Our research focuses on understanding the biological role of betalains in plants and fungi and on the development of functional semisynthetic derivatives. We are particularly interested in fluorescent flowers pigmented by betalains.
Yellow flowers of Mirabilis jalapa (four o’clock flower or marvel of Peru) and Portulaca grandiflora (moss-rose) emit green fluorescence when irradiated with blue light. However, this phenomenon is apparently unrelated to pollination, and the explanation for the natural occurrence of betalains may be associated with a different property, such as the high antioxidant potential of these pigments.
Using green synthetic methods, modern steady-state and time-resolved spectroscopy and quantum-chemical calculations, we are developing new betalains that have the potential for advanced technological applications. Our efforts are leading to a deeper understanding of both structure-property relationships and of the molecular interactions that modulate the electronic properties of betalains in solution.
Below are some examples of ongoing and completed projects.
Goncalves LCP, Tonelli RR, Bagnaresi P, Mortara RA, Ferreira AG et al. (2013) A nature-inspired betalainic probe for live-cell imaging of Plasmodium-infected erythrocytes. Plos One 8: e53874. DOI
Goncalves LCP, Da Silva SM, DeRose PC, Ando RA, Bastos EL (2013) Beetroot-pigment-derived colorimetric sensor for detection of calcium dipicolinate in bacterial spores. Plos One 8: e73701. DOI
Goncalves LCP, Di Genova BM, Dorr FA, Pinto E, Bastos EL (2013) Effect of dielectric microwave heating on the color and antiradical capacity of betanin. J Food Eng 118: 49-55. DOI
Goncalves LCP, Trassi MAD, Lopes NB, Dorr FA, dos Santos MT et al. (2012) A comparative study of the purification of betanin. Food Chem 131: 231-238. DOI
Fluorescent probes for live cell imaging
Betaxanthins, yellow betalains resulting from the spontaneous aldimine coupling of betalamic acid and amino acids, are fluorescent (ΦFL < 10–3 in water) and can be found in the vacuole of vegetal cells. We designed several artificial betalains that accumulate in subcellular compartments of animal cells. For example, a coumarinic betalain (namely, BtC-120) was used to stain P. falciparum-infected erythrocytes (Figure 1).
Figure 1. Fluorescence emission of M. jalapa; the image was modified to improve contrast. The last image is an overlay of the DIC image, the fluorescence signal from the BtC-120 probe (pseudo-colored green) and the Hoechst dye (pseudo-colored blue).DOI
Metal complexes of betalains
The 1,2,3,4-tetrahydropyridine-2,3-dicarboxylic acid moiety present in betalains as well as the dipicolinic portion of neobetalains interact with metal cations. We are interested in the potential use of these natural products as chromophoric ligands. For example, betanin (Bn), the magenta betalain of the red beet (B. vulgaris), form a stable orange complex with Eu(III), which was used to quantify B. anthracis, the causative agent of anthrax (Figure 2).
Figure 2. Effect of the addition of CaDPA on an aqueous solution of [Eu(Bn)]+. (left) Absorption profile for the formation of Bn by the addition of CaDPA to a solution of [Eu(Bn)]+; (right) Quantification of bacteria of the genus Bacillus by the amount of CaDPA released upon thermal treatment. DOI
We make, characterize and study the properties of new molecules and materials. Thus, students and associate researchers have the opportunity to get in touch with several important laboratory techniques. Our lab is well equipped for organic synthesis, steady-state and time-resolved spectrophotometry, quantum-chemical calculations and electrochemical measurements. NMR spectroscopy, mass spectrometry, electronic and confocal microscopy, thermogravimetric analysis, X-Ray crystallography and other techniques are available in the Analytical Facility of the Institute of Chemistry (INFO).
Due to the interdisciplinary nature of our research, we closely collaborate with researchers from other fields including physics, biological and medical sciences, and engineering.
Bartoloni FH, Goncalves LCP, Rodrigues ACB, Dorr FA, Pinto E et al. (2013) Photophysics and hydrolytic stability of betalains in aqueous trifluoroethanol. Monatsh Chem 144: 567-571. DOI
Bastos, EL, Bartoloni, FH, Gonçalves, LCP (2014) Acid Base and Solvation Properties of Metal Phenolates. In: Zabicky, J. (Org.). The Chemistry of Metal Phenolates. Chichester: Wiley, 191-262.DOI
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