Submitted to: Journal of the Association of Official Analytical Chemists
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/16/2010
Publication Date: 2/18/2011
Citation: Sun, J., Chen, P., Lin, L., Harnly, J.M. 2011. A non-targeted approach to chemical discrimination between green tea extract-based dietary supplements and green tea leaves by LC/MS. Journal of the Association of Official Analytical Chemists. 94:487-497. Interpretive Summary: Green tea extract-based dietary supplements (GTDS) have gained popularity in the U.S. market in recent years. This study evaluated the chemical composition differences of GTDS samples in comparison with green tea (GT) leaves using an analytical technique called fingerprinting. The similarity between the GTDS sold in solid form as capsules or tablets with GT was measured to be 0.55 to 0.91, while the GTDS sold in liquid forms was 0.12 to 0.89, suggesting that the variance in chemical composition between solid and liquid GTDS products was significant. Flavonol aglycones, a group of chemical compounds that were measured, were higher in GTDS than levels found in green tea leaves, thought to be a result of changes during the manufacturing and storage process. In some of the GTDS samples, botanical extracts or additives not indicated on the label as present in the product were found. The results demonstrate the need for quality control for GTDS products.
Technical Abstract: Green tea extract-based dietary supplements (GTDS) have gained in popularity in the U.S. market in recent years. This study evaluated the phytochemical composition of several GTDS in comparison to the composition of green tea leaves using a LC-MS fingerprinting technique coupled with chemometric analysis. Five components found to be primarily responsible for the major differences noted in composition between GTDS and green tea leaves were identified as (-)epicatechin gallate, strictinin, trigalloylglucose, quercetin-3-O-glucosyl-rhamnosylglucoside, and kaempferol-3-O-galactosyl-rhamnosylglucoside according to the accurate mass measurement and MS/MS data. The similarity coefficient between the GTDS in sold form with green tea was 0.55 to 0.91, while the GTDS in liquid form was 0.12 to 0.89, which suggests that the variance in chemical composition among the GTES samples was significant. Flavonol aglycones were higher in GTDS than in tea leaves, indicating degradation of flavonol glycosides or oxidation of catechin during the GTDS manufacturing and storage process. In some GTDS samples, botanical extracts or additives were present but were not indicated on the product label as ingredients. The results demonstrate the importance of quality control for GTDS products.