Department of Pediatrics, Stanford University School of Medicine, 300 Pasteur Drive, Room S214, Stanford, CA, 94305, USA.
Institute of Medical Biochemistry and Laboratory Diagnostics, 1st Faculty of Medicine, Charles University, Kateřinská 32, 120 00, Prague, Czech Republic.
Pediatr Res. 2019 May;85(6):865-873. doi: 10.1038/s41390-019-0310-2. Epub 2019 Jan 26.
The action spectrum for bilirubin photodegradation has been intensively studied. However, questions still remain regarding which light wavelength most efficiently photodegrades bilirubin. In this study, we determined the in vitro effects of different irradiation wavelength ranges on bilirubin photodegradation.
In our in vitro method, normalized absolute irradiance levels of 4.2 × 10 photons/cm/s from light-emitting diodes (ranging from 390-530 nm) and 10-nm band-pass filters were used to irradiate bilirubin solutions (25 mg/dL in 4% human serum albumin). Bilirubin and its major photoisomer concentrations were determined; the half-life time of bilirubin (t) was calculated for each wavelength range, and the spectral characteristics for bilirubin photodegradation products were obtained for key wavelengths.
The in vitro photodegradation of bilirubin at 37 °C decreased linearly as the wavelength was increased from 390 to 500 nm with t decreasing from 63 to 17 min, respectively. At 460 ± 10 nm, a significantly lower rate of photodegradation and thus higher t (31 min) than that at 500 nm (17 min) was demonstrated.
In our system, the optimum bilirubin photodegradation and lumirubin production rates occurred between 490 and 500 nm. Spectra shapes were remarkably similar, suggesting that lumirubin production was the major process of bilirubin photodegradation.
胆红素光降解的作用光谱已经得到了深入研究。然而，对于哪种光波长能最有效地降解胆红素，仍存在一些问题。在这项研究中，我们确定了不同辐照波长范围对胆红素光降解的体外影响。
在我们的体外方法中，使用发光二极管的归一化绝对辐照度水平为 4.2×10 个光子/cm/s（波长范围为 390-530nm）和 10nm 带通滤波器来辐照胆红素溶液（4%人血清白蛋白中的 25mg/dL）。测定胆红素及其主要光异构体的浓度；计算每个波长范围的胆红素半衰期（t），并获得关键波长下胆红素光降解产物的光谱特征。
在 37°C 下，胆红素的体外光降解随波长从 390nm 增加到 500nm 而呈线性下降，t 分别从 63 分钟降至 17 分钟。在 460±10nm 时，光降解速度明显较低，因此 t （31 分钟）比 500nm（17 分钟）高。
在我们的系统中，胆红素光降解和光胆红素生成的最佳速率发生在 490nm 至 500nm 之间。光谱形状非常相似，表明光胆红素的生成是胆红素光降解的主要过程。
