Enzymatic Preparation of Methylated Theaflavins and their Antioxidant Activities

Abstract

We investigated the antioxidant activities of two methylated theaflavins, theaflavin 3-O-(3-O-methyl) gallate (TF3MeG) and theaflavin 3-O-(3-O-methyl)gallate 3 -O-gallate (TF3MeG3 G), which were prepared from epigallocatechin-3-O-(3-O-methyl) gallate(EGCG3 Me) in the presence of burdock root-polyphenol oxidase (PPO). Formation of the methylated theaflavins was maximum at 30∼60 min of enzymatic reaction time, and decreased thereafter. The results suggest that the formation rate of methylated theaflavins in tea leaves can be increased by adjusting the PPO reaction during the fermentation process. The radical scavenging activities of TF3MeG and TF3MeG3 G were lower than those of the corresponding non-methylated theaflavins for peroxyl or DPPH radicals. However, the activity of TF3MeG3 G was much higher than that of the starting material (EGCG3 Me). The lipid solubility, estimated by 1-octanol /water partition coefficient, was in the order of TF3MeG3 G>TF33 diG≥TF3 G≥TF3MeG >TF3G≥TF. The lipid solubility of TF3MeG3 G was much higher than those of the other theaflavins and catechins.

Modulatory Effect of Theaflavins on Apical Sodium-Dependent Bile Acid Transporter (ASBT) Activity

“…Further, it may be possible to directly demonstrate the importance of the benzotropolone ring of TF2A and TF2B in ASBT inhibition by utilizing the CH 3 -TFs. Ishiyama et al have reported the synthesis of CH 3 -TF2A by adding burdock root-polyphenol oxidase to the mixture of CH 3 -EGCg and epicatechin . Since TF2B is a polymerized compound of epigallocatechin gallate and epigallocatechin, it may be synthesized from CH 3 -epigallocatechin gallate and epigallocatechin in the same way as described by Ishiyama et al…”

Metabolic stability and inhibitory effect of O-methylated theaflavins on H2O2-induced oxidative damage in human HepG2 cells

“…1 H NMR (600 MHz), 13 C NMR (150 MHz), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple bond correlation (HMBC) spectra were recorded at ambient temperature, and the chemical shifts are given in δ (ppm) relative to the solvent signal (acetone-d 6 Preparation of theaflavins. TF3′G and TF3,3′G (1 and 2) were prepared from black tea leaves by modifying a previous method.…”

“…It has been suggested that the number of hydroxyl groups is important in DPPH radical scavenging activity by comparison with EGCG, ECG, and EGCG3′′ Me, 14) or TFs and O-methylated TFs. 6) In the case of DPPH radical scavenging assay, direct reaction of the DPPH radical and antioxidants was observed. However, in the case of inhibitory effect on oxidative damage in cells, the involvement of several factors, such as metabolic stability and absorption of the antioxidants, was also considered.…”

“…5) Ishiyama et al have reported that the O-methylation of TFs decreases peroxyl and DPPH radical scavenging activity. 6) It is suggested that the number of hydroxyl groups is directly involved with the radical scavenging activity. However, when an inhibitory effect on oxidative damage in cells is considered, O-methylation of TFs is expected to be effective because it has been reported that O-methylated polyphenols have high metabolic stability in pooled human liver S9 fractions and absorbability in Caco-2 cells.…”