Leishmanicidal, cytotoxic and apoptotic effects of Gossypium hirsutum bulb extract and its separated fractions on Leishmania major

Background & objectives: Leishmaniasis is a major global health problem with no safe and effective therapeutic drugs. This study evaluated the cytotoxic and apoptotic effects of crude extract and fractions of Gossypium hirsutum bulb on Leishmania major stages using advanced experimental models.Methods: Bulbs of G. hirsutum were collected from the Kerman province of Iran. The bulb was extracted using Soxhlet apparatus and different fractions were obtained by column chromatography (CC). Different concentrations of the extract and the fractions were evaluated against L. major and compared with Glucantime®. The cytotoxicity and apoptotic values were analysed by flow cytometry. The fractions obtained in CC were monitored by thin layer chromatography, and fractions with similar chromatographic patterns were mixed.Results: The extract and two fractions, F4 and F5 inhibited the proliferation of L. major promastigotes and amastigotes in a dose-dependent manner at 72 h post-treatment. No significant cytotoxic effects were observed for extract and fractions, as the selectivity index was over 1000, far beyond >10. The mean apoptotic values for L. major were superior to those of Glucantime®.Interpretation & conclusion: Both the crude extract and fractions (F4 and F5) had significant antileishmanial effects on L. major stages, and were were superior relative to Glucantime®. No cytotoxic effects were associated with the extract or fractions and they showed excellent apoptotic index, a possible mechanism behind inducing parasite death. Further investigations are essential to study the effect of G. hirsutum bulb fractions in animal model and clinical settings for planning strategies for the prevention and control of leishmaniasis.