Comparative Analysis of the Chemical Constituents and Hypoglycemic Activities of Two Chinese Juhua Teas (Chrysanthemum morifolium Ramat. and Coreopsis tinctoria Nutt.)

Chrysanthemum morifolium Ramat. (CM) and Coreopsis tinctoria Nutt. (CT), known as "Juhua" in China, are frequently consumed as tea. However, comparative studies on their chemical composition and biological activity are lacking. This study analyzed the chemical constituents of CM and CT aqueous extracts using high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC-DAD-ESI-QTOF-MS) and assessed their hypoglycemic and antioxidant activities. Both extracts primarily contained flavonoids and phenolic acids; CM contained 35 flavonoids (27 flavones, 4 flavonols, 3 flavanones, and 1 flavanonol) and 14 caffeoylquinic acids (CQAs), while CT contained 41 flavonoids (3 flavones, 6 flavonols, 20 flavanones, 5 flavanonols, and 7 chalcones) and 12 CQAs. CT demonstrated significantly higher total phenolics and flavonoids—three times more phenolics and two times more flavonoids than CM. It showed greater α-glucosidase inhibition, glycosylation reduction, and 2-NBDG uptake enhancement compared to CM. Additionally, CT's antioxidant capacity was superior to that of CM. These findings indicate that while both CM and CT are rich in flavonoids and phenolic acids, their compositions differ significantly. The higher concentration of these compounds in CT contributes to its more pronounced hypoglycemic and antioxidative effects, providing valuable insights for the future use of Juhua in diabetes treatment.