Four undescribed tryptamine-derived alkaloids, hunteriasines A -D, were isolated and identified from Hunteria umbellata (Apocynaceae), together with fifteen known indole alkaloids. The chemical structure and absolute configuration of hunteriasine A were determined by spectroscopic and X-ray crystallographic data analyses. Hunteriasine A, featuring with a unique scaffold comprised of tryptamine and an unprecedented 12-carbon unit moiety, is a zwitterionic indole-derived and pyridinium-containing alkaloid. Hunteriasines B -D were identified by spectroscopic data analyses and theoretical calculations. A plausible biogenetic pathway for hunteriasines A and B was proposed. The lipopolysaccharide-stimulated mouse macrophage cell line J774A.1 cell-based bioactivity assays revealed that (+)-eburnamine, strictosidinic acid, and (S)-decarbomethoxydihy-drogambirtannine enhance the release of interleukin-1 beta.