Search

Theafulvins, isolated from black tea, chromatograph as a hump on reversed phase column packings. When whole black-tea brews are similarly analysed other phenolic compounds appear as more or less resolved peaks ‘floating’ on this hump. Model solutions of isolated theafulvins containing individual pure compounds (flavanols, flavonols and caffeine) have been prepared and their chromatographic behaviour compared with that of the pure compound chromatographed alone. In the case of quercetin, epicatechin and epicatechin gallate, a statistically significant hyperchromic effect has been observed in which the peak area ‘floating’ on top of the theafulvin hump is larger than expected from the area obtained for the pure compound alone. There was little or no effect with catechin and caffeine, and rutin showed a weak and inconsistent response. The data are discussed by reference to the established literature on copigmentation but it is not possible to define the mechanism responsible for the hyperchromism at this stage.

A method has been developed which enables the easy and inexpensive preparation of gram quantities of (–)-epigallocatechin gallate from green tea ( Camellia sinensis ). A decaffeinated aqueous brew of commercial green tea is treated with caffeine (30 m m ). The precipitate is redissolved after decaffeination with chloroform and further purified by solvent partition with ethyl hexanoate and propyl acetate. Commercial leaf (25 g) yields 400 mg (–)-epigallocatechin gallate at better than 80% purity, as judged by reversed phase HPLC.

Research involvement among registered dietitians (RDs) is important in advancing dietetics practice and ensuring high-quality and cost-effective health care. There are no standardized approaches to measuring levels of research involvement. The aim of the study was to develop a standardized measure of research involvement and test its validity and reliability among RDs. The Research Involvement Questionnaire (RIQ) was developed and underwent content validation, resulting in a content validity index of 0.92. A postal questionnaire survey of RDs was undertaken at two time points. RDs were purposively selected and, based on their number of publications and grants, were assigned by the authors to one of four levels of research involvement: evidence-based practice, collaborating on research, leading research, and leadership in research. Of 192 questionnaires mailed, 111 RDs (58%) returned the first RIQ, of whom 82 (74%) also returned the second RIQ. Total scores and scores for each level were higher for RDs with higher levels of research involvement (P

1. Nine habitual tea-drinking volunteers were recruited and asked to follow a low-polyphenol and low-caffeine diet for 6 days and to provide daily 24-h urine samples. On day 4 of the experiment strong black tea brewed under standardized conditions was re-introduced to the volunteers' diet. 2. 1H-NMR and HPLC profiling of the urine samples indicated that consumption of black tea (6-10 mugs per day) was associated with a significant (p = 0.00017) increase in hippuric acid excretion relative to control, increasing from 153-512 to 742-1374 mg day(-1). The excretion of substantial amounts of hippuric acid has not previously been associated with black tea consumption. 3. For some volunteers, the quantity of benzoic acid processed exceeded the acceptable daily intake (ADI), but this is not considered to constitute any hazard. 4. A mass-balance analysis indicated that the necessary quantity of benzoic acid could not be obtained from the contents of gallic acid, flavanols, flavonol glycosides and theaflavins in black tea even if 100% transformation was obtained, suggesting that the thearubigins (the major and chemically ill-defined polyphenols of black tea) may be an important source.

Rats maintained on green, black or decaffeinated black tea (2.5%, w/v) as their sole drinking fluid displayed higher hepatic CN- insensitive palmitoyl CoA oxidase activity than controls; the extent of increase was similar with the three types of tea. Morphological examination of the liver using electron microscopy revealed an increase in the number of peroxisomes in the tea-treated animals. The same treatment of the animals with green and black tea resulted in a similar rise in hepatic microsomal lauric acid hydroxylation. Analysis by HPLC of the aqueous tea extracts employed in the current study showed that the total flavanol content of the green variety was much higher than the black varieties, and confirmed the absence of caffeine in the decaffeinated black tea. It may be concluded from the present studies that neither caffeine nor flavanoids are likely to be responsible for the proliferation of peroxisomes observed in rats treated with tea.