Estudo químico e biológico em alcaloides de Hippeastrum aulicum (KER GAWL.) HERB. : uma espécie da família Amaryllidaceae

Abstract

The species of Amaryllidaceae family are found in warm and tropical regions around the world. This family produces a well-known group of isoquinolines alkaloids which have demonstrated a wide range of biological activities such as antiviral, anticancer, acetylcholinesterase (AChE) inhibition, antimalarial, among others. In this paper it is going to be reported the chemical study of alkaloids present in the Brazilian species Hippeastrum aulicum and the investigation of antiparasitic activity against Trypanosoma cruzi and Leishmania infantum of the isolated alkaloids. In order to conclude the study and investigation it was performed classical acid-base extraction of methanol extracts of bulbs and leaves of H. aulicum, followed by chromatographic separation techniques. 11 alkaloids were obtained: haemanthamine (1), albomaculine (2), haemanthidine (3), 6-epihaemanthidine (4), haemanthamine Noxide (5), 7-methoxy-O-methyllycorenine (6), aulicine (7), lycorine (8), trisphaeridine (9), galanthine (10) and norpluvine (11). Haemanthamine N-oxide was obtained for the first time from natural source and it has been characterized by spectrometric and spectroscopic methods. The alkaloids 1, 2, 6, 7 and 8 were tested in vitro against parasites Trypanosoma cruzi and Leishmania infantum in different concentrations. Haemanthamine (1) showed to be an important agent against promastigote form of L. infantum with IC50 of 0,6 ?M while 7-methoxy-O-methyllycorenine (6) displayed activity against trypomastigote forms of T. cruzi, which is more active (IC50 = 89,55 ?M) and more selective (IS > 2,2) than the standard (benzonidazol, IC50 = 440,7 ?M, IS = 1,0) .