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

摘要

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 (H-1/C-13) 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 degrees/C-3 degrees) were established by CD spectrometry combined with quantum chemical calculations.