Conjugated eicosapentanoic acid (cEPA) inhibits L. donovani topoisomerase I and has an antiproliferative activity against L. donovani promastigotes

Conjugated eicosapentaenoic acid inhibits the relaxation activity of purified L. donovani topoisomerase I, with an efficiency higher than that displayed by the corresponding human enzyme. Docking of the acid compound over the 3D structure of the enzyme shows that the complex is stabilized by a large network of interaction between the compound and many residues located in proximity of the active site, including the catalytic tyrosine 222, providing an explanation for its efficient inhibitory effect. The acid has also a strong antiprotozoal activity against L. donovani promastigotes ( EC= 75 µM) whilst it has no effect against murine macrophages (IC ~ 2 mM). Taken together the results indicate that L. donovani topoisomerase I can be considered an interesting molecular target and that conjugated eicosapentaenoic acid can be taken in consideration as a possible lead compound against leishmaniasis