TY - JOUR
T1 - Antioxidant activity of fractions from Quercus sideroxyla bark and identification of proanthocyanidins by HPLC-DAD and HPLC-MS
AU - Rosales-Castro, Martha
AU - González-Laredo, Rubén Francisco
AU - Rocha-Guzmán, Nuria Elizabeth
AU - Gallegos-Infante, José Alberto
AU - María José Rivas-Arreola, María José
AU - Karchesy, Joseph J.
N1 - Funding Information:
Author MRC appreciates doctoral scholarship from CONACYT-M é xico. This study was financially supported by Fondo Sectorial CONAFOR-CONACYT, M é xico (2006-41839).
PY - 2012/7
Y1 - 2012/7
N2 - 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- tetramethylchroman- 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.
AB - 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- tetramethylchroman- 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.
KW - Antiradical activity
KW - Bark
KW - HPLC
KW - Proanthocyanidins
KW - Quercus sideroxyla
UR - http://www.scopus.com/inward/record.url?scp=84869400610&partnerID=8YFLogxK
U2 - 10.1515/hf-2011-0157
DO - 10.1515/hf-2011-0157
M3 - Artículo
SN - 0018-3830
VL - 66
SP - 577
EP - 584
JO - Holzforschung
JF - Holzforschung
IS - 5
ER -