Destruction of aspen wood by the fungusPhanerochaete sanguinea quantitative1H and13C NMR spectroscopies of biologically degraded lignin

The lignin of mechanically ground aspen wood and lignins isolated from aspen wood attacked by the fungusPhanerochaete sanguinea have been investigated by quantitative¹H and¹³C NMR spectroscopies. It has been shown that the biodestruction of the lignin takes place through the cleavage of alkyl-aryl and aryl-aryl bonds and is accompanied by demethylation (demethoxylation) reactions, and the oxidation of C and C atoms. In addition to reactions in which the C—C bonds are cleaved, the formation of ether bonds has been observed. An interconnection has been shown between the variations in the amount of functional groups, fragments, and the bonds in biolignins and the loss in mass of the wood. A method is proposed for evaluating the carbohydrate content in lignin preparations using the NMR method.Wood Chemistry Branch of the Institute of Organic Chemistry, Siberian Division of the Russian Academy of Sciences, Irkutsk. Irkutsk State University. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 547–557, July–August, 1994.     

Chemical transformations of lignin during the biodegradation and organosolv pulping of deciduous wood

The lignins from the liquors in the organosolv pulping of aspen wood treated with wood-destroying fungi have been investigated using quantitative¹H and¹³C NMR spectroscopy and exclusion liquid chromatography. It has been shown that the biodegradation of lignin takes place in different ways according to the complex of enzymes produced by the fungi. Phanerochaete sanguinea causes degradation through predominant cleavage at alkyl-phenyl bonds, and Trametes villosus at the C-C bonds of the aliphatic chain. In addition to degradation reactions, polymerization (condensation) reactions also take place with the appearance of new C_ar-O-C and C_ar-C bonds. It has been established that the biological pretreatment of aspen wood ensuring partial degradation of the lignin leads to its more ready extraction in the process of organosolv pulping.Wood Chemistry Division of the Irkutsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 603–610, July–August, 1995. Original article submitted May 23, 1994.     

Triterpene glycosides ofThalictrum squarrosum I. Structure of squarrofuric acid

Squarrofuric acid has been isolated fromThalictrum squarrosum by the acid hydryolysis of a methanolic extract. It is suggested that is is an artefact formed on hydrolysis and has the structure of 3, 30-dihydroxy-22,25-epoxylanost-9(11)-en-21-oic acid.¹H and¹³C NMR spectra are given for squarrofuric acid and nine of its derivatives. The mass-spectral characteristics and physicochemical constants of the compounds studied are presented.Irkutsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Irkutsk State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 376–384, May–June, 1987.     

A comparison of the surface properties of lignin and sulfonated lignins by FTIR spectroscopy and wicking technique

The comparison of the FTIR spectra indicated that the sulfonation without caused changes in the main structure of lignin and only in the lignin chains. The surface properties, e.g. the surface free energy and related components, e.g. the Lifshitz–van der Waals and Lewis acid–base interactions components, of lignin and lignosulfonates, LGSs, with different ions, e.g. Na⁺–, Mg²⁺–, and Ca²⁺–, studied and compared by wicking technique indicated that the surface free energy of lignin is lower than that of all used LGSs. This suggests that the sulfonation can enhance the surface property for lignin by increasing of the Lifshitz–van der Waals component and Lewis base component of lignin.     

13C NMR spectra of 3- and 5-substituted flavone derivatives

Summary The¹³C NMR of a number of 3- and 5-hydroxyflavones and of 3- and 5-methoxyflavones have been studied for the first time and all the signals have been assigned. A comparison of the chemical shifts of the¹³C nuclei with the acidity and basicity parameters of the compounds investigated and with the results of calculations of -charge density has been made. It has been shown that the chemical shifts of the individual signals in the¹³C NMR spectra are qualitatively connected with estimates of the reactivities of the compounds studied.Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. A. A. Zhdanov Irkutsk State University. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 513–519, July–August, 1977.     

12-Epinapelline and its N-oxide fromAconitum baicalense

12-Epinapelline and its N-oxide have been isoated from the epigeal part ofAconitum baicalense Turcz. ex Rapaics (A. Czekanovskyi Steinb.). The structures of these compounds have been determined with the aid of two-dimensional¹H and¹³C NMR spectroscopy, and IR and mass spectrometry.Irkutsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 888–892. November–December, 1993.     

New diterpene lactones fromEuphorbia pallasii

Three new diterpene lactones have been isolated from a chloroform extract of the roots ofEuphorbia pallasii: pseudojolkinolide A psuedojolkinolide B, and 16-hydroxypseudojolkinolide B. Structures have been proposed for them on the basis of chemical transformations and IR, UV,¹³C and¹H NMR, and mass spectra.Irkutsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 337–345, May–June, 1985.     

Enzymatic oxidation of lignin and compounds modeling it. III. Formation of singlet oxygen in the peroxidase oxidation of lignin

The main emitters of radiation in the aerobic oxidation of lignin are the carbonyl groups in an excited state and singlet oxygen. It has been shown that the main source of O₂(¹) may be the radical anion O^–·₂. Singlet oxygen and the radical anion are by-products of the radical oxidation of lignin.Siberian Scientific-Research Institute of Cellulose and Board, Bratsk. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 510–514, July–August, 1984.     

Intramolecular interactions and nature of the lowest electronically excited states in compounds modeling the structural unit of lignin. II. Phenolate anions

Quantum-chemical calculations of the electronic structures of the phenolate ions of compounds modeling lignin in the ground and electronically excited states have been made by the CNDO/S method. The intramolecular electron donor-acceptor interactions in the phenolate anion on excitation and the nature of the lowest electronically excited states are discussed on the basis of the results obtained.Siberian Scientific-Research Institute of Pulp and Board, Bratsk. A. A. Zhdanov Irkutsk State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 275–282, March–April, 1988.     

Study of the IR spectra of the products of the ethanolysis of oak and pine lignins

Summary The IR spectra of a number of compounds formed in the ethanolysis of the lignin of foliate and coniferous species have been studied using samples of ethanol lignin, vanillin, syringic aldehyde, p-hydroxybenzaldehyde, guaiacylacetone, coniferyl and sinapic aldehydes, vanilloyl methyl ketone, -hydroxypropiovanillone, -ethoxypropiosyringone, and vanillic and gallic acids. Differences in the absorption at 1330–1340 cm^–1 have been found in the spectra of samples of ethanol lignin from oak and pine. Oak lignin has a strong maximum which is absent in pine lignin. Thus, the lignins of foliate and confierous species can be distinguished by the absorption in the spectral region from 1330 to 1340 cm^–1.Khimiya Prirodnykh Soedinenii, Vol. 3, No. 2, pp. 208–213, 1967     

Electrohydraulic effect in water-plant heterodisperse systems I. Compositions of the solid residue and the aqueous phase

The electrohydraulic (EH) treatment of water-plant heterodisperse systems leads to the partial degradation of the main components of the plant materials: lignin, cellulose, and carbohydrates. The presence of p-hydroxyphenyl and guaiacyl structures has been established on the basis of the results of the GLC analysis of the ether-extracted phenolic products of plant materials subjected to EH treatment. It has been shown that part of the carbohydrates passes into the aqueous phase in the form of free monosaccharides: pentoses and hexoses.Institute of Chemistry of Plant Substances of Uzbekistan Academy of Sciences, Tashkent. Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk. Siberian Institute of Terrestrial Magnetism, the Ionosphere, and the Propagation of Radio Waves, Siberian Branch, Russian Academy of Sciences, Irkutsk. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 707–711, November–December, 1992.     

Synthesis of polyfunctionally substituted benzothiazines based on vinylthionahlobenzenes and 2-mercaptoethylamine

Regioselective nucleophilic substitution of the fluorine atoms in positions 2 and 5 of the benzene ring takes place in the reaction of 3,6-bis(vinylthio)-1,2,4,5-tetrafluoro- and 3-vinylthio-6-chloro-1,2,4,5-tetrafluorobenzenes with 2-mercaptoethylamine in isopropyl alcohol-water-dimethylformamide mixture at 40–45°C in the presence of KOH. The products of disubstitution obtained are converted into 1,4-benzothiazines on heating to 100°C in dimethylformamide in the presence of K₂CO₃ as a result of intramolecular substitution.Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk 664033, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 706–709, May, 1998.     

Metabolism of acetophenone compounds of the fungus Sportorichum pulverulentum

With the aim of revealing the specific reactions of biotransformation under lignolytic conditions, the metabolic transformation bySporotrichum pulverulentum of a number of acetophenone compounds not previously investigated that model fragments of the lignin molecule has been studied. It has been established that the metabolism of 4-hydroxyacetophenone 3-O--D-glucopyranoside takes place as a sequence of processes involving deglucosylation, the methylation of free phenolic hydroxy groups with the formation of methylated intermediates, and the further hydroxylation of the m-methylated metabolite.Irkutsk Institute of Organic Chemistry, Siberian Branch, USSR Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 987–902, November–December, 1987.     

Schematic structure of a fragment of the cottonplant lignin macromolecule

A schematic structure has been proposed for an average fragment of the macromolecule of cottonplant dioxane lignin on the basis of the results of a chemical study and quantitative¹H and¹³C NMR spectroscopy.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 234–236, March–April, 1996. Original article submitted June 27, 1994.     

Highly hydrophobic sisal chemithermomechanical pulp (CTMP) paper by fluorotrimethylsilane plasma treatment

Fluorinated thin layers were created on chemithermomechanical pulp (CTMP) sisal paper surfaces with fluorotrimethylsilane (FTMS) radio frequency-plasma conditions. It was found that the FTMS-discharge environments caused implantation of fluorine and –Si(CH₃) _x groups into the surface layers of the paper substrates. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy and Electron Spectroscopy for Chemical Analysis, as well as Atomic Force Microscopy and Scanning Electron Microscopy analyses revealed a smooth surface for the FTMS plasma-treated paper, apparently covered completely with a cross-linked polymerized network. Although the plasma reaction takes place with the cellulose, hemicelluloses and lignin, it appears that the chemical linkage is mainly to the lignin component on the CTMP paper surface by means of mainly C–O–Si–F, with some C–Si–F structures. The CTMP fibers apparently have a high lignin surface concentration. The water absorption for the plasma-treated CTMP paper was reduced from greater than 300 to 17 g of water/m² and the contact angle increased from less than 15° to greater than 120° the strength properties were only slightly reduced and the brightness was essentially unaffected with the FTMS plasma treatment.     

Intramolecular interactions and nature of the lowest electronically excited states in compounds modeling the structural unit of lignin. I. Molecular form

Quantum-chemical calculations of the electronic structure of molecules of model compounds of lignin in the ground and electronically excited states have been made by the CNDO/S method. The paper gives results on the energies and strengths of the oscillators of the electronic transitions and on the type of excited singlet and triplet states, shows the main configurations of the HOMOs and LUMOs participating in the transitions and their energies and statistical weights, and gives the distribution of charges and their redistribution on the passage of the molecules from the ground into the excited states. Donor-acceptor interactions in the molecules under investigation are discussed on the basis of the results obtained.Siberian Scientific-Research Institute of Pulp and Board, Bratsk. A. A. Zhdanov Irkutsk State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 265–274, March–April, 1988.     

Coumarins fromPhlojodicarpus sibiricus

Phlojodicarpin [8-(2,3-epoxy-1-hydroxy-3-methylbutyl)-7-methoxycoumarin, C₁₅H₁₆O₅, mp 143–145°C, [] _D ²⁵ -37.5°], and isophlojodicarpin [8-(1,2-epoxy-3-hydroxy-3-methylbutyl)-7-methoxycoumarin, C₁₅H₁₆O₅, mp 132–134°C, [] _D ²⁵ -102.5°] have been isolated from the epigeal part ofPhlojodicarpus sibiricus. The results of the IR, UV, PMR, and mass spectrometry of these compounds are given.Institute of Chemistry, Academy of Sciences of the Mongolian Peoples' Republic, Ulan-Bator. Irkutsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 47–49, January–February, 1981.     

Biodegradation of aromatic compounds by the yeast-like fungus Trichosporon cutaneum

The biodegradation reactions of veratryl- and guaiacylpropane compounds modeling structural fragments of the lignin macromolecule by the yeast-like fungusTrichosporon cutaneum D-46 have been investigated. It has been shown that the enzyme complex ofT. cutaneum is capable of catalyzing a series of reactions of the biotransformation of arylpropane substrates, namely: oxidation, the cleavage of the C-C bond of the propane chain, demethylation, and decarboxylation. The action of the enzymes was shown most actively in the case of substrates having an unsubstituted phenolic hydroxy group.Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk. Institute of Microbiology, Belorussian Academy of Sciences, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 558–564, September–October, 1992.     

Triterpene saponins from Thalictrum minus. VI. Structure of thalicoside C

From the epigeal part ofThalictrum minus L. (Ranuncluaceae) we have isolated a minor cycloartane trisdesmoside — thalicoside C — 3,16,22(S),29-tetrahydroxy-9,19-cyclo-20(S)-lanost-24-ene 3-O--galactopyranoside 22,29-di-O--D-glucopyranoside. Its structure was established from the results of chemical transformations and of FAB-mass and NMR spectroscopies (¹H₁,¹³C,¹H-¹H₁, and¹³C-¹H).Irkutsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedeninii, No. 1, pp. 103–109, January–February, 1993.