Quinone Derivatives as Promising Anti- Helicobacter pylori Agents from Aerial Parts of Mitracarpus hirtus .

Seven new naphthoquinone diglycosides ( 1 - 7 ), three new anthraquinones ( 8 - 10 ), and eight known analogues were obtained from the aerial parts of Mitracarpus hirtus collected from West Africa in a bioassay-guided phytochemical investigation. All isolated compounds were elucidated by comparison with the literature and interpretation of spectroscopic data, and the absolute configurations of the new naphthoquinone diglycosides ( 1 - 10 ) were confirmed by chemical methods and ECD calculations. Notably, compound 1 was found to be the first naphthoquinone diglycoside containing carboxylic acid and isopentenyl side chains isolated from a species in the genus Mitracarpus . Compounds 6 - 18 showed antibacterial activity against multiple Helicobacter pylori strains with MIC values ranging from 0.0625 to 64 μg/mL. Particularly, 1-hydroxybenzoisochromanquinone ( 17 ) and benzo[ g ]isoquinoline-5,10-dione ( 18 ), with MIC values of 0.0625 and 0.125 μg/mL, displayed 32-512-fold higher potencies than a positive control, metronidazole. Compound 18 also demonstrated high antibiofilm activity and killed biofilm-encased Helicobacter pylori cells more effectively than metronidazole.