The deactivation pathways of the excited-states of the mycosporine-like amino acids shinorine and porphyra-334 in aqueous solution.
In vitro studies on the structurally related mycosporine-like amino acids (MAAs) porphyra-334 and shinorine in aqueous solutions were carried out aiming at their full photochemical and photophysical characterization and expanding the evidence on the assigned UV-photoprotective role of the molecules in vivo. The experiments on shinorine confirmed a high photostability and a poor fluorescence quantum yield, in concordance with previous results on porphyra-334. The estimation of triplet production quantum yields for both MAAs was achieved by laser-flash photolysis measurements. In particular, photosensitization experiments on porphyra-334 support the participation of the triplet state in the photodecomposition mechanism yielding a more precise value of [capital Phi](T). As well, photoacoustic calorimetry experiments allowed the first direct quantification of the nonradiative relaxation pathways of the excited MAAs in solution, corroborating that the vast majority (ca. 97%) of the absorbed energy is promptly delivered to the surroundings as heat, consistently with the low photodecomposition and emission yields observed.
Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina.
Federico R
FR
Conde
M Sandra
MS
Churio
Carlos M
CM
Previtali
D000596:Amino Acids / Q000737:chemistry* / Q000528:radiation effects; D003511:Cyclohexanols / Q000737:chemistry* / Q000528:radiation effects; D003512:Cyclohexanones / Q000737:chemistry* / Q000528:radiation effects; D003514:Cyclohexylamines / Q000737:chemistry*; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000528:radiation effects; D015394:Molecular Structure; D010777:Photochemistry / Q000379:methods; D013053:Spectrophotometry; D013997:Time Factors; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry*
D000596:Amino Acids; D003511:Cyclohexanols; D003512:Cyclohexanones; D003514:Cyclohexylamines; C421025:porphyra-334; D014867:Water; C494891:shinorine; D005998:Glycine