Two alkaloids, guatterine and atherospermidine, have been isolated from Guatteria psilopus Mart. (Annonaceae). These alkaloids are related to micheline and liriodenine, of which they are, respectively, the 3-methoxy derivatives. Guatterine is readily oxidized to atherospermidine, and atherospermidine can be oxidized to 1-azaanthraquinone-4-carboxylic acid. Guatterine and micheline differ in the stereochemistry of the 7-hydroxyl group.