Key Word Index: Results and DiscussionVepris louisii; Rutaceae: Veprisinium salt: Quaternary dihydrofuroquinoline alkaloid: Pharmacology: Antimicrobial activity. AbstractThe water-soluble alkaloid fraction of Vepris louisii G. GILBERT shows significant antibacterial activity. The compound responsible for the activity has been shown to be a novel quaternary dihydrofuroquinoline alkaloid for which the name veprisinium salt is proposed. Its structure has been established primarily by spectral correlation to known alkaloids, chemical conversion to known derivatives and by partial synthesis.