Fusarimine (1), a novel polyketide-derived isoquinoline alkaloid with a rare N-ethyl-4-methyl-7-carboxyisoquinoline carbon skeleton, was isolated from cultures of Fusarium sp. LN-12, an endophytic fungus isolated from the leaves of Melia azedarach. The structure of 1 was elucidated on the basis of extensive spectroscopic data, especially by 2D NMR; X-ray crystallographic analysis confirmed the structure and delivered also the absolute configuration. © 2012 Elsevier Ltd. All rights reserved.