Comparison of the Content of Extractives in the Bark of the Trunk and the Bark of the Branches of Silver Fir (Abies alba Mill.)

Abstract

The main objective of our study was to investigate the possible differences in the chemical composition of extractives from the bark of silver fir (Abies alba) with respect to the location of the bark sample on the tree, viz. differences in extract composition between stem bark and branch bark samples. Extractives in the bark samples from branches, depending on the distance of the sample from the trunk, were also analysed, and the stem bark samples were analysed with respect to their inner and outer parts. The results of the chemical analysis of extractives were supported by information about their antifungal and antioxidant effects. After felling and sampling silver fir trees, the collected bark samples were ground and freeze-dried. Extraction of bark samples was followed by a system of accelerated extraction using only water as a solvent. The extracts were analysed chemically using gravimetry, spectrophotometry and chromatography. Free-radical-scavenging activity was measured using the DPPH method, and the antifungal effect towards three moulds and three wood-decaying fungi was investigated with antifungal assay using the agar well diffusion method. It was found that the moisture content in bark samples decreased intensively just after the bark samples were peeled off the stem. Detailed chromatographic analysis showed that the bark extracts contained 14 compounds, among which phenolic acids, flavonoids and lignans were found to be the characteristic ones. The content of hydrophilic extractives in the branch bark samples decreased with increasing distance of the sample location from the tree stem. The largest amounts of phenolic extractives were measured in stem bark, followed by branch bark sampled at the point at which the branch entered the tree. Analysis of the separated parts of the bark showed that the outer layers of stem bark contained larger amounts of phenolic extractives, as well catechin and epicatechin, compared to the inner layers. Concentrated extracts of branch bark showed the largest free-radical-scavenging activity among the investigated samples, while strong antifungal effects of the bark extract were not found.

Phytochemical Study, FTIR and GC-MS Characterization and Evaluation of the Antioxidant Activity of Letestua durissima Extracts

“…Extract contents are highest for the bark followed by the sapwood and then by the heartwood. Higher levels of extractives detected in the bark are in good agreement with data from the literature [25][26][27][28]. Higher levels of extractives in sapwood compared to heartwood is less common, as heartwood generally contains more extractives than sapwood due to the duramen formation process.…”

“…The concentration of flavonoids in the extracts of Letestua durissima depends on the polarity of the solvents used for extraction and on the part of the tree studied. Flavonoid contents in acetone extracts and toluene/ethanol mixture of sapwood of Letestua durissima are similar to those found for the sapwood of Coula edulis wood [27].…”

Identification of Lydicamycins as Main Antioomycete Compounds from the Biocontrol Agent Streptomyces sp. NEAU-S7GS2

“…The combined sample was concentrated under reduced pressure to remove the organic solvent and then redissolved with methanol to a concentration of 240 mg/mL. The antioomycete activity of the crude extract against Phytophthora and Pythium was evaluated by the agar well diffusion method, in which 20 and 40 μL of the extract solution were added into the wells located on the two sides of the solid plates. The addition of an equal volume of methanol was used as control.…”

Bark extractives as sources of carbon-efficient functional precursors and materials

“…37 Many hydrophilic extractives show antioxidant, anti-inflammatory, and antimicrobial properties. [38][39][40] In addition, hydrophilic extractives have been employed as an alternative to fossil-based plastics in particles and bio-based films. 41,42 From the technical perspective, extractives are compounds that are separated from a solid (bio)resource, such as bark, by means of solvent extraction.…”