In vitro antiprotozoal activity of organic and aqueous extracts of several Turkish Lamiaceae species

The in vitro antiprotozoal activities of methanolic extracts and subextracts prepared from the aerial parts of five Lamiaceae plants (Salvia tomentosa Miller, S. sclarea L., S. dichroantha Stapf., Nepeta nuda L. subsp. nuda and Marrubium astracanicum Jacq. subsp. macrodon (Bornm.) P.H. Davis were evaluated against four parasitic protozoa, Trypanosoma brucei rhodesiense, T. cruzi, Leishmania donovani and Plasmodium falciparum. The cytotoxic potentials of the extracts on L6 cells were also evaluated. Melarsoprol, benznidazole, miltefosine, chloroquine and podophyllotoxin were used as reference drugs. MeOH extracts showed antiprotozoal potential against three or four parasites. Hence, they were dispersed in water and partitioned against n-hexane and chloroform, respectively, to yield three subextracts that were screened in the same test systems. The n-hexane extract of N. nuda was the most active against T. brucei rhodesiense with IC50 value of 0.62µg/mL, whilst the CHCl₃ extracts of S. tomentosa and S. dichroantha showed significant activity against L. donovani (IC₅₀ 1.81 and 2.31µg/mL, respectively). All organic extracts displayed moderate trypanocidal potential against T. cruzi with hexane extract of S. sclarea being the most active one (IC50 18.17µg/mL). Again all organic extracts exhibited remarkable antimalarial activities and with IC50 values in the range of 2.54–3.78µg/ml, the chloroform subextracts appeared to be slightly more potent than the hexane subextracts (IC₅₀ values 3.37–4.64µg/mL). The extracts displayed low or no cytotoxicity towards mammalian L6 cells. This is the first study reporting the antimalarial, leishmanicidal and trypanocidal effects of the genera Salvia, Nepeta and Marrubium that are native to Turkey.

Keywords: Lamiaceae, Nepeta, Salvia, Marrubium, Antiprotozoal activity