Synthesis, Photophysical Properties and Biological Evaluation of New Conjugates BODIPY: Dinuclear Trithiolato-Bridged Ruthenium(II)-Arene Complexes

Abstract

The synthesis, photophysical properties and antiparasitic efficacy against Toxoplasma gondii β-gal (RH strain tachyzoites expressing β-galactosidase) grown in human foreskin fibroblast monolayers (HFF) of a series of 15 new conjugates BODIPY-trithiolato-bridged dinuclear ruthenium(II)-arene complexes are reported (BODIPY=4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, derivatives used as fluorescent markers). The influence of the bond type (amide vs. ester), as well as that of the length and nature (alkyl vs. aryl) of the spacer between the dye and the diruthenium(II) complex moiety, on fluorescence and biological activity were evaluated. The assessed photophysical properties revealed that despite an important fluorescence quenching effect observed after conjugating the BODIPY to the diruthenium unit, the hybrids could nevertheless be used as fluorescent tracers. Although the antiparasitic activity of this series of conjugates appears limited, the compounds demonstrate potential as fluorescent probes for investigating the intracellular trafficking of trithiolato-bridged dinuclear Ru(II)-arene complexes in vitro.

Keywords: BODIPY; Toxoplasma gondii; antiparasitic activity; antiprotozoal agents; fluorescence; photophysical properties.