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

Abstract

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 IC₅₀ 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.

Graphical Abstract

Keywords:

• Phytomonas serpens
• Leishmania amazonensis
• Acanthamoeba polyphaga
• Chalcone

Acknowledgements

The authors thank Fundação Oswaldo Cruz (Fiocruz), Rio de Janeiro, Brazil for providing P. serpens isolate (strain 9T).

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Funding

This study was funded, in part, by Brazil’s Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Apoio à Pesquisa e a Inovação Tecnológica do Estado de Sergipe (Fapitec/SE); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES; Finance Code 001); and Financiadora de Estudos e Projetos (FINEP).

Figure 1. Molecular structure of the chalcone and its derivatives obtained by Claisen-Schmidt condensation.