Thein vitroantileishmanial activity of essential oil fromAloysia gratissimaand guaiol, its major sesquiterpene againstLeishmania amazonensis

Abstract

AbstractLeishmaniases is a tropical disease caused by protozoa of the genusLeishmaniafor which the current treatment is expensive, besides increasing reports of parasite resistance. This study investigated the anti-Leishmania amazonensisactivity of the essential oil fromAloysia gratissima(AgEO) and guaiol, the major sesquiterpene constituent in the oil. Our results showed that AgEO killed promastigotes and intracellular amastigotes at an IC50of 25 and 0·16µg mL−1, respectively, while guaiol killed amastigotes at an IC50of 0·01µg mL−1. Both AgEO and guaiol were safe for macrophages up to 100µg mL−1, as evaluated by the dehydrogenase activity, membrane integrity and phagocytic capacity. AgEO and guaiol did not induce nitrite oxide (NO) in resting macrophages and inhibited the production of NO in lipopolysaccharide-stimulated macrophages. The ultrastructural analysis suggested that AgEO and guaiol act directly on parasites, affecting promastigotes kinetoplast, mitochondrial matrix and plasma membrane. Together, these results pointed out that AgEO and guaiol could be promising candidates to develop anti-Leishmaniadrugs.