Differences between lignin in unprocessed wood, milled wood, mutant wood, and extracted lignin detected by 13C solid-state NMR

Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy was applied to intact and isolated loblolly pine wood samples to identify potential structural changes induced by tree age, milling, lignin extraction, or naturally occurring mutations. Special attention was paid to ketone and aldehyde as well as nonpolar alkyl groups, which could be observed at low concentrations (<2 in 1000 C) using improved spinning-sideband suppression with gated decoupling. Carbonyl structures were present in intact wood, and there are more keto groups than aldehydes. Their concentrations increased from juvenile to mature wood and with milling time, whereas extraction did not alter the C=O fraction. Significant amounts of aldehyde and dihydroconiferyl alcohol residues were present in coniferyl aldehyde dehydrogenase-deficient wood, confirming solution-state NMR spectra of the corresponding lignin. These results demonstrate the utility of solid-state NMR as an assay for changes in the lignin structure of genetically modified plants.     

Solution-state nuclear magnetic resonance study of the similarities between milled wood lignin and cellulolytic enzyme lignin

The structures of milled wood lignin (MWL) and cellulolytic enzyme lignin (CEL) have been analyzed using traditional chemical methods and solution-state NMR techniques. Comparisons of the results obtained reveal that subtle differences exist between the two lignin preparations. Thioacidolysis produced higher monomer yields from CEL than MWL, suggesting MWL has a more condensed structure. Quantitative (13)C NMR determined the degree of condensation in MWL to be 0.43 unit per aromatic moiety as compared to 0.36 in CEL. The MWL also contained a lower amount of beta-O-4' substructures per aromatic ring than CEL, 0.41 versus 0.47, respectively. Carbohydrate analysis revealed that the MWL may contain a higher proportion of middle lamella material as compared to the CEL. Because the middle lamella is considered to have a more condensed lignin structure, on the basis of the bulk polymerization theory, these results could explain the differences in beta-O-4' and degree of condensation.     

Quantitative characterization of a hardwood milled wood lignin by nuclear magnetic resonance spectroscopy

The structure of Eucalyptus grandis milled wood lignin (MWL) was investigated by 2D 1H-13C HSQC, HMQC, and 1H-1H TOCSY correlation NMR techniques and by quantitative 13C NMR as well as by the permanganate oxidation degradation technique. The combination of 2D NMR and quantitative 13C NMR spectroscopy of nonacetylated and acetylated lignin preparations allowed reliable identification and calculation of the amount of different lignin structures. About 85% of side-chain moieties were estimated on the structural level. This information was substantiated by data on the quantity of various functional groups and interunit linkages as a whole. A modified method for calculation of the h:g:s ratio has been suggested and compared with previously suggested approaches. E. grandis MWL has been determined to have an h:g:s ratio of 2:36:62. The amounts of various phenolic/etherified noncondensed/condensed guaiacyl and syringyl moieties were approximately estimated. E. grandis MWL contained approximately 0.60/Ar of beta-O-4 moieties along with small amounts of other structural units such as pino/syringyresinol (0.03/Ar), phenylcoumaran (0.03/Ar), and spirodienone (0.05/Ar). The degree of condensation was estimated at approximately 21%; the main condensed structures are 4-O-5 moieties (approximately 0.09/Ar). The structure of E. grandis MWL was compared with those of other lignin preparations isolated from various hardwoods.     

基于红外光谱的不同农作物秸秆磨木木质素差异表征

木质素是植物细胞壁中主要组分之一,其苯丙烷结构单元的单体结构和连接方式的复杂性直接影响木质素脱除和利用效果,了解不同农作物秸秆中木质素的差异,对提高秸秆的综合利用效率是非常必要的。该文选取代表性棉秆、玉米秸和小麦秆,分别提取磨木木质素,利用傅里叶变换中红外技术对棉秆、玉米秸和小麦秆三类秸秆磨木木质素进行红外表征,分析比较三类秸秆磨木木质素的差异,结果表明:1)三类秸秆磨木木质素G/S相对比值差别不大,并无明显规律;2)三类秸秆磨木木质素中,对羟基结构单元:玉米秸小麦秆棉秆;愈创木基结构单元:棉秆玉米秸小麦秆;紫丁香基结构单元:玉米秸小麦秆棉秆;3)玉米秸和小麦秆磨木木质素相似度较高,而棉秆磨木木质素则更加接近于木本植物。     

Thermal properties of two organic (peat, pine bark) and two inorganic (perlite, clay) horticultural substrates

Thermal properties such as thermal conductivity and heat capacity of two organic (peat, pine bark) and two inorganic (perlite, expanded clay) horticultural substrates are studied. The thermal conductivity is determined using the apparatus described by JANSE & BOREL (1965). The relation between moisture content and moisture tension and thermal conductivity is determined for these horticultural substrates. The heat capacity is calculated as a function of the moisture content for the four horticultural substrates. A very good relation is found between thermal conductivity and soil moisture tension which can be used as a characteristic for the heat economy of horticultural substrates.     

Characterization of residual lignin after SO(2)-catalyzed steam explosion and enzymatic hydrolysis of Eucalyptus viminalis wood chips

The lignin component found in both water insoluble (WI) and water and alkali insoluble (WIA) fractions derived from SO(2)-impregnated steam-exploded eucalyptus chips (SEE) was isolated and characterized. Dioxane lignins with a sugar content lower than 2% (w/w) were obtained after each material was treated with commercial cellulases. The C9 formulas of both SEE-WI and SEE-WIA dioxane lignins were C(9)H(6.83)N(0.04)O(2.24)(OCH(3))(1.21)(OH(aro))(0.56)(OH(ali))(0. 77) and C(9)H(8.65)N(0.29)O(1.97)(OCH(3))(0.90)(OH(aro))(0. 46)(OH(ali))(1.02), respectively. The weight-average molecular weight (M(w)) of the SEE-WI lignin corresponded to 3.85 kDa, whereas the SEE-WIA lignin had an M(w) of 3.66 kDa for the same polydispersity of 2.4. The SEE-WIA lignin was shown to be more thermally stable than the SEE-WI lignin, requiring temperatures in the range of 520 degrees C for complete degradation. FTIR and (1)H NMR analyses of both untreated and peracetylated lignin fractions showed that (a) the alkali insoluble lignin contained a relatively higher degree of substitution in aromatic rings per C9 unit and that (b) alkaline extraction removed lignin fragments containing appreciable amounts of phenolic hydroxyl groups.     

Determination of nitrate in a pine bark substrate

Abstract

An experiment was conducted to evaluate extraction methods for the determination of nitrate in a synthesized pine bark substrate. It was found that prior to nitrate determination, oven dryino of the pine bark sample was necessary followed by rewetting and extraction in a vacuum for 72 hours. Using this technique, about 65% of applied nitrate was recovered.     

Loblolly pine plant community structure and soil solution aluminum,organic acids,calcium, magnesium,and pH

Abstract

Vegetative cover may influence soil chemical properties by producing organic acids that can modify the toxicity are responsible for high levels of nontoxic soil solution aluminum (Al). This study was conducted to determine the effect of loblolly pine (Pinus taeda L.) plant community structure, i.e., differing vegetative covers, on exchangeable cation distribution, and soil solution concentration of aluminum (Al) and organic acids. Soil was sampled were taken from 8‐year‐old forest plots with differing plant community structure (herbaceous‐hardwood‐pine, herbaceous‐pine, hardwood‐pine, and pine only), and measured for exchangeable cations. Soil solution extracts were analyzed for Al, organic acids, and the major cations and anions. There were significant differences in exchangeable Al, and calcium (Ca) among communities. Soil pH was highest in the herbaceous‐pine community, while other communities did not differ in soil pH. Oxalic, citric, malic, and succinic acids were detected in soil solution for all communities, but did not differ significantly among communities. Calculated Al activity was less than those determined by the 8‐hydroxy quinoline (15 sec) method. For these conditions, calculated Al activities did not change by accounting for the Ca‐ and magnesium (Mg)‐organic acid complex. The Al activities found were similar to previous reported levels that were considered nontoxic.     

Composition and antioxidant activity of the essential oils of Xylopia aethiopica (Dun) A. Rich. (Annonaceae) leaves, stem bark, root bark, and fresh and dried fruits, growing in Ghana

The chemical composition of the essential oils obtained from the leaves, the barks of the stem and the root, as well as from the fresh and dried fruits of Xylopia aethiopica, growing in Ghana, was investigated by gas chromatography/mass spectrometry analyses. Kovats indices, mass spectra, and standard compounds were used to identify a total of 93 individual compounds. The monoterpene hydrocarbons formed the main portion in all studied samples. beta-Pinene was predominant in all cases, while trans-m-mentha-1(7),8-diene was the main compound in the essential oils of the leaves and the barks of roots and stems. Their potential antioxidant activity was also investigated and found to be significant in scavenging superoxide anion radical.     

Characterization of sago palm (Metroxylon sagu) lignin by analytical pyrolysis

Dioxane lignin prepared from sago palm (Metroxylon sagu) was characterized by analytical pyrolysis coupled to gas chromatography-mass spectrometry. Large abundances of the p-hydroxybenzoates ester-linked to the lignin were proven by analytical pyrolysis as well as by mild alkaline treatment that produced p-hydroxybenzoic acid in 16.3% yield. Pyrolysis in the presence of tetramethylammonium hydroxide (TMAH) before and after alkaline treatment also showed the presence of ester- and ether-linked p-hydroxybenzoates. Quantitative results of pyrolysis showed that the sago palm lignin is of syringyl type. The relative abundances of TMAH/pyrolysis products derived from the syringyl beta-aryl ether substructures were 4.9 times those of the guaiacyl equivalents. Proton nuclear magnetic resonance analysis also showed the presence of the p-hydroxybenzoates and the predominance of the syringyl moiety over the guaiacyl ones in the sago palm lignin.     

Preclinical evaluation of rapeseed, raspberry, and pine bark phenolics for health related effects

Rapeseed, raspberry, and pine bark are promising bioactive sources of plant phenolics selected from among ca. 100 previously screened plant materials for in vitro preclinical evaluation of health related effects. Phenolic extracts and isolated fractions of the selected materials were investigated for antioxidant, antimicrobial, antiinflammatory, and antimutagenic properties as well as for cell permeability. It was shown that rapeseed and pine bark phenolics and raspberry anthocyanins were good or excellent antioxidants toward oxidation of phosphatidylcholine membrane (liposomes), rapeseed oil (crude) phenolics were effective radical scavengers (DPPH test), and both raspberry and pine bark phenolics inhibited LDL oxidation. Rapeseed oil phenolics, principally vinylsyringol, raspberry anthocyanins, and pinoresinol and matairesinol, the principal components of pine bark phenolic isolate, were effective against formation of the proinflammatory mediator, prostaglandin E(2). Raspberry ellagitannins inhibited the growth of Proteus mirabilis and Klebsiella oxytoca. Pine bark and rapeseed had minor effects on the permeability of model drugs in Caco-2 experiments. None of the tested extracts were mutagenic nor toxic to Caco-2 cells or macrophages. Thus, phenolic isolates from rapeseed, raspberry, and pine bark and are safe and bioactive for possible food applications including functional foods intended for health benefit.     

Procyanidin fractions from pine (Pinus pinaster) bark: radical scavenging power in solution, antioxidant activity in emulsion, and antiproliferative effect in melanoma cells

Pine (Pinus pinaster) bark is a rich source of procyanidin oligomers. From a total polyphenolic extract, we have generated fractions of different procyanidin composition. The mixtures, devoid of gallate esters, were active as free radical scavengers against ABTS(*+), DPPH, and HNTTM. Pine bark fractions were tested for antioxidant activity in solution (hydrogen donation and electron transfer) and emulsion (inhibition of lipid peroxidation) and compared with their galloylated counterparts from grape origin. While galloylation clearly influenced the free radical scavenging efficiency in solution, it did not seem to play a determinant role in protection against lipid peroxidation in emulsion. The fractions were very mild inhibitors of cell proliferation. Because gallate esters appear to interfere with crucial cell functions, gallate free pine procyanidins may be the innocuous chemopreventative agents of choice for many applications in food and skin protection.     

Accumulation of,and interactions between,calcium and heavy metals in wood and bark of Picea abies

Spreading of wood ashes from the pulp and paper industry will change the content and proportions of calcium (Ca), copper (Cu), cadmium (Cd), and zinc (Zn) in forest soils and thus also in the forest trees. The accumulation and distributions of, and interaction between, Ca and heavy metals in wood and bark of two‐year‐old Norway spruce (Picea abies [L.] Karst.) were investigated in this study. The treatment was carried out for 3 months in nutrient solutions, and there was a low or a high addition of Ca, Cd, Cu or Zn. The metal accumulation in, and distribution between, the bark, the wood formed during the treatment period (new wood), and the wood formed before the treatment period (old wood) was analyzed with AAS. The contents of the metals in the stems (i.e., bark, new wood, old wood) increased with elevated addition of the metal in question, also at the low addition of Ca, Cu, and Zn. Interactions between Ca and the heavy metals were found. Elevated Ca additions decreased the Cd content of the bark and the Zn content of the old wood, and tended to decrease the Cu content of the bark and the Cd content of the old wood. The Ca content decreased in both, wood and bark after Cu addition and the high Cd addition. Thus, even small changes in metal availability and proportions in forest soil, such as after spreading of wood ashes in the forest, will be reflected in the content of the metals in the wood and bark of forest trees.     

Comparison of proanthocyanidins in commercial antioxidants: grape seed and pine bark extracts

The major constituents in grape seed and pine bark extracts are proanthocyanidins. To evaluate material available to consumers, select lots were analyzed using high-performance liquid chromatography, gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), gel permeation chromatography (GPC), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Atmospheric pressure chemical ionization (APCI) LC/MS was used to identify monomers, dimers, and trimers present. GC/MS analyses led to the identification of ethyl esters of hexadecanoic acid, linoleic acid, and oleic acid, as well as smaller phenolic and terpene components. The GPC molecular weight (MW) distribution indicated components ranging from approximately 162 to approximately 5500 MW (pine bark less than 1180 MW and grape seed approximately 1180 to approximately 5000 MW). MALDI-TOF MS analyses showed that pine bark did not contain oligomers with odd numbers of gallate units and grape seed contained oligomers with both odd and even numbers of gallate. Reflectron MALDI-TOF MS identified oligomers up to a pentamer and heptamer, and linear MALDI-TOF MS showed a mass range nearly double that of reflectron analyses.     

Characterization and quantitation of polyphenolic compounds in bark, kernel, leaves, and peel of mango (Mangifera indica L.)

The contents of secondary plant substances in solvent extracts of various byproducts (barks, kernels, peels, and old and young leaves) in a range of Brazilian mango cultivars were identified and quantitated. The results show that the profiles of secondary plant substances such as xanthone C-glycosides, gallotannins, and benzophenones in different byproducts vary greatly but are fairly consistent across cultivars. The free radical scavenging activity of the solvent extracts was evaluated using a high-performance liquid chromatography-based hypoxanthine/xanthine oxidase assay and revealed dose-dependent antioxidant capacity in all extracts. Four (mangiferin, penta- O-galloyl-glucoside gallic acid, and methyl gallate) of the major phenolic compounds detected were also evaluated in additional in vitro bioassay systems such as oxygen radical absorbance capacity, 2,2-diphenyl-1-picrylhydrazyl, and ferric reducing ability of plasma. Mangiferin in particular, detected at high concentrations in young leaves (Coite = 172 g/kg), in bark (Momika = 107 g/kg), and in old leaves (Itamaraka = 94 g/kg), shows an exceptionally strong antioxidant capacity.     

Efficient preparation of catechin thio conjugates by one step extraction/depolymerization of pine (Pinus pinaster) bark procyanidins

The skin penetrating antioxidant cysteamine derivative of (-)-epicatechin as well as other thio conjugates were efficiently obtained with high yields from pine (Pinus pinaster) bark by simultaneous one pot extraction and depolymerization using water and cysteamine hydrochloride. The influence of the concentration of bark, acid, and cysteamine, as well as the reaction time on the total conversion, was studied. The total conversion into the epicatechin and catechin conjugates was as high as 47 g/kg pine bark with 1666 g cysteamine/kg bark and 28 g/kg with 166 g cysteamine/kg bark. A fast cleanup step by absorption/desorption on XAD-16 greatly facilitated further purification of the active major component. At a pilot scale, 4beta-(2-aminoethylthio)epicatechin (1) (conversion 263 g, purity 35% by reversed phase high-performance liquid chromatography/weight) was obtained from 17 kg of pine bark after simultaneous extraction/depolymerization followed by cleanup with the polymeric resin in approximately 10 h. The results show that pine (P. pinaster) bark is a suitable source of flavanols for the preparation of active thio derivatives. Conditions are given for the fast and efficient preparation of the conjugates.     

Silvicultural use of wood ashes — Effects on the nutrient and heavy metal balance in a pine (Pinus sylvestris,L) forest soil

In a sustainable forestry recirculation of nutrients through the application of ashes from forest residues can be an essential way to guarantee healthy and vital forests. Wood ashes can also be regarded as a measure against soil acidification. Wood ashes were applied at various rates to the soil in a 35 years old pine (Pinus sylvestris, L) stand at Ringamåla in Blekinge, South Sweden. The experiments started in 1984. The different treatments gave a clear effect on soil chemistry with decreased acidity and aluminum ion concentrations. The base saturation increased in both mor and upper mineral soil layers. Generally no significant increases were found in soil concentrations of heavy metals, except for Cu which increased significantly in the mor layer. Also the extractable Mn concentration increased, in spite of the increased pH in the soil after application of ashes. In order to achieve a biological circulation of nutrients through ash application without polluting the environment, it is of ultimate importance that the wood chips used in power plants and other furnaces have a low concentration of heavy metals and other pollutants.     

The use of moss,lichen and pine bark in the nationwide monitoring of atmospheric heavy metal deposition in Finland

Mosses, lichens and pine bark were compared as indicators of atmospheric heavy metal deposition in Finland. The samples were collected from the nationwide sampling network systematically covering the country as a whole. All three bioindicators showed a fairly similar result concerning heavy metal deposition. The major emission sources and the areas affected were reflected in the metal concentrations in the samples. However, there were differences between the accumulation of metals. The correlation between concentrations in mosses and lichens was generally higher than that between mosses and bark or lichens and bark. Concentrations in lichens were the highest and lichens reflected the regional differences in background areas as well as the local emission sources. The concentrations in the mosses were slightly lower than those in lichens and also the mosses pinpointed the emission sources and the extend of the areas polluted. Bark had the lowest concentrations and bark did not generally reveal regional differences as well as mosses and lichens. In spite of the differences, all three bioindicators proved to be suitable for monitoring atmospheric heavy metal deposition.     

低木质素含量棉秆皮纤维的提取和表征

为了实现棉秆皮纤维在纺纱上的应用,该文在150℃以上的温度下用质量分数为4%的碱从棉秆皮中提取了纤维,测定了温度和时间对棉秆皮纤维细度、木质素质量分数及力学性能的影响。将棉秆皮纤维与棉按质量比30/70的比例进行混纺,研究了木质素的质量分数对混纺纱性能的影响。结果表明:随着温度的升高和时间的延长,棉秆皮纤维的细度和木质素质量分数逐渐下降。但是,当温度升高至170℃后,棉秆皮纤维的断裂强度迅速降低。160℃、60 min提取的纤维性能较理想:纤维细度28.3 dtex、木质素质量分数4.5%、断裂强度1.8 c N/dtex、杨氏模量46 c N/dtex。与闪爆及常压碱处理等方法相比,高温方法提取的纤维木质素质量分数低60%以上。棉秆皮纤维的木质素质量分数从5.5%降至4.5%后,混纺纱的条干变异系数和毛羽指数分别降低了75.1%和29.6%,而断裂强度和伸长率分别提高了11.1%和9.8%。高温提取的棉秆皮纤维可纺出细度为22.4 tex、断裂强度为12.0 c N/tex的纱线。     

Characterization of lignin structures and lignin-carbohydrate complex (LCC) linkages by quantitative 13C and 2D HSQC NMR spectroscopy

To characterize the lignin structures and lignin-carbohydrate complex (LCC) linkages, milled wood lignin (MWL) and mild acidolysis lignin (MAL) with a high content of associated carbohydrates were sequentially isolated from ball-milled poplar wood. Quantification of their structural features has been achieved by using a combination of quantitative (13)C and 2D HSQC NMR techniques. The results showed that acetylated 4-O-methylgluconoxylan is the main carbohydrate associated with lignins, and acetyl groups frequently acylate the C2 and C3 positions. MWL and MAL exhibited similar structural features. The main substructures were β-O-4' aryl ether, resinol, and phenylcoumaran, and their abundances per 100 Ar units changed from 41.5 to 43.3, from 14.6 to 12.7, and from 3.7 to 4.0, respectively. The S/G ratios were estimated to be 1.57 and 1.62 for MWL and MAL, respectively. Phenyl glycoside and benzyl ether LCC linkages were clearly quantified, whereas the amount of γ-ester LCC linkages was ambiguous for quantification.