From the stem bark of Strychnos myrtoides in addition to strychnobrasiline and malagashanine, four minor alkaloids, viz. malagashanol, 12-hydroxy-19-epi-malagashanine, myrtoidine and 11-demethoxymyrtoidine were isolated and their structures were established by 2-D NMR techniques. They belong to the series N-b,C(21)-secocuran and the two last show an additional alpha-beta unsaturated gamma-lactonic ring among C(18)-C(21). The biogenesis of these alkaloids is also discussed. (C) 1999 Elsevier Science Ltd. All rights reserved.