Schultesia guianensis Malme is a wild shrub of the Gentianaceae family, occurring in Africa and tropical America. In northeastern Brazil it has the popular name of "mata zombando," because it is considered to be highly toxic toward cattle (1). The aerial part of the plant was brought to our laboratory by a farmer who reported cattle poisoning on his farm in the county of Quixadá, Ceará. Earlier reports in the literature showed that the plant is toxic to cows when fresh plant is administered in the amount of 30 g/kg (2). A positive Dragendorff's test suggested the presence of alkaloids and stimulated a detailed chemical screening of the basic fraction of the plant extracts. An EtOH extract from the dry plant (6.1 kg) was concentrated and extracted with 1 N HCl, giving, after traditional workup (see Experimental section), the crude bases (23.0 g). Silica gel chromatography of the basic fraction (20.0 g) allowed the isolation of four pure substances. Three compounds were shown to be the well-known alkaloids gentianine [4-(2-hydroxyethyl)-5-vinylnicotinic acid lactone], gentiocrucine (3-aminomethylene-dihydropyran-2,4-dione), and gentianidine [4-(2-hydroxyethyl)-6-methylnicotinic acid lactone], by spectroscopic studies and, in the case of gentianine and gentianidine, by comparison of melting points with those recorded in the literature (3). This is the first report of the presence of gentianine, gentiocrucine, and gentianidine in the Schultesia genus; they may be artifacts formed from the reaction of terpenoids with the NH₃ used in isolation, as indicated earlier (3). The fourth compound was isolated as white crystals, mp 192.0-193.0°C. Its IR spectrum showed absorptions for hydroxyl (3550 cm⁻¹), amide (3300, 770 cm⁻¹), vinyl (930 cm⁻¹) and lactam carbonyl groups (1680 cm⁻¹). Its ¹H NMR spectrum (Table 1) showed the presence of methyl, methylene, and methine protons, together with an unconjugated vinyl group and a hydroxyl group. The mass spectrum showed a molecular ion at m/z 330, in agreement with the composition C₁₈H₂₂N₂O₄. The structure of the compound was shown to be that of the novel dilactam alkaloid 1 by X-ray crystallography corresponding to (4bS,5S,6R,10bR,12R)-3,4,4b,5,6,7,8,9,10b,12-decahydro-12-hydroxy-5-methyl-6-vinyl-1H-pyrido[4',3':4,5]pyrano[3,2-h]isoquinoline-1,10(2H)-dione.