Ellagic Acid scientific update |
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J Agric Food Chem. 2006 Oct 4;54(20):7686-91.
Meyers KJ, Swiecki TJ, Mitchell AE.
Department of Food Science and Technology, University of California Davis, Davis, California 95616, and Phytosphere Research, 1027 Davis Street, Vacaville, California 95687.
Understanding the Native Californian Diet: Identification of Condensed and Hydrolyzable Tannins in Tanoak Acorns (Lithocarpus densiflorus).
The tanoak (Lithocarpus densiflorus) acorn was a staple food in the Native American diet and is still used in traditional dishes. Acorns from the genus Quercus have been shown to contain a large range of hydrolyzable tannins. However, neither hydrolyzable nor condensed tannins have been characterized in tanoak acorns. The aim of this study was to identify the full range of hydrolyzable and condensed tannins in extracts of tanoak acorns using liquid chromatography/electrospray ionization-mass spectrometry/mass spectrometry. Condensed tannins were identified as B type oligomers of (epi)-catechin (procyanidins) with a degree of polymerization up to six. Oligomers up to and including tetramers were identified by UV spectra and MS detection whereas pentamers and hexamers were detected only by MS. The total concentration of condensed tannins was 464 mg/100 g acorn pericarp. The concentration of propocyanidin monomers, dimers, trimers, and tetramers in acorn pericarp (mg/100 g acorn pericarp) were 95 +/- 10.9, 148 +/- 35.0, 90 +/- 17.9, and 131 +/- 1.9, respectively. No procyanidins were found in the acorn cotyledon tissue. A total of 22 hydrolyzable tannins were identified in methanolic extracts of acorn cotyledon tissue. Gallic acid derivatives predominated and included galloylated esters of glucose, hexahydrodiphenoyl esters of glucose, and methylated gallates. Galloylated esters of glucose were present as isomers of galloyl glucose, digalloyl glucose, and trigalloyl glucose. Mass spectral fragmentation patterns indicate the presence of one gallic acid-galloyl glucose isomer and two gallic acid-digalloyl-glucose isomers. No isomers of tetragalloyl glucose and pentagalloyl glucose were identified. Ellagic acid and ellagic acid pentoside were also identified.
Biochem Pharmacol. 2003 Sep 15;66(6):907-915.
Whitley AC, Stoner GD, Darby MV, Walle T.
Department of Cellular and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Avenue, PO Box 250505, 29425, Charleston, SC, USA
Intestinal epithelial cell accumulation of the cancer preventive polyphenol ellagic acid-extensive binding to protein and DNA
Ellagic acid (EA), a polyphenol present in many berries, has been demonstrated to be preventive of esophageal cancer in animals both at the initiation and promotion stages. To be able to extrapolate these findings to humans we have studied the transcellular absorption and epithelial cell accumulation of [14C]EA in the human intestinal Caco-2 cells. The apical (mucosal) to basolateral
(serosal) transcellular transport of 10microM [14C]EA was minimal with a P(app) of only 0.13x10(-6)cm/s, which is less than for the paracellular transport marker mannitol. In spite of observations of basolateral to apical efflux, Caco-2 cell uptake studies showed high accumulation of EA in the cells (1054+/-136pmol/mg protein), indicating facile absorptive transport across the apical membrane. Surprisingly, as much as 93% of the cellular EA was irreversibly bound to macromolecules (982+/-151pmol/mg protein). To confirm the irreversible nature of the binding to protein, Caco-2 cells treated with 10microM [14C]EA were subjected to SDS-PAGE analysis. This resulted in radiolabeled protein bands trapped in the stacking gel, consistent with [14C]EA-crosslinked proteins. Treatment of Caco-2 cells with 10microM [14C]EA also revealed irreversible binding of EA to cellular DNA as much as five times higher than for protein (5020+/-773pmol/mg DNA). Whereas the irreversible binding to protein required oxidation of EA by reactive oxygen species, this did not seem to be the case with the DNA binding. The avid irreversible binding to cellular DNA and protein may be the reason for its highly limited transcellular absorption. Thus, EA appears to accumulate selectively in the epithelial cells of the aerodigestive tract, where its cancer preventive actions may be displayed.
PJ Nutr. 2003 Aug;133(8):2669-74.
Mertens-Talcott SU, Talcott ST, Percival SS.
Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, USA.
Low concentrations of quercetin and ellagic acid synergistically influence proliferation, cytotoxicity and apoptosis in MOLT-4 human leukemia cells
Little information is available regarding possible synergistic or antagonistic biochemical interactions among polyphenols contained in fruits and vegetables. Identifying potential interactions among these compounds may help to define the efficiency of polyphenol-containing foods in cancer prevention as related to structure-function activity of the compounds. The objective of this study was to
investigate interactions between quercetin and ellagic acid, two polyphenolics that are present predominantly in small fruits, on cell death and proliferation-related variables in the MOLT-4 human leukemia cell line. Assays were performed to determine cell cycle kinetics, proliferation, apoptotic DNA-fragmentation and caspase-3-activity after 12, 24 and 48 h. Ellagic acid significantly potentiated the effects of quercetin (at 5 and 10 micro mol/L each) in the reduction of proliferation and viability and the induction of apoptosis. Significant alterations in cell cycle kinetics were also observed. The synergy was confirmed by an isobolographic analysis of the cell
proliferation data. The interaction of ellagic acid and quercetin demonstrated an enhanced anticarcinogenic potential of polyphenol combinations, which was not based solely on the additive effect of individual compounds, but rather on synergistic biochemical interactions.
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 Ellagic Acid scientific update
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