New C₂₀-diterpenoid alkaloids from Aconitum vilmorrianum and structural revision of 2-O-acetylorochrine and orochrine

¹Dedicated to Professor Xin-Sheng Yao on the occasion of his 80th birthday.

Abstract

Three new C₂₀-diterpenoid alkaloids vilmorrianines E (1), F (2), and G (3) were isolated from the whole plants of Aconitum vilmorrianum, along with one artifact N-chloromethyl vilmorrianine E hydrochloride (4), as well as two known alkaloids hemsleyaconitines F (5) and G (6). The structures of 1–4 were established by HR-ESI-MS, 1D-, 2D-NMR (HMQC, HMBC, and NOESY), and single-crystal X-ray diffraction analysis. In addition, the structures of naturally occurring 2-O-acetylorochrine (7) and orochrine (8) were revised to be the known alkaloids heterophylloidine (9) and deacetyl heterophylloidine (10), respectively, on the basis of consideration of transannular effect and chemical correlations.

Keywords:

• Aconitum vilmorrianum
• diterpenoid alkaloid
• vilmorrianine
• structural revision
• transannular effect

Acknowledgments

The authors would also like to thank Professor Xian-Li Zhou (School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, China) and Dr Li-Sheng Ding (Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China) for measuring HR-ESI-MS and providing compound heterophylloidine, respectively.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Nature Science Foundation of China [grant number 81273387].