Affiliation: Leishmaniasis Research Center, Kerman University of Medical Sciences, Kerman, Area code 76169- 14115, Iran.
Aim: Plant extracts or plant-derived compounds are likely to provide a valuable source of new medicinal agents. In the present work anti-leishmanial activity of methanolic extracts of Gossypium hirsutum, Ferula assa-foetida and Artemisia aucheri, was studied on Leishmania major promastigotes by colorimetric assay in comparison to a trivalent antimony compound (tartar emetic). Methods: L. major promastigotes were cultured at 24±1°C to stationary phase in RPMI 1640 medium, supplemented with 10% heat inactivated fetal calf serum (FCS) and antibiotics. The biological activity of three plant extracts was studied against L. major promastigotes in comparison to tartar emetic. The optical density (OD) due to cleavage of the tetrazolium salt MTT [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] into a colored product formazan by the parasite was measured using an ELISA reader, to determine IC50 values (50% inhibitory concentrations). All experiments were repeated in triplicate. Results: All three plant extracts and tartar emetic inhibited the growth of promastigote stage of L.major after 72 hours of incubation. Tartar emetic as positive control gave a 50% inhibitory concentration (IC50) of 4.7µg/ml, while the IC50 values of G. hirsutum, F. assa-foetida and A. aucheri, were determined as 3.6, 5.9 and 7.5µg/ml, respectively. Although G. hirsutum was more active than the others, but all extracts had profound effects on promastigotes of L. major. Conclusion: This study provides valuable data on potent activity of three plant extracts. Further works are required to evaluate the leishmanicidal effect of these plant extracts on animal models or human volunteers.