A non-targeted approach to chemical discrimination between green tea dietary supplements and green tea leaves by HPLC/MS.

摘要

Green tea-based dietary supplements (GTDSs) have gained popularity in the US market in recent years. This study compared the phytochemical composition of GTDS and green tea leaves using an HPLC/MS fingerprinting technique coupled with chemometric analysis. The 5 components most responsible for class separation among samples were identified as (--)- epicatechin gallate, strictinin, trigalloylglucose, quercetin-3-O-glucosylrhamnosylglucoside and kaempferol-3-O-galactosyl-rhamnosylglucoside, according to accurate mass measurements and MS/MS data. Similarity coefficients between the GTDSs in solid form and green tea were 0.55-0.91, while for the GTDSs in liquid form they were 0.12-0.89, which suggested that chemical composition variance across the GTDSs was significant. Flavonol aglycone concentrations were higher in GTDSs than in tea leaves, indicating that degradation of flavonol glycosides or oxidation of catechin occurred during the manufacture and storage processes. In some GTDS samples, compounds were identified that were on the label. Results suggest that quality control procedures for GTDS products are urgently needed.