Interaction of dicentrinone, an antitrypanosomal aporphine alkaloid isolated from Ocotea puberula (Lauraceae), in cell membrane models at the air-water interface

In the present work, the oxoaporphine alkaloid dicentrinone was isolated, for the first time, from leaves of Ocotea puberula (Lauraceae). This alkaloid exhibited antiparasitic activity against trypomastigote forms of Trypanosoma cruzi (IC₅₀ of 16.4 ± 1.7 μM), similar to the positive control benznidazole (IC₅₀ of 18.7 ± 4.1 μM), reduced mammalian cytotoxicity (CC₅₀ > 200 μM), and a selectivity index (SI) higher than 12. These results were correlated with the effects observed using cellular membrane models, represented by 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), in Langmuir monolayers. Dicentrinone was incorporated in the films, submitted to lateral compression, and characterized by tensiometry. As observed in compression-decompression and time-stability curves, dicentrinone expanded the lipid monolayers, decreased the compressional modulus of the film, and reduced the stability of the monolayer. Brewster Angle Microscopy and interfacial Infrared Spectroscopy showed that dicentrinone causes the monolayers to be segregated in phases, and to increase the number of gauche/trans conformers ratio for the lipid acyl methylene groups, indicating configurational disorder. As a result, dicentrinone caused a disturbance in the cell membrane models, altering the physicochemical properties of the lipid surface such as thermodynamic, rheological, morphological, and structural aspects. These results can be useful to understand the interactions between dicentrinone and lipid biological surfaces at the molecular level.

Keywords: Air–water interface; Alkaloids; Anti-T. cruzi; Cell membrane models; DPPE; Dicentrinone; Langmuir monolayers.