A Novel Atisane Diterpenoid from Spiraea japonica var. acuta.

A novel ent-atisane lactone, spiramilactone E (1), was isolated from Spiraea japonica var. acutaYu. Its structure was elucidated by extensive spectroscopic analyses, and unequivocally confirmed by single-crystal X-ray diffraction (Fig. 4;2). Compound 1 contains a γ-lactone moiety between the 6-OH function and C(20), and β-configuration for the 7-OH group, in contrast to known related diterpenes previously isolated from the S. japonica complex. [ABSTRACT FROM AUTHOR]