title: Antiplasmodial alkaloids from the stem bark of Strychnos malacoclados.
abstract: From the stem bark of Strychnos malacoclados, one new bisindole alkaloid, 3-hydroxylongicaudatine Y (1), was isolated along with the known alkaloids vomicine (2), bisnordihydrotoxiferine (3), divarine (4), longicaudatine (5), longicaudatine Y (6), and longicaudatine F (7). All the compounds were tested for their antimalarial activity against the chloroquine-sensitive 3D7 and -resistant W2 strains of Plasmodium falciparum. Longicaudatine was the most active compound with IC₅₀ values of 0.682 and 0.573 µM, respectively. The activity of compounds 1, 3, 4, 6, and 7 against the two strains ranged from 1.191 to 6.220 µM and 0.573 to 21.848 µM, respectively. Vomicine (2), the only monomer isolated, was inactive. The alkaloids of the longicaudatine-type ( 1, 5-7) were more active than those of the caracurine-type (3- 4). The presence of the ether bridge in the molecule seems to increase the antiplasmodial activity. Compounds 1, 5, and 7 were tested against the WI-38 human fibroblast cell line. Longicaudatine was the most cytotoxic compound with an IC₅₀ of 2.721 µM. Longicaudatine F was 40-46 times more active against the two strains of P. falciparum than against the human fibroblasts and was thus considered as the more selective alkaloid. The structures of the compounds were determined based on the analysis of their spectral data.
authors.affiliation: Laboratory of Phytochemistry, Center for Studies on Medicinal Plants and Traditional Medicine, Institute of Medical Research and Medicinal Plants Studies (IMPM), Yaoundé, Cameroon. alembertt2002@yahoo.fr
authors.forename: Alembert T
authors.initials: AT
authors.lastname: Tchinda
authors.forename: Annie R N
authors.initials: AR
authors.lastname: Ngono
authors.forename: Victorine
authors.initials: V
authors.lastname: Tamze
authors.forename: Marie-Caroline
authors.initials: MC
authors.lastname: Jonville
authors.forename: Martine
authors.initials: M
authors.lastname: Cao
authors.forename: Luc
authors.initials: L
authors.lastname: Angenot
authors.forename: Michel
authors.initials: M
authors.lastname: Frédérich
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D000981:Antiprotozoal Agents / Q000494:pharmacology*; D002163:Cameroon; D002460:Cell Line; D005347:Fibroblasts / Q000187:drug effects; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy / Q000382:microbiology; D008517:Phytotherapy; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology; D018547:Plant Stems / Q000737:chemistry; D010963:Plasmodium falciparum / Q000187:drug effects; D031451:Strychnos / Q000737:chemistry*
chemical_list: D000470:Alkaloids; D000981:Antiprotozoal Agents; D010936:Plant Extracts