title: Inhibitory effect of polyphenol-enriched apple extracts on mast cell degranulation in vitro targeting the binding between IgE and FcepsilonRI.
abstract: Extracts from immature fruit of the apple (Rosaceae, Malus sp.), which contain procyanidins (polymers of catechins) as the major ingredients, are known to inhibit histamine release from mast cells. We analyzed in this study the mechanism for the anti-allergic activity of two polyphenol-enriched apple extracts. These extracts, termed "crude apple polyphenol (CAP)" and "apple condensed tannin (ACT)", reduced the degranulation of mast cells caused by cross-linking of the high-affinity receptor for IgE (FcepsilonRI) with IgE and the antigen in a dose-dependent manner. Furthermore, western blotting revealed that phosphorylation of the intracellular signal-transduction molecules caused by cross-linking of FcepsilonRI was markedly decreased by the addition of CAP or ACT. We then analyzed the effects of CAP and ACT on the binding of the IgE antibody to FcepsilonRI on mast cells, which is the first key step in the allergic reaction mediated by mast cells, and found that this binding was markedly inhibited by both CAP and ACT. These results indicate that the inhibition of binding between FcepsilonRI and IgE by either CAP or ACT was the probable cause of the suppression of mast cell activation. This is the first report demonstrating the molecular mechanism for the anti-allergic effect of procyanidin-enriched extracts from apples.
authors.affiliation: Atopy (Allergy) Research Center, Juntendo University School of Medicine, Hongo, Tokyo, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tokura
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nakano
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Ito
authors.forename: Hironori
authors.initials: H
authors.lastname: Matsuda
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nagasako-Akazome
authors.forename: Tomomasa
authors.initials: T
authors.lastname: Kanda
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Ikeda
authors.forename: Ko
authors.initials: K
authors.lastname: Okumura
authors.forename: Hideoki
authors.initials: H
authors.lastname: Ogawa
authors.forename: Chiharu
authors.initials: C
authors.lastname: Nishiyama
mesh_terms: D018926:Anti-Allergic Agents / Q000494:pharmacology; D044946:Biflavonoids / Q000494:pharmacology; D002392:Catechin / Q000494:pharmacology; D015550:Cell Degranulation / Q000187:drug effects*; D003432:Cross-Linking Reagents; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000494:pharmacology*; D007073:Immunoglobulin E / Q000378:metabolism*; D027845:Malus / Q000737:chemistry*; D008407:Mast Cells / Q000502:physiology*; D010636:Phenols / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology; D059808:Polyphenols; D044945:Proanthocyanidins / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D017455:Receptors, IgE / Q000378:metabolism*
chemical_list: D018926:Anti-Allergic Agents; D044946:Biflavonoids; D003432:Cross-Linking Reagents; D005419:Flavonoids; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; D044945:Proanthocyanidins; D017455:Receptors, IgE; D007073:Immunoglobulin E; C017674:procyanidin; D002392:Catechin