Analysis of Phenolic Compounds in Rooibos Tea (Aspalathus linearis) with a Comparison of Flavonoid-Based Compounds in Natural Populations of Plants from Different Regions

Tea samples from 17 populations of "wild tea" ecotypes Aspalathus linearis (rooibos tea) and 2 populations of Aspalathus pendula were analyzed. Recent advances in column technology together with high-resolution mass spectrometry were applied to improve resolution, facilitating the identification of several new compounds as well as grouping of the wild tea ecotypes according to their chemical composition. The collisional cross-section data obtained from ion mobility-mass spectrometry is reported for the flavonoids in rooibos for the first time. Enzyme pathways for the synthesis of the unique flavonoids found in rooibos tea are also proposed. A. linearis and A. pendula produce similar combinations of main phenolic compounds, with no diagnostically different discontinuities between populations or species. Northern resprouters (Gifberg and Nieuwoudtville) contain higher phenylpropenoic acid glucoside levels while teas from Wupperthal and surrounding areas were found to contain unique dihydrochalcones (phloridzin and a sieboldin analog), which are reported here for the first time.