Antioxidant activity of fractions from Quercus sideroxyla bark and identification of proanthocyanidins by HPLC-DAD and HPLC-MS
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Martha Rosales-Castro
,
Nuria Elizabeth Rocha-Guzmán
Abstract
The most active phenolics in Quercus sideroxyla Humb. & Bonpl. residual bark were identified and evaluated following a chromatographic fractionation. Bark powder was defatted with hexane and crude extract (CE) was obtained by extraction with aqueous acetone (70%). A liquid partition with ethyl acetate was performed to produce an organic extract (OE), which was subsequently purified by column chromatography (Toyopearl HW-40F, methanol), and resulted in six methanolic fractions (MF1 to MF6) and an oligomeric fraction (OLF) eluted with acetone 67%. Extraction yields, total phenolic and flavanol contents were determined. The antioxidant activity of bark extracts was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), Trolox (6-hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylic-acid)-equivalent antioxidant capacity (TEAC), and ferric ion reducing antioxidant power (FRAP) assays. Their median effective concentration (EC50) data and rate constants for DPPH radical scavenging were also estimated. Identification of major phenolics was carried out by high performance liquid chromatography with diode array detection (HPLC-DAD) and high performance liquid chromatography with electrospray ionization coupled to mass spectrometry (HPLC-ESI-MS) instruments. Bioactive gallic acid, catechin, epicatechin, gallocatechin, catechin gallate, dimeric procyanidins, galloylated dimeric proanthocyanidins, trimeric procyanidins, and tetrameric proanthocyanidins were detected and identified in Q. sideroxyla bark extracts. MF2 was the most active fraction containing gallocatechin as its major compound; MF5 and OLF contain galloylated procyanidins, which may explain their higher antiradical activity. OLF besides galloylated procyanidins has gallocatechin, which presumably contributes to its higher antiradical activity. Consequently, Q. sideroxyla bark could be a good source of therapeutic health products or nutraceutical ingredients that may exert a potential prevention or treatment action against diseases in biological systems.
©2012 by Walter de Gruyter Berlin Boston
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- Meetings
- Meetings
- Masthead
- Masthead
Artikel in diesem Heft
- Original Papers
- Identification of new lignans in Norway spruce knotwood extracts
- Isolation and characterization of β-cadinene synthase cDNA from Chamaecyparis formosensis Matsum
- Antioxidant activity of fractions from Quercus sideroxyla bark and identification of proanthocyanidins by HPLC-DAD and HPLC-MS
- New diarylpropanoids from Lindera glauca Bl. heartwood
- Extracting value-added products before pulping: Hemicellulosic ethanol from Eucalyptus globulus wood
- Effect of various pulp properties on the solubility of cellulose in sodium hydroxide solutions
- Dissolution and acetylation of ball-milled birch (Betula platyphylla) and bamboo (Phyllostachys nigra) in the ionic liquid [Bmim]Cl for HSQC NMR analysis
- Study of thin films of kraft lignin and two DHPs by means of single-molecule force spectroscopy (SMFS)
- Characterization of mixed-mode I/II fracture properties of adhesively bonded yellow-poplar by a dual actuator test frame instrument
- Grading of structural timber of Populus × euramericana clone I-214
- Measurement of wood shrinkage in jack pine using three dimensional digital image correlation (DIC)
- Internal stress measurement during drying of rubberwood lumber: effects of wet-bulb temperature in various drying strategies
- Tensile behaviour of radiata pine with different moisture contents at elevated temperatures
- Within-process and seasonal changes during industrial production of high-density fibreboard. Part 1: Influence of wood species composition on polyoses in the products
- Within-process and seasonal changes during industrial production of high-density fibreboard. Part 2: PLS modelling of chemical alterations, refining conditions and panel thickness swell
- Short Note
- Effect of grain angle on shear strength of Douglas-fir wood
- Meetings
- Meetings
- Masthead
- Masthead
