title: Metabolic stability and inhibitory effect of O-methylated theaflavins on H2O2-induced oxidative damage in human HepG2 cells.
abstract: Seven new O-methylated theaflavins (TFs) were synthesized by using O-methyltransferase from an edible mushroom. Using TFs and O-methylated TFs, metabolic stability in pooled human liver S9 fractions and inhibitory effect on H(2)O(2)-induced oxidative damage in human HepG2 cells were investigated. In O-methylation of theaflavin 3'-O-gallate (TF3'G), metabolic stability was potentiated by an increase in the number of introduced methyl groups. O-methylation of TF3,3'G did not affect metabolic stability, which was likely because of a remaining 3-O-galloyl group. The inhibitory effect on oxidative damage was assessed by measuring the viability of H(2)O(2)-damaged HepG2 cells treated with TFs and O-methylated TFs. TF3,3'G and O-methylated TFs increased cell viabilities significantly compared with DMSO, which was the compound vehicle (p < 0.05), and improved to approximately 100%. Only TF3'G did not significantly increase cell viability. It was suggested that the inhibitory effect on H(2)O(2)-induced oxidative damage was potentiated by O-methylation or O-galloylation of TFs.
authors.affiliation: a Research Laboratories for Fundamental Technology of Food, Asahi Group Holdings, Limited , Moriya-shi , Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Masanobu
authors.initials: M
authors.lastname: Kirita
authors.forename: Yuko
authors.initials: Y
authors.lastname: Abe
authors.forename: Satoshi
authors.initials: S
authors.lastname: Miyata
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Tagashira
authors.forename: Tomomasa
authors.initials: T
authors.lastname: Kanda
authors.forename: Mari
authors.initials: M
authors.lastname: Maeda-Yamamoto
mesh_terms: D044946:Biflavonoids / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D002392:Catechin / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D004355:Drug Stability; D056945:Hep G2 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008745:Methylation; D018384:Oxidative Stress / Q000187:drug effects*; D010100:Oxygen / Q000737:chemistry*
chemical_list: D044946:Biflavonoids; C056068:theaflavin; D002392:Catechin; D006861:Hydrogen Peroxide; D010100:Oxygen
keywords: O-methylated theaflavin; black tea; metabolic stability; oxidative damage; polyphenol