Antitrypanosomal activity of Elatol isolated from red seaweed Laurencia obtusa

Chagas' disease is one of the most important endemic diseases in Latin America, affecting 18 million people[1]. The current treatment for this infection is very limited, and available drugs (nifurtimox and benznidazole) have many side effects[2]. Elatol, isolated from the Brazilian red seaweed Laurencia obtusa[3], is a sesquiterpene compound with a halogenated chemical structure. It is a secondary metabolite used by algae as a source of chemical defenses against other organisms. Here, we report the effect triggered by Elatol on epimastigote and trypomastigote forms of Trypanosoma cruzi. The Elatol concentration found to inhibit 50% of growth (IC₅₀) of epimastigotes was 14µg/ml and the 50% effective concentration (EC₅₀) for trypomastigotes was 0.46µg/ml. Epimastigotes treated with Elatol were fixed with 2.5% glutaraldehyde. For transmission electron microscopy, cells were post-fixed in osmium tetroxide, dehydrated in acetone, and embedded in Epon. Ultrathin sections were observed in Tecnai TEM. For scanning electron microscopy, parasites were placed on a specimen support with poly-L-lysine, dehydrated in ethanol, critical-point dried in CO₂, coated with gold, and observed in a Shimadzu SS-550 SEM. The ultrastructure studies on the epimastigote showed alterations in the mitochondria and cytoplasmatic extraction, with multiple vacuoles. Observations by scanning electron microscopy revealed alterations in the shape and size of the epimastigotes. These findings represent an exciting advance in the search for new antiprotozoal agents from natural sources. Further in vitro and in vivo studies are necessary.

Acknowledgements: This study was supported through grants from DECIT/SCTIE/MS and MCT by CNPq, FINEP, and CAPES.

References: 1. Salas, C. et al. (2008) Bioorg. Med. Chem. 16: 668–674.

2. WHO, Control of Chagas Disease (2002) 1–95.

3. Pereira, R.C. et al. (2003) Brazilian Journal Biology 63: 665–672.