Characterization of the Oxidation Products of (-)-Epigallocatechin Gallate, a Bioactive Tea Polyphenol, on Incubation in Neutral Solution

Stability and Oxidation Products of Hydrolysable Tannins in Basic Conditions Detected by HPLC/DAD–ESI/QTOF/MS

“…The relatively stable oxidation products of polyphenols can be isolated for structure determination (e.g. Tanaka et al ., ; Hatano et al ., ). Also, some in vitro methods have been developed to measure the pro‐oxidant capacity of tannins and to detect short‐lived oxidation products such as radicals that cannot be isolated as pure compounds.…”

Water-Soluble Complexes Formed by Natural Polyphenols and Bovine Serum Albumin: Evidence from Gel Electrophoresis

“…Lane 1, reaction mixture after incubating ethacrynic acid and BSA for 24 h; lane 2, BSA. molecular weights such as theasinensin A; 11,13) thus, the slow formation of the macromolecular complex may be correlated with the oxidation of EGCG. To confirm the participation of such oxidation products in the formation of the macromolecular complexes, the reaction mixture formed after incubating a mixture of BSA and an oxidation product (theasinensin A) was analyzed by gel electrophoresis.…”

Effect of Cyclodextrins on the Thermal Epimerization of Tea Catechins

“…Both epi type catechins and non-epi type catechins are also labile to dimerization (Roginsky et al, 2005), hydrolysis (Ito et al, 2003), oxidation and polymerization (Hatano et al, 2004). The present results show that addition of β-CD to the reaction solution of (-)-EGCg suppresses the thermal degradation and leads to an increase of the ratio of (-)-GCg, a non-epi type catechin.…”

“…It has been pointed out that thermal degradation other than epimerization might occur during the thermal processing of tea catechins. These degradation reactions include dimerization (Roginsky et al, 2005), hydrolysis (Ito et al, 2003), or oxidative and polymerization reactions (Hatano et al, 2004). Here, we designate the unidentified degradation products other than the epimerization product as "other products".…”