1236228-58-2

Upstream product

• 1171821-21-8 LDN-0096693 
• 17365-11-6 (1R,2R,3R,5S)-5-carboxy-2,3,5-trihydroxycyclohexyl 3,4,5-trihydroxybenzoate 
• 970-73-0 epigallocatechin 
• 490-46-0 (2R,3R)-2-(3,4-dihydroxyphenyl)-3,4-dihydro-1[2H]-benzopyran-3,5,7-triol 
• 208515-36-0 LDN-0096568 
• 2596-50-1 (-)-epigallocathechin gallate 

Relevant academic research and scientific papers

Reaction of the black tea pigment theaflavin during enzymatic oxidation of tea catechins

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. CXIV. Structures of novel fermentation products, theogalinin, theaflavonin and desgalloyl theaflavonin from black tea, and changes of tea leaf polyphenols during fermentation

Continuing chemical examination of black tea has led to the isolation of three novel fermentation products, theogallinin (1), theaflavonin (10) and desgalloyl theaflavonin (11). The structure of 1 was established on the basis of physico-chemical evidence to be a condensation product linked through pyrogallol-pyrogallol rings in theogallin (2) and (-)-epigallocatechin 3-O-gallate (3), while 10 and 11 were characterized as B,B'-linked bisflavonoids formed by an oxidative coupling of isomyricitrin (12) and tea catechins [3 and (-)-epigallocatechin (4)]. Furthermore, high performance liquid chromatography analyses of the changes of tea polyphenols during fermentation have revealed that original tea catechins are more rapidly transformed by endogenous phenol oxidase to theasinensins (e.g. 6, 8) and oolongtheanin (13) than the formerly known black tea pigments, theaflavins.

Tannins and Related Compounds. LXIX. Isolation and Structure Elucidation of B,B'-Linked Bisflavanoids, Theasinensins D-G and Oolongtheanin from Oolong Tea. (2)

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.

Tannins and Related Compounds. XV. A New Class of Dimeric Flavan-3-ol Gallates, Theasinensins A and B, and Proanthocyanidin Gallates from Green Tea Leaf. (1)

Along with four dimeric proanthocyanidin gallates, viz. prodelphinidin B-2 3'-O-gallate (IV) and procyanidins B-2 3,3'-di-O-gallate (V), B-2 3'-O-gallate (VI) and B-4 3'-O-gallate (VII), two novel dimeric flavan-3-ol gallates (VIII and IX) named theasinensins A and B, in which two flavan units are linked at the B-ring, have been isolated from fresh green tea leaves, and their structures have been established on the basis of spectroscopic evidence in conjunction with enzymatic hydrolyses with tannase.Three new monomeric acylated flavan-3-ols have also been isolated, and their structures were similarly characterized as (-)-epigallocatechin 3-O-p-coumaroate (I), (-)-epigallocatechin 3,3'-di-O-gallate (II) and (-)-epigallocatechin 3,4'-di-O-gallate (III).In addition, the occurrence of the know (-)-epicatechin 3-O-gallate (X), (-)-epigallocatechin 3-O-gallate (XI), (+)-catechin (XII), (-)-epicatechin (XIII), (-)-epigallocatechin (XIV) and (-)-epicatechin 3-O-(3-O-methyl)-gallate (XV) in green tea leaves was confirmed.Keywords - green tea leaf; Thea sinensis; Theaceae; tannin; theasinensin; proanthocyanidin gallate; flavan-3-ol p-coumaroate; flavan-3-ol gallate