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.     

Quantitative1H and13C NMR spectroscopy of lignins from an aqueous ethanolic cook of aspen wood

General and comparative characteristics obtained by¹H and¹³C NMR spectroscopy of the lignins from aqueous ethanolic cooks are presented. It is shown that degradation of the lignin macromolecule takes place during the digestion of aspen wood. The mean length of the lignin side chains decreases and ether bonds are cleaved, while the degree of condensation of the substances increases.Irkutsk State University. Irkutsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 277–285, March–April, 1993.     

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_α and C_γ 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.     

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.     

Biotransformation of Aspen Lignin by the Fungus Trametes villosus

Quantitative ¹ H and ¹³ C NMR spectroscopies demonstrate that biotransformation of aspen wood by the fungusTrametes villosusresults in oxidation and destruction of lignin with cleavage of C-C alkyl-alkyl bonds in side chains and partial demethoxylation in addition to cleavage of lignocarbohydrate bonds. New C _ar -O-C bonds form while lignin is being destroyed at alkyl-alkyl bonds. Cleavage of rings and destruction of C _ar -C bonds was not observed.     

IR-spectroscopic investigation of aspen wood biolignins

Aspen wood biolignins have been investigated by IR spectroscopy and -, procedure has been developed for determining the amounts of -, ß- and -carbonyl groups in the lignins obtained from aspen wood after the action of the lignin-destroying fungusPhanerochaete sanguinea. A large contribution of the C-oxidation reaction and the appearance in the biolignins of ester groups and also nonconjugated ketone and aldehyde groups have been revealed. The latter may, presumably, be -, consequence of the oxidation of the C atoms of the propane chain and the appearance of -O-4 structural units in the lignin.Institute of Organic Chemistry, Siberian Division of the Russian Academy of Sciences, Irkutsk, fax (3952) 46 03 31. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 474–478, May–June, 1995. Original article submitted July 25, 1994.     

NMR investigation of alkaloids. III.13C NMR spectra and reconsideration of the stereochemistry of herbamine and herbadine

The stereochemistry previously proposed for herbamine (V) and herbadine (II) as C₂-H has been reconsidered on the basis of a comparative study of the¹³C NMR of these compounds and of vincamajine, quebrachidine, ajmaline, vincamajoreine, and majoridine, and it has been established unambiguously that herbamine and herbadine belong to the dihydroindole alkaloids with C₂-H, herbamine being C₃-hydroxyvincamajine, and herbadine C₆-hydroxyquebrachidine.For Communication II, see [1].Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 731–735, November–December, 1982.     

A peucedanol glucoside fromPhlojodicarpus turczaninovii

The new coumarin peucedanol 3--D-glucopyranoside (I), C₂₀H₂₆O₁₀·C₂H₅OH, mp 160–162°C, has been isolated from an ethanolic extract of the epigeal part ofPhlojodicarpus turczanovii growing in the Monoglian People's Republic (Gobi-Altai). The acid hydrolysis of (I) formed D-glucose and peucedanol (II), and also decursinol and marmesin. The results of IR, UV, PMR, and¹³C NMR spectroscopy are given.Institute of Chemistry, Academy of Sciences of the Mongolian People's Republic, Ulan-Bator. Irkutsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 190–192, March–April, 1985.     

6-Chloroapigenin fromEquisetum arvense L.

A new compound 6-chloroapigenin, C₁₅H₉C10₅, M⁺ 304, mp 305–306°C, _max 274, 336 (methanol) has been isolated from the ether-soluble fraction of a methanolic extract of the field horsetail. On the basis of the results of UV and PMR spectroscopy and mass spectrometry, the structure of 6-chloro-4,5,7-trihydroxyflavone has been established for this compound.Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR, All-Union Scientific-Research Institute of Medicinal Plants, Moscow. I. M. Sechenov First Moscow Medical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 499–501, July–August, 1980.     

The crystal and molecular structures of 1,1′-divinyl-2,2′-biimidazolyl

The crystal and molecular structures of 1,1-divinyl-2,2-biimidazolyl (L) were determined by x-ray crystallographic analysis. It was established that the molecule of L has crystallographic symmetry 2 and a cisoid conformation with an angle of rotation of 128° between the imidazole rings. The length of the C²-C² bond is increased to 1.485(11) Å compared with the length of the analogous bond in unsubstituted 2,2-biimidazolyl (1.423 Å). Localization of the N=C multiple bond is observed [1.297(9) Å]. The other N-C bonds of the ring are almost equalized (1.374 Å) and are close to the standard values for bonds of the C _sp ²-N type in imidazoles. The angle between the plane of the heterocycle and the plane passing through the atoms of the vinyl group amounts to 7°.N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 117907 Moscow. Irkutsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, 664033 Irkutsk. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1376–1380, June, 1992.     

13C NMR spectra of a number of penta- and hexacyclic triterpenoids derived from glycyrrhetic acid

The¹³C NMR spectra of 22 derivatives of 18- and 18-glycyrrhetic acids that have been investigated and an assignment of the signals has been made. It has been shown that a modification of the carboxy group of glycyrrhetic acid leads mainly to a change in the chemical shifts of the -, -, and -carbon atoms of ring E. The assignment of a number of signals has been confirmed by the use of the shift reagent Eu(fod)_s. It has been established that the C₂₈ and C₁₆ signals are the most sensitive to a change in the C₁₈ configuration in the spectra of glycyrrhetic acid derivatives.Institute of Chemistry, Bashkir Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 645–653, September–October, 1985.     

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 glycosides of Thalictrum squarrosum. III. Structures of squarrogenins 1 and 2

Two genins — squarrogenin 1 and squarrogenin 2 — have been isolated from nodding meadow rue by the hydrolysis of squarrosides A1 and A2. The compounds are epimeric at C-21 and have the following structures: 1 — (21R, 22S, 23R)-21-methoxy-21,23-epoxycycloart-24-ene-3,22-30-triol, C₃₁H₅₀O₅, mp 169–171°C (hexane-acetone), [] ₅₄₆ ²⁰ –11.06° (c 4.52; pyridine); and 2 — (21S, 22S, 23R)-21-methoxy-21,23-epoxycycloart-24-ene-3,22,30-triol, C₃₁H₅₀O₅, mp 190–193°C (hexane-acetone), [] ₅₄₆ ²⁰ +106.6° (c 0.3; pyridine). The results of¹H and¹³C NMR spectroscopy and of mass spectrometry for the new compounds are given.Irkutsk Institute of Organic Chemistry, Siberian Division of the USSR Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 510–516, July–August, 1989.     

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.     

Culcitoside C1 from the starfishCulcita novaeguineae andLinckia guildingi

By repeated chromatography on Polikhrom-1, silica gel, and Florisil, ethanolic extracts of two species of starfish,Culcita novaeguineae andLinckia guildingi, have yielded the new steroid glycoside culcitoside C₁ (I): 5-cholestan-3,4,6,8,15,24-hexaol 24-O-[2,4-di-O-methyl--D-xylopyranosyl-(12)--L-arabinofuranoside], C₃₉H₆₈O₁₄, mp 245–248°C, []_D -35.8°, c 0.6; methanol). Its structure was shown by the results of acid hydrolysis, acetylation and methylation, and¹H and¹³C NMR spectroscopy.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 801–804, November–December, 1985.     

Structures of daurosides A and B — New acylated coumarin glycosides fromHaplophyllum dauricum

From the roots and epigeal parts ofHaplophyllum dauricum (L.) G. Don., new acylated courmarin glycosides have been isolated: dauroside A, C₂₃H₂₈O₁₃, mp 145–147°C (ethanol), [] _D ²² – 72.7° (methanol), and dauroside B, C₃₀H₃₂O₁₄, mp 145–150°C (methanol) [] _D ²² 0° (pyridine). Their structures have been established on the basis of chemical transformations and IR, UV, mass,¹H NMR and¹³C NMR spectra.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 142–147, March–April, 1983.     

Cerebrosides of the Far Eastern sponge Hymeniacidon assimilis

Cerebrosides have been isolated from chloroform-ethanol extract of the spongeHymeniacidon assimilis. Their structures have been established with the aid of¹H NMR spectroscopy, acid hydrolysis, and ozonolysis as the -galactosides of the C₁₆-, C₁₇-, and C₁₈-erythro-⁴-sphingenines of normal, iso, and anteiso structures acylated in the amino groups with C₂₁-, C₂₂-, and C₂₃--hydroxy acids. The cerebrosides fromH. assimilis differ in structure from the corresponding compounds isolated previously from sponges.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Institute of Marine Biology, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 634–639, September–October, 1989.     

Synthesis of gibberellins A8 and A56 from gibberellin A3

A mixture of gibberellin A₃ derivatives with 1(10)-ene-2,3-diol and 1(10)-ene-2,3-diol (2:5) groups, readily obtained from gibberellin A₃, has been used for a new and simple synthesis of gibberellin A₈ and its esters. The hydrolysis of GA₃ and the iodolactonization of a mixture of the 2-epimers was carried out in aqueous solution in a single flask, as also was a synthesis of GA₅₆ from GA₃ by a method that we have modified. The mixture of 1-iodides of GA₈ and GA₅₆ was separated by chromatography on SiO₂ in the form of methyl or p-bromophenacyl esters which were then deiodinated and the methyl or p-bromphenacyl ester of GA₈ was isolated. Free GA₈ was obtained by the dephenylation of the latter ester. By two-dimensional NMR spectroscopy we succeeded in assigning all the signals in the¹³C and¹H NMR spectra of the methyl esters of GA₈ and GA₅₆. In an attempt to obtain GA₅ methyl ester by the action of trimethylchlorosilane/sodium iodide on the 2,3-diol system in GA₅₆ methyl ester, the 8,13-epimer of the latter was formed, the structure of its molecule being established from the results of X-ray structural analysis.Novosibirsk Institute of Organic Chemistry, Siberian Division of the Russian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 663–669, September–October, 1994.     

Triterpene glycosides of Thalictrum squarrosum. IV. Structures of squarrosides A1, A2, B1, and B2

Four new cycloartane glycosides have been isolated from a methanolic extract ofThalictrum squarrosum Stephan ex Willd.: squarroside A1 (I) — (21R, 22S, 23R)-3-(-D-glucopyranosyloxy)-21-methoxy-21,23-epoxycycloart-24-ene-22,30-diol, C₃₀H₆₀O₁₀; squarroside A2 (II) — the (21S)-epimer of compound (I); squarroside B1 (III) (21R, 22S, 23R)-3gb-[O--L-rhamnopyranosyl-(1 6)--D-glucopyranosyloxy]-21-methoxy-21,23-epoxycycloart-24-ene-22,30-diol, C₄₃H₇₀O₁₄; and squarroside B2 (IV) — the (21S)-epimer of compound (III). The proposed structures were determined on the basis of¹H and¹³C NMR spectroscopy, FAB mass spectrometry, and chemical transformations.Irkutsk Institute of Organic Chemistry, Siberian Branch, USSR Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 516–523, July–August, 1989.