Bis-spirolabdane diterpenoids from Leonurus japonicus and their anti-platelet aggregative activity.

Six bis-spirolabdane diterpenoids along with four known analogues were isolated from the aerial parts of Leonurus japonicus. Their structures and absolute configurations were elucidated by spectroscopic analyses, single-crystal X-ray diffraction, and a modified Mosher's method. The inhibitory activity of the compounds against the abnormal increase in platelet aggregation induced by adenosine diphosphate was investigated. Only the (13R)-bis-spirolabdane diterpenoids exhibited a significant effect.
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