Photophysicochemical characterization of mycosporine-like amino acids in micellar solutions

DALILA E. ORALLO; SONIA G. BERTOLOTTI; MARÍA S. CHURIO

Photochemical and Photobiological Sciences

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2017

1474-905X

The properties and photochemical and photophysical behavior of the mycosporine-like amino acids(MAAs) shinorine and porphyra-334 were experimentally evaluated in solutions of direct ionic micelles assimple biomimicking environments. The preferential partition of the natural molecules in the aqueousphase of sodium dodecyl sulfate (SDS) or cetyltrimethylammonium chloride (CTAC) micellar systems isconfirmed. Although the proton dissociation of the carboxylic groups in the MAAs is slightly inhibited inCTAC solutions, the molecules are predicted to be in the form of zwitterions in all the explored mediaaround physiological pH. The increase in the fluorescence quantum yield, emission lifetime and stationaryanisotropy in the presence of CTAC micelles suggest electrostatic attractions of the MAAs with thesurface of the cationic micelles. Consistently, the triplet?triplet absorption spectra in CTAC solutionsreveal the typical environmental features of the micellar interface, while in the presence of SDS they aresimilar to those determined in neat water. Finally, the photostability of the MAAs increases in the micellarsystems, more noticeably in the case of CTAC. It is concluded that the ability of the two MAAs to act asUV screens is susceptible to the influence of electrostatic interactions with organized microheterogeneousenvironments.