Photophysical properties of betalainic metal complexes

Abstract

Betalains are vacuolar plant pigments that interact selectively with cell membranes and show biological activity. These pigments are produced by the spontanous aldiminic coupling of amines and betalamic acid, an unstable and fluorogenic ±,²-unsaturated aldehyde. Obtaining of this precursor allows the semi-sinthesis, i.e., the partial synthesis, of natural and artificial betalaines, allowing the study as well as the application of these pigments. For example, a weakly fluorescent semisynthetic betalaine has been developed for the in vitro staining of red blood cells infected with Plasmodium falciparum, the malaria-causing parasite in humans. Furthermore, in the presence of europium chloride, betanin (the main betalain of the reed beet) is converted to an orange complex, which has been used to quantify Bacillus anthracis spores. This project proposes to expand the application of betalains by developing new semi-synthetic devivatives able to bind metal ions (Zn (II) , Eu (III) , Tb (III) , Dy (III) and Gd (III)). The properties of the complexes formed will be investigated and the application of this chiral ans water-soluble ligands will be prospected. (AU)