A comparative study on the bioactivities and chemical compositions of Dancong summer tea and Anhua dark tea: Excavation of glycolipid-lowering functional factors.

Drinking tea is beneficial to reduce the incidence of obesity. Unlike Fuzhuan brick tea (DT, a typical dark tea) widely reported to have good glycolipid-lowering activity (GLA), there is little information on GLA of Dancong summer tea (OT, a typical oolong tea). A comparative study on GLA and chemical compositions of OT and DT was systematically conducted. The results showed that OT had advantages in high content of polyphenols, leading to its better GLA including glycolipid digestion enzyme inhibitory activity and cholesterol micellar solubility inhibition activity than DT's. A total of 21 compounds mainly including catechins, flavonoids, phenolic acids and phenylpropanoids were screened as the key differentially active micromolecules (KDAM) by UPLC-QTOF-MS/MS-based untargeted metabolomic analysis combined with multivariate analysis, which resulted in the difference of GLA between OT and DT. Moreover, the high affinity capacity and interaction mode between KDAM with α-glucosidase/α-amylase/pancreatic lipase/cholesterol esterase were validated by molecular docking. Although the accumulation of polyphenols makes OT has a poor flavor as a beverage, our research demonstrated that OT with high content of polyphenols could be used in functional foods to facilitate the prevention of obesity.