Bioassay-guided isolation of neo-clerodane diterpenoids from Scutellaria barbata

Abstract

Bioassay-guided isolation of the aerial part of Scutellaria barbata yielded three new neo-clerodane diterpenoids scutebatas P–R (1–3), together with two known ones: scutebata E (4) and scutebarbatine B (5). The chemical structures of the isolated compounds were elucidated by spectroscopic methods (NMR and MS) and by comparison with the spectroscopic data reported in the literature. All compounds except 3 showed weak cytotoxicity with IC₅₀ values ranging from 35.11 to 42.73 μM against K562 cell lines, and compounds 1, 2, and 5 also displayed weak activities against HL60 cell lines.

Keywords::

• Scutellaria barbata
• Lamiaceae
• neo-clerodane diterpenoid
• cytotoxicity

Acknowledgments

This work was supported by the Key International Cooperation Project of CMST (No. 2008DFA31040) and the Special Funds for Young Teachers of Ocean University of China (No. 841113070). Special thanks are attributed to Professor J. Li and her research group (Key Laboratory of Marine Drugs, Chinese Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao, China) for the cytotoxic activity tests.

Notes

^1. These authors contributed equally to this paper.