Floral betalamic pigments: fluorescence and antiradical capacity

Abstract

Betalains are colorful, water-soluble and nontoxic chemical substances, which replace anthocyanins in the pigmentation of a reduced number of plants and fungi. In this research plan, we propose to continue our study on photophysical and antiradical properties of betalains, focusing their structural modification and structure-activity relationships. Phenolic betalains and the corresponding tert-butyldimethylsilyl ethers will be semisynthesized to investigate the effect of structure on the antiradical capacity of betalains. A route for the obtaining of water-soluble, stable betalamic probes bearing a BODIPY moiety is presented. Furthermore, we propose the preparation of amphiphilic betalains by the N-alkylation of the 2-piperidene ring or by aldiminic coupling with fatty amines; in this subproject, the precursor compounds are renewable and the oxidation of the products lead to neobetalamic derivatives containing a 2,6-dipicolinic portion with chelating properties. Finally, we shall continue our investigation into the formation of betalamic and neobetalamic complexes with Eu(III) and its application in the determination of calcium dipicolinate (CaDPA), which is present in considerable amounts in bacterial spores, including Bacillus anthracis, the causative agent of anthrax. Photophysical properties of most compounds obtained will be characterized both experimentally and by quantum-chemical methods. (AU)