Protection of human albumin against UV-C irradiation by natural antioxidants

The use of UV-C light as a means to inactivate pathogens in biological media containing blood components or plasma derivatives has recently been rediscovered. Although highly effective, these treatments may have deleterious effects on plasma proteins such as albumin, fibrinogen and immunoglobulins. Here we investigate the use of three natural antioxidants, gallic acid, nicotinic acid and ascorbic acid, as potential stabilizers of human albumin (HA) during irradiation by UV at 254 nm. The effects of UV-C on HA were monitored by measuring the absorbance changes in the protein spectrum at 320 nm. Experiments carried out at irradiance levels of 3.5–15 W m–2 and application times of up to 40 min showed that albumin undergoes rapid aggregation and that this process is dose-dependent. When added at 0.2 mM to the protein solution, all of the antioxidants inhibited HA aggregation, with ascorbic acid being the most effective. To quantitatively describe the observed effects, a fluence-based model was developed. The model predicted a quadratic dependence of the spectral changes of HA on the radiation dose and was validated by experiments performed under different exposure conditions.