Bioactive Azepine-Indole Alkaloids from <i>Psychotria nemorosa</i>
Luiz Carlos Klein‐Júnior, Sylvian Cretton, Yvan Vander Heyden, André Luís de Gasper, Samad Nejad Ebrahimi, Philippe Christen, Amélia T. Henriques
Abstract
Phytochemical investigation of the alkaloid extract of the aerial parts of Psychotria nemorosa led to the isolation and characterization of 10 azepine-indole alkaloids, i.e., cimitrypazepine (1), fargesine (2), nemorosines A (3), and B (12), nemorosinosides A–F (4–9), as well as two β-carboline derivatives, 10-hydroxyisodolichantoside (10) and 10-hydroxydolichantoside (11), an isoxazole alkaloid, nemorosinoside G (13), serotonin (14), bufotenine (15), and (S)-gentianol (16). Compounds 3–13 have not yet been described. These compounds were isolated by semipreparative HPLC, and their structures were determined by means of HRMS, NMR, and ECD measurements. In addition, the monoamine oxidase-A (MAO-A), MAO-B, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibitory activities were evaluated. Alkaloids 1–3 inhibited the MAO-A activity with IC50 values of 1.4, 1.4, and 0.9 μM, respectively.