Plants traditionally used against malaria: phytochemical and pharmacological investigation of Momordica foetida

摘要

Leaves from Momordica foetida traditionally used to treat symptoms of malaria in parts of East Africa were studied for in vitro antimalarial activity. Using an [3H] hypoxanthine-incorporation assay the antiplasmodial activity of hydrophilic and lipophilic extracts against the chloroquine-sensitive strain poW and the multiresistant clone Dd2 of Plasmodium falciparum was determined. The petrol ether/ethyl acetate extract showed significant activity with IC50 values of 7.3 μg/mL (poW) and 13.0 μg/mL (Dd2). Cytotoxicity was estimated on two human cell lines HepG2 and ECV-304 and a selectivity index (SI) was calculated, ranging between 12 and 15. Phytochemical analysis led to the isolation of a number of phenolic glycosides, e.g. eriodictyol-, 5,7,4’-trihydroxyflavanone-, kaempferol- and 5,7-dihydroxychromone-7-O-beta-D-glucopyranoside, not previously known from M. foetida. In order to prove one possible mode of action the influence of the crude extracts as well as the isolated compounds on the heme degradation with chloroquine as reference compound was evaluated. The ethyl acetate extract showed about 88% inhibition of heme degradation, quite similar to chloroquine (84 %), and also eriodictyol-7-O-beta-D-glucopyranoside (2) inhibited heme degradation by 86 %.