RESUMEN
The somatic mutation and recombination test (SMART) in wing cells of Drosophila melanogaster was used to test the mutagenic and recombinogenic activities of five aporphinoid alkaloids isolated from Ocotea acutifolia: thalicminine (1), (+)-dicentrine (2), (+)-ocoteine (3), (+)-6S-ocoteine N-oxide (4), and (+)-leucoxine (5). Third-stage larvae derived from the standard cross with wing cell markers mwh and/or flr(3) were treated chronically. The frequencies of mutant spots observed in marked heterozygous descendants revealed significant dose-dependent genotoxicity for alkaloids 1-4; compounds 1 and 2 were the most active. Alkaloids 1-4 also induced mitotic recombination. The presence of a methoxyl group at C-3 (as in compound 3) lowers its genotoxic effect relative to that of unsubstituted analogue 2, and the introduction of an N-oxide functionality (3 vs. 4) further reduces genotoxicity. The very planar conformation of oxo-aporphine alkaloid 1 may account for its higher genotoxicity vs. its less-planar analogues 3 and 4. As previously reported for (+)-dicentrine (2), alkaloids 1, 3, and 4 may also be DNA intercalating agents, interfering with the catalytic activity of topoisomerases.