Diterpenes from buds of Wikstroemia chamaedaphne showing anti-hepatitis B virus activities.

Phytochemical study of the buds of Wikstroemia chamaedaphne Meisn. led to the isolation of seven previously undescribed diterpenes, including one tigliane diterpene (wikstchalide A), two daphnane diterpenes (wikstroelides W-X), and four lathyrane diterpenes (laurifoliosides A-B and 2-epi-laurifoliosides A-B), along with four known diterpenes. The structures of these compounds were established by extensive spectroscopic evidence and electronic circular dichroism (ECD) calculations. Wikstchalide A possesses a 5,6-epoxy ring in the tigliane skeleton. Two compounds exhibited potential anti-hepatitis B virus activities, with IC50 values of 46.5 and 88.3 μg/mL against hepatitis B virus (HBV) surface antigen (HBsAg), and six compounds showed certain inhibitory effects on HBV-DNA replication with the inhibition ratios ranging from 2.0% to 33.0% at the concentrations ranging from 0.39 to 6.25 μg/mL.