Secondary Metabolites from the Leaves of the Medicinal Plant Goldenseal (Hydrastis canadensis).

The study presented herein constitutes an extensive investigation of constituents in Hydrastis canadensis L. (Ranunculaceae) leaves. It describes the isolation and identification of two previously unknown compounds, 3,4-dimethoxy-2-(methoxycarbonyl)benzoic acid (1) and 3,5,3'-trihydroxy-7,4'-dimethoxy-6,8-C-dimethyl-flavone (2), along with the known compounds (±)-chilenine (3), (2R)-5,4'-dihydroxy-6-C-methyl-7-methoxy-flavanone (4), 5,4'-dihydroxy-6,8-di-C-methyl-7-methoxy-flavanone (5), noroxyhydrastinine (6), oxyhydrastinine (7) and 4',5'-dimethoxy-4-methyl-3'-oxo-(1,2,5,6-tetrahydro-4H-1,3-dioxolo-[4',5':4,5]-benzo[1,2-e]-1,2-oxazocin)-2-spiro-1'-phtalan (8). Compounds 3-8 have been reported from other sources, but this is the first report of their presence in H. canadensis extracts. A mass spectrometry based assay was employed to demonstrate bacterial efflux pump inhibitory activity against Staphylococcus aureus for 2, with an IC50 value of 180 ± 6 μM. This activity in addition to that of other bioactive compounds such as flavonoids and alkaloids, may explain the purported efficacy of H. canadensis for treatment of bacterial infections. Finally, this report includes high mass accuracy fragmentation spectra for all compounds investigated herein which were uploaded into the Global Natural Products Social molecular networking library and can be used to facilitate their future identification in H. canadensis or other botanicals.