Objectives: The aim of this study was to evaluate the cytotoxicity and antileishmanial activity of cisplatinbonded carbon nanotubes both against promastigotes and amastigotes of Leishmania major in vitro. Methods: Cisplatin-bonded single-walled carbon nanotubes (CP-SWCNT) and cisplatin-bonded multiwalled carbon nanotubes (CP-MWCNT) were considered as test compounds. In addition, SWCNT, MWCNT, free cisplatin and meglumine antimoniate (Glucantime1) were considered as controls. The effect of each compound was evaluated both on promastigote and amastigote stages of L. major and the results were compared. Results: There was a statistically significant difference between the half-maximal inhibitory concentration (IC50) of CP-SWCNT and each of the controls, including SWCNT, cisplatin and Glucantime1 (P < 0.05). In addition, IC50 values of CP-MWCNTand each of the controls, including MWCNT, cisplatin and Glucantime1, were significantly different both for promastigotes and amastigotes (P < 0.05). However, the selectivity index (SI) of CP-SWCNT was <10 (5.23), indicating that this compound is not completely safe. Moreover, the SI values of CP-MWCNT (12.54) and Glucantime1 (16.28) were >10, indicating the selective effect of these two compounds on the parasite. Moreover, the IC50 of CP-MWCNT (0.11 0.09 mM) for amastigotes was 41-fold lower than that of Glucantime1 (4.52 1.31 mM), suggesting that a lower dose of CP-MWCNT in comparison with Glucantime1 is required to kill 50% of amastigotes. Conclusions: According to the potent in vitro antileishmanial activity of CP-MWCNT at low concentration against L. major, we suggest that they are evaluated in an animal model.
