ACTIVITY OF TEPHROSIA VOGELII CRUDE EXTRACT AGAINST LEISMANIA MAJOR IN EXPERIMENTALLY INFECTED BALB/c MICE

Abstract

Leishmaniasis, a vector-borne disease caused by obligate intra-macrophage protozoa, is endemic in large areas of the Tropics, Subtropics and the Mediterranean basin and 350 million people are considered at risk. The drugs currently used in the treatment of leishmaniases are pentavalent antimonials such as Sodium stibogluconate (Pentostam) which are known to be expensive, toxic and resistance has been widely reported. Moreover, there is no vaccine that has been developed against leishmaniasis. Therefore, a need exists to investigate the activity of medicinal plants that may have anti-parasitic properties for the treatment of the leishmaniases. This study investigated the activity of Tephrosia vogelii against cutaneous leishmaniasis caused by Leishmania major using the BALB/c mouse model in vivo and in vitro. Pentostam and Amphotericin B were used as positive controls while Phosphate Buffered Saline and Roswell Park Memorial Institute 1640 Medium were used as negative controls in vivo and in vitro respectively. Five groups of eight female mice were used in the study. They were inoculated intradermally on the left hind footpad with 106 L. major infective promastigotes. The mice were treated intraperitoneally with the different drugs at daily doses for 28 days except for T. vogelii which was administered both orally and intraperitonealy. All experiments were performed in triplicate. The mean standard deviation of at least three experiments was determined and statistical analysis of the differences between mean values obtained for the experimental groups was done by the students’t-test. P. values of equal to or less than 0.05 (P≤0.05) were considered significant. Toxicity level for T. vogelii therapy was lower than standard drugs. There was significant difference in the test drugs against promastigotes (P<0.05). T. vogelii had an IC50 and IC90 of 12μg/ml and 68.5μg/ml respectively, while the positive controls had IC50 of 5.5μg/ml and 7.8 μg/ml for pentostam and amphotericin B respectively and IC90 of 18μg/ml and 25.5 μg/ml for pentostam and amphotericin B respectively. In the amastigote assay, the infection rates decreased with increase in concentration. There was significant difference between the standard drugs and T. vogelii in the infection rates (P=0.01). The Multiplication indices for L. major amastigotes in macrophages treated with 200µg/ml of the test drugs were significantly different (P<0.05). 200µg/ml of T.vogelii extract showed a multiplication index of 20.57%, 5.65% for Amphotericin B and 9.56% for pentostam. T. vogelii administered intraperitonealy resulted in larger lesion size reduction than the oral administration. The parasite loads and the Leishman Donovan Units in the spleens and liver of the treated mice were significantly low in T. vogelii administered intraperitonealy than those administered orally. However, standard drugs had better efficacy for reduction of parasite load (P=0.001). There was also significant levels of Nitric oxide produced in the macrophages (P<0.05). T. vogelii extract has anti leishmanial activity and further tests should be done on the extract to establish the active compounds responsible for antileishmanial activity.