Synthesis of chalcone derivatives by Claisen-Schmidt condensation and in vitro analyses of their antiprotozoal activities.

Chalcone is a molecule with known biological activities. Based on this, a series of chalcone derivatives bearing methyl, phenyl or furanyl substituents at different positions of A and B rings were synthesised, characterised, and evaluated regarding antiprotozoal activity. Molecules were synthesised via base catalyzed Claisen-Schmidt condensation and characterised by IR and NMR spectral data. Antiprotozoal activity against Phytomonas serpens , Leishmania amazonensis and Acanthamoeba polyphaga was performed. All compounds inhibited more than 50% of the growth of P. serpens while five had this effect on L. amazonensis and all of them no more than 35% of inhibition on A. polyphaga . Remarkably interesting antiprotozoal effects were recorded with compound 5, with IC 50 of 1.59 µM for P. serpens and 11.49 µM for L. amazonensis . The addition of a naphthyl group to the B ring can be postulated to be the cause of the 10 times increase observed in its trypanocidal activity.