Research Article
Baeckeins A and B, Two Novel 6-Methylflavonoids from the Roots of Baeckea frutescens
Abstract
A pair of novel isomeric 6-methylflavonoids, named baeckeins A (1) and B (2), were isolated from the roots of Baeckea frutescens. The two compounds possess a unique C23 skeleton, resulting from the 6-methylation and 8-arylation of a flavonol (=3-hydroxy-2-phenyl-4H-1-benzopyran-4-one) framework and the formation of an unusual lactone ring E. Their structures were elucidated by detailed spectroscopic analyses, including HR-ESI-MS and 1D- and 2D-NMR data (HSQC, HMBC, and ROESY). A plausible biogenetic pathway for compounds 1 and 2 is also proposed (Scheme).
