Flavanol digallates in green tea leaf

Antioxidant activity of O-protected derivatives of (-)-epigallocatechin-3-gallate: inhibition of soybean and rabbit 15-lipoxygenases

“…Consequently EGCG was permethylated by dimethyl sulfate, 20 or peracylated with acetic anhydride, propionic anhydride or butyric anhydride in the presence of N,N-dimethylaminopyridine in dichloroethane, and purified by flash chromatography on silica gel giving molecules II-V in moderate to good yields. (Figure 1) Substances II 21,22 and V 23,24 have been reported previously, but substance V has been characterized only incompletely. Substances III and IV have been prepared by us for the first time.…”

Pathway of Gallic Acid Biosynthesis and Its Esterification with Catechins in Young Tea Shoots

“…2 ) In contrast, the digallic acid esters appear likely to be the minor ones and their composition has not been determined. 3 ) Three pathways have been proposed for the biosynthesis of gallic acid; a) p-oxidation of the side-chain of 3,4,5-trihydroxycinnamic acid,4,5) b) dehydrogenation of shikimic acid, presumably with 3-dehydroshikimic acid as an intermediate, [6][7][8][9][10][11] and c) hydroxylation of protocatechuic acid. 12 ,13) Shikimic acid has been demonstrated to be a good precursor for the aromatic acids in the mould, Phycomyces blakesleeanus, 6) and in plants such as Rhus typhina, Acer saccharinum, 9,10) and tea leavesy, 14) The aim of the present investigation was to obtain information on the preferential pathway in young tea shoots for gallic acid synthesis and its esterification with catechins.…”

Isolation and Chemical Structures of Two New Catechins from Fresh Tea Leaf

“…2.2 to 4.6 liters). The unknown compounds X and Y were further purified by chromatography on a Sephadex LH-20 column using methanol--chloroform-hexane (2: 1 : 1, v/v) as a solvent 2 ) and recrystallized from a mixture of water and methanol, giving chromatographically homogeneous off-white, amorphous powder: yield X 33 mg, Y 138 mg.…”