In Vitro Antileishmanial Activity of Achillea santolina Essential Oil against Leishmania infantum Promastigote by Methylthiazole Tetrazolium (MTT) and Trypan Blue Colorimetric Methods

Leishmaniasis causes parasitic infections, especially in developing countries. The disease has not yet been controlled because of the absence of an effective vaccine and low-cost treatment. Achillea santolina essential oil (ASEO) might control the disease as it has antimicrobial properties. This study investigated the in vitro antileishmanial activity of ASEO against Leishmania infantum promastigote using the methylthiazole tetrazolium (MTT) and trypan blue colorimetric methods. The standard strain of L. infantum (MCAN/IR/96/LON49) promastigotes was prepared and cultured in a 96-well Novy-MacNeal-Nicolle (NNN) medium. The effects of different concentrations of saline, ASEO, and glucantime (10, 50, 100, 200, 500, and 1000 mg/mL) were examined in 24-, 48-, and 72-hour intervals using the MTT and trypan blue test methods.The use of ASEO reduced viability in all concentrations compared to the control group in times of 48 (p<0.05) and 72 h (p<0.05). Treatment with glucantime and ASEO had similar efficiency with the concentration of 1000 mL/mg in both methods after 72 h. The results showed that viability was significantly lower in the ASEO group with increases in time using both methods (p<0.05). Cohen's Kappa coefficient showed a significant agreement between the obtained results for the two methods (Kappa=0.856; p<0.001).In sum, the results showed in vitro antileishmanial activity of ASEO, but more clinical studies are needed to confirm the efficiency. ASEO can be used as an agent and/or in combination with synthetic agents for the treatment of leishmaniasis disease.