Anti Leishmanial Effect of Zinc Sulphate on the Viability of Leishmania tropica and L. major Promastigotes

BACKGROUND: Cutaneous leishmaniasis (CL) is an endemic disease in developing countries. Although pentamidine orantimonite (Glucantime) has been recommended for cutaneous leishmaniasis treatment by the World Health Organization, there are some concerns too such as high cost, side effects, need for frequent injections, and restricted efficacy. Therefore, different methods have been used for CL treatment so far. OBJECTIVES: This study assessed the sensitivity of two parasite agents of cutaneous leishmaniasis: Leishmania major and L. tropica to zinc sulphate in vitro. In the present study, the zinc sulphate effect on urban and rural strains of cutaneous leishmaniasis, viability of old world, in vitro is under investigation. MATERIALS AND METHODS: The design of the present study was experimental (laboratory-trial) based. Iranian endemic species of L. major and L. tropica were appropriately collected, proliferated, and maintained in the standard culture. Afterward, the proper concentrations of zinc sulphate were provided, sterilized, and added to the cultures containing parasites. In different intervals, parasites were counted by two methods: the slide and cell proliferation ELISA. RESULTS: Both parasite species showed sensitivity to zinc sulphate in vitro and in comparison with the control group, their numbers were reduced. Zinc sulphate (in concentrations of 0.5, 1, 2, and 3 percent) was added to the cultures containing parasites, and the total number of the live parasites was counted through the slide method (Neubauer slide) every day up to the fifth day. The results were analyzed and found statistically significant (P < 0.05). In the second phase, the counting process was repeated with the addition of zinc sulphate compound with different concentrations (3, 4, 5, and 6 percent) and live parasite numbers were counted by ELISA method after 24 hours. The findings revealed that all the cultures containing zinc sulphate showed a slower growth in comparison to the control group. The mentioned difference was statistically significant (P < 0.05). CONCLUSIONS: Considering the safety of zinc sulphate compound in comparison with Glucantime, there is a possibility of using it in the treatment of CL caused by both species of L. major and L. tropica. It is obvious that more researches are mandatory both in vivo and in vitro to figure out its daily dosage, proper concentration, time and duration, and possible side effects.