In vitro studies on the antileishmanial activity of herbicides and plant extracts against leishmania major parasites

Abstract

Natural products and herbicides are potential sources of new and selective agents for the treatment of important tropical diseases caused by parasites. Leishmaniasis is a major health problem worldwide and affects millions of people especially in developing nations. There is no immunoprophylaxis (vaccination) available for Leishmania infections and conventional treatments are unsatisfactory. Therefore, antileishmanial drugs are urgently needed. In this study, the antileishmanial activity of two herbicides (acriflavine and trifluralin) and two plant biocides (triterpenoid saponin and plumbagin) extracts against Leishmania major parasites was evaluated in vitro. Different doses of acriflavine, trifluralin, saponin and plumbagin extracts were tested against L. major promastigotes and amastigotes. Pentostam and pentamidine were used as the reference drugs under the same experimental conditions. Anti-parasitic effect was observed for saponin and acriflavine for amastigote and promastigote suppression with a 50% inhibitory concentration (IC 50) values of 80 and 20 μg mL -1, respectively compared to the standard drugs, pentostam, which had an IC 50 value of 130 μg mL -1 for amastigotes and pentamidine which had an IC 50 value of 24 μg mL -1 for promastigotes. The optimal efficacy of the compounds tested was 100%, albeit the concentrations at optimal efficacy were significantly different (p<0.05) among the test compounds. Significant differences were also discerned in 90% cytotoxic concentration (CC 90) and 50% Cytotoxic Concentration (CC 50) after 24 h exposure (p<0.05). Highest CC 90 was recorded in acriflavine while saponin had the lowest CC 90.The in vitro activity of the test compounds (trifluralin, plumbagin, acriflavine and saponin) against intracellular L. major amastigotes (IC 50 = 150, 400, 200 and 80 μg mL -1, respectively) in the absence of obvious cytotoxicity on murine macrophage cells (CC 50 3,400 μg mL -1) demonstrates the potential of these biocides and herbicides in the treatment of cutaneous leishmaniasis.