Conde Federico R, Churio M Sandra, Previtali Carlos M
Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina.
Photochem Photobiol Sci. 2004 Oct;3(10):960-7. doi: 10.1039/b405782a. Epub 2004 Sep 6.
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. 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.
针对结构相关的类菌孢素氨基酸（MAAs）紫菜-334和肌醇六磷酸在水溶液中的情况开展了体外研究，目的是对它们进行全面的光化学和光物理表征，并进一步证明这些分子在体内所赋予的紫外线光保护作用。对肌醇六磷酸的实验证实了其具有高光稳定性和低荧光量子产率，这与之前对紫菜-334的研究结果一致。通过激光闪光光解测量实现了对两种MAAs三线态产生量子产率的估算。特别是，对紫菜-334的光敏化实验支持三线态参与光分解机制，从而得出更精确的大写Phi值。此外，光声量热法实验首次直接量化了溶液中激发态MAAs的非辐射弛豫途径，证实绝大多数（约97%）吸收的能量会迅速以热的形式传递给周围环境，这与观察到的低光分解和发射产率一致。
