The present master thesis describes the phytochemical study and the antiplasmodial activity against Plasmodium falciparum (W2) of Himatanthus articulatus (Vahl) Woodson. The ethanol extract (EEHS) obtained by percolation of the bark powder, gave, after concentration, a precipitate (EEHSP) and a pasty residue that was submitted to lyophilization (EEHS). Fractionation of EEHS was carried out by successively re-extraction with DCM, AcOEt and MeOH under reflux, by acid-base partitioning for separation of alkaloids and by chromatography over silica gel column. Furthermore, the bark powder was extracted with 1 N HCl for the separation of alkaloids. TLC prospection of EEHS and EEHSP was carried out while EEHS, FrDCM EEHS, FrAcOET EEHS, FrMeOH EEHS and FAHS2 DCM were also analyzed by HPLC - DAD. Column chromatography of FrAcOET EEHS afforded a substance (S1). EEHS, the major fraction obtained in its chromatographic column (F71), DCM FAHS2 and S1 were analysed by UPLC-PDA-MS/ESI. Spectroscopic analyses of S1 (IR, UV, MS/ESI, 1H and 13CNMR) allowed its identification as plumieride. Antiplasmodial activity against P. falciparum (W2) was evaluated for EEHS, EEHSP, FrDCM EEHS, FrAcOET EEHS, FrMeOH EEHS, FAHS1 DCM, DCM FAHS2, FAEEHS, FNEEHS, FNHS DCM and S1 by the parasite lactate dehydrogenase (pLDH) method. In the TLC prospection, EEHS and EEHSP showed positive results for polyphenols and tannins, saponins, triterpenes and steroids, alkaloids and flavonoids. EEHS fractions were analyzed by HPLC-DAD showing suggestive peaks of iridoids. Analyses by UPLC-PDA-MS/ESI showed that EEHS contains plumieride as the major substance whose psedomolecular peak was observed at m/z 471 (M + H). S1 was identified as plumeride. Until now it was not reported the presence of alkaloids for the species but spots suggestive of alkaloids were observed on TLC with Dragendorff reagent of FAHS1 DCM, DCM FAHS2, FAEEHS, FNEEHS and FNHS DCM were observed. UV spectra registered online by HPLC-DAD for FAHS2 showed that the major peak is suggestive of a β-carboline alkaloid. UPLC-PDA-MS/ESI analysis of FAHS2 DCM showed an intense peak corresondng to a pseudomolecular ion 329 u that could be possibly attributed to the alkaloid 10-hydroxy-antirine-N-oxide (MM 328 u). The antiplasmodial assays were negative for EEHS, EEHSP, FrDCM EEHS, FrAcOET EEHS, FrMeOH EEHS, S1, FAEEHS, FAHS1 DCM, FNEEHS, FNHS DCM and moderately active (CI50 22,89 μg/mL) for FAHS2 DCM. These results indicate that the antiplasmodial activity might be attributed to the plant alkaloids whose presence in H. articulatus is reported here by the firist time.
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