Effect of Blue Light on the Electronic and Structural Properties of Bilirubin Isomers: Insights into the Photoisomerization and Photooxidation Processes

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• 作者：Lucas C. Cardoso ; Ranylson M. L. Savedra ; Mariana M. Silva ; Giovana R. Ferreira ; Rodrigo F. Bianchi ; Melissa F. Siqueira
• 刊名：Journal of Physical Chemistry A
• 出版年：2015
• 出版时间：August 27, 2015
• 年：2015
• 卷：119
• 期：34
• 页码：9037-9042
• 全文大小：469K
• ISSN：1520-5215

文摘

The central process of neonatal phototherapy by employing blue light has been attributed to the configurational conversion of (4Z,15Z)-bilirubin to (4Z,15E). Indeed, photoisomerization is the early photochemical event during this procedure. However, in this paper, we show that the bilirubin solutions under continuous blue light exposure undergo a photooxidation process. To ascertain the role of this photodegradation in the phototherapy, we evaluated UV鈥搗isible absorption spectra obtained from bilirubin solutions in CHCl₃, milli-Q water, and physiological saline, as well as FTIR spectroscopy for bilirubin in CHCl₃. These analyses also showed that the first 2 h of phototherapy are the most relevant period. In addition, quantum molecular modeling using B3LYP/6-31G(d,p) and ZINDO/S-CIS was performed to evaluate the electronic and structural properties of four bilirubin isomers, showing that the (4Z,15E)-bilirubin isomer is the most polar configuration. Therefore, it can be more soluble in aqueous environments than the other configurations. This clarifies why this is the faster isomer excreted during the phototherapy.