Chemical constituents of Narcissus tazetta var. chinensis and their antioxidant activities.

Two new flavan derivatives tazettones C-D (1-2), one new β-coumaranone (tazettone E, 3), one new flavan (tazettone F, 4), and one new phenylpropanoid (tazettone G, 5), together with six known flavonoids (6-11), were isolated from the bulbs of Narcissus tazetta var. chinensis Roem. Their structures were elucidated by spectroscopic analysis. In addition, the structures of 1-3 were confirmed by single crystal X-ray diffraction. All isolated compounds were tested for antioxidant activity by Cell Counting Kit-8 (CCK-8) assay. Compounds 6-8 and 10-11 exhibited potent antioxidant activity against H2O2-induced impairment in human SH-SY5Y neuroblastoma cells at tested concentrations.