Abstract:

This study was aimed to analyze the flavonoids from winter jujube and the antioxidant activity was also assessed.
Winter Jujube was extracted with 60% ethanol and separated by macroporous resin chromatography to obtain crude
flavonoids (FW-1). FW-1 was further purified on silica gel column into FW-2. The composition and chemical structure of
FW-1 and FW-2 was analyzed by LC-MS, and their radical scavenging activity against ·OH and O2
－· and DPPH radicals
was measured. Results showed that total flavonoid contents in FW-1 and FW-2 were 55% and 94%, respectively. The
HPLC chromatogram of FW-2 showed that the main peak was E and based on mass spectra, it was identified as bisflavonoid
with a relative molecular weight of 790. Flavonoids at low concentration showed higher radical scavenging
capacity against ·OH than VC but less effective in scavenging superoxide anion radical than VC. The DPPH radical
scavenging rate of flavonoids at 200 μg/mL was higher than 85%, and the effect was dose-dependent. In conclusion,
the main component of the flavonoids extracted from winter jujube was bis-flavonoid and it demonstrated higher
antioxidant activity.

Key words: Winter jujube, flavonoids, LC-MS, antioxidant activity