Unlike well-known glycosides from polar fraction of plant extracts,
a series of uncommon indole alkaloids with a carboxylic acid
group or a moiety of carboxylate were reported from the aqueous
fraction of A. scholaris leaves extract, which might contribute to
antibacterial activity of this plant since the polar fraction showed
more potent antimicrobial activity than the crude extract. Alkaloid
4 possessed a novel skeleton with a 6/5/6 fused-ring and a sixmembered
ring, the absolute configuration of which was assigned
by quantum theory. In addition, alkaloids 6 and 10 showed the best
antibacterial activity against P. aeruginosa with an MIC value of
3.13 mg/mL, while alkaloids 4, 7, and 10 showed moderate antifungal
activity against E. floccosum with an MIC value of 31.25 mg/
mL, respectively.