Flavonoidal alkaloids from the flowers of Chromolaena odorata (L.) R.M.King & H.Rob.

ABSTRACT

A pair of epimers of flavonoid alkaloids, with a pyrrolidone moiety, 2S,5''R-eupodoratin A (1), 2S,5''S-eupodoratin A (2), together with two known analogues, drahebephin A (3), drahebephin B (4), were isolated from the flowers of Chromolaena odorata (L.) R.M.King & H.Rob. Their structures were elucidated on the basis of HR-ESI-MS, 1D/2D NMR spectral analyses. The absolute configuration of compounds (1) and (2) was determined by its experimental and calculated electronic circular dichroism (ECD) spectra. All compounds were isolated from the Asteraceae family for the first time. The ABTS·+ scavenging activity of compound (4) reached 93.56% at a concentration of 0.5 mM, while the scavenging capacity of positive control Trolox was 55.94%. In addition, all compounds show moderate antimicrobial activity against Escherichia coli (ATCC, 337304), Staphylococcus aureus (ATCC, 337371) and Candida albicans (ATCC, 186382) with a MIC value of more than 50 µg/mL.