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1.
When (±)--oxo-guaiacylglycerol--(vanillic acid) ether (1) is degraded byFusarium solani M-13-1, the-ketone is initially reduced to giveerythro andthreo guaiacylglycerol--(vanillic acid) ethers (2), arylglycerol--aryl ethers, both of which are enantiomerically pure. The absolute configuration in each2 was determined by Mosher's method; the products were converted to,-di-(R)--methoxy--trifluoromethylphenylacetates (MTPA esters) (3) oferythro (-)- andthreo (+)-veratrylglycerol--(methyl vanillate) ethers (3), whose1H nuclear magnetic resonance (NMR) spectra were examined and compared with those of four di-(R)-MTPA ester (3) diastereomers from chemically synthesizederythro (±)-3 andthreo (±)-3. To assign the- and-MTPA-OCH3 peaks, the1H NMR scans of several compounds that have substructures of 3 and their 3,4,5-trimethoxyphenyl analogues were examined. When a racemic alcohol reacts with (R)-MTPA to give a pair of (R)-MTPA ester diastereomers, the value was defined as the absolute value of the difference in the1H chemical shifts of the peak between the diastereomers. It was found that the values of-MTPA-OCH3 were larger than those of-MTPA-OCH3 owing to a shielding effect of the veratryl ring located on the-MTPA-OCH3, and that the-MTPA-OCH3 peaks in the 3,4,5-trimethoxyphenyl compounds shifted downfield relative to those in the veratryl compounds. On the basis of the1h NMR data of (R)-MTPA esters, the absolute configuration of the four chemically prepared diastereomers (3) were determined. The catabolicerythro 3 [fromerythro (-)-3] andthreo 3 [fromthreo (+)-3] were identical to (R, S, R)-erythro 3 and (R, S, S)- threo 3, respectively. An hydrogen species in the fungal reduction would attack the-ketone fromre-face of both (R)-1 and (S)-1, givingerythro (S, R)-2 andthreo (S, S)-2, respectively.Part of this paper was presented at the 33rd Lignin Symposium, Tsukuba, November 1988  相似文献   

2.
Sphingomonas paucimobilis SYK-6 produces unique and specific enzymes, such as-etherases,O-demethylases, and ring fission dioxygenases, for lignin degradation. Cleavage of arylglycerol--aryl ether linkage is the most important process in the lignin metabolic pathway ofS. paucimobilis SYK-6. We reported the genes (ligD, ligE, ligF) for enzymes that cleaved-aryl ether linkage of dimeric compounds in previous studies. In this study we synthesized the fluorescent high-molecular-weight lignin (UBE-DHP) by dehydrogenative polymerization. We investigated the-aryl ether cleavage ability of these enzymes produced in recombinantEscherichia coli. When UBE-DHP was incubated with LigF, 4-methylumbeliferone was released as a result of-aryl ether cleavage of O-methylumbelliferyl--hydroxypropiovanillone (compound III) incorporated in UBE-DHP. Here, we report that-etherase ofS. paucimobilis SYK-6 can be expressed inE. coli and is able to cleave the-aryl ether linkage in synthetic high-molecular-weight lignin.  相似文献   

3.
Synthesis conditions of terpene-phenol-aldehyde resin with a high softening point were studied based on the reactions among-pinene, phenol, and formaldehyde. A suitable catalyst system and the best processing conditions were obtained by laboratory experiments. The influence of the raw materials ratios, reaction temperature, reaction time, and catalyst dose on the softening point, yield, and color of the synthesized resin was examined. The physical and chemical characteristics of the resin were determined: softening point 140°C (ball and ring method); color value 7 (Gardner); acid value (KOH mg/g) <1; bromine value (Br2 mg/100g) <64; saponification value (KOH mg/g) <1; average molecular weight 830. The yield of resin was more than 85% (based on the total raw material).  相似文献   

4.
Sodium, potassium, magnesium, calcium and physicochemical parameters were monitored for one year in a mangrove tidal creek near Bragança, North Brazil, to determine their tidally induced and seasonal variations and the main parameters controlling the concentration of these cations. On a daily basis, cation concentrations showed a strong tidal rhythm due to the mixing of estuarine and mangrove waters. Mean concentrations were highest at the end of the dry season (December 1996) and lowest (April 1997) towards the end of the rainy season. Average values over one year were: Na+ = 329± 118mM, K+ = 6.9±2.5mM, Mg++=37 ±14 mM and Ca++= 6.9±2.4mM. Dissolved oxygen concentration was higher during the dry season due to enhanced aquatic primary production, with a maximum daily average value of 8.5mg/L in July 1996, and a minimum value of 4mg/L in June 1997. Cation concentrations were transformed relating them to the respective average values in standard seawater at salinity 35. Although cation concentrations and salinity tightly correlated, this standardization showed that the concentrations of K+, Ca++ and Mg++ did not depend solely on salinity and reflected the seasonal variation in aquatic primary production. It also allowed the discrimination of their sources (marine, riverine and groundwater). Thermodynamic equilibrium calculations indicate that phytoplankton may be regulating the concentration of these cations in the water column indirectly by inducing precipitation through pH increase and directly through metabolic uptake.  相似文献   

5.
Ethyl acetate extracts ofCupressus lusitanica suspension cell cultures were examined for their biological activities (viz., tyrosinase inhibitory, antioxidant, and antimicrobial activities). The extract from elicitor-treated cells showed all of the biological activities, whereas the extract from cultures without elicitor was not bioactive to a discernible extent. The biological activities shown by the cell culture extracts were almost solely accounted for by-thuj aplicin contained in the extracts. These results suggest that the ethyl acetate extract ofC. lusitanica cells treated with the elicitor is a valuable bioactive source without isolation or purification of-thujaplicin.  相似文献   

6.
A modified synthetic method for phenolic-O-4 lignin substructure model dimers was developed involving protection of the phenolic hydroxyl group of acetophenons with benzoyl chloride, bromination with 4-dimethylaminopyridiniumbromide perbromide, condensation with phenols in the presence of 18-crown-6-ether, condensation with paraformaldehyde, reduction with NaBH4 and debenzoylation. This method results in shorter reaction times and increasing yields without the application of strict anhydrous and drastic conditions or chloric solvents. This alternative route could be applied to the-O-4 dilignol syntheses of four combinations of guaiacyl and syringyl derivatives.  相似文献   

7.
The protected structure of -oxoacteoside (tomentoside A), 2-oxo-2-(3,4-dihydroxyphenyl)ethyl 3-O-(2,3,4-tri-O-acetyl--l-rhamnopyranosyl)-4-O-caffeoyl--d-glucopyranoside 14 was synthesized in 14% overall yield in 11 steps, starting from d-glucose for biological and medicinal studies of phenylpropanoid glycosides. The first step was the preparation of a 3-O-rhamnopyranosyl disaccharide sugar core 2 from a suitably protected rhamnosyl trichloroacetimidate 10 and glucose derivative (diacetone-d-glucose 1) in 71% yield. To the glucose moiety of this sugar core, several protection/deprotection procedures were performed sequentially to obtain a fully acetylated sugar core 7 with a 4-OH group on the glucose moiety, in 57% yield in five steps. Thereafter, to the 4-OH group of the glucose moiety, selective 4-O-caffeoylation was achieved by proton-transfer esterification with 3,4-di-O-allylcaffeic acid 16 to give the caffeoyl disaccharide 11 in 97% yield. Then, it was converted to trichloroacetimidate 13 for a glycosylation donor in 90% in two steps. Finally, anomeric glycosylation was conducted with 2-oxo-2-(3,4-di-allyloxyphenyl)ethyl alcohol 19 with catalytic amounts of BF3·Et2O to give 2-oxo-2-(3,4-di-allyloxyphenyl)ethyl 2,6-di-O-acetyl-3-O-(2,3,4-tri-O-acetyl--l-rhamnopyranosyl)-4-O-(3,4-di-allyloxycaffeoyl)--d-glucopyranoside 14 in 60% yield. Deprotected intermediates of compounds 2, 11, 14, and 19 which were obtained in high yield would be useful for biological and medicinal studies of phenylpropanoid glycosides.Part of this study was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April, 2002  相似文献   

8.
The inhibitory effects of 102 methanol extracts of 40 mycelia, 9 culture fluids, and 53 fruiting bodies of 40 strains of Ganoderma lucidum on 5-reductase were investigated. The methanol extract of the fruiting body of each strain was found to show the strongest 5-reductase inhibitory activity among the extracts tested.  相似文献   

9.
Preparation of liquid polyols from d-(+)-glucose (Glc) and its derivative, methyl--d-glucoside (m-Glc), has been studied. Direct reaction of -caprolactone (CL) with Glc (CL:Glc = 2:1–5:1 in weight ratio) at 150°C using tin(II) 2-ethyl hexanoate (SnEht2) (series A), in which melted Glc was suspended in CL, resulted in a dark-brown coloration of the reactants. The reaction was accompanied by formation of high molecular weight resins, a pH drop, production of water, and a considerable decrease in the hydroxyl value from the theoretically expected one. In the case of Glc/ethylene glycol (EG)/CL reaction system with SnEht2 catalyst at 150°C (series B), in which the weight ratio of Glc to EG was fixed at 1:1, Glc dissolved in the EG/CL mixture, but the brown coloration of the reactant mixture still occurred. In this case, the formation of water was enhanced, but the other effects found in series A were suppressed to a considerable extent. In the m-Glc/CL/SnEht2 reaction system (series C), in which m-Glc reacted with two to five times weight amounts of CL under the same conditions adopted in series A, development of the color, the production of high molecular weight materials and water, and the changes in pH and hydroxyl value were not observed. These results are discussed based on the chemical structural differences: Glc exists mostly in the hemiacetal form, but tautomerizes to the aldehyde, whereas m-Glc is an acetal and is protected from reversion to the aldehyde.  相似文献   

10.
The present work was undertaken from the standpoint of radical-capturing ability with regard to the antioxidative ability of flavonoids, especially flavonols distributed widely in woody plants. In regard to the flavonols, six methyl derivatives were initially prepared from quercetin and its litinoside. Their radical-capturing constants were determined strictly by the stopped-flow spectroscopic method. It was proved that the radical-capturing ability of quercetin mainly involves the vicinal C3. and C4, hydroxyl groups and the C3 hydroxyl group. To clarify the reaction mechanism begun at the C3 hydroxyl group of quercetin, 5,7,3,4-tetramethylquercetin (TMQ), flavon-3-ol (F30) and so on were treated with 2,2-azo-bis-(2,4-dimethylvaleronitrile) (AMVN). Six products (1–6) containing one depside and its two hydrolytic products, two valeronitrile adducts, and others were isolated from the reaction mixture of TMQ and their structures determined by instrumental analyses. Similarly, F30 gave four products, 7–10, which corresponded to the above products 1–3 and 5 (one depside, its two hydrolytic products, and one adduct), respectively. 3,5,7,3,4-Pentamethylquercetin (PMQ) and flavon-3-O-methylate (F3M) gave no products. The quantitative change of the products with reaction time was determined spectroscopically. An initial reaction pathway for the radical-capturing reaction of flavon-3-ols with AMVN was proposed based on the products and their amounts. The main route — formation of depside and its hydrolytic products via ketohydroperoxide (3) or ketohydroperoxy radical (4) - was similar to that of the oxidation reaction of quercetin with quercetinase and light.Part of this paper was presented at the 46th and 47th annual meetings of the Japan Wood Research Society, Kumamoto and Kouchi, April 1996 and 1997  相似文献   

11.
Bergmann  Ben A. 《New Forests》2003,25(3):185-199
Performance of Paulownia elongata, Paulownia fortunei, and Paulownia×Henan 1 was monitored at three sites in North Carolina between 1996 and 2000, and P. elongata clones were tested at an additional two sites. The primary objective was to define the potential for growing Paulownia in the state. Species and clones within species differed in survival and height and diameter growth whenever genotype was included as a treatment. P. elongata was superior at two and P. fortunei was superior at one of the three sites that included P. elongata, P. fortunei, and P.×Henan 1. Trees produced through vegetative means were more likely to survive and were taller and of greater DBH than seed produced trees. Mortality in trees produced from seed was greater for P. fortunei and P. ×Henan 1 than for P. elongata. Application of animal waste or different rates of nitrogen as inorganic fertilizer did not have a pronounced effect on tree survival and growth.  相似文献   

12.
A method to estimate the content of -carbonyl structures in lignin was developed. This method consists of two successive treatments: NaBD4 treatment of pulp to reduce an -carbonyl structure in lignin, and nitrobenzene oxidation. NaBD4 was used to convert an -carbonyl structure to a deuterium-labeled hydroxymethine structure. The ratio of D-vanillin [(HO)(H3CO)C6H3CDO] to H-vanillin [(HO)(H3CO)C6H3CHO] or that of their syringyl analogues obtained by nitrobenzene oxidation was used as the measure of the content of -carbonyl structure. Model experiments demonstrated that when sodium hydroxide was used as alkali for the nitrobenzene oxidation, the retention of deuterium at the side chain -position was very low due to the displacement of deuterium with hydrogen by an unknown reaction mechanism. In order to depress this unexpected displacement, the reaction conditions of the nitrobenzene oxidation were modified. The modified nitrobenzene oxidation employs 0.5mol/l of lithium hydroxide as a reaction medium instead of 2.0mol/l sodium hydroxide. By this modification, this method could successfully trace the formation and the degradation of the -carbonyl structure in milled wood lignins.This paper was presented in part at the 11th International Symposium on Wood and Pulping Chemistry, Nice, France, June 2001 and at the 46th Lignin Symposium, Kyoto, Japan, November 2001  相似文献   

13.
Wind velocity, vertical stand structure and seasalt distribution were measured at various heights inside a plantation of coastal pine forest, with thinning and unthinning, to assess whether any relationships exist between the wind profile, stand structure and seasalt distribution in the coastal pine forest. The vertical stand structure, i.e., optical stratification porosity (OSP), which is defined as vertical distribution of the proportion of sky hemisphere not obscured by tree elements inside a forest stand, was determined for each height by computer analysis of digital images taken with a hemispherical lens. The distribution of OSP in the coastal forest follows the Lambert-Beer's law with absorbency coefficient (). The relative windspeed within canopy can be described using the exponential form with the attenuation coefficient (). The sea-salt was collected using salt gauze (a surgical dressing of loosely woven cotton) both inside and outside the coastal forest, and the distribution of sea-salt within canopy was also in accordance with an exponential function. The relationships among windspeed, OSP and sea-salt indicate that the distributions of both sea-salt and windspeed within canopy were very closely correlated with the distribution of OSP. A linear relationship between OSP and sea-salt has been found. Additionally, linear regression between coefficients and has been obtained as well. Based on these relationships between OSP, wind and sea-salt in the coastal forest, the sea-salt distribution and wind profile within the canopy of the coastal forest can be predicted according to OSP. These results may therefore be useful in analyzing the effects of sea-salt on vegetation and evaluating the filter functions of coastal forests.This revised version was published online in November 2005 with corrections to the Cover Date.  相似文献   

14.
5-Reductase inhibitory activity of methanol extracts of the heartwood of 13 tropical wood species were examined. Strong 5-reductase inhibitory activity was observed withShorea species. From melapi (Shorea sp.), two known resveratrol trimers, vaticanol A and ampelopsin C, and two novel trimers were isolated as active compounds. The structures of the two novel resveratrol trimers were elucidated by one- and two-dimensional nuclear magnetic resonance spectroscopic analyses, including1H-1HCOSY, HMQC, and HMBC. The compounds were named melapinol A and melapinol B. There were no significant differences among the 5-reductase inhibitory activities of the four resveratrol trimers, which were significantly stronger than those of-linolenic acid and epigallocatechin gallate, known 5-reductase inhibitors.  相似文献   

15.
Sugi (Cryptomeria japonica D. Don) wood was treated with supercritical water (374°C, 22.1MPa), and fractionated into the water-soluble portion, the methanol-soluble portion, and the methanol-insoluble residue. The methanol-soluble portion mainly consisted of the lignin-derived products. To characterize the compounds in the methanol-soluble portion, gel permeation chromatographic (GPC) and gas chromatographic-mass spectrometric (GC-MS) analyses were performed. The GPC analysis indicated that the methanol-soluble portion contained lignin-derived monomeric and dimeric products. GC-MS analysis detected 31 products which were expected to be monomeric compounds, and 18 of these were identified to be guaiacol, methylguaiacol, ethylguaiacol, vinylguaiacol, eugenol, propylguaiacol, vanillin, cis-isoeugenol, homovanillin, trans-isoeugenol, acetoguaiacone, propioguaiacone, guaiacylacetone, 2-methoxy-4-(1-hydroxypropyl)phenol, homovanillic acid, 2-methoxy-4-(prop-1-en-3-one)phenol, coniferyl aldehyde, and ferulic acid. In addition, 22 dimeric products were detected, and 4 of these were believed to be compounds with biphenyl type (5-5), diphenylethane type (-1), stilbene type (-1), and phenylcoumaran type (-5) structures. These results clearly indicated that the methanol-soluble portion included various monomeric and dimeric compounds produced as a result of the cleavage of ether linkages and propyl chains of lignin.  相似文献   

16.
To characterize the mechanism of the reaction of lignin with aqueous acetic acid (AW) containing a small amount of H2SO4, guaiacylglycerol--guaiacyl ether (GOG), and guaiacylglycerol--syringol ether (GOS) were refluxed in 90% AW with 0.28% H2SO4 for 0–120 min. Reaction products and their silylated derivatives were characterized by analytical methods such as gas chromatography-mass spectrometry and nuclear magnetic resonance. When the model compounds were allowed to react at boiling temperature for 0 min (heat-up time 30 min), most of their primary alcohol groups and some of their secondary alcohol groups were acetylated, but their phenolic groups were not. About 90% of GOG was degraded, polymerized, or both during boiling for at least 15 min, yielding guaiacol and isocoumaran compounds (GOG-e and GOG-f) in addition to homovanillin (II) as guaiacylvinyl alcohol (I) and other minor products. GOS yielded syringol, homovanillin (II), and a novel compound (V) together with unknown products but not the corresponding isocoumaran compounds.  相似文献   

17.
The effect of sulfometuron (Oust) on the root growth of loblolly pine (Pinus taeda L.) seedlings was studied in the field and in two soil types in the greenhouse. In the greenhouse study sulfometuron was applied to the foliage only, the soil only, and to both foliage and soil at the rates of 0.10, 0.21, and 0.42 kg ai/ha. Twenty-eight days after application root growth significantly decreased for all methods of application and with increasing rates e.g., 0.10, 0.21, and 0.42 kg ai/ha sulfometuron reduced new root length by 42%, 53%, and 64%, respectively. Application in the field at the rate of 0.30 kg ai/ha resulted in a 68% reduction in root growth. However, by the end of the growing season treated seedling root and shoot biomass were 115% and 64% greater, respectively. To ensure earlier season survival the rate of sulfometuron applied should be kept at a minimum level that will allow both weed control and adequate root growth. Low rates would be particularly important during a dry planting season.  相似文献   

18.
The inhibitory effects of 17 samples prepared from Thailand plants on 5-reductase activity were examined. The acetone extract of leaves ofArtocarpus altilis showed potent 5-reductase inhibitory activity. Fractionation guided by 5-reductase inhibition led to the isolation of 2-geranyl-2,3,4,4-tetrahydroxydihydrochalcone from the acetone extract of leaves ofA. altilis. This compound showed more potent inhibitory effect (IC50=38M) than-linolenic acid known as a naturally occurring potent inhibitor.  相似文献   

19.
Ozonation as a quantitative tool to analyze the stereo structures of arylglycerol--aryl ether linkages was examined using wood meal, milled wood lignin, and a lignin model compound, 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol (veratrylglycerol--guaiacyl ether, VG). The procedure was improved. When mild postreduction was conducted for ozonation products, the total yield of erythronic and threonic acids from this model compound was 74%, which is 15% higher than the yield without postreduction. A decrease in the recovery of these two acids under prolonged ozonation treatment was successfully suppressed by postreduction. Theerythro/threo ratio of VG determined by the ozonation method with postreduction is in good agreement with the ratio determined by1H-nuclear magnetic resonance. Excellent reproducibility of the yield was obtained by adopting a procedure that included trimethylsilylation of ammonium salts of ozonation products using a dimethylsulfoxide-hexamethyldisilazane-trimethylchlorosilane mixture and subjecting it to gas chromatography analysis. It was concluded that arylglycerol--aryl ether structures comprise at least 35% of the C3-C6 structure in birch wood meal, with anerythro/threo ratio of 2.8.This paper was presented at the 43rd Lignin Symposium, Fuchu, Japan, October 1998; and at the 10th ISWPC, Yokohama, Japan, June 1999  相似文献   

20.
This study used a vibration test method to show that grain angles of face veneer have substantial effects on sound velocities and dynamic Youngs moduli of three types of wood-based composites. The sound velocity at 0° grain angle of face veneer was the highest, and it decreased with increasing grain angle in the range of 0° to 90°. This tendency was similar to that for dynamic Youngs modulus. The relationship between the grain angle of face veneer and the sound velocity of three types of wood-based composites can be expressed in the form of Hankinsons equation or a second-order parabolic equation. This study also showed that the application of orthotropic elasticity theory was valid for the three types of wood-based composites. The relationship between the grain angle of the face veneer and the Youngs modulus of three types of wood-based composites can be expressed in the form of the Jenkin equation, Hankinsons equation, or a second-order parabolic equation. Rule of mixture can also be used to predict the Youngs modulus of wood-based composite from the Youngs moduli of the two elements.Part of this study was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003 and the 15th Annual Meeting of Chugoku Shikoku Branch of the Japan Wood Research Society, Higashi-Hiroshima, Japan, September 2003  相似文献   

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