Antioxidant profiling of vine tea (Ampelopsis grossedentata): Off-line coupling heart-cutting HSCCC with HPLC-DAD-QTOF-MS/MS.

Vine tea with strong antioxidant activity is commonly consumed as healthy tea/beverage. However, detailed information about its antioxidants is incomplete. Here, off-line hyphenation of heart-cutting high-speed countercurrent chromatography (HSCCC) with high performance liquid chromatography-diode array detector-quadrupole time-of-flight tandem mass spectrometry (HPLC-DAD-QTOF-MS/MS) were described for systematic profiling antioxidants in vine tea. At first, antioxidants were rapidly screened by 1,1-diphenyl-2-picryl-hydrazyl radical-high performance liquid chromatography (DPPH-HPLC). Subsequently, stepwise HSCCC using petroleum ether-ethyl acetate-methanol-water (4:9:4:9, v/v/v/v) and (4:9:5:8, v/v/v/v) as solvent systems was optimized to fractionate and enrich antioxidants from ethyl acetate fraction of vine tea. Finally, heart-cutting mode was used to collect five interesting HSCCC fractions for HPLC-DAD-QTOF-MS/MS analysis. Desirable orthogonality between HSCCC and HPLC led to identification of fifteen antioxidant flavonoids, while four minor flavonoids were first reported in vine tea. Results showed that the developed system is efficient to comprehensively explore antioxidants from complex natural herbs.