| dc.description.abstract | is a disease of major public health and economic importance. It is one of the major infections affecting the poorest regions of the world. In Kenya many communities use a variety of medicinal plants to treat a number of infections. This study investigated the leishmanicidal effects of extracts from Terminalia spinosa, Leonotis nepetifolia and Albizia anthelmintica against Leishmania major promastigotes in vitro. Communities in Baringo use these plants to treat kala-azar or splenomegaly related ailments. Therefore the study aimed at confirming this.
Methanol extract of A. anthelmintica had the highest antipromastigote activity of 61.21 % at 1000 ug/ml followed by that ofA. anthelmintica water extract (43.18 % killing) at the same concentration. All extracts displayed some antipromastigote activity compared to negative control (P<0.05). The mortalities induced by all extracts were above 30 % except the leaves water extract from L. nepetifolia which was the least active (25.89 % killing) at 1000 ug/ml. When the IC50s of various extracts were compared, extracts from A. anthelmintica showed the lowest value (ICso of 1.2877 mg Iml) implying the highest activity on L. major promastigotes in vitro. Extracts from the other plants had ICsos above 4mg/ml.
The study also investigated the effects of the extracts on L. major-infected macrophages and hence nitric oxide production. Terminalia spinosa stem bark water and leaves methanol extracts had the highest NO levels among extracts (Optical densities of 0.269 and 0.25 respectively) at 1000 ug/ml. All extracts activated the L. major- infected macrophages to produce NO compared to negative control (P<0.05). This implies the extracts have immunomodulatory effect on L. major-infected macrophages in vitro and hence production of nitric oxide. Albizia anthelmintica (stem bark) methanol extract had the lowest infection rate (37 %) at 1 000 ug/rnl (compared to 25 % of Pentostam® at the same concentration), implying highest activity among extracts. The rest of the extracts had infection rates above 50 %. The same pattern observed for infection rates was also noted for the multiplication indices.
It was observed by light microscopy that effective antiamastigote concentrations of various extracts inflicted no significant damage on L. m~jor-infected macrophages in vitro (P<0.05). At a concentration of 1 000 ug/ml of Pentostam, 49 % of the macrophages were damaged after incubation for 48 hours, but for A. anthelmintica stem bark methanol extract, only 26 % of the macrophages were damaged at the same concentration. The damage caused by the rest of extracts was not significant as the percentage of damaged macrophages was below 20 % at 1 000 ug/ml.
Overall, the results of this work especially for A. anthelmintica, present extracts which are nontoxic to mouse peritoneal macrophages at concentrations that effectively kill a higher percentage of intracellular parasites in vitro. Through bioassay-guided chemical fractionation especially for A. anthelmintica, active compounds will be isolated and tested for leishmanicidal activity in vivo. | |
