Isolation and identification of (—)‐gallocatechin gallate and circular dichroism of green tea flavanols

Abstract

Partly racemic (-)-gallocatechin gallate was isolated from green tea hy counter-current distribution and column chromatography on Sephadex LH-20. The structure was proven by tnass spectroscopy of the pertrimethylsilyl ether and by n.m. r. and circular dichroism (c.d.). The compound is probably an artifact produced by heating (-)-epigallocatechin gallate. Circular dichroism curves of several tea flavanols are presented.

Preparation of Epimers of Tea Catechins by Heat Treatment

“…The IH-NMR data of the product were similar to those of ( -)-EGCg, except for differences in the chemical shifts and coupling constants at the 2-, 3-, and 4-protons, and are in good agreement with those of ( -)-GCg reported by Wilkins et al 21) and Collier et al 16) The 13C-NMR chemical shifts of the product were close to those of ( -)-EGCg, but slight differences were observed in the shifts at the C-2, C-3, and C-4 carbons. Although the optical rotation magnitude and melting point of the product ( 86.1 ° and 232-234°C) are higher than those of ( GCg (-29 0 and 210-2I2°C, respectively), the optical Table II.…”

The Inhibition of α-Amylase by Tea Polyphenols

“…were prepared from crude catechins (containing 90% catechins) as described in our previous paper.9) Isomers of the above compounds were made by heating the corresponding catechin solution. 10 ) Crude theafIavins, theafIavin (TFI), theafIavin monogallate A (TF2A), theafIavin monogallate B (TF2B), and theafIavin digallate (TF3) were prepared from black teaY)…”

Troxerutin flavonoid has neuroprotective properties and increases neurite outgrowth and migration of neural stem cells from the subventricular zone

“…Gallocatechin gallate and theaflavin exhibited 100% efficacy in preventing fibrils formation of Aß 42 in an extracellular chemical reaction since these molecules provide a higher number of aromatic rings and hydroxyl groups in their structures as compared to other compounds tested (Phan 2019). A number of these aromatic rings and reactive hydroxyl groups in TRX molecule [ 79 ] is comparable to that of theaflavin [ 80 ], rutin [ 81 ] and more than that of gallocatechin gallate [ 82 ] so it was assumed that the neutralizing activity of TRX against Aß 42 induced inhibition in neuronal differentiation and neurite growth in our experiments might be due to the disaggregating or antifibrillization effects of TRX. Future detailed studies are needed to prove if TRX prevents fibrillization of Aß42 in a reaction mixture.…”