(±)-Zanthonitidine A, a Pair of Enantiomeric Furoquinoline Alkaloids from Zanthoxylum nitidum with Antibacterial Activity

ABSTRACT: A pair of new enantiomeric furoquinoline alkaloids, (±)-zanthonitidine A (1), together with nine known ones (2–10) were isolated from the radix of Zanthoxylum nitidum. Their chemical structures were elucidated based on the extensive spectroscopic analysis. The racemic mixture of 1 was separated by chiral column chromatography, and the absolute configurations of (+)-1 and (−)-1 were determined by the comparison of experimental and calculated electronic circular dichroism spectra. Antibacterial activities of compounds 1–9 were evaluated, and compounds (+)-1, (−)-1, 3, 7 and 8 showed antibacterial activities against Bacillus subtilis, Enterococcus faecalis or Staphylococcus aureus. GRAPHICAL ABSTRACT: [Image: see text] ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13659-018-0169-7) contains supplementary material, which is available to authorized users.