Two new polyketides from the roots of Stemona tuberosa.

Two polyketides, stemonones A ( 1 ) and B ( 2 ) with new skeletons, were isolated from the roots of Stemona tuberosa . Their absolute structures were fully characterized by comprehensive spectroscopic analyses and comparison of experimental electronic circular dichroism (ECD) spectra with calculated ones. The plausible biosynthetic pathways for 1 and 2 were also proposed. Anti-inflammatory assay confirmed that the two compounds showed moderate inhibitory effects on β -glucuronidase release in rat polymorphonuclear leukocytes (PMNs) induced by platelet-activating factor. [ABSTRACT FROM AUTHOR]