Antiparasitic Activities of Acyl Hydrazones from Cinnamaldehydes and Structurally Related Fragrances

<b>Background:</b> New drugs for the treatment of protozoal parasite infections such as toxoplasmosis and leishmaniasis are required. Cinnamaldehyde and its derivatives appear to be promising antiparasitic drug candidates. <b>Methods:</b> Acyl hydrazones of cinnamaldehyde, 4-dimethylaminocinnamaldehyde, and of the synthetic fragrances silvial^TM and florhydral^TM were prepared and tested for activity against <i>Toxoplasma gondii</i> (<i>T. gondii</i>) and <i>Leishmania major</i> (<i>L. major</i>) parasites. <b>Results:</b> Three cinnamaldehyde acyl hydrazones (3-hydroxy-2-naphthoyl <b>2a</b> and the salicyloyls <b>2c</b> and <b>2d</b>) showed good activity against <i>T. gondii</i>, and two compounds derived from cinnamaldehyde and florhydral^TM (3-hydroxy-2-naphthoyls <b>2a</b> and <b>4a</b>) exhibited moderate activity against <i>L. major</i> promastigotes. <b>Conclusions:</b> In particular, the identified antitoxoplasmal activities are promising and might lead to the development of new potent and cost-effective drug candidates for the therapy of toxoplasmosis.