In Vitro Efficacy Study Of Some Selected Medicinal Plants Against Leishmania Spp

In this study, 112 gradient extracts in petroleum ether, chloroform and methanol as solventsrnand three essential oils obtained from the root and aerial parts of ten Ethiopian medicinalrnplants belonging to eight families were screened for their in vitro leishmanicidal activitiesrnagainst clinical isolates of L. donovani and L. aethiopica. Those that showed antipromastigoternactivity were further tested on promastigote and axenic amastigote forms of thernparasites. Toxicity study was done on human monocytic leukemia (THP-1) cell line andrnerythrocytes in vitro. Assays were done using simple microscopic cell counting, fluorescencernor absorbance measurements as parameters. Phytochemical investigation was done on thernplant extracts using chemical test method.rnResults of the preliminary screening test indicated that 78 extracts (69.6 %) had significantrngrowth inhibitory effect (> 90%) on at least one Leishmania spp. at the test concentrationsrnused. The non-polar and medium polar fractions were more active on both promastigote andrnaxenic amastigote forms than the polar ones. Fourty eight (61.5%) and 55 (70.5%) of thernextracts had EC50 values less than 10 μg/ml against axenic amastigotes of Leishmania rnaethopica and Leishmania (L.) donovani respectively. Extracts with EC50 < 3 μg/ml werernobtained from petroleum ether extracts of Artemesia abyssinica (leaves), Crotonrnmacrostachys (berries and leaves), Echnops kebericho (tuber), Erythrina brucei (stembark)rnand chloroform extract of Echnops kebericho (tuber). Cytotoxicity and hemolysis testsrnindicated that 71(91%) and 76 (97.4%) extracts respectively were safe (SI > 1) at EC50rnvalues. The most cytotoxic extracts on THP-1 cells (SI < 1) were obtaned from Albiziarnschimperiana (CC50 = 1.05 + 0.03 to 13.01 + 0.49 μg/ml) where as strongly haemolyzingrnxirnextract (SI < 1) were obtained from polar fractions of Albizia schimperiana (stembark &rnrootbark) and Aloe (stem). The anti-leishmanial effect of essential oils on promastigote (MICrn0.0097 to 0.1565 μl/ml) and axenic amastigote (EC50’s 0.018 + 0.006 to 53.36 + 7.65 nl/ml)rnof L. donaovani and L. aethopica was comparable or at times higher than that of the standardrnanti-leishmanial drugs. The oils also had low to moderate toxicities (SI= 0.8 to 44) on THP-1rncell line (CC50’s 0.40 + 0.01 to 350 + 5.0 μl/ml) and erythrocytes (LC50’s 0.70 + 0.27 to 2.62 +rn1.0). Essential oil from Echnops kebericho had the highest activity against Leishmania andrnalso highest cytotoxicity on THP-1 cells. Essential oil from Artemesia abyssinica showed thernhighest haemolytic effect. The phytochemical screening demostrated presence of alkaloids,rnpolyphenols, tannins, flavonoids, saponins, anthraquinones, coumarins, terpenes, phytosterolsrnand whithanoids in different fractions and most of these class of phytochemicals werernpreviously reported to have ant-leishmanial activity.rnFindings from this study revealed that extracts from Artemesia abyssinica, Crotonrnmacrostachys, Echnops kebericko and Erythrina brucei and all the essential oils havernpotential anti-leishmanial activities and this warrants fractionation and isolation of activernconstituents for further in vitro/in vivo evaluation.

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