COMPARISON OF DIFFERENT EXTRACTION METHODS FOR THE EXTRACTION OF TOTAL PHENOLIC COMPOUNDS FROM SPRUCE BARK (original) (raw)
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Revista De Chimie, 2020
This work assessed the qualitative and quantitative polyphenols profile in a crude ethanol extract separated from spruce bark (two fractions with <0.25 and 1 mm diameter) using ultrasound assisted extraction (UAE) as a green extraction method. The evaluation of phenolic acids and condensed tannins profile was performed using instrumental (UV-VIS spectrometry), qualitative (Thin Layer Chromatography, TLC) and quantitative (HPTLC densitometry) methods. Using ultrasound assisted extraction (UAE) technique under specific parameters, the higher total phenolic content (TPC) was 29.785 mg GAE/g-1 for spruce bark fraction with particle size <0.25 mm and 14.448 mg GAE/g-1 for fraction with 1 mm diameters. The TLC assay of the crude ethanol extract was performed considering the standards: gallic, sinapic, p-coumaric and vanillic acids, catechin, epicatechin and tannic acid. Smaller material particle sizes lead to higher yield of polyphenols in ethanol extract. The quantitative evaluation by HPTLC densitometry revealed following amounts: sinapic acid 0.84 mg/g, p-coumaric acid 0.61 mg/g, catechin 1.03 mg/g, tannic acid 2.81 mg/g. Considering the chemical composition, the spread and availability, spruce bark could be considered as a resource with environmental and economic benefits.
Extraction and chemical characterization of Norway spruce inner and outer bark
Nordic Pulp & Paper Research Journal, 2012
Possible chemical utilization of bark requires appropriate knowledge of its composition. Extraction of valuable components before burning is an interesting option for utilization of bark. Here, Norway spruce inner and outer bark were extracted separately with a successive series of solvents of increasing polarity and the extracts, as well as the residues, were analyzed to obtain an overall picture of the bark composition. The lipophilic extractives contained the same major components as found in wood. Inner bark contained over 10% of stilbene glucosides with piceatannol (astringenin) as the main stilbene. Tannins of the proanthocyanidin type were extracted with hot water. Further extraction with pressurized hot water at 140°C or 160°C yielded 11-14% of non-cellulosic polysaccharides, on original bark basis, with pectic polysaccharides built up of arabinose, galacturonic acid and rhamnose dominating. Inner bark contained two times more cellulose than outer bark, but the opposite was ...
Crystals, 2020
Extracts from spruce bark obtained using different deep eutectic solvents were screened for their total phenolic content (TPC) and antioxidant activities. Water containing choline chloride-based deep eutectic solvents (DESs) with lactic acid and 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol, with different molar ratios, were used as extractants. Basic characteristics of the DESs (density, viscosity, conductivity, and refractive index) were determined. All the DESs used behave as Newtonian liquids. The extractions were performed for 2 h at 60 • C under continuous stirring. TPC was determined spectrophotometrically, using the Folin-Ciocalteu reagent, and expressed as gallic acid equivalent (GAE). The antioxidant activity was determined spectrophotometrically by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The TPC varied from 233.6 to 596.2 mg GAE/100 g dry bark; radical scavenging activity (RSA) ranged between 81.4% and 95%. This study demonstrated that deep eutectic solvents are suitable solvents for extracting phenolic compounds from spruce bark.
Spruce bark as a source of antioxidant active substances
Bioresources, 2019
The antioxidant potential of extracts from spruce bark was studied after Soxhlet extraction with ethanol and n-hexane. Ethanol spruce bark extracts were pre-extracted with a mixture of ethanol and n-hexane in a ratio of 1:5. Residues of the extracts and pre-extracts were added to lard (200 mg/kg) to examine its influence on oxidation stability of lard. The composition of the bark extractives was analyzed by GC/MS. The highest antioxidant activity was observed in the original ethanol extracts (15.0 mmol/mg), which had greater antioxidant activity than alpha-tocopherol (13.9 mmol/mg). The n-hexane extract from the spruce bark had 70% less antioxidant activity than the ethanol extract. The high antioxidant activity of the ethanol extract was due to the presence of resin acids (35%) and stilbenes (12%). These antioxidant-active substances increased the oxidation stability of the lard by 5 h, while the n-hexane extract increased the oxidation stability by only 0.5 h. The spruce bark was found to be an alternative feedstock of compounds with potential for use in foodstuffs as antioxidant.
Isolation of bioactive compounds from spruce bark waste using sub- and supercritical fluids
The Journal of Supercritical Fluids, 2016
The aim of this study was to investigate the possibility of isolating bioactive phenolics compounds from spruce bark (Picea abies), using sub-and supercritical fluids. In order to improve the yields and to assure a higher recovery of the phenolic compounds, in the first part of this study, extraction of lipophilic compounds was performed using only supercritical (SC) CO 2 as solvent. Amount of obtained lipophilic compounds was quantified. In the second step, to the SCCO 2 a cosolvent was added, namely 70% (v/v) aqueous ethanol, in order to isolate the bioactive phenolic compounds more efficiently. Effect of temperature, pressure and cosolvent flow rate on the yield of phenolic compounds was observed, at 40-60 • C, 100-200 bar and at 1.2 mL/min and 2.5 mL/min, respectively. Obtained extracts were analysed for their total phenolics (TPC), tannins (TTC) and flavonoids (TFC) content, as well as their antioxidant activity using UV-vis spectrophotometric methods. The maximum extraction yield of phenolic compounds (30.46 ± 1.20)% was achieved at 100 bar pressure and 40 • C and the determined total phenolics content was 314.49 mg/g dry extract, the total flavonoids content was 100.67 mg/g dry extract and the total tannins content was 26.38 mg/g dry extract. Additionally, the content of different phenolic compounds, typically found in woody biomass was assessed using high pressure liquid chromatography, ferulic acid and p-coumaric acid being the two major quantifiable phenolic compounds identified. Lastly, the consumption of solvents for production of kg of product with highest possible purity was determined and discussed.
Closed-system microwave-assisted extraction was applied to extract total phenolics from spruce (Picea abies) bark, using 96.6% ethanol as an extractant. The influence of particle size (0.3; 1.0; 2.5 mm), time (3 to 20 min), and temperature (60; 80; 100 °C) on polyphenol recovery was also studied. Higher extraction temperature and smaller particle size resulted in a higher yield of extracted polyphenols. However, the effect of extraction time on yield was more complicated. The effect of all three factors is tentatively explained.
Holzforschung, 2000
A few lignans, that is, 7-hydroxymatairesinol, secoisolariciresinol, lariciresinol, and nortrachelogenin, predominate in a large proportion of the industrially important softwood species used. Some other lignans, of which some still are unidentified, are also present in lower amounts. Softwood knots, i.e., the branch bases inside tree stems, commonly contain exceptionally large amounts of free aglycone lignans, which has provided a great opportunity to isolate sufficient amounts of softwood lignans for structural characterisation. Here we present the identification and characterisation of two new 9-epimers of 7-hydroxy divanillyl butyrolactol lignans, (7S,8R,89R,99R)-4,49,7-trihydroxy-3,39-dimethoxylignano-99,99-lactol and (7S,8R,89R,99S)-4,49,7-trihydroxy-3,39dimethoxylignano-99,99-lactol, in knotwood of Colorado spruce (Picea pungens), from tentative GC-MS analysis to final determination of the structure by NMR spectroscopy and X-ray analysis. Further analyses have verified the occurrence of these lignans, which were earlier incorrectly addressed by our group as isomers of liovil, in several spruce, pine, and fir species.