Polyphenols of Cocoa: Inhibition of Mammalian 15-Lipoxygenase
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Tankred Schewe
Abstract
Some cocoas and chocolates are rich in ()epicatechin and its related oligomers, the procyanidins. Fractions of these compounds, isolated from the seeds of Theobroma cacao, caused dosedependent inhibition of isolated rabbit 15-lipoxygenase-1 with the larger oligomers being more active; the decamer fraction revealed an IC 50 of 0.8 M. Among the monomeric flavanols, epigallocatechin gallate (IC 50 = 4 M) and epicatechin gallate (5 M) were more potent than ()epicatechin (IC50 = 60 M). ()Epicatechin and procyanidin nonamer also inhibited the formation of 15-hydroxyeicosatetraenoic acid from arachidonic acid in rabbit smooth muscle cells transfected with human 15-lipoxygenase-1. In contrast, inhibition of the lipoxygenase pathway in J774A.1 cells transfected with porcine leukocytetype 12- lipoxygenase (another representative of the 12/15- lipoxygenase family) was only observed upon sonication of the cells, suggesting a membrane barrier for flavanols in these cells. Moreover, epicatechin (IC50 approx. 15 M) and the procyanidin decamer inhibited recombinant human platelet 12-lipoxygenase. These observations suggest general lipoxygenase inhibitory potency of flavanols and procyanidins that may contribute to their putative beneficial effects on the cardiovascular system in man. Thus, they may provide a plausible explanation for recent literature reports indicating that procyanidins decrease the leukotriene/prostacyclin ratio in humans and human aortic endothelial cells.
Copyright © 2001 by Walter de Gruyter GmbH & Co. KG
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- Erratum
- Acknowledgement
- Content Index
- Author Index
- Subject Index
Articles in the same Issue
- New Control of Mitochondrial Membrane Potential and ROS Formation A Hypothesis
- Brix from Xenopus laevis and Brx1p From Yeast Define a New Family of Proteins Involved in the Biogenesis of Large Ribosomal Subunits
- Mig-6 Is a Negative Regulator of the Epidermal Growth Factor Receptor Signal
- β-Carotene Inhibits Growth of Human Colon Carcinoma Cells in Vitro by Induction of Apoptosis
- Ligand-Mediated Protection against Phage Lysis as a Positive Selection Strategy for the Enrichment of Epitopes Displayed on the Surface of E. coli Cells
- Structural and Redox Properties of the Leaderless DsbE (CcmG) Protein: Both Active-Site Cysteines of the Reduced Form Are Involved in Its Function in the Escherichia coli Periplasm
- Polyphenols of Cocoa: Inhibition of Mammalian 15-Lipoxygenase
- Total Antioxidant Capacity and Nuclear DNA Damage in Keratinocytes after Exposure to H2 O2
- Recombinant Cryptic Human Fibronectinase Cleaves Actin and Myosin: Substrate Specificity and Possible Role in Muscular Dystrophy
- Rat Tripeptidyl Peptidase I: Molecular Cloning, Functional Expression, Tissue Localization and Enzymatic Characterization
- Determination of NADH in Frozen Rat Brain Sections by Laser-Induced Fluorescence
- Human -Calpain: Simple Isolation from Erythrocytes and Characterization of Autolysis Fragments
- Erratum
- Acknowledgement
- Content Index
- Author Index
- Subject Index
