Baeckeins L and M, two novel C-methylated triflavonoids from the roots of Baeckea frutescens L.

Abstract

Baeckea frutescens is a medicinal plant distributing from Southeast Asia to Australia. A pair of novel diastereomeric C-methylated triflavonoids named baeckeins L (1) and M (2) were isolated from the roots of B. frutescens. The structures of these isolates were elucidated by analysis of the 1D (¹H/¹³C) and 2D NMR (HSQC/HMBC/NOESY) and HR-ESI-MS spectroscopic data, and the absolute configurations of chiral carbons (C-2/C-3/C-2°/C-3°) were established by CD spectrometry combined with quantum chemical calculations.

Keywords:

• Baeckea frutescens
• C-methylated triflavonoid
• Baeckeins L and M
• Absolute configuration

Acknowledgements

We appreciate the kind help from Mr. Mao-Xiang Lai (Guangxi Academy of Chinese Medicines and Pharmaceutical Science) for collecting the plant materials.

Additional information

Funding

This work was supported by the [National Natural Science Foundation of China] under Grant [NO. 81303162], and the [China Postdoctoral Science Foundation] under Grant [NO. 2018M630841].