title: (-)-Epicatechin enhances the chlorinating activity of human myeloperoxidase.
abstract: The heme-containing enzyme myeloperoxidase (MPO) accumulates at inflammatory sites and is able to catalyse one- and two-electron oxidation reactions. Here it is shown that (-)-epicatechin, which is known to have numerous beneficial health effects, in low micromolar concentration enhances the degradation of monochlorodimedon (MCD) or the chlorination of taurine in a concentration-dependent bell-shaped manner whereas at higher concentrations it sufficiently suppresses the release of hypochlorous acid. Presented reaction mechanisms demonstrate the efficiency of micromolar concentrations of the flavan-3-ol in overcoming the accumulation of compound II that does not participate in the chlorination cycle. In case of MCD the mechanism is more complicated since it also acts as peroxidase substrate with very different reactivity towards compound I (3 x 10(5) M(-1) s(-1)) and compound II (8.8M(-1)s(-1)) at pH 7. By affecting the chlorinating activity of myeloperoxidase (-)-epicatechin may participate in regulation of immune responses at inflammatory sites.
authors.affiliation: Institute for Medical Physics and Biophysics, Medical Faculty, University of Leipzig, Leipzig, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Kirchner
authors.forename: Jörg
authors.initials: J
authors.lastname: Flemmig
authors.forename: Paul Georg
authors.initials: PG
authors.lastname: Furtmüller
authors.forename: Christian
authors.initials: C
authors.lastname: Obinger
authors.forename: Jürgen
authors.initials: J
authors.lastname: Arnhold
mesh_terms: D002392:Catechin / Q000494:pharmacology*; D003512:Cyclohexanones / Q000378:metabolism*; D054879:Halogenation / Q000187:drug effects; D006801:Humans; D009195:Peroxidase / Q000378:metabolism*; D013654:Taurine / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D003512:Cyclohexanones; D013654:Taurine; C043410:N-chlorotaurine; C006991:chlorodimedone; D002392:Catechin; D009195:Peroxidase