Cycloartane triterpenoids from Pseudolarix amabilis and their antiviral activity.

Seven undescribed cycloartane triterpenoids, pseudolarnoids A-G, together with ten known ones, were isolated from the seeds of Pseudolarix amabilis (J. Nelson) Rehder. Their structures were elucidated on the basis of spectroscopic analysis, X-ray crystallography, and ECD data. Pseudolarnoids A-C are cycloartane triterpenoids with a unique 16S, 23R-spirolactone moiety. Pseudolarnoids F, G, and pseudolarolide C demonstrated potent antiviral effects on HSV-1 in vitro.