Benzophenone Suppression of Quercetin Antioxidant Activity towards Lipids under UV‐B Irradiation Regime: Detection by HPLC Chromatography

Abstract

Quercetin, a well-known flavonoid antioxidant, has been employed to control benzophenone-sensitized peroxidation of the lipid mixture in methanol solution, induced by continuous UV-B irradiation. Surprisingly, the detected quercetin antioxidant activity was almost negligible. The presented data suggests that the reason is not in its own UV-B-induced degradation but rather in its interrelationship with benzophenone during UV-B stress. On the other side of this relationship, benzophenone anticipated sensitizing role towards lipids; that is, the initiation of lipid peroxidation has been affected as well. These results, obtained by HPLC chromatography, partly confirm but partly relativize to some extent recent results obtained with the same system by spectrophotometric method.

Quercetin degradation induced by continuous UV-B irradiation in the presence of benzophenone

“…Thus, UV-B induced changes of the QC-BZP-PL90 mixture studied by HPLC chromatography allowed a kinetic analysis of clearly separated species [30]. Isocratic elution of the mixture with methanol as a mobile phase gave chromatograms recorded at absorption maxima of the separated components: QC, tret.…”

“…Also, two isosbestic points at λ = 273 nm and λ = 322 nm indicate the formation of at least one degradation product. By comparing QC degradation rates in the absence (QC-PL90) and in the presence of BZP (QC-BZP-PL90), it was evident that BZP accelerates QC degradation up to 10 times [30]. It was concluded that suppression of QC antioxidant activity on one side, and the inhibition of BZP sensitizing activity on the other is somehow related to BZP( 3 BZP)-QC mutual interaction.…”

“…In our previous papers [29,30], QC antioxidant ability in BZP-sensitized lipid peroxidation in methanol solution un-der continuous UV-B irradiation by spectrophotometric [29] and HPLC method was tested [30]. The results showed that the QC antioxidant activity was significantly decreased under the above mentioned conditions.…”

“…The results showed that the QC antioxidant activity was significantly decreased under the above mentioned conditions. Based on the results obtained by HPLC [30], which provide the separation of involved species, the assumption is that the decreased antioxidant activity could be related to BZP-QC mutual interaction. Therefore, the main objective of this paper is further examination of the mentioned interaction so the observed phenomena can be explained.…”