Human leishmaniases are a spectrum of diseases caused by protozoan parasites of the genus Leishmania. In this
study antileishmanial activity of the methanolic and water leaf extracts from Aloe secundiflora plant were
analysed by determining the minimum inhibition concentration (MIC), nitric oxide (NO) production stimulation,
infection rates (IR) and multiplication index (MI). Cytotoxicity of these plant extracts was also assessed. The
MIC levels of water and methanolic plant extracts, amphotericin B and pentostam were 2000 μg/ml, 1000 μg/ml,
125μg/ml and 250 μg/ml respectively against Leishamnia major promastigotes. This study revealed that water
and methanolic plant extracts significantly inhibited the growth of Leishmania parasites (P ≤ 0.05) as compared
to amphotericin B with respect to the parasite infection rates and MIC levels. The IC50 for the water and
methanolic plant extracts was 279.488 μg/ml and 42.824 μg/ml respectively. The elevated inhibitory activity
observed in this study against Leishmania major parasites provides evidence and basis for their potential use as
therapeutic agents against leishmaniasis.