Plant phenols

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

“…Three polyphenols were isolated crystalline from the column as above: 45 mg gallic acid as brown needles, 280 mg (-)-epicatechin as offwhite needles which began to decompose at 206"c and melted with further decomposition at 208.5-210. 5 Recrystallisation from water produced the three major flavanols with melting points and rotations at the d line in agreement with literature values.…”

“…The U.V. data of the unknown correlate very well with those of Bradfield & Penney and appear to be similar to those of substance H of Vuataz et al 5 The absorption coefficient of the unknown suggests that it is a gallate ester. The mass spectra of the pertrimethylsilyl ethers of the unknown and (-)-epigallocatechin gallate were identical except for small intensity differences.…”

“…Results and DiscussionThe extraction procedure is similar to that of Vuataz et al5 in the production of the crude flavanol extract. The isolation of crude flavanols was similar to the work of Millin et a1.8 in the use of counter-current distribution and column chromatography on Sephadex LH-20.Several properties of the unknown compound derived from the (-)-epicatechin gallate fraction were studied.…”

VOLATILES IN TEA Some Aspects of the Chemistry of Tea. A Contribution to the Knowledge of the Volatile Constituents

“…The involvement of epicatechin gallate in tea fermentation had been proved by Bhatia (3) in 1961, on the basis of his own work and the reports of Swiss and Russian investigators (8,31). This finding shaped the thinking of chemists concerned with the structure of theaflavin and of its esters.…”

Chromatography

“…In addition to the reviews by Dietrich (264), Harborne (450), and Strachota (1142), there are also review articles (451,857) on the chromatography of an especially interesting group of phenols, the flavonoid pigments. Columns of magnesia (803), Florisil (258), and cellulose (662,812,1237) are conventionally used for the fractionation of phenols, but the introduction of polyamide columns (244,369,408,488), eluted with aqueous alcohol solutions, constitutes a significant new advance in this field. Polyamides may also be used in thin layers (289), particularly in the form of polyamide-impregnated filter paper (731,1251).…”