Amazonian plants from Peru used by Quechua and Mestizo to treat malaria with evaluation of their activity.

Indigenous Quechua and Mestizo populations from distinct areas in Loreto, Peru, were interviewed about traditional medication for the treatment of malaria. An ethnographic survey concerning the native theory of illness aetiology in the specific case of malaria permitted the elaboration of an efficient ethnopharmacological enquiry. The survey took place on three main zones corresponding to villages on the Napo and the Pastaza rivers (for the Quechua), and in the surroundings of Iquitos (for the Mestizos) and led to the collection of 14 plants. Serial extractions in hexane, dichloromethane, and methanol were performed on the different parts of the plants collected. The extracts were then tested for antiplasmodial activity in vitro. Seven plants displayed antiplasmodial activity (IC(50) from 2 to 25 microg/mL) and usually low cytotoxicity, indicating their antiplasmodial specificity. The results give scientific validation to the traditional medical knowledge of Quechua and Mestizo populations from Loreto and confirm a source of potentially active plants.

Quassia amara L. (Simaroubaceae) leaf tea: effect of the growing stage and desiccation status on the antimalarial activity of a traditional preparation.

In French Guiana, Quassia amara L. (Simaroubaceae) leaf tea is a well-known widely used traditional antimalarial remedy. Impact of the vegetal sampling condition on in vivo and in vitro antimalarial activity was assessed. Traditional infusions were prepared with juvenile or mature leaves, both either fresh or dried. Results showed that growing stage and freshness of vegetal material exert a striking effect on antimalarial activity, both in vitro and in vivo. By far, leaf tea made from fresh juvenile (FJ) Quassia amara leaves was the most active. In vitro, active component (simalikalactone D) concentration correlates biological activities, although unexplained subtle variations were observed. In vivo, tea made with dried juvenile (DJ) leaves displays a peculiar behavior, meaning that some components may help simalikalactone D delivery or may be active in vivo only, therefore enhancing the expected curative effect of the traditional preparation.

Simalikalactone D is responsible for the antimalarial properties of an Amazonian traditional remedy made with Quassia amara L. (Simaroubaceae).

French Guiana (North-East Amazonia) records high malaria incidence rates. The traditional antimalarial remedy most widespread there is a simple tea made out from Quassia amara L. leaves (Simaroubaceae). This herbal tea displays an excellent antimalarial activity both in vitro and in vivo. A known quassinoid, simalikalactone D (SkD), was identified as the active compound, with an IC(50) value of 10nM against FcB1 Plasmodium falciparum chloroquine resistant strain in vitro. Lastly, it inhibits 50% of Plasmodium yoelii yoelii rodent malaria parasite at 3.7 mg/kg/day in vivo by oral route. These findings confirm the traditional use of this herbal tea.

Validation of use of a traditional antimalarial remedy from French Guiana, Zanthoxylum rhoifolium Lam.

Zanthoxylum rhoifolium bark (Rutaceae) is a medicinal plant, traditionally used in French Guiana to treat and prevent malaria. Bioassay-guided extractions of Zanthoxylum rhoifolium bark have shown that antiplasmodial activity is concentrated in the alkaloid fraction. Further fractionation of this extract has yielded seven benzophenanthridine alkaloids, dihydroavicine 1, dihydronitidine 2, oxyavicine 3, oxynitidine 4, fagaridine 5, avicine 6 and nitidine 7. Antimalarial activity of the last five compounds has been evaluated, and nitidine was the most potent, displaying an IC(50)<0.27microM against Plasmodium falciparum. Investigation of the traditional remedy, a trunk bark decoction in water, has shown that fagaridine 5, avicine 6 and nitidine 7 are also present in the decoction, therefore justifying the traditional use of Zanthoxylumrhoifolium bark as antimalarial.

A non-radiolabelled ferriprotoporphyrin IX biomineralisation inhibition test for the high throughput screening of antimalarial compounds.

Intraerythrocytic malaria parasites produce large amounts of toxic ferriprotoporphyrin IX (FP) during their digestion of host cell haemoglobin. The inhibition of biomineralisation of FP to haemozoin (or beta-haematin) by antimalarial drugs underlies their mode of action. We have developed an in vitro microassay for testing the inhibition of biomineralisation by drugs. It is based on the detection by optical density measurement of solubilised beta-haematin remaining after contact with drugs. The assay uses a 192-microM haemin chloride solution in dimethyl sulfoxide, 96-well filtration microplates as well as normal microplates; it lasts 18-24h and requires a spectrophotometer. We determined by this assay the IC(50) of chloroquine phosphate (28microM) and quinine base (324microM) and showed that unlike previous methods it is insensitive to inorganic anions. We also determined the activity of synthetic dyes and plant extract to determinate the interference of coloured compounds on the accuracy of the test. We found that methylene blue, thionine (IC(50) 38 and 87microM, respectively), and an extract of plants that contains quinoline derivatives, inhibited the biomineralisation of FP regardless of their intrinsic colour.