Studies on medicinal plants of Ivory Coast: investigation of Sida acuta for in vitro antiplasmodial activities and identification of an active constituent.

Sida acuta Burm. (Malvaceae) originating from Ivory Coast was selected after an ethnobotanical survey: traditional healers of malaria commonly used this plant for the treatment. Extracts were tested on two strains of Plasmodium falciparum: FcM29-Cameroon (chloroquine-resistant strain) and a Nigerian chloroquine-sensitive strain. Extracts were obtained by preparing decoction in water of the powdered plant, the technique used by most of the traditional healers. An ethanol extract was then made and tested. The IC50 values obtained for these extracts ranged from 3.9 to -5.4 microg/ml. Purification of this active fraction led to the identification of cryptolepine as the active antiplasmodial constituent of the plant.

In vitro antiplasmodial activity of extracts of Alchornea cordifolia and identification of an active constituent: ellagic acid.

Extracts of leaves of Alchornea cordifolia were studied for their antiplasmodial activities. Chloroformic and ether extracts were found to be inactive while the ethanolic extract exhibited mild in vitro activity against Plasmodium falciparum. Fractionation of this extract led us to isolate ellagic acid as the active constituent of the extract with IC(50) in the range of 0.2-0.5 microM. Cytotoxicity of ethanolic fraction and ellagic acid was also estimated on human fibroblasts cells (IC(50) on Hela cells = 7.3 microM at 24 h for ellagic acid).

Antiplasmodial activity of plant extracts used in west African traditional medicine.

Five plants originating from Ivory Coast were selected after an ethnobotanical survey, Alchornea cordifolia, Mitragyna inermis, Nauclea diderrichii, Pterocarpus santalinoides, and Terminalia glaucescens. Traditional healers for the treatment of malaria commonly used these plants. Extracts of these plants were tested on three strains of Plasmodium falciparum, FcB1-Colombia and FcM29-Cameroon (chloroquine-resistant strains) and a Nigerian chloroquine-sensitive strain. Extracts were obtained by preparing decoction in water of the powdered plant, the technique used by most of the traditional healers. A radioactive micromethod allowed the evaluation of the in vitro activity of the extracts on P. falciparum. Concentrations inhibiting 50% of the parasite growth (IC(50)) ranged from 2.34 to more than 500 microg/ml according to the plant. For the most active plants (A. cordifolia and T. glaucescens) ethanol and pentane extracts were made and tested. The IC(50) values obtained for these extracts ranged from 0.35 to 43.40 microg/ml. The stage specificity of the ethanol extracts of A. cordifolia and T. glaucescens and pentane extract of T. glaucescens on the parasite erythrocytic cycle were determined. The ethanol extract of T. glaucescens showed its highest activity at the transition from the trophozoite to the schizont stages. Cytotoxicity was estimated on human fibroblasts (HeLa) cells and a cytotoxicity/antiplasmodial index was calculated, it ranged between 5 and 21, and the best antiplasmodial extract (T. glaucescens ethanol extract) had the higher index (>20).

In vitro antiplasmodial activity of stem and root extracts of Nauclea latifolia S.M. (Rubiaceae).

Aqueous extracts from Nauclea latifolia S.M. (Rubiaceae), a plant commonly used in Ivory Coast by traditional healers for the treatment of malaria, were tested on two strains of Plasmodium faliparum: FcB1-Colombia (chloroquine-resistant) and a Nigerian strain (chloroquine-sensitive). The extracts were obtained from stems and roots of the plant in two forms, infusion and decoction, both methods used by most traditional healers. The in vitro activity of N. latifolia extracts on P. falciparum was assessed both visually and by a radioactive method. The visual analysis allowed determination of the time of extract action on the erythrocytic cycle, as well as the parasitic stage of most inhibitory effect. Similar results were obtained applying fresh, frozen or lyophilized extracts. The IC50 values determined were within the range already reported for other antimalarial plants such as Azadirachta indica A. Juss (Meliaceae) or Artemisia annua L. (Asteraceae). Aqueous extracts of N. latifolia inhibited P. falciparum (FcB1 strain) mainly at the end of the erythrocytic cycle (32nd to 48th hour).

In vitro antimalarial activity of vegetal extracts used in West African traditional medicine.

Among strategies for the development of new antimalarials, a study of plants traditionally used in Africa against malaria has been pursued. Extracts obtained from the plants Azadirachta indica, Cinnamonum camphora, Lippia multiflora, Vernonia colorata, Guiera senegalensis, Combretum micranthum, and Ximenia americana, commonly used in Cote d'Ivoire by native healers for the treatment of malaria, were tested on two strains of Plasmodium falciparum: FcB1-Colombia (chloroquine-resistant) and F32-Tanzania (chloroquine-sensitive). Extracts were obtained after infusion and decoction, both techniques being used by most native healers. The antimalarial activities of the extracts were tested first by parasite 3H-hypoxanthine incorporation and second by visual evaluation of the activities of plant extracts on thin blood smears, which also permitted the determination of parasitic stages and parasite alteration. Among the seven plants tested, some had an apparent inhibitory effect on P. falciparum growth in vitro, while other seemed to be less efficient.

Composition and antimalarial activity in vitro of volatile components of Lippia multiflora.

The essential oil of Lippia multiflora was prepared by hydrodistillation of leaves and stalks and characterized by GC and mass spectroscopy. The oil was tested for antimalarial activity on in vitro cultures of Plasmodium falciparum (FcB1-Columbia chloroquine-resistant strain and F32-Tanzania chloroquine-sensitive strain). The dilutions inhibiting the in vitro growth of the parasite by 50% 24 and 72 hr after administration of the essential oil to the parasite culture were 1/12,000 and 1/21,000, respectively. When tested on a highly synchronized culture, the essential oil inhibited growth mostly at the trophozoite-schizont step, indicating a potential effect on the first nuclear division of the parasite.

Antimalarial activity in vitro of Cochlospermum tinctorium tubercle extracts.

Resistance of Plasmodium falciparum to current antimalarial compounds has drastically increased during the last few years and is now a major public health problem. We have studied plants traditionally used in Africa against malaria. Extracts of the tubercles of Cochlospermum tinctorium A. Rich, commonly used in Burkina Faso, were tested in vitro on 2 strains of P. falciparum, one (FcB1-Colombia) chloroquine resistant and the other (F32-Tanzania) chloroquine sensitive. Extracts were obtained by infusion and decoction. The 50% inhibitory concentrations (IC50) were determined by measuring [3H]hypoxanthine incorporation and also by microscopical examination which permitted the determination of parasite stages. We obtained similar results with fresh extracts, frozen extracts, and lyophilized extracts of C. tinctorum. IC50 values were of the order of 1-2 micrograms/mL, about one-tenth of those reported for extracts of neem leaves (Azadirachta indica) and about half the values reported for Artemisia annua extracts.