Anthocyanins are naturally occurring phenolic compounds whose known antioxidant activity has been related to the protection against oxidative stress related pathologies (i.e. cardiovascular diseases, cancer, neurodegeneration, inflammation) as mainly demonstrated by in vitro studies.

The aim of the present work was to study the effect of the daily ingestion of a purified anthocyanin extract from red grape skin on the antioxidant capacity of serum. The study was carried out on rats orally administrated with the extract for ten days in either normal physiological conditions or exposed to a pro-oxidant chemical (CCl₄). The ORAC (Oxygen Radical Absorbance Capacity) assay was applied. Ussing chamber experiments excluded any toxic effect of the extract on the intestinal epithelium. The oral administration of the extract significantly (P<0.05) enhanced the ORAC value of the deproteinised serum of about 50%. When the animals were treated with CCl₄, the serum antioxidant capacity significantly (P<0.01) decreased. Interestingly, the anthocyanin administration was able to completely reverse the CCl₄ induced negative effect on serum ORAC activity.

In conclusion, results demonstrated that the anthocyanin extract daily ingestion enhances the antioxidant capacity of the serum in either normal physiological condition or during oxidative stress induction, revealing a protective role against the decrease in the serum antioxidant capacity induced by the exposure to a pro-oxidant compound.