Characterization and Antioxidant Activity of Flavonoid-Rich Extracts From Leaves of Ampelopsis Grossedentata

Leaves of Ampelopsis grossedentata have been consumed in southern China as health tea and herbal medicine. In this study, two kinds of flavonoid-rich extracts from leaves of A. grossedentata were prepared by traditional solvent extraction (product A) and recrystallization (product B). By analysis of ultraviolet-visible (UV) spectrometry, infrared (IR) spectrometry, electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance (NMR) spectrometry and high-performance liquid chromatography (HPLC)-ESI/MS, the major flavonoid in two products was identified as (+)-dihydromyricetin (DMY). Also, by HPLC, the contents of DMY in leaves, product A and product B were measured to be 32.96 ± 1.18%, 77.15 ± 1.98% and 95.12 ± 2.86%, respectively. Various antioxidant tests (1,1-diphenyl-2-picrylhydrazyl radical scavenging, reducing power, antioxidant activity in linoleic acid system) showed that the antioxidant activity of the flavonoid-rich extracts could be comparable with that of tertiary butylhydroquinone. The flavonoid-rich extracts from A. grossedentata leaves have a promise to be a new natural antioxidant with potential application in food industry. PRACTICAL APPLICATION Leaves of Ampelopsis grossedentata are consumed in southern China as health tea (Tengcha) and herbal medicine. In this study, the flavonoid-rich extracts from leaves of A. grossedentata, which were rich in (+)-dihydromyricetin, were prepared by traditional solvent extraction and recrystallization. Also, the antioxidant activity of the extracts can be comparable with that of tertiary butylhydroquinone. The results obtained in this study suggest that leaves of A. grossedentata may have potential as a new source of natural antioxidant and health food with great commercial interest in the food and phytopharmaceutical market.