Effects of Ricinus Communis Linneaus (Euphorbiaceae) Extracts on Leishmania Major Promastigotes and on Infected Balb/c Mice

Abstract

The effect of castor oil plant seed oil fractionally extracted with diethyl-ether and the aqueous extracts of its leaves was tested in vitro on Leishmania major (Yorkimov and Schokor, 1913) promastigotes and in vivo on Leishmania major lesions in inbred BALB/c mice. Four experimental groups of 35 female mice each were used namely seed oil group (oil topically applied); Aqueous leaf extract group (extract administered intraperitoneally); Pentostam'P (sodium stiboglnconate) group (drug administered intraperitoneally) and a control group (untreated infected mice). Before infection, footpad measurements were taken - by measuring the left hind footpad (LHFD) and the contralateral right hind - footpad (RHFD).- All the mice were infected intradermally with L. major-- stationary primary phase metacyclic promastigotes at a dosage of 1 x 106 per 1O~1on the left hind footpad of every mouse and lesion sizes measured weekly at 7 day intervals. Treatment was commenced 30 days post-infection. Within this time lesion sizes were measured using vanier calipers every 7 days. The experimental groups were treated for six weeks and observed for another 2 weeks before being sacrificed. Impression smears and cultures of spleen were made to determine the parasite load and visceralization while right hind , footpad, (RHFD), was left as a contralateral control. Results of the study showed that there was antileishmanial effect due to the R. communis oil that was significantly better than the effect of the leaf extracts (Tukey test, q=4.059, P<0.05). However, the effect compared poorly to the standard treatment drug. Notwithstanding, it was found that the R. communis aqueous leaf extracts was much better at preventing metastasis, visceralization, and a much lower Leishmania donovani Unit (LDU) than the seed oil possibly due to the that the leaf infusion was administered intraperitoneally. Surprisingly enough the seed oil appeared to have visible effects at reducing lesion size that was significantly better than the leaf extract. However sodium stibogluconate still proved better. It is recommeded that R. communis seed oil be explored furthur as a potential canditate for use in combination therapy with other antileishmanial drugs used for the treatment of cutaneous leishmaniases.