Pyromeconic acid derivatives from Conyza canadnsis (L.) Cronq

A new pyromeconic acid derivative, pyromeconic acid-3-O-β-D-glucopyranoside-3'-(O-β-D-glucopyranoside)-6'-(O-4"-hydro-xybenzoate) (1), along with two known ones, were isolated from the whole plants of Conyza canadensis. Their structures were elucidated based on the analysis of their spectroscopic data. The in vitro antibacterial testing results showed that all of these three compounds were inactive towards two bacterial strains, Escherichia coli and Staphyloccocus aureus.