Intestinal epithelial cell accumulation of the cancer preventive polyphenol ellagic acid - Extensive binding to protein and DNA

Department of Cellular and Molecular Pharmacology and Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Avenue, PO Box 250505, Charleston, SC 29425, USA.
Biochemical Pharmacology (Impact Factor: 5.01). 10/2003; 66(6):907-15. DOI: 10.1016/S0006-2952(03)00413-1
Source: PubMed


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 10 microM [14C]EA was minimal with a P(app) of only 0.13 x 10(-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+/-136 pmol/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+/-151 pmol/mg protein). To confirm the irreversible nature of the binding to protein, Caco-2 cells treated with 10 microM [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 10 microM [14C]EA also revealed irreversible binding of EA to cellular DNA as much as five times higher than for protein (5020+/-773 pmol/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.

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    • "Although remarkable binding of EA to intestinal epithelium has been previously described in rats (Whitley, Stoner, Darby, & Walle, 2003), in a previous clinical trial we did not detect high amounts of EA in the colonic mucosa of colorectal cancer patients who consumed the same pomegranate extracts (Núñez-Sánchez et al., 2014). In the present pharmacokinetic study, the delayed EA absorption did not depend on specific volunteers and was indistinctly observed after the intake of either PE-1 or PE-2, which indicated that other factors could be involved, such as the diet, bowel transit time, interaction with the microbiota, etc. "
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    ABSTRACT: Ellagic acid (EA) is a polyphenol that must be released from the non-bioavailable ellagitannins in pomegranates, walnuts or strawberries to be absorbed. To estimate whether EA bioavailability could be improved after consumption of a high free EA amount, we conducted a crossover pharmacokinetic study in healthy volunteers that consumed two pomegranate extracts providing either 130 mg punicalagin+524 mg EA (PE-1) or 279 mg punicalagin+25 mg EA (PE-2). Targeted metabolomics (UPLC-ESI-qTOF-MS/MS) identified plasma free EA but not phase-II conjugates. EA pharmacokinetics showed high interindividual variability. Cmax ranged from 12 to 360 nM (PE-1: 74.8 ± 54.4 nM; PE-2: 64.1 ± 76.8 nM). In vitro digestion supported in vivo results. EA bioavailability was limited by the ellagitannin, pH and protein environment. A higher free EA intake does not enhance its bioavailability but promotes urolithin production. Bioavailability of EA, as the unchanged fraction that reaches the systemic circulation, is not as low as previously thought.
    Full-text · Article · Dec 2015
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    • "Pomegranate ellagitannin are also being investigated for their potential use as food bio-preservatives and for the formulation of products in the nutraceutical industry [2]. Pomegranate peel attracts attention due to its apparent wound healing properties [4], immune modulatory activity [5], antibacterial activity [6] and antiatherosclerotic and antioxidative capacities [8]. Antioxidative activity has often been associated with a decreased risk of various diseases [12]. "
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    ABSTRACT: Pomegranate (Punicagranatum L. ) fruit is widely being consumed and its fruit’s peel having hydrolysable ellagitannin (ETs: polyphenolic compound) is an underutilized industrial waste from commercial point of view. In this present study an economical and efficient technique has been explored for the production of purified ellagitannin powder from pomegranate peel. Ellagitannin was isolated from fresh and fermented peel, purified with Amberlite XAD- 16 resin packed column and converted into ellagitannin powder by vacuum drying. About 38 gpurified ellagitannin powder was obtained from 1 kg fresh pomegranate peel. Total ellagitannin content(TEC) was 89. 78-91. 78 % as GAE possessing antioxidant activity (AOA) of 91. 16-96. 21 % as DPPH. Cost estimation of purified ellagitannin powder preparation process was Rs. 5510 from 1 kg fresh pomegranate peel. Worth of purified ellagitannin powder (38 g) estimated Rs. 25441 in international market. Studied method can be adopted for commercial production of purified ellagitannin powder.
    Full-text · Article · Mar 2015
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    • "Polyphenols are plant metabolism products and they have antioxidant functions [32] [43]. Ellagic acid (EA) (2,3,7,8-tetrahydroxybenzopyrano[5,4,3-cde]benzopyran-5-10-dione) is a polyphenol present in many plant species such as pomegranate plants, grapes, raspberries, blackberries, strawberries and walnuts [14] [75]. Several line of studies have shown that EA has different pharmacological effects such as anti-bacterial, anti-inflammatory, immune regulatory and inhibition of tumorigenesis and also it is considered as a potent antioxidant [6] [12] [18]. "
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    ABSTRACT: Traumatic brain injury (TBI) remains one of the main clinical problems globally and is a common cause of death among youth. Cognitive defects such as thinking, memory and behavior or mental health disorders are considered as the most frequent effects of severe and moderate TBI. It has been reported that ellagic acid (EA), a natural polyphenol, exhibits protective effects against oxidative damage. This study was performed to examine the EA preventive effects on cognitive impairments, long-term potentiation (LTP) deficits in hippocampus and brain inflammation induced by diffuse TBI in rat. Subchronic oral administration of 100 mg/kg EA, 7 consecutive days before induction of trauma (once daily) was used to elucidate the EA effects on passive avoidance memory and hippocampal LTP following TBI. To illustrate the possible mechanisms related to the preventive effects of EA on brain function following TBI, brain content of IL-1β, IL-6 and blood-brain barrier (BBB) permeability were determined. EA pretreatment significantly (p<0.001) prevented TBI-induced memory and hippocampal LTP impairments in rat. Furthermore TBI induced elevation in brain content of IL-1β, IL-6 and BBB permeability were decreased significantly (p<0.001) due to EA pre-treatment. Our findings suggest that EA can prevent cognitive and LTP deficits and also prevent brain inflammation following TBI. Copyright © 2015. Published by Elsevier Inc.
    Full-text · Article · Jan 2015 · Life Sciences
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