Phytochemical study of plants used in traditional medicine in the treatment of malaria in the Comoros islands
An ethnobotanical survey was carried out in the Comoros Islands about plant species used traditionally for the treatment of various diseases including malaria. The in vitro antiplasmodial activity of 76 vegetal extracts obtained from 17 species traditionaly used to treat malaria symptomes, was evaluated using Plasmodium falciparum choloroquine-resistant strain (W2). The results showed that 10 plant extracts had a moderate activity (5 < IC50 ≤10µg/ml), and 6 showed particularly interesting in vitro activity with IC50 value ≤5µg/ml . The phytochemical study realized on three selected plants, Flueggea virosa (Roxb. Ex Willd.) Voigt subsp. Virosa (Euphorbiaceae), Piper capense L.f. (Piperaceae), and Flacourtia indica (Burm. F.) Merr. (Flacourtiaceae) allowed us to isolate compounds from the most active extracts. The structures of isolated compounds were elucidated by spectrometric methods and their antiplasmodial activity was evaluated in vitro against the chloroquine-resistant strain W2 of Plasmodium falciparum, according to Azas, 2002 . From F. virosa, rutine, gallic acid, methyl gallate, bergenin, (–)-norsecurinine, securinol A, N-methyltetrahydro-β-carboline and N-methyltryptamine were isolated. The highest antiplasmodial activity was found for methyl gallate (IC50=14.1µM). Together with apigenine dimethylether and piperchabamide A, a new amide alkaloid, Kaousine and the Z form of antiepilepsirine were isolated from the aerial part of P. capense. Lower activity was observed for kaousine and apigenine dimethylether, whereas antiepilepsirine demonstrated the same activity that the chloromethylenic extract of P. capense (IC50=7µg/ml) . Pyrocatechol, homaloside D and poliothrysoside were isolated from the decoction of the aerial parts of F. indica. The poliothrysoside presented a strong antiplasmodial activity (IC50=7.4µM) and a good selectivity index (>28) similar to chloroquine.
References: 1. Mohamed Kaou, A. et al. (2008)J. Ethnopharmacol 116: 74–83.
2. Azas, N et al. (2002) Parasitol Res. Ss: 165–171.
3. Mohamed Kaou, A. et al. (2010) Fitoterapia (In press).