Effect of elatol, isolated from red seaweed Laurencia dendroidea, on Leishmania amazonensis

In the present study, we investigated the antileishmanial activity of sesquiterpene elatol, the major constituent of the Brazilian red seaweed Laurencia dendroidea (Hudson) J.V. Lamouroux, against L. amazonensis. Elatol after 72 h of treatment, showed an IC(50) of 4.0 μM and 0.45 μM for promastigote and intracellular amastigote forms of L. amazonensis, respectively. By scanning and transmission electron microscopy, parasites treated with elatol revealed notable changes compared with control cells, including: pronounced swelling of the mitochondrion; appearance of concentric membrane structures inside the organelle; destabilization of the plasma membrane; and formation of membrane structures, apparently an extension of the endoplasmic reticulum, which is suggestive of an autophagic process. A cytotoxicity assay showed that the action of the isolated compound is more specific for protozoa, and it is not toxic to macrophages. Our studies indicated that elatol is a potent antiproliferative agent against promastigote and intracellular amastigote forms, and may have important advantages for the development of new anti-leishamanial chemotherapies.