Screening Phytochimique, Étude Toxicologique, Évaluation des Activités Antiplasmodiale et Antiradicalaire de la Tige Feuillée de Senna occidentalis Linn (Fabaceae) - K., Esseh; Y-G., Afanyibo; K.Y.S., Ahama-Esseh; K., Idoh; K., Koudouvo; A., Agbonon; M., Gbeassor (European Scientific Journal, ESJ, 2019)
La valorisation de la mÃ©decine traditionnelle passe par des Ã©tudes pharmacologiques sur les plantes mÃ©dicinales. Ainsi pour lutter efficacement contre le paludisme, premier problÃ¨me de santÃ© publique au Togo, des Ã©tudes pharmacologiques, phytochimiques et toxicologiques ont Ã©tÃ© rÃ©alisÃ©es sur Senna occidentalis. La compilation des rÃ©sultats des enquÃªtes ethnobotaniques effectuÃ©es au CERFOPLAM de 2010 Ã 2013 sur le paludisme et ses symptÃ´mes affiliÃ©s ont permis de sÃ©lectionner Senna occidentalis afin de vÃ©rifier les propriÃ©tÃ©s qui lui sont attribuÃ©es. Les diffÃ©rents tests ont Ã©tÃ© rÃ©alisÃ©s sur les extraits aqueux et hydro-Ã©thanoliques 50 : 50 de la plante. Lâ€™activitÃ© antiplasmodiale in vitro a Ã©tÃ© rÃ©alisÃ©e sur une culture des parasites (Plasmodium falciparum : souche sauvage) selon le microtest optique. Le screening phytochimique a Ã©tÃ© caractÃ©risÃ© par la chromatographie sur couche mince suivie de tests colorimÃ©triques. La toxicitÃ© prÃ©liminaire a Ã©tÃ© rÃ©alisÃ©e sur Artemia salina puis le potentiel antioxydant in vitro des extraits a Ã©tÃ© mesurÃ© par le test de rÃ©duction du radical 2,2-diphÃ©nyl1-picryl-hydrazyl et le dosage des polyphÃ©nols. Le test antiplasmodial a montrÃ© que lâ€™extrait aqueux a une activitÃ© modÃ©rÃ©e sur le P. falciparum avec une CI50 de 91,08 Â± 0,61 Âµg/mL tandis que lâ€™extrait hydro-Ã©thanolique est trÃ¨s actif avec une CI50 de 1,00 Â± 0,05 Âµg/mL. La drogue de rÃ©fÃ©rence (Quinine) prÃ©sentant une CI50 = 0,45 Â± 0,01 Âµg/mL. Le screening phytochimique rÃ©vÃ¨le la prÃ©sence des grands groupes chimiques tels que les flavonoÃ¯des, les tanins, les saponosides, les coumarines et les alcaloÃ¯des qui seraient Ã lâ€™origine de lâ€™activitÃ© antiplasmodiale observÃ©e. Les tests antiradicalaires ont permis de retenir que Senna occidentalis nâ€™est pas antioxydant et possÃ¨de trÃ¨s peu de polyphÃ©nols. Cet aspect confirme lâ€™Ã©tat de stress que peut subir le Plasmodium falciparum vis-Ã -vis des diffÃ©rents extraits testÃ©s. Etant donnÃ© que les CL50 sont 3,31 mg/mL et 3,70 mg/mL donc trÃ¨s supÃ©rieures Ã 0,1 mg/mL, les deux extraits de plantes testÃ©s ne sont pas cytotoxiques. Tous ces rÃ©sultats combinÃ©s justifient le choix des tradipraticiens dans lâ€™utilisation de Senna occidentalis pour soigner leurs patients atteints du paludisme. The valorization of traditional medicine involves pharmacological researches on medicinal plants. Thus, to effectively fight malaria, the major public health problem in Togo, pharmacological, phytochemical and toxicological studies were carried out on Senna occidentalis. The compilation of the results on ethnobotanical surveys carried out at CERFOPLAM from 2010 to 2013 on malaria and its affiliated symptoms lead to selecting Senna occidentalis in order to confirm the characteristics attributed to it. Various tests were carried out on aqueous and hydroethanolic extracts 50:50 of the plant. The antiplasmodial activity in vitro was carried out on cultivated parasites (Plasmodium falciparum: wild strain) according to the optical micro-test. Phytochemical screening was characterized by thin layer chromatography followed by colorimetric tests. The preliminary toxicity was carried out on Artemia salina then the in vitro antioxidant potential of the extracts was measured by the reduction test of the 2, 2-diphenyl-1-picryl- hydrazyl radical and the determination of the polyphenols. The antiplasmodial test showed that the aqueous extract has a moderate activity on P. falciparum with an IC50 of 91.08 Â± 0.61 Î¼g / mL while the hydroethanolic extract is very active with an IC50 of 1, 00 Â± 0.05 Î¼g / mL. The reference drug (Quinine) with an IC50 = 0.45 Â± 0.01 Î¼g / mL. Phytochemical screening reveals the presence of large chemical groups such as flavonoids, tannins, saponosides, coumarins and alkaloids that may be responsible for the observed antiplasmodial activity. The antiradical tests have held that Senna occidentalis is not antioxidant and has got very few polyphenols. This aspect confirms the state of stress that Plasmodium falciparum can undergo against the various extracts tested. Since the LC50’s are 3.31 mg / mL and 3.70 mg / mL, therefore, higher above 0.1 mg / mL, the two extracts from plants which were tested are not cytotoxic. The combination of all these results justif the choice of traditional healers in using Senna occidentalis to treat their patients suffering from malaria.