Vitro Effects of Turmeric and Licorice Total Extracts on L. Major Promastigotes

Pentavalent antimonial compounds are the main treatment option for cutaneous leishmaniasis. However, their clinical use has limitations such as lack of efficacy by oral route, long-term treatment period, emergence of drug resistance in about 10-15% of cases, cardiac toxicity, and reversible renal insufficiency. Curcumins are phenolic derivatives extracted from turmeric rhizome which have anti-leishmania effects. Intraperitoneal injection of licochalcone A, extracted from licorice root, prevents ulcer in BALB/c mice infected by L. major. As a part of screening of Iranian herbs with potential antileishmanial activity, the effects of total extract of turmeric and licorice on L. major culture were assessed in this study.

Serial concentrations of 0.4, 0.5, 1, 2.5, 5 and 10 mg/ml were prepared from the dried plant extract. Moreover, 400 microliters of the parasite suspension was added to all test tubes except for the negative control in which only the culture media was added. Amphotericin B 0.1 mg/ml was used as the positive control. The average numbers of promastigotes of all three series of test tubes were calculated. For each concentration, percent of alive parasites at different times were recorded. The results were expressed as IC50 of each extract.

The 2 mg/ml concentration of turmeric extracts resulted in rapid death of promastigotes compared to 0.2 mg/ml concentration which killed them after 88 hours of exposure. The effects of licorice total extract were similar to negative control at lower concentrations (0.5 and 1 mg/ml). Increasing the concentration up to 16 mg/ml killed more promastigotes.

The results of this study showed that both turmeric and licorice total extracts have antileishmanial effects in-vitro. However, the overall activity of licorice on promastigotes is much less than turmeric. It also kills parasites at higher doses.