Hydrophilic Extractives Research Articles

Fractioning and chemical characterization of barks of Betula pendula and Eucalyptus globulus

The composition of birch (Betula pendula Roth.) and eucalypt (Eucalyptus globulus Labill.) barks was studied after grinding and fractioning into different particles sizes.There was a significant difference in the fractionation of both barks in relation to the yield of fines (5.9% and 28.3% of particles under 0.450 for birch and eucalypt, respectively) and of coarser particles over 2mm (70.7% and 41.4%).The chemical composition of birch and eucalypt barks, as a mass weighed average of all granulometric fractions was, respectively: ash 2.9% and 12.1%; total extractives 17.6% and 6.5% (hydrophilic extractives were dominant), lignin 27.9% and 28.8% and holocellulose 49.8% and 62.6%. Birch bark contained a considerable amount of suberin (5.9%) whereas eucalypt bark contained a very small amount (<1%). The carbohydrate composition differed between birch and eucalypt barks, i.e., respectively, glucose 47.0% and 68.4%, and xylose 33.8% and 23.2% of total neutral monosaccharides.Ash elemental composition was different in both species. Birch bark contained in relation to eucalypt bark, in the 0.250–0.450mm fraction, more N (0.69% vs. 0.26%) and P (0.075% vs. 0.001%), and less Ca (0.39% vs. 0.62%), K (0.24% vs. 0.31%) and Mg (0.07% vs. 0.15%). High concentration of Zn was found in birch bark (217mg/kg vs. 11mg/kg in eucalypt bark).After grinding and granulometric separation, extractives were present preferentially in the finest fraction with an enrichment in dichloromethane and ethanol solubles especially in the case of birch bark. Eucalypt bark had a high content of cellulose and hemicelluloses especially in the coarser fraction. The fibrous character of this fraction shows its potential as a fiber source.

Chemical characterization of barks from Picea abies and Pinus sylvestris after fractioning into different particle sizes

The composition of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) barks was studied after grinding and fractioning into different particles sizes.Both barks fractionated well and with similar fraction yield profile. The yield of fines was low and the major fractions were larger particles, i.e. 2.4% and 3.1% of particles under 0.425mm and 66.0% and 50.3% of particles over 2mm, respectively for spruce and pine bark.The chemical composition of spruce and pine barks, as a mass weighed average of all granulometric fractions was, respectively: ash 3.3 and 4.6%; total extractives 21.6 and 18.8% (hydrophilic extractives were dominant), lignin 27.9 and 33.7% and holocellulose 42.7 and 37.6%. Suberin accounted for 1.3% and 1.6% of spruce and pine bark, respectively. The non-cellulosic monosaccharides showed in both barks predominance of arabinose followed by xylose and mannose.Ash elemental composition showed that N represented about 35% of the total inorganics, Ca 35% and K 17%. Zn, Cu, Ni, Cr and Pb were present in both barks at levels under 1% of the total inorganics. Spruce bark had in average higher contents compared to pine bark, except for Pb and Cr.Size reduction of spruce and pine bark did not apply randomly to the different components and instead resulted into partial separation of the inorganic and organic matter into different size particles. Fine particles concentrated higher amounts of inorganic material and of extractives.

Structure and antioxidant activity of diarylheptanoids extracted from bark of grey alder (Alnus incana) and potential of biorefinery-based bark processing of European trees

Abstract The bark of trees has a big potential as a source of green chemicals. The aim of the present work was to valorise the potential of deciduous tree species with this regard. Three widely spread trees in Europe (grey alder, ash tree, aspen) were in focus as a source of polyphenols, and the yields of polyphenolic compound in the extracts were considered as evaluation criteria. The highest yields of hydrophilic extractives were found in barks of grey alder and aspen (36.8 and 22.9%, respectively). In the former, the highest antioxidant activity was found towards free radicals (DPPH• and ABTS•+) and superoxide anion radical. Open chain diarylheptanoids, mainly oregonin, were identified as the major constituents of the grey alder hydrophilic extract. In addition to oregonin, the presence of 2 linear diarylheptanoids [platyphylloside and 1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-β-D-glucopyranoside] was confirmed. For the first time, the compounds 1,7-bis-(3,4-dihydroxyphenyl)-3-hydroxyheptane-5-O-β-D-xylopyranoside and 1,7-bis-(3,4-dihydroxyphenyl)-heptane-3-one-5-O-β-D-glucopyranoside were detected in grey alder bark. The results of experiments in vitro and in vivo have shown the high potential for diarylheptanoids-containing extracts in prophylaxis and/or treatment of diseases due to the metabolic disorders and ageing. The biological activity of grey alder extract was confirmed in in vitro experiments by incubation of human blood samples. In vivo experiments with rats also showed positive results. The conclusion is that grey alder extracts have a high potential for prevention of ageing related pathologies. Besides diarylheptanoids, the bark contains condensed tannins in commercially available quantity (12.5%). Eco-friendly wood adhesives were obtained on a tannins basis. The bark left after polyphenols isolation can be used in soil melioration and as a sorbent for the removal of oil products from water surface. The investigation of the phenolic pool of grey alder could contribute to cluster technologies within the biorefinery-based bark processing.

Extractives in the cones of Pinus species

Amount and composition of lipophilic and hy- drophilic extractives were analyzed in the cones of five coniferous species, namely Pinus halepensis, P. brutia, P. pinea, P. sylvestris and P. nigra, growing natively in Turkey. Lipophilic extractives amounts, identified by GC, were found to be the highest in P. brutia (35.1 mg g −1 ) and P. halepensis (31.3 mg g −1 ) while the lowest values were found in P. sylvestris (9.0 mg g −1 ). Resin acids were the major lipophilic group in all cones. The predominant resin acids were abietic acid in P. pinea, P. halepensis and P. bru- tia, dehydroabietic acid in P. sylvestris, and isopimaric acid in P. nigra. Compared to lipophilic extractives, the amount of total hydrophilic extractives showed similar gravimetric values while sugars and sugar alcohols were the dominant group.

Extractives in bark of different conifer species growing in Pakistan

AbstractThe amount and composition of lipophilic and hydrophilic extractives, including proanthocyanidins, has been analysed as a first screening in the bark of six Pakistani coniferous tree species, namelyPinus wallichiana,Pinus roxburghii,Pinus gerardiana,Abies pindrow,Taxus fuanaandCedrus deodara. The predominant lipophilic extractives were common fatty and resin acids, fatty alcohols and sterols. In all bark samples, short-chain fatty acids were more abundant than long-chain fatty acids. Generally, the amount of free fatty acids was also larger than the amount of triglycerides. Oleic acid was the most common fatty acid, except inC. deodara, where lignoceric acid dominated. The largest amounts of fatty acids and fatty alcohols were found inP. wallichianaandP. gerardiana.P. gerardianacontained an exceptionally large amount of resin acids, approximately 3% of the bark weight, compared to the other species. The amount of free sterols was approximately at the same level or larger than the amount of steryl esters in most samples. In addition to proanthocyanidins, different known lignans, stilbenes, ferulates and flavonoids were generally predominant amongst the hydrophilic extractives. Resveratrol glycoside was abundant inP. wallichiana, whileC. deodaraandP. gerardianacontained large amounts of lignans and lignan derivatives. All bark extracts contained large amounts of proanthocyanidin-related catechin and its derivatives. Furthermore,C. deodaraandP. roxburghiicontained quite large amounts of taxifolin. In particular,P. wallichianaandA. pindroware potential rich sources of proanthocyanidins, representing approximately 16% and 5% of the bark weight, respectively.

Effect of bio-treatment on the lipophilic and hydrophilic extractives of wheat straw

Wheat straw, an important papermaking raw material in China, was treated with a white-rot fungus of Phanerochaete chrysosporium ME446, and the lipophilic and hydrophilic extractives from the control and bio-treated samples were analyzed by GC and GC–MS. Bio-treatment of wheat straw could alter the chemical composition of both the lipophylic and hydrophilic extractives. Sugars and phenolic substances such as coniferyl alcohol, 4-hydroxycinnamic acid, 1-guaiacylglycerol and ferulic acid were substantially degraded or consumed by the fungus. More lipophilic substances such as wax, glycerides and steryl esters were degraded into the corresponding components, resulting in much higher concentrations of fatty acids and sterols in the bio-treated samples. Obviously, the bio-treatment of wheat straw was of benefit to pitch control in pulping and papermaking processes, in the view of degradation of the more lipophilic substances. In addition, the bio-treatment could increase the lignin concentration in hot-water extractives of wheat straw.

Extractives of Turkish and Pakistani Tree Species

The composition and amount of hydrophilic and lipophilic extractives in knots and stemwood of eight Turkish and one Pakistani tree species were analysed. Lignans were the main polyphenols in most studied species and pinosylvins in the pines. The two studied juniper species contained no or only little lignans. Most species also contained juvabiones or phenolic diterpenoids. Both polyphenols and lipophilic extractives were more abundant in the knots than in the stemwood.

Aspen Knots, a Rich Source of Flavonoids

Hydrophilic extractives in heartwood, sapwood, and knots of three aspen species were analyzed by gas chromatography, gas chromatography‐mass spectrometry, and high‐performance size‐exclusion chromatography. The amounts of flavonoids were considerably higher in the knots relative to the stem wood. Flavonoids identified were dihydrokaempferol, naringenin, kaempferol, catechin, and taxifolin. In addition, glycosides of dihydrokaempferol, naringenin, and kaempferol were identified by mass spectrometry and shown to be glucosides by enzymatic hydrolysis by β‐D‐glucosidase. Dihydrokaempferol and its glucoside dominated in all knot samples although there were variations in the amounts and composition of the extractives. The total amounts of flavonoids varied between 11 and 43 mg/g in Populus tremula, 12 and 62 mg/g in Populus tremuloides and 47 and 82 mg/g in Populus grandidentata. The aspen knots were found to be a rich source of bioactive flavonoids. This work is part of the activities at the Åbo Akademi Process Chemistry Centre within the Finnish Centre of Excellence Programme (2000–2005) selected by the Academy of Finland and is a part of the project “Bioextra” funded by the National Technology Agency of Finland (Tekes).

Degradation of wood extractives in thermo-mechanical pulp by soybean lipoxygenase

Fatty acids and their esters are major constituents of wood extractives and are known to cause a range of newsprint manufacturing problems including pitch deposition, poor paper machine runnability, low paper friction and strength. This study investigated the potential of using soybean lipoxygenase to degrade wood extractives present in thermomechanical pulp (TMP) samples. Lipoxygenase treatments of TMP resulted in a 15% reduction in total extractives. The enzyme showed a high specificity towards lipophilic extractives fractions, primarily consisting of fatty acids and their esters. After 2 h pulp treatments, the lipophilic extractives content was reduced by more than 25%, while there was little change in hydrophilic extractives. The activity of lipoxygenase towards individual wood extractives was determined by using a mixture extracted from TMP. It was found that several extractive compounds such as resin acids and lignans inhibited lipoxygenase catalyzed reactions with fatty acids. Transition metal ions present in the TMP contributed to further fragmentation of fatty acid hydroperoxides produced by lipoxygenase reaction with wood extractives.

Antioxidant activity of knotwood extractives and phenolic compounds of selected tree species.

The antioxidant potency and the radical scavenging capacity of superoxide and peroxyl radicals were assessed for 13 hydrophilic knotwood extracts of commercially important wood species, or fractions thereof, as well as for five pure wood-derived lignans and the flavonoid taxifolin. The chemical composition of the knotwood extracts was determined by gas chromatography combined with mass spectrometry. Most of the investigated wood species were rich in hydrophilic extractives (10-20% of the dry wood) with one or a few compounds dominating in each extract. All extracts had a high antioxidative potency and/or radical scavenging capacity as compared to the well-known antioxidants Trolox and butylated hydroxyanisole. The pure wood-derived lignans and taxifolin also had a high antioxidative potency and/or radical scavenging capacity. However, the antioxidant potency and/or radical scavenging capacity of several of the hydrophilic knotwood extracts were higher than that of the dominating compounds in pure form.

Lignans and Lipophilic Extractives in Norway Spruce Knots and Stemwood

Summary The hydrophilic and lipophilic extractives in the heartwood of knots from 7 Norway spruce trees were analysed by GC, GC-MS and HPSEC. The knots contained extremely large amounts of lignans, 6–24% (w/w), with hydroxymatairesinol comprising 65–85% of the lignans. Even the knots of the young trees contained 4–8% (w/w) of lignans. The variation in the amount of lignans was large among knots, both within a single tree and between trees. In addition to the lignans, knots also contained 2–6% (w/w) of a complex mixture of lignan-like compounds with 3, 4 and even up to 6 phenyl propane units, here called oligolignans. The amounts of lignans in the knots were similar in the radial direction from the pith into the outer branch, but decreased dramatically outwards in the branch, almost disappearing after 10–20 cm. The ratio of the 2 epimers of hydroxymatairesinol differed between different knots and even within the knot. A new spruce lignan, nortrachelogenin, or its enantiomer, wikstromol, was detected in knots from trees in northern Finland as opposed to samples from southern Finland. The amount of lipophilic extractives was small compared to the amount of hydrophilic extractives in the knots. Five of the dead knots contained more resin acids and free diterpenyl alcohols than ordinary stemwood. In the other knots, the amount of lipophilic extractives was on the same level as stem heartwood. The stem sapwood contained larger amounts of esterified fatty acids than the knots.

Carbohydrate and14C Incorporation into Developing Grains of Triticale, Wheat and Rye

Abstract Contents of and 14C-assimilate incorporation into hydrophilic extractives, lipophilic extractives, starch and a residue (fibre) fraction were followed during kernel development of three triticales: Lasko (plump kernel), WW 31433 (shrivelled kernel), Sv 8008 (shrivelled kernel), one wheat (Holme), and one rye (Kungs II). Holme was characterized by a rapid increase in dry matter, mainly starch, and a rapid incorporation of 14C into the kernel. Kungs II exhibited a low incorporation rate and a long grain-filling period. Both strategies resulted in smooth, plump kernels. Lasko had a plump kernel which reached about the same final weight as Holme, although incorporation of starch commenced later and did not show the same intensity as in Holme. Both shrivelled triticales exhibited high kernel weights. However, the shrivelling could not be related to a high content of hydrophilic extractives or to a low starch content. The results rule out the possibility that shrivelling is attributed to a general shortage of hydrophilic extractives (mainly sugars).

Carbohydrates in raw and germinated seeds from mung bean and chick pea

AbstractThe contents of hydrophilic extractives, lipids, protein, starch, non‐starch polysaccharides, Klason lignin and ash were determined in raw and germinated seeds of mung bean (Phaseolus aureus) and chick pea (Cicer arietinum). Several low molecular weight carbohydrates were found in the hydrophilic extractives. During germination, due mainly to their use as an easily available source of germinating energy, there was a rapid decrease of the raffinose family oligosaccharides in mung bean and a somewhat slower decrease in chick pea. Changes in the content and composition of dietary fibres during germination was small.

The hydrophobic and water-repellent properties of wattle bark extractives

Based on the fact that bark is an almost perfect water barrier and assuming that bark is impregnated with materials which aid in rendering it impermeable to water, the hydrophobic and water-repellent properties of several bark extractives were investigated. Products obtained after extraction with polar and non-polar solvents showed widely different properties. Some were extremely hydrophobic and water-repellent with a water-solid-air contact angle higher than 100°. These were the products obtained from extraction with benzene and mineral turpentine. Alcohol and acetone extractives had contact angles as low as 23° but coatings from some of these materials nevertheless had a high efficiency as water barriers. The efficiency of the various extractives as water repellents or water barriers was determined by coating wood with 10 per cent solutions of the extractives in different solvents and determining the extent to which water could be prevented from being absorbed and causing swelling of the wood and thereby reduce the dimensional changes of the wood. The extractives obtained with nonpolar solvents were extremely efficient as true water repellents while the polar aleohol extracts were far better than could be expected from their almost hydrophilic properties. Nature has therefore provided for hydrophilic film-formers combined with hydrophobic materials which act as a double line of defence against water absorption. The hydrophilic extractives, in addition, act as a bridging agent between the strongly hydrophobic extractives and the hydrophilic cell wall material. Since some of the extractives from wattle bark have excellent hydrophobic properties, and since this bark is available in large quantities as a waste product after tannins have been extracted, the utilization of certain wattle bark extractives as water repellents could be economically attractive.