Comparative study of the reversed-phase high-performance liquid chromatography of black tea liquors with special reference to the thearubigins

Black Tea Is a Powerful Chemopreventor of Reactive Oxygen and Nitrogen Species: Comparison with Its Individual Catechin Constituents and Green Tea

“…Typically, 10 g of total catechins in BT (20 l of BT) contains approximately 1.4 g of theaflavins, 2.4 g of EGCG and 1.0 g of epicatechin. These were the values obtained by us with our locally available sample of BT (see Materials and Methods) and agrees fairly well with other recently published values (26,27). BT at 10 g concentration of total catechin (Fig.…”

“…It was estimated that 100 l of black tea was equivalent to 50 g of total catechins and the black tea passed through Sephadex G50 spin column was devoid of all individual polyphenols [data not shown]. The HPLC quantification of individual polyphenols broadly matched with the results of other standard quantifications published recently (26,27).…”

Isolation and analysis of a polymeric thearubigin fraction from tea

“…The HPLC equipment, columns, and gradients, used for the analysis of the theafulvin fraction were the same as those described in detail previously (Bailey et al , 1991. Sufficient of the theafulvin fraction (2-3 mg) was dissolved in distilled water (1 ml), to give a brown solution of about the same colour as a tea liquor.…”

“…Berkowitz el af (1971) found that on a range of reversed phase columns. These pigments were classified on this basis as Group I11 pigments, and were thought to be unresolved polymeric thearubigins (Bailey et al 1991). The present paper describes the isolation and analysis of a fraction of these pigments.…”

A New Type of Tea Pigment—From the Chemical Oxidation of Epicatechin Gallate and Isolated from Tea

“…TheaÑavin, theaÑavin-3-O-gallate, theaÑavin-3@-O-gallate, theaÑavin-3,3@-di-O-gallate and epitheaÑavic acid are examples (Collier et al 1973). By contrast, thearubigins are found to be a highly heterogeneous mixture of pigments, generally characterised by a very broad hump when analysed by reverse-phase HPLC (Bailey et al 1991). At present there is little Ðrm knowledge on their composition and structure.…”