116310-07-7Relevant academic research and scientific papers
Reaction of the black tea pigment theaflavin during enzymatic oxidation of tea catechins
Li, Yan,Shibahara, Akane,Matsuo, Yosuke,Tanaka, Takashi,Kouno, Isao
experimental part, p. 33 - 39 (2010/04/06)
Degradation of the black tea pigment theaflavin was examined in detail. Enzymatic oxidation of a mixture of epigallocatechin and epicatechin initially produced theaflavin, while prolonged reaction decreased the product. Addition of ethanol to the reaction mixture at the point when theaflavin began to decrease afforded four new products, together with theanaphthoquinone, a known oxidation product of theaflavin. The structures of the new products were determined by spectroscopic methods. One of the products was an ethanol adduct of a theanaphthoquinone precursor, and this reacted with theaflavin to give two further products. A product generated by coupling of theaflavin with epicatechin quinone was also obtained. The structures of the products indicate that oxidation and coupling with quinones are key reactions in the degradation of theaflavins. The degradation of theaflavin probably contributes to production of thearubigins.
Tannins and Related Compounds. LXIX. Isolation and Structure Elucidation of B,B'-Linked Bisflavanoids, Theasinensins D-G and Oolongtheanin from Oolong Tea. (2)
Hashimoto, Fumio,Nonaka, Gen-Ichiro,Nishioka, Itsuo
, p. 1676 - 1684 (2007/10/02)
Chemical examination of the aqueous acetone extract of commercial oolong tea has led to the isolation of four new theasinensins D-G, and a new type of dimeric flavan-3-ol named oolongtheanin, together with previously reported theasinensins A, B, and C.On the basis of chemical and spectroscopic evidence, theasinensins D and E were characterized as atropisomers (4 and 5) of theasinensins A (1) and C (3), respectively, while theasinensins F and G were shown to be B,B'-linked bisflavanoids (6 and 7) consisting of (-)-epicatechin 3-O-gallate and (-)-epigallocatechin 3-O-gallate units, in which the biphenyl bonds possess S- and R-chiralities, respectively.Similarly, oolongtheanin was characterized as a novel metabolite (8), probably derived from theasinensins by oxidation of one of the B-rings.Keywords - oolong tea; Camellia sinensis var. viridis; Theaceae; polyphenol; theasinensin; oolongtheanin; oxidative metabolite; bisflavanoid; flavan-3-ol; fermentation.
