A little biology goes a long way: How lessons gleaned from botanical standard reference material development can provide guidance in making effective herbal extracts

Green tea (Camellia sinensis), a popular beverage enjoyed world-wide, has been reported to contain compounds used in treatment of cancer, genital warts, cardiovascular disease, and as an antimicrobial. Accurate measurement and detection of these compounds is necessary for assuring good manufacturing practices and in the conduct of clinical trials. As part of a collaborative effort between the National Institute of Standards and Technology (NIST) and the National Institutes of Health (NIH) Office of Dietary Supplements analytical methods have been developed for the determination of catechins, gallic acid, theanine and methyl xanthines in a suite of green tea containing standard reference materials (SRMs).

The metabolic pool of catechins in green tea leaf tissue can be altered by both biotic factors and tea leaf processing. Traditional green tea leaf extraction methods underestimated 'true' analyte levels in green tea leaves, particularly levels of epigallocatechin gallate (EGCG). Understanding the biology and chemistry of catechins, plant primary cell walls and the antimicrobial properties of catechin galloyl esters helped guide analytical method development. Enzyme assisted extraction using of 0.1% EDTA combined with a secondary pressurized fluid extraction increased the recovery of catechins and limited interference of biopolymer fragments to optimize extraction efficiency. This talk describes how quantitative extraction in SRM development may provide useful guidelines to herbal manufacturers.