Kinetics and concentration profile associated with the regulated radiodegradation of bilirubin in an organic solvent were
assessed. The pure unconjugated specimen was prepared in chloroform (40.0 µM). The depletion of bilirubin was almost linear
with dose, and complete degradation was accomplished with doses in excess of 100 Gy. The method was also evaluated for the
explicit production of the long-wavelength isomer of biliverdin, which was characterized spectrometrically by an absorbance
band in the region 600–650 nm. Results including differences in air, N2 and O2 purged samples are presented to identify the atmospheric medium for optimum production of biliverdin. The process was regulated
by controlling the dose. The general rate constant of the depletion process was estimated at a dose rate of 5.67·10−2Gy·s−1. The method is a convenient substitute for light illumination studies of bilirubin.
Biliverdin is a useful component in various aspects of biochemistry and biosynthesis, but its synthetic preparation is often
long-winded. Micro-production (and subsequent isolation) by solar photolysis and gamma radiolysis of bilirubin provides rapid
in vitro generation. Both methods are competitive, and this article discusses their merits and limitations for application
in biosynthetic research. The investigation assumed a comparative study to evaluate the relative potential of the photolytic
and radiolytic phenomena in this respect. The calculated rate of incident energy in the case of solar photolysis was roughly30.4.10-2 W, and about 5.70.10-4 W during gamma-irradiation (from a 137Cs source). In both cases the bilirubin (40 µM) degradation was pronounced in the initial few minutes of exposure, producing
respective depletion rates of approximately 6.8 µM/min and 2.4 µM/min. Overall, both applications showed declining bilirubin
concentrations close to 90%, after about 30 minutes. However, the corresponding production of biliverdin was higher by about
50% in the photolytic application. To account for heat-up effects in the photolytic application, thermal effects were studied
up to 65 °C, and it was found that, as a result of this, a reduction in bilirubin concentration of about 40% was encountered.
The species of interest were monitored spectrophotometrically, and the composite results showed that regulated production
of biliverdin is possible under certain conditions.