Aporphines are a class of alkaloids mostly reported in Magnoliids. The genus Annona, Annonaceae, presents great structural diversity of these compounds. Chemical investigation of leaves from Annona crassiflora Mart. resulted in the identification of an undescribed aporphine alkaloid, which was named as crassiflorine, in addition to six known analogues: anonaine, annoretine, xylopine, tetrahydropalmatrubine, litseglutine B, and stephalagine. The structure of crassiflorine was established through 1D and 2D NMR data in combination with HREIMS and IR analyses. The cytotoxic activity for all tested compounds was marginal (IC50 > 30 mu M) against breast carcinoma (MCF-7) and colorectal carcinoma (HCT-116) cell lines.