Showing papers on "Bark published in 2018"
TL;DR: The results showed the interactions between inhibitors and tyrosinase were driven by hydrogen bond, electrostatic, and hydrophobic interactions, and high levels of total phenolic and extractable condensed tannins suggested that longan bark might be a good source of tyrosine inhibitor.
Abstract: In this study, the content, structure, antityrosinase activity, and mechanism of longan bark condensed tannins were evaluated. The findings obtained from mass spectrometry demonstrated that longan bark condensed tannins were mixtures of procyanidins, propelargonidins, prodelphinidins, and their acyl derivatives (galloyl and p-hydroxybenzoate). The enzyme analysis indicated that these mixtures were efficient, reversible, and mixed (competitive is dominant) inhibitor of tyrosinase. What’s more, the mixtures showed good inhibitions on proliferation, intracellular enzyme activity and melanogenesis of mouse melanoma cells (B16). From molecular docking, the results showed the interactions between inhibitors and tyrosinase were driven by hydrogen bond, electrostatic, and hydrophobic interactions. In addition, high levels of total phenolic and extractable condensed tannins suggested that longan bark might be a good source of tyrosinase inhibitor. This study would offer theoretical basis for the development of lon...
89 citations
TL;DR: The bark of Acacia mearnsii De Wild contains significant amounts of water-soluble components acalled “wattle tannin”, which has the ability to inactivate α-amylase, lipase and glucosidase and has been studied for its antimicrobial activities and anti-hypertensive effects.
Abstract: The bark of Acacia mearnsii De Wild. (black wattle) contains significant amounts of water-soluble components acalled “wattle tannin”. Following the discovery of its strong antioxidant activity, a wattle tannin dietary supplement has been developed and as part of developing new dietary supplements, a literature search was conducted using the SciFinder data base for “Acacia species and their biological activities”. An analysis of the references found indicated that the name of Acacia nilotica had been changed to Vachellia nilotica, even though the name of the genus Acacia originated from its original name. This review briefly describes why and how the name of A. nilotica changed. Tannin has been analyzed using the Stiasny method when the tannin is used to make adhesives and the hide-powder method is used when the tannin is to be used for leather tanning. A simple UV method is also able to be used to estimate the values for both adhesives and leather tanning applications. The tannin content in bark can also be estimated using NIR and NMR. Tannin content estimations using pyrolysis/GC, electrospray mass spectrometry and quantitative 31P-NMR analyses have also been described. Tannins consists mostly of polyflavanoids and all the compounds isolated have been updated. Antioxidant activities of the tannin relating to anti-tumor properties, the viability of human neuroblastoma SH-SY5Y cells and also anti-hypertensive effects have been studied. The antioxidant activity of proanthocyanidins was found to be higher than that of flavan-3-ol monomers. A total of fourteen papers and two patents reported the antimicrobial activities of wattle tannin. Bacteria were more susceptible to the tannins than the fungal strains tested. Several bacteria were inhibited by the extract from A. mearnsii bark. The growth inhibition mechanisms of E. coli were investigated. An interaction between extracts from A. mearnsii bark and antibiotics has also been studied. The extracts from A. mearnsii bark inhibit the growth of cyanobacteria. Wattle tannin has the ability to inactivate α-amylase, lipase and glucosidase. In vivo experiments on anti-obesity and anti-diabetes were also reported. Several patents relating to these enzymes for anti-diabetes and anti-obesity are in the literature. In addition, studies on Acacia bark extract regarding its antitermite activities, inhibition of itching in atopic dermatitis and anti-inflammatory effects have also been reported. The growth of bacteria was inhibited by the extract from A. mearnsii bark, and typical intestinal bacteria such as E. coli, K. pneumoniae, P. vulgaris and S. marcescenes was also inhibited in vitro by extracts. Based on these results, the Acacia bark extract may inhibit not only the growth of these typical intestinal bacteria but also the growth of other types of intestinal bacteria such as Clostridium and Bacteroides, a so-called “bad bacteria”. If the tannin extract from A. mearnsii bark inhibits growth of these “bad bacteria” in vivo evaluation, the extracts might be usable as a new dietary supplement, which could control the human intestinal microbiome to keep the body healthy.
69 citations
TL;DR: This review synthesizes and interprets recent advances in applied chemical ecology of bark beetles for scientists and land managers in western North America.
Abstract: We summarize the status of semiochemical-based management of the major bark beetle species in western North America. The conifer forests of this region have a long history of profound impacts by phloem-feeding bark beetles, and species such as the mountain pine beetle (Dendroctonus ponderosae) and the spruce beetle (D. rufipennis) have recently undergone epic outbreaks linked to changing climate. At the same time, great strides are being made in the application of semiochemicals to the integrated pest management of bark beetles. In this review, we synthesize and interpret these recent advances in applied chemical ecology of bark beetles for scientists and land managers.
62 citations
18 Jan 2018
54 citations
TL;DR: The antioxidant, antimicrobial and antifungal activity of spruce bark extracts assessed in terms of food and cosmetic fortification is novel.
54 citations
TL;DR: This work provides the first large-scale transcriptomic dataset on the suberin-synthesizing tissue of poplar bark, contributing to the understanding of tree bark development at the molecular level and proposed a number of hypotheses that can be used in future research leading to novel biological insights into suber in biosynthesis and its physiological function.
Abstract: The tree bark periderm confers the first line of protection against pathogen invasion and abiotic stresses The phellogen (cork cambium) externally produces cork (phellem) cells that are dead at maturity; while metabolically active, these tissues synthesize cell walls, as well as cell wall modifications, namely suberin and waxes Suberin is a heteropolymer with aliphatic and aromatic domains, composed of acylglycerols, cross-linked polyphenolics and solvent-extractable waxes Although suberin is essentially ubiquitous in vascular plants, the biochemical functions of many enzymes and the genetic regulation of its synthesis are poorly understood We have studied suberin and wax composition in four developmental stages of hybrid poplar (Populus tremula x Populus alba) stem periderm The amounts of extracellular ester-linked acyl lipids per unit area increased with tissue age, a trend not observed with waxes We used RNA-Seq deep-sequencing technology to investigate the cork transcriptome at two developmental stages The transcript analysis yielded 455 candidates for the biosynthesis and regulation of poplar suberin, including genes with proven functions in suberin metabolism, genes highlighted as candidates in other plant species and novel candidates Among these, a gene encoding a putative lipase/acyltransferase of the GDSL-motif family emerged as a suberin polyester synthase candidate, and specific isoforms of peroxidase and laccase genes were preferentially expressed in cork, suggesting that their corresponding proteins may be involved in cross-linking aromatics to form lignin-like polyphenolics Many transcriptional regulators with possible roles in meristem identity, cork differentiation and acyl-lipid metabolism were also identified Our work provides the first large-scale transcriptomic dataset on the suberin-synthesizing tissue of poplar bark, contributing to our understanding of tree bark development at the molecular level Based on these data, we have proposed a number of hypotheses that can be used in future research leading to novel biological insights into suberin biosynthesis and its physiological function
50 citations
TL;DR: The whole cell wall and enzyme lignin preparations sequentially isolated from ball-milled bark, inner bark, and wood were comparatively investigated by nuclear magnetic resonance (NMR) spectroscopy and three classical degradative methods, demonstrating that the guaiacyl (G) units were predominant in the willow bark lign in over syringyl (S) and minor p-hydroxyphenyl (H) units.
Abstract: Understanding the chemical structure of lignin in willow bark is an indispensable step to design how to separate its fiber bundles. The whole cell wall and enzyme lignin preparations sequentially isolated from ball-milled bark, inner bark, and wood were comparatively investigated by nuclear magnetic resonance (NMR) spectroscopy and three classical degradative methods, i.e., alkaline nitrobenzene oxidation, derivatization followed by reductive cleavage, and analytical thioacidolysis. All results demonstrated that the guaiacyl (G) units were predominant in the willow bark lignin over syringyl (S) and minor p-hydroxyphenyl (H) units. Moreover, the monomer yields and S/G ratio rose progressively from bark to inner bark and wood, indicating that lignin may be more condensed in bark than in other tissues. Additionally, major interunit linkage substructures (β-aryl ethers, phenylcoumarans, and resinols) together with cinnamyl alcohol end groups were relatively quantitated by two-dimensional NMR spectroscopy. Bark and inner bark were rich in pectins and proteins, which were present in large quantities and also in the enzyme lignin preparations.
48 citations
TL;DR: Comparative antioxidant potential and antimicrobial activity in extracts of bark and leaves of T. arjuna clearly indicated comparative antioxidant potential as compared to that of crude ethanolic extract, ethyl acetate fraction, chloroform fraction, aqueous fraction and even ascorbic acid.
47 citations
Book•
18 Mar 2018
45 citations
TL;DR: The authors examined the role of bark cover and bark traits throughout the wood decomposition process and found that bark effects on WD decomposition are species-specific and wood size-specific, and that bark can enhance coarser wood debris decomposition but slow twig decomposition.
Abstract: 1. Woody debris (WD) represents a globally significant carbon stock and its decomposition returns nutrients to the soil while providing habitat to microbes, plants and animals. Understanding what drives WD decomposition is therefore important.
2. WD decomposition rates differ greatly among species. However, the role of bark in the process remains poorly known.
3. We ask how, and how much, interspecific variation in bark functional traits related to growth and protection have afterlife effects on the decomposition of wood, partly mediated by animals. We examine the roles of bark cover and bark traits throughout the wood decomposition process.
4. Synthesis. We find that: (1) bark effects on WD decomposition are species‐ and wood size‐specific, (2) bark can enhance coarser WD decomposition but slows twig decomposition in some species, and (3) bark acts as an environmental filter to faunal assemblages in the early stage of wood decomposition.
45 citations
TL;DR: In this paper, the use of eucalyptus bark, in the form of briquettes, as an energy source was evaluated and a gain of energy density through the process of briquetting, when compared to the raw biomass, as well as an improvement on the physic-mechanical characteristics.
TL;DR: In general, the N. oleander and C. erectus species were found to have the highest absorption rate from the atmosphere and soil than other studied species, and are very suitable tools for managing air pollution in highly industrialized areas.
TL;DR: In this paper, a literature review of different cork by-products and their bioactive compounds is presented and the promising application of these wastes as cosmetic and pharmaceutical ingredients is analysed.
TL;DR: With bark, high temperatures, intensive OM degradation and humification were achieved later than with straw and the increase in HS concentration during composting was higher, and the fulvic fraction predominated in HS whereas with straw, humic acids predominated.
09 Feb 2018
TL;DR: Since cinnamaldehyde disrupts both the cell wall and tubulin polymerization, it may serve as an effective antifungal, either by chemical modification to improve its specificity and efficacy or in combination with other antIFungal drugs.
Abstract: Cinnamon (Cinnamomum zeylanicum) bark extract exhibits potent inhibitory activity against Candida albicans but the antifungal mechanisms of this essential oil remain largely unexplored. We analyzed the impact of cinnamon bark oil on C. albicans RSY150, and clinical strains isolated from patients with candidemia and candidiasis. The viability of RSY150 was significantly compromised in a dose dependent manner when exposed to cinnamon bark oil, with extensive cell surface remodelling at sub inhibitory levels (62.5 μg/mL). Atomic force microscopy revealed cell surface exfoliation, altered ultrastructure and reduced cell wall integrity for both RSY150 and clinical isolates exposed to cinnamon bark oil. Cell wall damage induced by cinnamon bark oil was confirmed by exposure to stressors and the sensitivity of cell wall mutants involved in cell wall organization, biogenesis, and morphogenesis. The essential oil triggered cell cycle arrest by disrupting beta tubulin distribution, which led to mitotic spindle defects, ultimately compromising the cell membrane and allowing leakage of cellular components. The multiple targets of cinnamon bark oil can be attributed to its components, including cinnamaldehyde (74%), and minor components (< 6%) such as linalool (3.9%), cinamyl acetate (3.8%), α-caryophyllene (5.3%) and limonene (2%). Complete inhibition of the mitotic spindle assembly was observed in C. albicans treated with cinnamaldehyde at MIC (112 μg/mL). Since cinnamaldehyde disrupts both the cell wall and tubulin polymerization, it may serve as an effective antifungal, either by chemical modification to improve its specificity and efficacy or in combination with other antifungal drugs.
TL;DR: Changes in sugar metabolism associated with leaf and stem bark thickening partially assist (but not totally preserve) young tissues of loquat plants under B stress, thus leading to an increased level of lipid peroxidation.
TL;DR: The results showed that both fungal and bacterial communities in bark are dominated by genera with ubiquitous attitudes, such as Aureobasidium, Cryptococcus, Deinococcus and Hymenobacter, indicating intense microbial migration to surrounding environments.
TL;DR: In this paper, the pyrolysis of water-insoluble (W-I) tannins from Pinus radiata bark methanol-water extraction was carried out in pursuit of a renewable source of high-value chemicals, in particular catechols.
TL;DR: Sector analysis in poplar tree stems was used to shed light on cell identity, cell fate, and patterns of development within the vascular cambium.
Abstract: We used sector analysis to study cambium development and dynamics and to test whether fundamental developmental and functional differences exist between cambial initials as true 'stem cells' and more differentiated mother cells. In many higher plants, a cylindrical lateral meristem, the vascular cambium, forms along the plant axis. Most notably in stems of perennial tree species, this meristem gives rise to xylem (wood) towards the inside of the trunk and phloem (bark) towards the outside. As such, the vascular cambium is responsible for the production of most of the planet's forest biomass, significantly contributing to the global carbon cycle. Using the bacterial uidA reporter gene in Agrobacterium-based in vivo stem transformation experiments in poplar trees, we created 379 cambium sectors that originated from the transformation of individual cells. Results from our analysis of sector frequency and patterns are consistent with the poplar cambium featuring a single layer of true cambial initials (being able to divide both anti- and periclinally). We show that initials are frequently lost from the cambium, that such cell loss rarely occurs at mother cell level, that phloem and xylem differentiation are controlled independently, and that the frequency of mother cell replenishment is not pre-determined.
TL;DR: In this paper, mild hot water treatment of willow hybrid Karin was studied to find a practical means of isolating its noncell-wall components for their utilization in a willow biorefinery proposed to aid valorization of the willow biomass.
Abstract: Willow bark is a rich source of heterogeneous polyphenolic compounds and a potential feedstock for biorefinery processes aiming at chemicals and fiber production. Here, mild hot water treatment of willow hybrid Karin was studied to find a practical means of isolating its non-cell-wall components for their utilization in a willow biorefinery proposed to aid valorization of the willow biomass. A short aqueous treatment of the bark at 80 °C liberated the extract in >20% yield under unpressurized conditions. The extract was characterized using mainly gas chromatography-mass spectrometry and one- and two-dimensional NMR techniques. Authentic analytes were applied to confirm the identification and quantification of the main components that were picein, (+)-catechin, triandrin, glucose, and fructose. Fructose was converted into 5-hydroxymethylfurfural in an acidic treatment which led to its condensation with the phenolic components and formation of a recalcitrant precipitate that should be avoided.
TL;DR: In this article, the authors provided information about separation and identification of natural bioactive compounds from beech (Fagus sylvatica L.) bark with potential therapeutic applications such as antibacterial activity against human pathogens.
Abstract: The study provides information about separation and identification of natural bioactive compounds from beech (Fagus sylvatica L.) bark with potential therapeutic applications such as antibacterial activity against human pathogens. Beech is a common material used in the wood industry, but its bark is separated from the wood and is considered a by-product. In this study, natural compounds with biological activity were obtained from beech bark by hot water extraction. The high-performance liquid chromatography (HPLC) was used to analyze the phenolic compounds in the beech bark extracts. Spectrophotometric methods were employed for the determination of total phenolic content. Microdilution technique was used for testing the antimicrobial activity of the extract. The following strains were tested: Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa. The yield of extracted polyphenols was of 22.952 mg gallic acid/g dry bark. The compounds identified by HPLC were vanilic acid, catechin, taxifolin and syringin. The extracts were active against Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus. The effect of polyphenolic extract on Gram-negative bacteria was absent at a concentration of 30 mg/mL beach bark extract. Altogether, the use of pure water for extraction of polyphenols from beech bark proved to be an effective eco-friendly method. This method sustains the concept of green chemistry by involving the use of renewable plant resources and also by using water as solvent.
TL;DR: Bark presented chemical features that point to their possible upgrade, whether by taking advantage of the high extractives with bioactive compounds or the production potential for hemicellulose-derived oligomers with possible use in nutraceutical and pharmaceutical industries.
Abstract: The present work determines the chemical and thermal characteristics as well as the phytochemical and antioxidant potential of the polar extractives of the Picea abies bark from an industrial mill, their wood and bark components and also different bark fractions obtained by mechanical fractionation (fine B1, Φ<0.180 mm, medium B3, 0.450 < Φ<0.850 mm and coarse B6, 2 < Φ<10 mm). The aim is to increase the knowledge on the Picea abies bark to better determine possible uses other than burning for energy production and to test an initial size reduction process to achieve fractions with different characteristics. Compared to wood, bark presented similar lignin (27%), higher mineral (3.9% vs 0.4%) and extractives (20.3% vs 3.8%) and lower polysaccharides (48% vs 71%) contents. Regarding bark fractions the fines showed higher ash (6.3%), extractives (25%) and lignin (29%) than the coarse fraction (3.9%, 19% and 25% respectively). Polysaccharide contents increased with particle size of the bark fractions (38% vs 52% for B1 and B6) but showed the same relative composition. The phytochemical profile of ethanol and water extracts presented higher contents for bark than wood of total phenols (2x higher), flavonoids (3x higher) and tannins (4-10x higher) with an increasing tendency with particle size. Bark antioxidant activity was higher than that of wood for ferric-reducing antioxidant power (FRAP, 10 vs 6 mmolFe2+/gExt for the ethanol extract) and free radical scavenging activity (DPPH, 6 vs 18 mg/L IC50 for the ethanol extract) methods. The different bark fractions antioxidant activity was very similar. Bark thermal properties showed a much lower volatiles to fixed carbon ratio (V/FC) than wood (3.1 vs 5.2) although the same higher heating value (20.3 MJ/kg). The fractions were quite similar. Bark presented chemical features that point to their possible upgrade, whether by taking advantage of the high extractives with bioactive compounds or the production potential for hemicellulose-derived oligomers with possible use in nutraceutical and pharmaceutical industries.
TL;DR: Arfan et al. as mentioned in this paper extracted phenolic compounds from Mallotus philippinensis bark using methanol, and six fractions (I-VI) were separated from the extract on a Sephadex LH-20 column using ethanol and acetone-water as the mobile phases and were evaluated for their total antioxidant activity, antiradical activity against DPPH • (2,2-diphenyl-1-picrylhydrazyl radical), and reducing power.
Abstract: Arfan M., Amin H., Karamac M., Kosinska A., Wiczkowski W., Amarowicz R. (2009): Antioxidant activity of phenolic fractions of Mallotus philippinensis bark extract . Czech J. Food Sci., 27 : 109–117. Phenolic compounds were extracted from Mallotus philippinensis bark using methanol. Six fractions (I–VI) were separated from the extract on a Sephadex LH-20 column using ethanol and acetone-water as the mobile phases and were evaluated for their total antioxidant activity, antiradical activity against DPPH • (2,2-diphenyl-1-picrylhydrazyl radical), and reducing power. The total phenolics and tannin contents in the fractions were determined. The content of total phenolics in the fractions ranged from 54 mg/g (fraction I) to 927 mg/g (fraction VI). Condensed tannins were detected in fractions II–VI. Total antioxidant activity (TAA) of phenolic fractions of Mallotus philipinensis bark extract ranged from 0.58 mmol Trolox/g (fraction I) to 6.82 mmol Trolox/g (fraction IV). Fraction IV also showed the strongest antiradical activity against DPPH
TL;DR: In this paper, physico-mechanical and surface properties of flooring tiles coated with thin layers made of larch bark are presented for the first time, and two types of adhesives are involved to bond the bark particles, namely polyurethane and a formaldehyde-free tanninhexamine resin.
TL;DR: Garmoxanthone exhibited strong antibacterial activity which partially validated the ethnobotanical use of G. mangostana in the treatment of infections.
TL;DR: In this article, a bio-based formulation free of formaldehyde, phenol, and isocyanates was used as hardener for plywood production, and the influence of pH on gel time, rheological behavior, and pot life was evaluated.
TL;DR: The results suggest that ethanol leaf and bark extracts of A.officinalis were effective in inhibiting α-amylase and α-glucosidase and also have antioxidant, antimicrobial potentials which justify the ethnobotanical use of this plant.
Abstract: Avicennia officinalis is a medicinally important mangrove plant and used in traditional medicinal practices to treat various ailments like rheumatism, paralysis, asthma, dyspepsia, tumors etc. The objective of the present study was to evaluate the carbohydrate metabolizing enzyme inhibitory, antioxidant, antimicrobial and cytotoxic potentials of ethanol leaf and bark extracts of A. officinalis. The carbohydrate metabolizing enzyme inhibition potential was studied by α-amylase and α-glucosidase inhibitory activities. The antioxidant activity was investigated by measuring the scavenging potential of extracts against DPPH, ABTS and superoxide radicals. The antimicrobial activity was studied by agar well diffusion method and the cytotoxicity potential by MTT assay. The study revealed that A.offiicnalis bark extract inhibited the activity of α-amylase and α-glucosidase in a dose dependent manner with an IC50 value of 0.66 and 0.71 mg/ml respectively. The leaf extract also demonstrated inhibition potential against α-amylase and α-glucosidase with an IC50 value of 0.29 and 1.19 mg/ml respectively. The ethanol bark extract also exhibited scavenging potential against DPPH, ABTS and superoxide radicals in a dose dependent manner with IC50 values of 112, 114 and 82 μg/ml respectively and ethanol leaf extract with IC50 values of 200, 41.9 and 207.6 μg/ml respectively. Both leaf and bark extracts exhibited dose dependent antiproferative activity on TC1 murine cell lines. Both leaf and bark extracts exhibited antimicrobial activity against bacteria (Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and fungi (Candida albicans, C. krusei). The qualitative phytochemical assay, UV-Vis and FTIR analysis revealed the presence of different phytoconstituents in the leaf and bark extracts of A.officinalis. The results suggest that ethanol leaf and bark extracts of A.officinalis were effective in inhibiting α-amylase and α-glucosidase and also have antioxidant, antimicrobial potentials which justify the ethnobotanical use of this plant.
TL;DR: A series of field-based experiments were conducted using sand, gravel, wood fuel, and bark from Betula pubescens (downy birch) in order to investigate the use of raised structures within a fire as mentioned in this paper.
Abstract: Following on from our previous research into the prehistoric aceramic distillation and production of birch bark tar, this series of exploratory experiments investigated the use of raised structures within a fire. These field-based experiments were conducted using sand, gravel, wood fuel, and bark from Betula pubescens (downy birch). The structures that were created were simple raised sand mounds, which reflected known Neanderthal combustion surfaces from the Middle Palaeolithic. The bulk of the experiments were recorded throughout using a thermocouple to provide temperature readings from the base of the bark pyrolysis chamber. The experiments proved successful at producing birch bark tar and several containers were used to catch the tar for later analysis. Based on the results, the authors contend that not only could Neanderthals control fire but that regular birch bark tar production by Neanderthals was most likely a result of specific chaines operatoires in order to provide the necessary control and outcomes.
TL;DR: A reductive fractionation process for the valorization of Quercus suber bark toward hydrocarbons in gasoline and diesel ranges and optionally 4-ethylguaiacol has been developed as mentioned in this paper.
Abstract: A reductive fractionation process for the valorization of Quercus suber bark toward hydrocarbons in gasoline and diesel ranges and optionally 4-ethylguaiacol has been developed. The procedure involves three steps: (1) tandem hydrogen-free Pd/C-catalyzed transfer hydrogenolysis of lignin where the carbohydrates serve as an inherent hydrogen donor under slightly alkaline conditions to also facilitate the depolymerization of suberin, (2) optional distillation, to isolate the 4-ethylguaiacol, (3) hydrodeoxygenation of the mixture from the first step by a Pt-MoO3/TiO2 catalyst generated hydrocarbons in gasoline and diesel ranges. The yield of 4-ethylguaiacol (90% purity) is 2.6% of dry bark weight (12% of acid insoluble lignin), and yield of hydrocarbon bio-oil is 42% of dry bark weight. This corresponds to a theoretical maximum yield of 77% for lignin and suberin. The carbon yield of the obtained bio-oil is thereby 64% from the total initial bark.