterocyclic compounds based on thieno[3,2-c]pyrazole derivative for antimicrobial evaluation. The key intermediate, 5-amino-3-methyl-1-phenyl-1H-thieno[3,2-c]pyrazole-6-carbohydrazide 3, was prepared by Gewald’s synthesis of Ethyl 5-amino-3-methyl-1-phenyl-1H-thieno[3,2-c]pyrazole-6-carboxylate 2. This intermediate reacted with various reagents to afford different fused and polyfunctional substituted. The structures of these compounds were confirmed by elemental analysis, IR, ¹H NMR, ¹³C NMR and mass spectral data. All the new synthesized compounds were screened for various microorganisms such as Aspergillus fumigatus; Geotrichum candidum; Syncephalastrum racemosum (Fungus); Candida albicans (Yeast fungus); Staphylococcus aureus; Bacillus subtilis (as Gram-positive bacteria); Pseudomonas aeruginosa and Escherichia coli (as Gram-negative bacteria) by the disc diffusion method. In general, the novel synthesized compounds possessed moderate to high antimicrobial activity against the previously mentioned microorganisms.     

Synthesis and structure of silicon-containing <Emphasis Type="Italic">N</Emphasis>-methyland <Emphasis Type="Italic">N</Emphasis>-benzoylamides of diisopropylphosphoric acid

Diisopropyl N-benzoyl-N-(trimethylsilyl)phosphoramidate reacts with ClCH₂SiMe₂Cl under mild conditions to form diisopropyl N-benzoyl-N-[(chlorodimethylsilyl)methyl]phosphoramidate (III). Diisopropyl N-methyl-N-(trimethylsilyl)phosphoramidate with ClCH₂SiMe₂Cl affords an N-transsilylation product which does not rearrange into diisopropyl N-[(chlorodimethylsilyl)methyl]-N-methylphosphoramidate (XV) even under severe conditions (4 h, 130°C). Compound XV was prepared by the reaction of diisopropyl phosphorochloridate with N-[(methoxydimethylsilyl)methyl]-N-methylamine followed by treatment of diisopropyl N-[(methoxydimethylsilyl)methyl]-N-methylphosphoramidate with boron trichloride. Analysis of experimental and calculated ²⁹Si chemical shifts points to a five-coordinate silicon atom in compound III and a fourcoordinate silicon atom in compound XV. According to B3LYP calculations with due regard to solvent effects, compound III is an isomer with a C=O→Si bond. By variation of substituents at silicon, phosphorus, and carbonyl carbon atoms, chelate structures with either C=O→Si or P=O→Si dative bonds can be obtained.     

Influence of Linkage Stereochemistry and Protecting Groups on Glycosidic Bond Stability of Sodium Cationized Glycosyl Phosphates

Energy-resolved collision-induced dissociation (ER-CID) experiments of sodium cationized glycosyl phosphate complexes, [GP _x +Na]⁺, are performed to elucidate the effects of linkage stereochemistry (α versus β), the geometry of the leaving groups (1,2-cis versus 1,2-trans), and protecting groups (cyclic versus non-cyclic) on the stability of the glycosyl phosphate linkage via survival yield analyses. A four parameter logistic dynamic fitting model is used to determine CID_50% values, which correspond to the level of rf excitation required to produce 50% dissociation of the precursor ion complexes. Present results suggest that dissociation of 1,2-trans [GP _x +Na]⁺ occurs via a McLafferty-type rearrangement that is facilitated by a syn orientation of the leaving groups, whereas dissociation of 1,2-cis [GP_x+Na]⁺ is more energetic as it involves the formation of an oxocarbenium ion intermediate. Thus, the C1?C2 configuration plays a major role in determining the stability/reactivity of glycosyl phosphate stereoisomers. For 1,2-cis anomers, the cyclic protecting groups at the C4 and C6 positions stabilize the glycosidic bond, whereas for 1,2-trans anomers, the cyclic protecting groups at the C4 and C6 positions tend to activate the glycosidic bond. The C3 O-benzyl (3 BnO) substituent is key to determining whether the sugar or phosphate moiety retains the sodium cation upon CID. For 1,2-cis anomers, the 3 BnO substituent weakens the glycosidic bond, whereas for 1,2-trans anomers, the 3 BnO substituent stabilizes the glycosidic bond. The C2 O-benzyl substituent does not significantly impact the glycosidic bond stability regardless of its orientation.

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Thermodynamics of the terpolymer of carbon monoxide,ethylene, and 1-butene

The heat capacity and the temperatures and enthalpies of physical transformations of the alternating terpolymer of carbon monoxide, ethylene, and 1-butene (the content of butene units is 10.7 mol.%) were studied by adiabatic and differential scanning calorimetry in the temperature range from 6 to 520 K. The energy of terpolymer combustion was measured at 298.15 K on an calorimeter with an isothermal shell and static bomb. The standard thermodynamic functions C°_p(T), H°(T)–H°(0), S°(T)–S°(0), and G°(T)–H°(0) for the range from Т → 0 to 400 K, the standard enthalpy of combustion, and the thermodynamic parameters of formation of the partially crystalline CO—ethylene—1-butene terpolymer at 298.15 K, as well as the thermodynamic characteristics of its synthesis in the range from T → 0 to 400 K were calculated.     

The molecular designs and properties of asymmetric heterocycles (HBrBN<Subscript>3</Subscript>)<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> (<Emphasis Type="Italic">n</Emphasis> = 1-4)

The structures and properties of asymmetric heterocycles (HBrBN₃) _n (n = 1-4) are systematically studied at the B3LYP/6-31G* level. The molecules (HBrBN₃) _n (n = 2-4) have the core structures of a 2n-membered ring with alternating boron and α-nitrogen atoms. The relationships between geometrical parameters and oligomerization degree n are discussed. The calculated IR spectra have four main characteristic regions. Trends in thermodynamic properties with temperature and oligomerization degree n are discussed. Thermodynamic analysis of the gas-phase oligomerizations shows that formation of the most stable heterocycles (HBrBN₃) _n (n = 2-4) is enthalpy driven in the range of 200-800 K.     

Structure and Reactivity of Bicyclo[2.2.1]hept-2-ene-<Emphasis Type="Italic">endo</Emphasis>-5,<Emphasis Type="Italic">endo</Emphasis>-6-dicarboxylic (endic) Acid Hydrazide

Establishing of the structure of hydrazinolysis product obtained from bicyclo[2.2.1]hept-2-ene-endo-5, endo-6-dicarboxylic (endic) acid was performed by preparation of the compound under alternative conditions followed by comparison of the characteristics and spectral parameters of the resulting substances, and also by quantum-chemical calculations by the density functional method of the chemical shifts in ¹H and ¹³C NMR spectra of different reaction products. The X-ray diffraction analysis of the hydrazide was also carried out. The compound obtained was assigned a structure of N-aminobicyclo[2.2.1] hept-2-ene-endo-5,endo-6-dicarboximide. The products were prepared by its reactions with arylsulfonyl chlorides, benzoyl chlorides, m-tolyl and p-toluene-sulfonyl isocyanates, phenyl isothiocyanate, with o-nitrobenzaldehyde, and oxiranes (1,2-epoxycyclohexane and 2,3-epoxypropylcarbazole). The aromatic sulfonamides, carboxamides, and ureas were epoxidized by performic acid obtained in situ from the formic acid and hydrogen peroxide. Products of [3+2]-cycloaddition of aryl azides to the strained double bond in the N-aminobicyclo[2.2.1] hept-2-ene-endo-5,endo-6-dicarboximide and its derivatives. The structures of compounds obtained were confirmed by their IR, 1H and 13C NMR spectra.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-and <Emphasis Type="Italic">C</Emphasis>-trimethylsilyl-substituded anililes

N-Metallation of bromoanilines with ethylmagnesium bromide followed by a reaction with trimethylchlorosilane provided N-mono and N-bis(trimethylsilyl)bromoanilines depending on the structure of substrate. The metallation of bissilylated bromoanilines with butyllithium permitted the introduction of a trimethylsilyl substituent in the aromatic ring. Previously unknown 2-bromo-N,N-bis(trimethylsilyl)aniline, 2,6-dibromo-N-trimethylsilylaniline, 2,6-dibromo-N,N-bis(trimethylsilyl)aniline, 2-bromo-6-trimethylsilylaniline, 2-bromo-6-trimethylsilyl-N,N-bis(trimethylsilyl)aniline, 2-bromo-6-trimethylsilyl-N-trimethylsilylaniline, 2,4,6-tribromo-N-trimethylsilylaniline, and 2,4,6-tribromo-N,N-bis(trimethylsilyl)aniline were prepared. The structures of the compounds obtained were established by the chromato-mass spectrometry and ¹H, ¹³C, and ²⁹Si NMR spectroscopy.     

Synthesis and characterization of half-sandwich ruthenium(II) complexes with N-alkyl pyridyl-imine ligands and their application in transfer hydrogenation of ketones

A series of new arene ruthenium(II) complexes were prepared by reaction of ruthenium(II) precursors of the general formula [(η⁶-arene)Ru(μ-Cl)Cl]₂ with N,N′-bidentate pyridyl-imine ligands to form complexes of the type [(η⁶-arene)RuCl(C₅H₄N-2-CH=N-R)]PF₆, with arene = C₆H₆, R = iso-propyl (1a), tert-butyl (1b), cyclohexyl (1c), cyclopentyl (1d) and n-butyl (1e); arene = p-cymene, R = iso-propyl (2a), tert-butyl (2b). The complexes were fully characterized by ¹H NMR and ¹³C NMR, UV–Vis and IR spectroscopies, elemental analyses, and the single-crystal X-ray structures of 2a and 2b have been determined. The single-crystal molecular structure revealed both compounds with a pseudo-octahedral geometry around the Ru(II) center, normally referred to as a piano stool conformation, with the pyridyl-imine as a bidentate N,N ligand. The activity of all complexes in the transfer hydrogenation of cyclohexanone in the presence of NaOH and iso-propanol is reported, the compounds showing turnover numbers of close to 1990 and high conversions. Complex 2b was also shown to be very effective for a range of aliphatic and cyclic ketones, giving conversions of up to 100 %.     

Electrophilic heterocyclization of 6-alken(yn)ylsulfanyl-pyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4(5<Emphasis Type="Italic">H</Emphasis>)-ones

6-Allylsulfanyl-1-arylpyrazolo[3,4-d]pyrimidin-4(5H)-ones react with iodine and sulfuric acid to give angular pyrazolothiazolopyrimidine derivatives. The reaction of 6-(prop-2-yn-1-ylsulfanyl)-1-(4-tolyl)-pyrazolo[3,4-d]pyrimidin-4(5H)-one with sulfuric acid gives angularly fused pyrazolo[4,3-e][1,3]thiazolo-[3,2-a]pyrimidin-4-one, whereas in the reaction with sodium methoxide linearly fused pyrazolo[3,4-d][1,3]-thiazolo[3,2-a]pyrimidin-4-one was formed. Linearly fused pyrazolo[3′,4′:4,5]pyrimido[2,1-b][1,3]thiazole derivatives were also obtained by reaction of 1-aryl-6-(3-phenylprop-2-en-1-ylsulfanyl)pyrazolo[3,4-d]pyrimidin-4(5H)-ones with sulfuric acid.     

Synthesis and structure of 1-(buta-1,3-dien-2-yl)pyrazoles and their behavior in Diels-Alder reactions

A convenient procedure has been developed for the synthesis of cis-and trans-isomeric 1-(buta-1,3-dien-1-yl)-1H-pyrazoles by reaction of the corresponding pyrazoles with β-methylacrolein diethyl acetal and subsequent 1,4-cleavage of the nucleophilic substitution products. The behavior of the title compounds in Diels-Alder reactions with maleic anhydride has been studied. According to the ¹H NMR data, 1-(buta-1,3-dien-1-yl)-1H-pyrazole is a mixture of cis and trans isomers. Butadienylpyrazoles having methyl groups in the pyrazole ring do not react with maleic anhydride.     

Two-dimensional correlation NMR study of the structure of by-product in the reaction of 2-methylquinoline with 3,5-di-<Emphasis Type="Italic">tert</Emphasis>-butyl-1,2-benzoquinone

The reaction of 2-methylquinoline with 3,5-di-tert-butyl-1,2-benzoquinone afforded a mixture of 5,7-di-tert-butyl-3-hydroxy-2-(quinolin-2-yl)cyclohepta-2,4,6-trien-1-one and previously unknown 10-tert-butylindolo[1,2-a]quinoline-8,11-dione. The structure of the latter was determined by two-dimensional heteronuclear correlation NMR spectroscopy.     

Synthesis and antimicrobial activity of novel substituted 4-[3-(1<Emphasis Type="Italic">H</Emphasis>-benzimidazol-2-yl)-4-hydroxybenzyl]-2-(1<Emphasis Type="Italic">H</Emphasis>-benzimidazol-2-yl)phenol derivatives

A series of novel substituted bis-benzimidazole derivatives were synthesized by reaction of 5,5′-methylenebis(2-hydroxybenzaldehyde) with various substituted o-phenylenediamines in glacial acetic acid. The structure of the newly synthesized compounds was elucidated by ¹H and ¹³C NMR, FT-IR, and MS spectra, and their antimicrobial activity against gram positive and gram negative bacteria and antifungal activity were evaluated. The thienyl-substituted derivative showed significant activity against Bacillus licheniformis. Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumonia (bacteria), and Fusarium solani (fungi). The activities of the fluoro-substituted substituted derivative against some bacterial strains and of the thienyl-substituted derivative against fungi were found to be similar to those of standard drugs.     

Thermodynamic properties of a liquid crystal carbosilane dendrimer

The temperature dependence of the heat capacity of a first-generation liquid crystal carbosilane dendrimer with methoxyphenyl benzoate end groups is studied for the first time in the region of 6–370 K by means of precision adiabatic vacuum calorimetry. Physical transformations are observed in this interval of temperatures, and their standard thermodynamic characteristics are determined and discussed. Standard thermodynamic functions C_p^°(T), H°(T) ? H°(0), S°(T) ? S°(0), and G°(T) ? H°(0) are calculated from the obtained experimental data for the region of Т → 0 to 370 K. The standard entropy of formation of the dendrimer in the partially crystalline state at Т = 298.15 K is calculated, and the standard entropy of the hypothetic reaction of its synthesis at this temperature is estimated. The thermodynamic properties of the studied dendrimer are compared to those of second- and fourth-generation liquid crystal carbosilane dendrimers with the same end groups studied earlier.     

3<Emphasis Type="Italic">H</Emphasis>-Benzo[<Emphasis Type="Italic">a</Emphasis>]imidazo[4,5-<Emphasis Type="Italic">j</Emphasis>]acridine as a new fluorescent heterocyclic system: synthesis,spectral studies,and quantum chemical investigation

The synthesis, spectral studies, and theoretical calculations of a new fluorescent heterocyclic system are described. New 3H-benzo[a]imidazo[4,5-j]acridines were obtained in high yields by the reaction of 1-alkyl-5-nitro-1H-benzimidazoles with (naphthalen-1-yl)acetonitrile via nucleophilic substitution of hydrogen, and their structures were established by spectral (UV-Vis, FT-IR, 1H and 13C NMR) and analytical data. Study of the optical and solvatochromic properties of the dyes revealed their high molar absorption coefficients and high fluorescence quantum yields which in some cases exceeded quantum yields of well-known fluorescent dyes such as fluorescein. Density functional theory (DFT) calculations using the B3LYP hybrid functional and 6-311++G(d,p) basis set were performed to obtain optimized geometries and frontier orbital structures of the synthesized compounds. The electronic absorption spectra were also simulated by the time-dependent density functional theory (TD-DFT) method.     

Synthesis,Structure, and Fluorescence of a Novel Samarium Compound

A novel samarium compound, [Sm(Phen)₂(H₂O)₅]₂(Phen)₂(Bipy)Cl₆ · 7H₂O (I) (Phen = 1,10-phenanthroline and Bipy = 2,2'-bipyridine), was prepared by a solvothermal reaction. The crystal structure of I was characterized by X-ray single-crystal diffraction method (CIF file CCDC no. 1025736). Compound I is an isolated structure with the samarium ions possessing a nine-coordinated distorted monocapped square antiprism geometry. There are abundant hydrogen bonding and π–π stacking interactions which connect the molecules together to yield a three-dimensional (3D) supramolecular structure. The fluorescence spectra data reveals that I can display the characteristic emission ⁴G_5/2 → ⁶H _J transitions (J = 5/2, 7/2, 9/2 and 11/2, respectively) of Sm³⁺ ions.