Screening of selected essential oils for their in vitro antileishmanial activity against Leishmania amazonensis

Leishmaniasis is a group of tropical diseases caused by a number of species of protozoan parasites belonging to the genus Leishmania (1). In this work we have investigated the in vitro leishmanicidal activity of seven essential oils (EO) from herbaceous plant species against promastigote forms of Leishmania amazonensis. The EOs were obtained from leaves by hydrodistillation in a Clevenger-type apparatus for 3h. Samples of EOs were dissolved in dimethylsulfoxide (DMSO) and evaluated in concentrations of 8, 32 and 128µg/mL for 24h using the MTT colorimetric method (MTT) (2). The essential oil of Artemisia camphorata Vill (Asteraceae) showed significant activity against L. amazonensis, with 52.89% and 84.55% of lysis at concentrations of 32µg/mL and 128µg/mL, respectively. The EOs of Ageratum conyzoides L. (Asteraceae) and Plectranthus neochilus Schltr. (Lamiaceae) were also active, causing 74.90% and 76.44% of lysis at 128µg/mL. Amphothericin B (32µg/mL), used as positive control, caused 75.85% of lysis. GC-MS analysis of the active EOs revealed that 1,8-cineole (monoterpene), (E)-caryophyllene (sesquiterpene) and precocene I (chromene) are the major compounds of the EO of A. camphorata, P. neochilus and A. conyzoides, respectively. Our results indicated that the investigated EOs exhibited in vitro leishmanicidal activity against promastigote forms of Leishmania amazonensis. Further biological studies are in progress regarding the activity of their major compounds identified in the active EOs.

Acknowledgements: FAPESP (Proc. 07/54241–8)

References: 1. Da Silva Filho et al. (2008). Phytotherapy Res. 22: 1307–1310.

2. Muelas-Serrano, S et al. (2000). Parasitol. Res. 86: 999–1002.