Antimicrobial constituents from goldenseal (the Rhizomes of Hydrastis canadensis) against selected oral pathogens.

Two new C-methyl flavonoids, 6,8-di- C-methylluteolin 7-methyl ether (1) and 6- C-methylluteolin 7-methyl ether (2), were isolated from a commercially available sample of the roots of Hydrastis canadensis, along with seven known compounds, berberine (3), beta-hydrastine (4), canadine (5), canadaline (6), isocorypalmine (7), canadinic acid (8), and beta-sitosterol 3- O-beta- D-glucoside (9). The structures of the new compounds 1 and 2 were elucidated on the basis of their spectral data including 1D and 2D NMR techniques. Of these isolates, berberine (3) and, to a lesser extent, 1 and 2, showed antimicrobial activity when evaluated against the oral pathogens Streptococcus mutans and Fusobacterium nucleatum. Berberine (3) exhibited an additive antimicrobial effect when tested against S. mutans in combination with 1.