Metabolic stability and inhibitory effect of O-methylated theaflavins on H2O2-induced oxidative damage in human HepG2 cells |
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| Authors: | Yoshihisa Tanaka Masanobu Kirita Yuko Abe Satoshi Miyata Motoyuki Tagashira Tomomasa Kanda |
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| Institution: | 1. Research Laboratories for Fundamental Technology of Food, Asahi Group Holdings, Limited, Moriya-shi, Japanyoshihisa.tanaka@asahigroup-holdings.com;3. Research Laboratories for Fundamental Technology of Food, Asahi Group Holdings, Limited, Moriya-shi, Japan |
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| 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 H2O2-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 H2O2-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 H2O2-induced oxidative damage was potentiated by O-methylation or O-galloylation of TFs. |
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| Keywords: | black tea polyphenol O-methylated theaflavin oxidative damage metabolic stability |
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