Isolement et caractérisation des glycosides terpéniques de trois plantes médicinales camerounaises : Albizia chevalieri Harms, Calliandra calothyrsus Meisn (Mimosaceae), Lecaniodiscus cupanioides Planch.ex Benth (Sapindaceae) et évaluation de leurs propriétés biologiques.

Abstract

This work presents the phytochemical study of three Cameroonian medicinal plants, Calliandra calothyrsus Meissn. (Fabaceae), Albizia chevalieri Harms (Fabaceae) and Lecaniodiscus cupanioides Planch. ex Benth. (Sapindaceae). The study of the flowers of Calliandra calothyrsus led to the isolation of four compounds, three of them were described for the first time. From the roots of Lecaniodiscus cupanioides, seven compounds were isolated, including four new ones. Finally, the phytochemical study of the stem bark of Albizia chevalieri led to the isolation of three new saponosides. The structures were established by extensive analysis of NMR techniques, mainly 1D NMR (1H, 13C) and 2D NMR (1H, 13C, COZY, HSQC, HMBC, HSQC-TOCSY and ROESY/NOESY) coupled with high resolution mass spectrometry (HRESI- MS), and by comparison with data from the literature. The isolated compounds were submitted to various biological studies. The evaluation of the antiproliferative properties on two cancer cell lines of the human digestive tract (Hep3B and Caco-2) of the compounds isolated from C. calothyrsus show that the compounds possess antiproliferative activity against the Hep3B cell line, with IC50 values of 6.0 and 6.5 μM, respectively, which are of the order of that of sorafenib, one of the most clinically used molecules. However, no antiproliferative activity was detected for the same compounds on the Caco-2 cell line (CC50> 25 μM). For compounds isolated from Albizia chevalieri, the evaluation of their effect of inducing apoptosis on two human cancer cell lines (AsPC-1 and THP-1) showed that the percentage of apoptotic cells after 24 hours of treatment increased. in a concentration-dependent manner, which suggests that the compounds tested have proapoptotic activity on both cell lines. Finally, the anthelmintic activity of the fractions enriched in saponins of Calliandra calothyrsus (CCF) and Lecaniodiscus cupanioides (LCR) was evaluated on third stard larvae (L3) obtained from goats and sheep exhibiting a monospecific infection with Haemonchus contortus according to the larval stripping inhibition test (LEIA) with a range of increasing concentrations from 150 μg / mL to 1200 μg / mL compared to a negative control (PBS) in order to measure the kinetics of stripping according to the applied concentration. For both fractions (LCR and CCF), anthelmintic activity followed a curve showing a dose-response relationship. In general, the calculated IC50 values were lower for CCF than LCR. This result suggests a higher sensitivity of Haemonchus contortus to CCF compared to LCR.