Antioxidant constituents of chrysanthemum 'jinsidaju' cultivated in Kaifeng.

Dendranthema morifolium cv. 'jinsidaju', cultivated only in Kaifeng, has been eaten for more than 1000 years. During the antioxidant-activity-guided studies on its chemistry and health care function, two new bisabolane-type sesquiterpenes, (6R,7R)-7-hydroxybisabol-2,9E,11-triene-4-one (jinsidajuol A, 1) and (6R,7R)-7-hydroxy-11-methoxybisabol-2,9E-diene-4-one (jinsidajuol B, 2), and thirteen known compounds (3-15) were isolated from the flowers. Their structures were elucidated by 1D and 2D NMR spectroscopy and HRMS. 1 and 2 are the first example of bisabolane-type sesquiterpenes isolated from the genus Dendranthema. Compounds 6-8, 12 and 13 exhibited strong scavenging activities on the ABTS radical cation with IC₅₀ 3.33, 5.67, 2.00, 2.50, 5.33 μg/mL, respectively. The IC₅₀ values of all compounds on HepG2 human hepatoma tumor cell line were higher than 50 μM.