Bis-spirolabdane-type diterpenoids from Leonurus sibiricus.

ABSTRACT

Six new bis-spirolabdane-type diterpenoids, leosibirinone A (1), 3alpha-acetoxyleoheteronone C (2), leosibirinone B (3), 3alpha-hydroxyleoheteronone A (4), 3alpha-acetoxyleoheteronone E (5), and 3alpha-acetoxy-15-epileoheteronone E (6), were isolated from the aerial parts of Leonurus sibiricus. Their structures were identified on the basis of 1D and 2D NMR, including (1)H-(1)H COSY, HSQC, HMBC, and NOESY spectroscopic analyses.