Two new N-b-methylated beta-carbolinium glucoalkaloids, 3,4,5,6-tetradehydropalicoside and 3,4,5,6-tetradehydrodolichantoside, together with the known beta-carboline compounds desoxycordifoline (beta-carboline 3-carboxylate glucoalkaloid) and melinonine F (N-b-methylated harmanium cation), were isolated from Strychnos mellodora stembark. The structures of the compounds were elucidated on the basis of spectroscopic studies. (C) 1999 Elsevier Science Ltd. All rights reserved.