UV-induced change in the antioxidant activity of quercetin toward benzophenone-initiated lipid peroxidation.

The aim of this work was to estimate the degradation and change in the antioxidant activity of quercetin in the presence of two different mixtures of phospholipids in methanolic solution, under continuous UV-irradiation from three different sub-ranges (UV-A, UV-B and UV-C), in the presence and in the absence of the selected UV-absorbing photosensitizer, benzophenone. Quercetin was employed to control the lipid peroxidation process generated by UV-irradiation, by absorbing part of the UV incident light, and/or by scavenging the involved, created free radicals. The results showed that quercetin undergoes irreversible destruction, which was highly dependent on the energy input of the UV-photons, and was more expressed in the presence than in the absence of benzophenone. Simultaneously, quercetin expressed a suppression effect on lipid peroxidation processes in UV-irradiated phospholipid mixtures in both the absence and presence of benzophenone (more or less effective, respectively). In the UV-C-irradiated mixtures, photosensitizing function of benzophenone was significantly reduced due to its strong absorption in the UV-C spectral range, therefore affecting lower antioxidant activity of the remaining quercetin. [ABSTRACT FROM AUTHOR]