Evaluation of antiplasmodial activity of extracts from endemicmedicinal plants used to treat malaria in Côte d'Ivoire

Introduction: Plasmodium falciparum strainshad been increasingly resistant to commonlyused molecules including artemisinin. Itis therefore urges to find new therapeuticalternatives. Methods: In this study, the antiplasmodialactivity of 21 extracts obtained from sevenplants of the Anthocleista djalonensis,Cochlospermum planchonii, Harunganamadagascariensis, Hoslundia opposita,Mangifera indica, Margaritaria discoidea and Pericopsis laxiflora of the Ivorian pharmacopoeiawas evaluated on the chloroquine sensitive (NF54) and multi-resistant (K1) reference strains andon clinical isolates as well. The technique used was the microtiter method based on fluorescencereading with SYBR Green. Results: The aqueous extract of the bark of H. madagascariensis and methanolic extracts of P.laxiflora showed the best antiplasmodial activity with IC50 values of 6.16 μg/mL and 7.44 μg/mL, respectively. On the other hand, extracts of M. indica showed a very moderate activitywith IC50 values between 15 μg/mL and 50 μg/mL (5<IC50<50 μg/mL) on the same strains of P.falciparum. Only the aqueous extract of A. djalonensis had IC50 values greater than 50 μg/mL. Thephytochemical analysis showed a strong presence of polyphenols and alkaloids in extracts with acumulative rate of 90.47% and 95.23%, respectively. Conclusion: The results obtained were also justified by the composition of these plants, whichhave several secondary metabolites involved in the treatment of malaria. The antiplasmodialproperties of these plants could partially justify their use in malaria treatment. Further studies onthese extracts are needed to manufacture a stable galenic formulation for the development of animproved traditional medicin

P17 Activité anti plasmodiale de Talinum triangulare (TALINACEAE)

Introduction : L’émergence et l’extension des souches résistantes aux antipaludiques actuels nécessitent la recherche diligente de nouvelles molécules actives et les plantes médicinales représentent une alternative de choix. Méthodologie : Les extraits aqueux et hydro-éthanolique des feuilles de Talinum triangulare ont été testés ex vivo sur la chimio-sensibilité de Plasmodium falciparum à partir de la méthode colorimétrique à l’HRP2 (test ELISA). Les tests de chimio-sensibilité ont été réalisés sur des isolats cliniques de P. falciparum isolés sur des patients de parasitémie comprise entre 0,1 et 0,3 %, et à 5 % d’hématocrite. Ensuite, les composés chimiques présents dans ces extraits ont été identifiés par la méthode qualitative. Résultats : Les résultats ont révélé que tous les extraits ont une très bonne activité antipaludique avec des CI50 < 5 μg/mL avec une meilleure activité de l’extrait hydro-éthanolique. Le tri phytochimique réalisé a révélé la présence de métabolites secondaires tels que les alcaloïdes, les stérols et les polyterpènes. Conclusion : Talinum triangulare constitue une ressource prometteuse dans la recherche de molécules antipaludiques

Improved Protocol for Continuous Culture of Plasmodium falciparum Reference Strains

Parasitic biobank of Plasmodium falciparum is almost germinal in Côte d’Ivoire. However, several high-level research topics on this parasite involve the taking into account of nature isolates but also chemo-sensitive or resistant reference strains for a better validation of results. In addition, acquisition of these reference strains is still arduous for laboratories in developing countries due to complexity of administrative procedures. For those reasons, this study aimed in to combine several procedures into a consolidated one in order to enhance the multiplication of P. falciparum reference strains. Continuous culture of plasmodial strains was based on the Trager and Jensen procedures. The CELL culture protocols used are those of the Swiss TPH described by Sergio Wittlin; the “Growing Plasmodium falciparum cultures at high parasitemia” and the “Stockholm sorbitol method” of Methods in Malaria Research-6th edition 2013; and the INV-01 and INV-02 procedures of the Worldwide Antimalarial Resistance Network (WWARN). Reference Plasmodium falciparum strains NF54 sensitive to chloroquine (CQs) and K1 resistant to chloroquine (CQr) were received from the Swiss Tropical Institute and Public Health (Swiss TPH). The CQs NF54 strain reacted more quickly to the protocol unlike the CQr K1 strain. Parasitic densities (DP) obtained with NF54 strain were ranged from 0.4% at day zero (D0) to 11.4% at day eight (D8). Strain K1 finally adapted successfully after one month of follow-up. Related DPs ranged from less than 0.1% to more than 20% in just three growth cycles after adaptation. A joint protocol (from this work) called “CRLP-SwissTPH-Pasteur_001” is available and allows to efficiently multiply reference strains NF54 and K1. It is planned to spread out the tests to other plasmodial strains as well as to wild isolates in order to standardize this procedure