Search Results

You are looking at 1 - 10 of 41 items for :

  • "Fagus sylvatica" x
  • Refine by Access: All Content x
Clear All

The aim of this study was to investigate the role of (+)-catechin and (−)-epicatechin in the molecular processes of formation of red heartwood, a structural and color anomaly of living beech which causes substantial economic loss. The causes of the formation of red heartwood and the molecular carriers and participants are unknown. It has been proven that the activity of phenol oxidizing enzymes (POD, PPO) increases at the color boundary, but the phenolic compounds participating in these reactions, and probably building up the red chromophores are unknown. Catechins play an important role in defense reactions against oxidative stress in plant tissues and are also major phenolic constituents of beech wood. A simple and readily applicable TLC method has been implemented to measure the radial distribution of the concentrations of the two epimers in healthy and discolored beech disks. The reactions at the color boundary could also be tracked by use of this technique. The results show unequivocally the role of the two catechins, and presumably the role of other flavan-3-ols also, in the formation of the red chromophores. By establishing the exact composition of the red chromophores the color stability of red-heartwood material and its industrial utilization could also be enhanced.

Restricted access

This paper was aimed at analytical and antioxidant activity studies on a series of European beech (Fagus sylvatica L.) leaves extracts in order to select the most proper period of raw material harvesting and corresponding technological approach in the final purpose of obtaining some extracts with high antioxidant effect useful as new, industrial material protecting products. Thus, comparative thinlayer liquid chromatography (TLC) studies on five series of (70%) ethanol macerates (tinctures), corresponding to the five periods of beech leaves harvesting (May–July–September–early October–late October) revealed caffeic acid (chlorogenic acid isomers), apigenin, kaempferol, quercetin, and catechin derivates as being the common polyphenolic species; it must be mentioned that while spring leaves revealed the dominance of one major kaempferol diglycoside and only traces of chlorogenic acid and apigenin derivates, summer to early autumn leaves have shown the abundance of chlorogenic acid isomers and an increasing number of apigenin derivates, as well as the appearing of one new major kaempferol mono-glycoside; different, autumn late leaves emphasized the decline of chlorogenic acid isomers versus the augmentation of summer apigenin derivates, as of two quercetin and catechin derivates, visualized only as traces in summer to early autumn samples. Further, quantitative assays indicated total phenols contents (expressed as gallic acid equivalents/GAE) of 7.04–11.61–33.55–9.40–5.81 mg g−1 GAE and total flavonoids contents (expressed as rutin equivalents/RE) of 12.40–9.02–5.71–2.22–2.19 mg g−1 RE; among flavonoids, kaempferol glycosides levels of 2.92–2.01–1.38–0.52–0.17 mg g−1 were estimated (mean values). Once established September time as the most suitable period for leaves harvesting, antioxidant activity (AA) assessments of the subsequently beech leaves hot (70%) ethanol extracts indicated polar extracts as being moderate to augmented antioxidant products (49% ≤ AA ≤ 96%); differently, non-polar extracts indicated an augmented pro-oxidant effect (AA = −71%). The obtained results formed the foundation of new, anti-scale/anti-corrosion products based on beech leaves extracts.

Restricted access

Structure and diversity trends (β-diversity and species richness) across the Fagus sylvatica timberline in the central Apennines were investigated. Twenty-three belt transects were laid out across the upper forest line in the Simbruini Mountains. Number of species, plant cover, and height of different layers were recorded in each quadrat. The moving split-window method was used to detect ecological discontinuities across beech timberlines. We show how β-diversity changes along timberlines and we put forward some hypotheses about the possible dynamics of these transitions. Fourmodels resulted from the analysis of β-diversity trends: two β-diversity peaks indicated a transition where shrubs, mainly Juniperus communis ssp. alpina, (two high peaks) or beech scrub (two small peaks) formed a mantle that could allow forest expansion. One high β-diversity peak referred to an anthropo-zoogenic boundary maintained by disturbance, without the presence of a mantle. A little peak indicated a gradual transition at the upper potential timberline limit where beech forest had lost its typical floristical composition and structural characteristics.

Restricted access

The factors affecting the economically and sylviculturally disadvantageous formation of red heartwoord in beech are only partly understood. It has already been proved that at the color boundary of the red heart the total phenol concentration decreases sharply whereas the activity of oxidative enzymes (POD, PPO) increases substantially. The concentrations of (+)-catechin and (−)-epicatechin fall drastically and the five taxifolin and quercetin glycosides undergo hydrolysis. It is unclear, however, what role the flavonoids present at the boundary ((+)-catechin, (−)-epicatechin, taxifolin, and quercetin) have in the formation of the red chromophores of the heartwood. Understanding the transformation of the precursors and analysis of the products could result an enhanced utilization of redheartwood timber and better understanding of the physiology of red heartwood formation. In this work the role of catechins has been investigated by in-vitro transformation of (+)-catechin and (−)-epicatechin by extracts of beech wood enzymes. Thin-layer chromatography with scanning densitometry and acquisition of the products’ UV-visible reflection spectra proved suitable for monitoring the reactions and analyzing the products. Result have shown that rapid oxidation and oligomerization of the catechins is caused by beech enzyme extract. In-vitro products have also been compared with the chromophores of beech red heartwood. Conclusions have been drawn regarding the physiology of red heartwood formation.

Restricted access

has been revealed a proper and suitable technique for this purpose. In particular, we will study wood samples ( Pinus pinaster and Fagus sylvatica L.) from the ship Chrétienne C, (II century, BC), discovered over the coast of Provence (France) and

Restricted access

This study investigated if ecological traits of forest floor vegetation could be used as indicators of naturalness of beech forest in Hungary, by comparing near-natural unmanaged stands with managed ones. Seventeen patches in the unmanaged Kékes Forest Reserve were compared with 11 subcompartments of different ages in the surrounding managed forest. In each stand, the character state distributions of 9 ecological species traits were calculated based on presence/absence data of plants. Averages for unmanaged versus managed stands were compared. Significant effects of management were shown. The characteristics of herbaceous plants with higher frequency in managed stands include late start and longer duration of flowering, overwintering canopy, and small epizoochorous seeds. Unmanaged stands are richer in plants that bear leaves from spring to autumn, start flowering early or flower very shortly, produce large seeds. Relevance of this method is discussed for Central Europe, where in large areas intensive forest management rather than fragmentation or break in forest continuity is the major human disturbance.

Restricted access

Bryophyte vegetation on volcanic rock outcrops and dead wood is studied in a near-natural montane beech stand in northern Hungary. Substrate specificity of the species and  the existing interspecific relationships are described. The most important species combinations and their diversity are evaluated using information theoretical functions and Monte-Carlo simulations. All analyses are based on presence/absence data of 33 species in 1508 100 cm2 microplots. Most species exhibit strong substrate specificity. Of the species that occurred with frequencies higher than 10, 8 are associated to rock, 5 to dead wood and 5 to both substrate types. Analyses of interspecific associations and agglomerative classification reveal that frequent species of species-poor bare rocks are separated from species-rich assemblages of humus-rich outcrops and coarse woody debris.  Monte Carlo simulations reveal that many species combinations are significantly more frequent than expected under the assumption of random combining of species. Observed number, diversity and evenness of species combinations are significantly lower, whereas interspecific constraint (expressed as associatum) is significantly higher than under the neutral models even when data are stratified according to substrate type. The presence of coarse woody debris, not only provides habitat for wood inhabiting bryophytes, but also results in diverse rupicolous bryophyte assemblages on humus-rich outcrops.

Restricted access

Given the large applicability in both pharmaceutical and cosmetic field, this work was aimed at analytical (high-performance thin-layer chromatography [HPTLC] method), antioxidant (2,2-diphenyl-1-picrylhydrazyl [DPPH] method), and antimicrobial (diffusion method on Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, and Candida albicans ATCC 10231) studies on a series of whole vegetal extracts and corresponding aqueous, ethyl acetate and chloroform fractions (selective extracts) prepared from eight plant species growing in Romania. Briefly, it was revealed moderate to certain activity against S. aureus ATCC 6538 and E. coli ATCC 8739 in the case of greater burdock leaves (Arctium lappa), beech leaves (Fagus sylvatica) and great willowherb aerial part (Epilobium hirsutum) whole extracts. Purple loosestrife aerial part (Lythrum salicaria) and sea-buckthorn leaves (Hippophae rhamnoides) whole extracts showed only weak activity against these bacteria, while tarragon aerial part (Artemisia dracunculoides), chokeberries leaves (Aronia melanocarpa) and quince fruit (Cydonia oblonga) whole extracts have not shown activity. Subsequently studies on the selective extracts have revealed that combinations of glycosides of the same aglycones lead to very different antimicrobial properties indicating synergistic effects between polyphenols (demonstrated in the case of Fagus sylvatica extracts) or the contribution of other phytocompounds to the final effect (demonstrated in the case of Arctium lappa extracts) and, secondly, that the glycosyl chain in which they occur may also contribute to the final antimicrobial effect (demonstrated by the fact that the most active vegetal extracts emphasized the dominance of flavonoid monoglycosides). Moreover, inhibitory antimicrobial effects were revealed (Arctium lappa extracts). Finally, none of the studied extracts acted against C. albicans ATCC 10231. Concerning antioxidant activity, DPPH tests indicated high potency of all tested extracts (IC50 measuring from 2.66 to 4.80). Further studies on the most active vegetal extracts which aim to reveal MICs values and potential inhibitory or activatory effects in combination with chemical antibiotics are ongoing.

Open access

Thermogravimetric analysis

A tool to evaluate the ability of mixtures in consolidating waterlogged archaeological woods

Journal of Thermal Analysis and Calorimetry
Authors:
D. Donato
,
G. Lazzara
, and
S. Milioto

Abstract  

Waterlogged archaeological woods (Pinus pinaster, Ulmus cf. minor and Fagus sylvatica L.) were consolidated by using Colophony, Rosin 100, and a mixture of Poly(ethylene) glycol (PEG) 3000 and Poly(propylene) glycol (PPG) 425. The efficiency of the consolidants was estimated by determining the content entrapped into the cavity of degraded wood. For this purpose, thermogravimetry was demonstrated to be a reliable tool. In the case that the polymeric mixture was used for impregnation, it was also possible to discriminate the amount of PEG 3000 from that of PPG 425 captured by the wood capillaries. Regardless of the wood nature, all the consolidants were present in treated samples in large amount (at least 70% w/w). Thermogravimetric results were in agreement with those calculated by using the wood degradation degree and composition of the consolidant mixture. One of the advantages of using this technique consists into requiring very small amounts (a few mg) of sample against the grams necessary for the conventional experiments.

Restricted access

Scree forest communities Mercuriali-Tilietum Zólyomi et Jakucs 1958 of Börzsöny Mts were not processed until the present. These lime-dominated forests develop on andesite base-rock, mainly on periglacial scree surfaces. Using the Braun-Blanquet-Soó method 15 sampling spots were studied and analysed based on floristical composition, cenological aspects and habitat characteristics. The stand's species stock consists of tree species like Acer platanoides, Carpinus betulus, Fraxinus excelsior, Tilia platyphyllos, shrubs like Cornus mas, Corylus avellana, Euonymus verrucosus, Ribes uva-crispa and herbs like Cystopteris fragilis, Dryopteris filix-mas, Galeobdolon luteum, Galium schultesii, G. odoratum, Hedera helix, Melica uniflora, Mercurialis perennis, Mycelis muralis, Poa nemoralis, Waldsteinia geoides. Rare Tilio-Acerion species are Adoxa moschatellina, Gagea minima, Geranium lucidum. Cenological categories, life forms, geoelement distribution, and Borhidi's Social Behaviour Types were studied on the basis of the synthetic table. Relative ecological T, W, R values according to Zólyomi, and Borhidi's continentality were also evaluated. Results were compared to Parietario-Aceretum (Horánszky 1964) Soó 1971 community belonging to alliance Tilio platyphylli-Acerion pseudoplatani. This andesitic gorge forest community where highly dominant species are Acer pseudoplatanus, Fagus sylvatica, Fraxinus excelsior is a closely related to the scree forests.

Restricted access