Minor diterpenoids from Scutellaria galericulata

Three new neo-clerodane diterpenoids, one C-16 epimeric pair, scutegalerins C and D, and scutegalerin E, together with the known scutaltisin B, were isolated from the acetone extractof the aerial parts of Scutellaria galericulata. The chemical structures of the new compounds were elucidated by spectroscopic techniques and a comparison with data of similar compounds as (13S,16R,19S)-6a-acetoxy-2a,19;4a,18;15,16triepoxy-16,19-dimethoxy-neo-clerodane (scutegalerin C), (13S,16S,19S)-6a-acetoxy-2a,19;4a,18;15,16triepoxy-16,19-dimethoxy-neo-clerodane (scutegalerin D) and (11S,13R,16S,19S)-6a-acetoxy2a,19;4a,18;11,16;15,16-tetraepoxy-19-methoxy-neo-clerodan-3b-ol (scutegalerin E). Detailed NMR spectra of scutaltisin B were included to rationalize the new assignments in the H NMR spectrum and the correction of some of the previously reported carbon signals in the C NMR spectrum for the isolated mixture of the two C-11 epimers scutaltisin B and scutaltisin C. ã 2015 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.