Showing papers on "Bark published in 2011"
TL;DR: Pine tree bark shows a higher efficiency as bioindicator for urban pollution, accumulating higher concentrations of trace metals compared to plane tree bark, and both indicator species are suitable for comparative studies on bioindication of urban air pollution.
303 citations
TL;DR: The present review provides a coherent presentation of scattered literature on the chemistry, biogenesis, and biological activities of cinnamon to exhibit antioxidant, antimicrobial, and antidiabetic activities.
Abstract: The genus Cinnamomum comprises of several hundreds of species, which are distributed in Asia and Australia. Cinnamomum zeylanicum, the source of cinnamon bark and leaf oils, is an indigenous tree of Sri Lanka, although most oil now comes from cultivated areas. C. zeylanicum is an important spice and aromatic crop having wide applications in flavoring, perfumery, beverages, and medicines. Volatile oils from different parts of cinnamon such as leaves, bark, fruits, root bark, flowers, and buds have been isolated by hydro distillation/steam distillation and supercritical fluid extraction. The chemical compositions of the volatile oils have been identified by GC and GC-MS. More than 80 compounds were identified from different parts of cinnamon. The leaf oil has a major component called eugenol. Cinnamaldehyde and camphor have been reported to be the major components of volatile oils from stem bark and root bark, respectively. Trans-cinnamyl acetate was found to be the major compound in fruits, flowers, and fr...
205 citations
TL;DR: Results indicate a complex pattern of internal Cd allocation in P. × canescens resulting in higher ROS stress in wood than in bark and intermediate responses in roots and leaves, probably because of differential capacities of these tissues for the production of protective phenolic compounds.
Abstract: To characterize the dynamics of Cd²⁺ flux in the rhizosphere and to study cadmium (Cd) plant-internal partitioning in roots, wood, bark and leaves in relation to energy metabolism, reactive oxygen species (ROS) formation and antioxidants, Populus × canescens plantlets were exposed to either 0 or 50 µM CdSO₄ for up to 20 days in the nutrient solution. A strong net Cd²⁺ influx in root apex was observed after Cd exposure for 24 h, even if net Cd²⁺ influx decreased gradually in roots. A large amount of Cd was accumulated in roots. Cd ions were uploaded via the xylem to leaves and further transported to the phloem where significant accumulation was detected. Cd accumulation led to decreased photosynthetic carbon assimilation but not to the depletion in soluble carbohydrates. Increased levels of ROS were present in all tissues, except the bark of Cd-exposed poplars. To combat Cd-induced superoxide and hydrogen peroxide, P. × canescens appeared to rely mainly on the formation of soluble phenolics as these compounds showed the highest accumulation in the bark and the lowest in wood. Other potential radical scavengers such as proline, sugar alcohols and antioxidant enzymes showed tissue- and exposure time-specific responses to Cd. These results indicate a complex pattern of internal Cd allocation in P. × canescens resulting in higher ROS stress in wood than in bark and intermediate responses in roots and leaves, probably because of differential capacities of these tissues for the production of protective phenolic compounds.
196 citations
TL;DR: The data suggest the only ‘strategy' for avoiding topkill in fire-prone systems is to optimise bark thickness to maximise stem bud and cambium protection.
Abstract: To recruit to reproductive size in fire-prone savannas, juvenile trees must avoid stem mortality (topkill) by fire. Theory suggests they either grow tall, raising apical buds above the flames, or wide, buffering the stem from fire. However, growing tall or wide is of no advantage without stem protection from fire. In Litchfield National Park, northern Australia, we explored the importance of bark thickness to stem survival following fire in a eucalypt-dominated tropical savanna. We measured bark thickness, prefire height, stem diameter and resprouting responses of small stems under conditions of low to moderate fire intensity. Fire induced mortality was low (<10%), topkill was uncommon (<11% of 5 m to 37% of 1 m tall stems) and epicormic resprouting was common. Topkill was correlated only with absolute bark thickness and not with stem height or width. Thus, observed height and diameter growth responses of small stems are likely different pathways to achieving bark thick enough to protect buds and the vascular cambium. Juvenile height was traded off against the cost of thick bark, so that wide stems were short with thicker bark for a given height. The fire resilience threshold for bark thickness differed between tall (4–5 mm) and wide individuals (8–9 mm), yet tall stems had lower PTopkill for a given bark thickness. Trends in PTopkill reflected eucalypt versus non-eucalypt differences. Eucalypts had thinner bark than non-eucalypts but lower PTopkill. With deeply embedded epicormic buds eucalypts do not need thick bark to protect buds and can allocate resources to height growth. Our data suggest the only ‘strategy' for avoiding topkill in fire-prone systems is to optimise bark thickness to maximise stem bud and cambium protection. Thus, escape height is the height at which bark protects the stem and a wide stem per se is insufficient protection from fire without thick bark. Consequently, absolute bark thickness is crucial to explanations of species differences in topkill, resprouting response and tree community composition in fire-prone savannas. Bark thickness and the associated mechanism of bud protection offer a proximate explanation for the dominance of eucalypts in Australian tropical savannas.
183 citations
TL;DR: In this paper, the performance of four techniques, conventional maceration, Soxhlet extraction, microwave assisted extraction, and ultrasound assisted extraction (UAE), for extraction of Pinus radiata bark, in one and several stages, were evaluated.
158 citations
TL;DR: This study emphasises the need to take into account both the thermal properties of bark and the mechanism of bud protection in characterising the resprouting ability of savanna trees.
Abstract: We investigated the fire resistance conferred by bark of seven common tree species in north Australian tropical savannas. We estimated bark thermal conductance and examined the relative importance of bark thickness, density and moisture content for protecting the cambium from lethal fire temperatures. Eucalypt and non-eucalypt species were contrasted, including the fire-sensitive conifer Callitris intratropica. Cambial temperature responses to bark surface heating were measured using a modified wick-fire technique, which simulated a heat pulse comparable to surface fires of moderate intensity. Bark thickness was a better predictor of resistance to cambial injury from fires than either bark moisture or density, accounting for 68% of the deviance in maximum temperature of the cambium. The duration of heating required to kill the cambium of a tree (τc) was directly proportional to bark thickness squared. Although species did not differ significantly in their bark thermal conductance (k), the thinner barked eucalypts nevertheless achieved similar or only slightly lower levels of fire resistance than much thicker barked non-eucalypts. Bark thickness alone cannot account for the latter and we suggest that lower bark moisture content among the eucalypts also contributes to their apparent fire resistance. Unique eucalypt meristem anatomy and epicormic structures, combined with their bark traits, probably facilitate resprouting after fire and ensure the dominance of eucalypts in fire-prone savannas. This study emphasises the need to take into account both the thermal properties of bark and the mechanism of bud protection in characterising the resprouting ability of savanna trees.
150 citations
TL;DR: In this paper, the authors evaluated the antibacterial, antifungal, antigonococcal, HIV-type 1 reverse transcriptase (RT) and determined phenolic content of twelve medicinal plants used by the Venda people to treat venereal diseases.
127 citations
TL;DR: In this article, a study on how bark content affects the quality of pellets is reported, and their quality parameters were evaluated, and combustion tests were also performed on the produced pellets.
Abstract: Increased use of pellets has resulted in a shortage of the traditional raw materials required for pellet making, including saw dust, shavings and cuttings from saw mills. Therefore, the pellets industry has started to look for alternative raw materials. Limited consumption of pulpwood from Scots pine (Pinus sylvestris L.) in Norway has made it a potential raw material for the pellets industry. A study on how bark content affects the quality of pellets is reported in this paper. Pellets from pinewood containing zero, five, 10, 30 and 100 percent bark were produced, and their quality parameters were evaluated. Combustion tests were also performed on the produced pellets. Pellets made from pure bark had the best mechanical properties compared with pellets made of wood containing various concentrations of bark. The differences were not substantial and the durability for all chosen assortments was in the same quality class in the CEN standard. A positive effect off the amount of steam added was found. The bulk densities of the blend pellets were higher than those of pure wood and bark. The ash content increased with the amount of bark in the pellets. There were no problems with sintering when the bark content was low (five and 10 percent). For pure bark pellets some sintering was registered.
115 citations
TL;DR: Overall, 80% methanol extract produced from the leaves exhibited significantly (P < 0.05) higher antioxidant activity, with high phenolic contents, and inhibition of peroxidation and reducing power, and showed superior antimicrobial activity.
Abstract: This paper describes the antioxidant and antimicrobial activities and phenolic components of different solvent (absolute methanol, absolute ethanol, absolute acetone, 80% methanol, 80% ethanol, 80% acetone and deionized water) extracts of leaves, flowers and bark of Gold Mohar [Delonix regia (Bojer ex Hook.) Raf.]. The extract yields from leaves, flowers and bark ranged from 10.19 to 36.24, 12.97 to 48.47 and 4.22 to 8.48 g/100 g dry weight (DW), respectively. Overall, 80% methanol extract produced from the leaves exhibited significantly (P 1.50 mg/100 g DW) phenolic acids. Besides, small amounts ( < 1.50 mg/100 g DW) of some other phenolic acids such as sorbic, sinapic, p-coumaric, m-coumaric, ferulic, caffeic, 3-hydroxybenzoic, 4-hydroxycinnamic and 4-hydroxybenzoic acids were also detected. The extracts of the tested parts of Gold Mohar, especially, the leaves, might be valuable for functional food and therapeutic applications.
98 citations
TL;DR: In this paper, the yields and compositions of bark oil during Cinnamomum cassia growth (1-3 years old for the branch bark; 5-12 years old on the stem bark) were determined.
94 citations
TL;DR: This is the first study demonstrating a dose-dependent relationship between induced terpenes and tree resistance to bark beetle colonization under field conditions, indicating that terpene induction may be instrumental in tree resistance.
Abstract: Background: Tree-killing bark beetles (Coleoptera, Scolytinae) are among the most economically and ecologically important forest pests in the northern hemisphere. Induction of terpenoid-based oleor ...
TL;DR: The chemical composition of the lipophilic extracts of the inner and outer bark fractions of Eucalyptus grandis (E. grandis× Eucaliaptus urophylla) was studied by gas chromatography-mass spectrometry.
TL;DR: Results indicate that Pinus cembra L. bark and needles are good sources of phytochemicals with antioxidant and antimicrobial activities.
Abstract: The chemical constituents and biological activity of Pinus cembra L. (Pinaceae), native to the Central European Alps and the Carpathian Mountains, are not well known. The aim of the present work was to examine the phenolic content, antioxidant and antimicrobial effects of hydromethanolic extracts of Pinus cembra L. bark and needles. Bark extract had higher concentrations of total phenolics (299.3 vs. 78.22 mg gallic acid equivalents/g extract), flavonoids (125.3 vs. 19.84 mg catechin equivalents/g extract) and proanthocyanidins (74.3 vs. 12.7 mg cyanidin equivalents/g extract) than needle extract and was more active as a free radical scavenger, reducing agent and antimicrobial agent. The EC₅₀ values in the 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) and reducing power assays were 71.1, 6.3 and 26 mg/mL for bark extract and 186.1, 24 and 104 mg/mL for needle extract, respectively. In addition, needle extract showed ferrous ions chelating effects (EC₅₀ = 1,755 μg/mL). The antimicrobial effects against Staphylococcus aureus, Sarcina lutea, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans were assessed by the agar diffusion method. Both extracts (4 mg/well) were active against all the microorganisms tested; bark extract showed higher inhibition on all strains. These results indicate that Pinus cembra L. bark and needles are good sources of phytochemicals with antioxidant and antimicrobial activities.
TL;DR: In this paper, a tannin-paraformaldehyde mixture was used for bonding of Mempisang (Annonaceae spp.) plywood board, which is a fast growing dicotyledonous tree species.
TL;DR: Methanol extracts from the leaves, bark and roots of four Cameroonian medicinal plants were tested for their in vitro cytotoxicity, antigonorrheal and antireverse transcriptase activities and showed that all extracts contained compounds belonging to the classes of phenols and terpenoids.
TL;DR: In this paper, the pine weevil caused severe damage to the bark of Scots pine (Pinus sylvestris L.) seedlings, and the effect of weevil damage on systemic monoterpene emissions from shoots was more profound.
DOI•
31 Mar 2011
TL;DR: The findings of this study lend credence to the usefulness of yet another biopesticide and its incorporation into traditional storage pest management system is recommended.
Abstract: The biological activity of Zanthoxylum xanthoxyloides against Sitophilus zeamais(Coleoptera: Curculionidae) and Callosobruchus maculatus (Coleoptera: Bruchidae) was investigated in the laboratory by admixing leaf, root and bark powders of Z. xanthoxyloides. Methanol extracts of the plant were applied at 2.0 ml per 50 g of grains to assess contact mortality, damage assessment, progeny development and repellent action. The root and bark powders caused 100% mortality of both S. zeamais and C. maculatus while complete protection of grains and progeny inhibition were achieved. Topical application of the extracts caused significant (P<0.01) insect mortality with fresh bark extract offering complete protection of grains and complete inhibition of progeny production by both S. zeamais and C. maculatus. The extracts also evoked moderate repellent effect against the two insect pests. The findings of this study lend credence to the usefulness of yet another biopesticide and its incorporation into traditional storage pest management system is recommended.
Key words: Coleoptera, extracts, pests, powders, progeny, Zanthoxylum.
TL;DR: In this article, the anticandidal; antibacterial and antioxidant activities of diluted acetone extract of S. persica (dry stems) and ethyl acetate extract of Tunisian Juglans regia L. bark were tested.
Abstract: Salvadora persica and Juglans regia L. are traditionally used for the treatment of oral infections. The anticandidal; antibacterial and antioxidant activities of diluted acetone extract of S. persica (dry stems) and ethyl acetate extract of Tunisian Juglans regia L. bark were tested. The chemical composition of the volatile oil of the stems of S. persica was also investigated. The essential oil of S. persica stems was rich on benzyl isothiocyanate (52.5%) and benzyl nitrile (38.3%). Comparatively to the diluted acetone extract of S. persica , ethyl acetate extract of walnut’s bark was more effective against Gram positive and Gram negative bacteria and the different species of Candida tested in the present work. Similarly, the walnut extract was rich on phenols (34.833 mg GAE.g -1 DW) and tannins (16.167 mg EC.g -1 DW) comparatively to the arak extract (0.443 mg GAE.g -1 DW and 0.39 mg EC.g -1 DW, respectively). The walnut extract displayed the highest DPPH scavenging ability with the lowest IC 50 value (IC 50 , 3 µg/ml), a high capacity to quench superoxide (IC 50 : 70 μg.ml -1 ), the greater reducing power and bleaching of βcarotene (EC 50 , 99 μg.ml -1 and IC 50 , 280 µg.ml -1 , respectively) as compared to S. persica extract. These findings support the interest of S. persica and especially walnut bark and their possible use in the developing countries due to their inexpensive cost in order to maintain oral hygiene and as a source of new antioxidant compounds.
TL;DR: Department of Biological Sciences, College of Science, Engineering and Technology, Osun State University, P. M. B. 4494, Osogbo, Osu State, Nigeria; Department of Biochemistry and Microbiology, Lead City University, Ibadan, Nigeria
Abstract: This study reports on the phytochemical properties and in-vitro antifungal activity of Senna alata Linn. crude stem bark extract on clinical test dermatophytes. The studies on the antifungal activities of crude extracts of Senna alata L. stem bark were carried out. The test was conducted on dermatophytes, which included clinical dermatophytes of the genera Trichophyton, Microsporum and Epidemophyton. These fungi are the causative agents of various types of dermotophytosis that attack various parts of the body and tend to the following conditions, Tinea capilis, Tinea cruris, Tinea corporis and Tinea pedis. The results obtained showed that the crude extract of the stem bark of Senna alata L. exhibited marked antifungal effects on Microsporum canslaslomyces, Trichophyton verrucosum,Trichophyton mentagrophytes, and Epidermophyton floccosum. The crude extract showed the highest inhibition on T. verrucosum and E. floccosum with 21.00 and 20.05 mm zones of inhibition respectively. The Minimum Inhibitory Concentration (MIC) was also performed and the result showed that the MIC of Senna alata L. crude stem bark extract on all the tested dermatophytes was 5.0 mg/mL. The result showed that the crude extract ofS. alata L stem bark was fungicidal for all tested dermatophytes at concentration of 10.00 and 5.00 mg/mL except E. floccosum which was only fungicidal at concentration of 10.00 mg/mL. The crude extract of S. alata L. stem bark screening showed vary degree of activities against all the tested dermatophytes. Phytochemical analysis revealed the presence of important secondary metabolites (tannins, steroids, alkaloids, anthraquinones, terpenes, carbohydrates and saponins) in the plant thus indicating the therapeutic potentials of the plant. It is concluded that S. alata L. stem bark could be a potential source of active antimicrobial agents, and a detailed assessment of its in vivo potencies and toxicological profile is therefore advocated.
Key words: Antifungal activity, crude extract, dermatophytes, phytochemicals, Senna alataL., stem bark, MIC.
Journal Article•
TL;DR: Detailed anatomical characterisation of the bark of this species is provided, which is necessary to assess its potential and showed large and conspicuous sclereids in dilatation growth.
Abstract: Quercus cerris L. var. cerris has a conspicuous bark which is generally thicker than that of other Quercus L. species in Turkey. The present study aimed to provide detailed anatomical characterisation of the bark of this species, which is necessary to assess its potential. The anatomical studies were conducted on the bark samples of nine 70- to 80-year-old trees growing in 3 sites of Andirin district from Kahramanmaras province in Turkey. For microscopic observation transverse and longitudinal sections were prepared and individual specimens were taken for maceration. The bark is composed of phloem, periderm, and a very substantial rhytidome. The rhytidome has sequential periderms with phloem tissue between them, and includes compact nodules of sclerified tissues. The phellem has typical cork cells arranged regularly in radial rows and showing rings. The phelloderm is poorly developed. The phloem is layered regularly from cambium until the last formed periderm in successive tangential bands of fibres and groups of sclereids alternated with axial parenchyma and sieve tubes. Uniseriate phloem rays transverse the fibre groups, and fused phloem rays originate conspicuous broad rays. The dilatation growth showed large and conspicuous sclereids. Numerous crystals and druses in axial parenchyma cells were also observed. Full illustration of this species is given.
TL;DR: As fire frequency and intensity decrease in remnant tallgrass prairie of North America as a result of habitat fragmentation, fire suppression, and changing land management, fire-sensitive species may increase in relative importance in gallery forests because of increased juvenile survival.
TL;DR: The results indicate that insect facilitation of the establishment of wood decay fungi cannot be neglected.
TL;DR: In this article, 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.
Abstract: 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.
TL;DR: In this article, the phytochemical compounds in different solvent extracts of Jatropha curcas Linn were determined by spectrophotometry, high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry analysis (GC-MS).
Abstract: The present study was conducted to determine the phytochemical compounds in different solvent extracts of Jatropha curcas Linn. plant and antibacterial activity of crude extracts. Aqueous, methanolic and hexane extracts of various plant parts were analysed for phytochemical compounds by spectrophotometry, high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry analysis (GC-MS). Antibacterial activity was studied by paper disc diffusion assay against Gram positive and Gram negative bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by micro-broth dilution. The root bark methanolic extract contained high phenolics (11.51 mg gallic acid equivalents/g DW) and flavonoids (0.94 mg rutin equivalents/g DW). Kernel meal aqueous extract contained high saponins (0.65 mg diosgenin equivalents/g DW) and the methanolic extract contained 1.13 mg/g DW phorbol esters. Phytochemicals detected by RP-HPLC were pyrogallol, gallic acid, naringin, rutin and vanillic acid. The main compounds detected by GC-MS were oxalic acid (root bark), acetic acid and oleic acid (stem bark). Inhibition zones ranged from 8.0 to 17.7 mm. Low MIC (1.2 to 2.3 mg/ml) and MBC (0.4 to 6.3 mg/ml) values were observed in methanolic extract of all plant parts. The present study showed that stem bark, root bark and kernel meal of J. curcas contained compounds with antibacterial activities. The results indicate the potential of J. curcas as a source of antibacterial compounds.
Journal Article•
TL;DR: The present study suggested the potential of Alstonia scholaris bark in diabetes as well as related cardiovascular complications due to its antidiabetic and antihyperlipidemic properties.
Abstract: streptozotocin (STZ) induced diabetes in rats. The diabetes was induced by single dose of STZ (65 mg/kg) in citrate buffer, while the normal control group was given the vehicle (citrate buffer) only. After three days of induction of diabetes, the diabetic animals were treated further four weeks with aqueous extract of Alstonia scholaris bark (150 mg/kg and 300 mg/kg) and glibenclamide (4 mg/kg). Blood glucose estimation was performed every week of the study. At the end of study period, animals were sacrificed for biochemical studies. STZ-induced diabetic rats showed marked hyperglycemia, hypertriglyceridemia and hypercholesterolemia at the end of study period. Body weight and liver glycogen levels were reduced and glycosylated haemoglobin levels were significantly increased in diabetic rats. The four week treatment with aqueous extract of Alstonia scholaris bark (150 mg/kg and 300 mg/kg) significantly ameliorated the alterations in fasting blood glucose, serum triglyceride, serum cholesterol, liver glycogen. glycosylated haemoglobin and body weight in diabetic rats. Thus the present study suggested the potential of Alstonia scholaris bark in diabetes as well as related cardiovascular complications due to its antidiabetic and antihyperlipidemic properties.
TL;DR: Sixteen new neolignans and lignans (1-16), together with 12 known analogues, have been isolated from an ethanol extract of the bark of Machilus robusta, and the known compounds (-)-pinoresinol and (+)-lyoniresinol were active against serum deprivation induced PC12 cell damage.
Abstract: Sixteen new neolignans and lignans (1–16), together with 12 known analogues, have been isolated from an ethanol extract of the bark of Machilus robusta. Compounds 1 and 2 showed activity against HIV-1 replication in vitro, with IC50 values of 2.52 and 2.01 μM, respectively. At 10 μM, 6, 8, and 9 reduced dl-galactosamine-induced hepatocyte (WB-F344 cells) damage, and 9 could additionally attenuate rotenone-induced PC12 cell damage. The known compounds (−)-pinoresinol (17) and (+)-lyoniresinol (18) were active against serum deprivation induced PC12 cell damage.
TL;DR: In this paper, the authors investigated the summative chemical composition of three bark layers (back, cork, and belly) of five Spanish cork samples and one cork sample from Portugal, finding that significant differences were found only for suberin and holocellulose contents: they were higher in the belly and cork than in the back.
Abstract: Cork is the bark of the cork oak tree (Quercus suber L), a renewable and biodegradable raw bioresource concentrated mainly in the Mediterranean region. Development of its potential uses as a biosorbent will require the investigation of its chemical composition; such information can be of help to understand its interactions with organic pollutants. The present study investigates the summative chemical composition of three bark layers (back, cork, and belly) of five Spanish cork samples and one cork sample from Portugal. Suberin was the main component in all the samples (21.1 to 53.1%), followed by lignin (14.8 to 31%), holocellulose (2.3 to 33.6%), extractives (7.3 to 20.4%), and ash (0.4 to 3.3%). The Kruskal-Wallis test was used to determine whether the variations in chemical composition with respect to the production area and bark layers were significant. The results indicate that, with respect to the bark layer, significant differences were found only for suberin and holocellulose contents: they were higher in the belly and cork than in the back. Based on the results presented, cork is a material with a lot of potential because of its heterogeneity in chemical composition.
01 Jan 2011
TL;DR: It has been observed that, out of these Eucalyptus species outer barks, those from temperate and Mediterranean zones, namely E. nitens and E. globulus, are richer in triterpenic acids than the species from sub-tropical and tropical regions.
Abstract: A comparative study on the triterpenic acids composition of the outer barks of several Eucalyptus species (E. globulus, E. grandis, E. urograndis, E. maidenii and E. nitens) is reported. The contents of the main triterpenic acids identified in the five species varied between 4.5 g/kg in E. urograndis and 21.6 g/kg in E. nitens. It has been observed that, out of these Eucalyptus species outer barks, those from temperate and Mediterranean zones, namely E. nitens and E. globulus, are richer in triterpenic acids than the species from sub-tropical and tropical regions. Furthermore, E. globulus outer bark is clearly the richest in ursane acids, while E. nitens outer bark is the richest in oleanane and lupane acids.
TL;DR: The importance of both fire and herbivory in the development of woody plant population structure and by extension, the relative proportion of trees and grasses in savanna landscapes is emphasized.
Abstract: Sclerocarya birrea ssp. caffra (marula), a typical savanna tree, is vulnerable to the effects of fire, herbivory and their combination. This paper investigated the relative importance of these agents of disturbance, at the level of the individual stem, by specifically focusing on the following questions: (i) What is the greatest cause of mortality in adult marula stems in conservation areas with both elephants and fire? (ii) Does fire interact with bark stripping to cause adult stem mortality and if so what is the dominant mechanism? (iii) At what stem diameter are marulas resistant to fire? Field surveys quantified the extent of damage in marula individuals in the Kruger National Park, South Africa, highlighting the high levels of extreme herbivory such as toppling (7%) and pollarding (8%), relative to bark stripping (only 6% with more than 50% of the circumference stripped). In addition to extreme herbivory, the progression from bark stripping through to invasion of the soft, exposed heartwood by wood borers, often facilitated by fire, through to toppling of the weakened stem after successive fires, appears to be the dominant mechanism by which fire interacts with herbivory to cause adult stem death. Bark stripping and fire manipulation experiments indicated that bark stripping failed to increase the vulnerability of stems to fire directly through transport tissue damage. However, the combination of bark stripping and fire reduced the ability of the stem to regrow bark, increasing the vulnerability of the exposed stem to boring insects and future fires. Fire manipulation experiments were used to identify the minimum stem diameter of resistance to fire. Marula resisted stem death when greater than 3.4 cm in basal diameter. This paper emphasizes the importance of both fire and herbivory in the development of woody plant population structure and by extension, the relative proportion of trees and grasses in savanna landscapes.
TL;DR: Four new phenolic glycosides, saccharumosides A-D (1-4) were isolated from the bark of sugar maple and the structures of 1-4 were elucidated on the basis of spectroscopic data analysis.
Abstract: Four new phenolic glycosides, saccharumosides A–D (1–4), along with eight known phenolic glycosides, were isolated from the bark of sugar maple (Acer saccharum). The structures of 1–4 were elucidated on the basis of spectroscopic data analysis. All compounds isolated were evaluated for cytotoxicity effects against human colon tumorigenic (HCT-116 and Caco-2) and nontumorigenic (CCD-18Co) cell lines.