Protection by Food-derived Antioxidants from UV-A1–Induced Photodamage, Measured Using Living Skin Equivalents

In a study of biomarkers of ultraviolet-A1 radiation (UV-A1)-induced skin damage, living skin equivalent cultures (LSE) were treated with the antioxidants hesperetin and quercetin-3-glucoside and irradiated with 25 or 50 J/cm2 UV-A1. Changes in the following biomarkers were measured; Interleukin 1-alpha (IL-1α), Heme Oxygenase-1 (HO-1), TdT-mediated dUTP nick end labeling (TUNEL) and 8-hydroxy-2′-deoxyguanosine (8-OHdG). IL-1α and HO-1 were analyzed by real-time PCR, Western blot, enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. TUNEL and 8-OHdG were determined by (immuno)histochemical techniques. Sections were stained with hematoxylin and eosin (H&E). UV-A1 induced keratinocyte and fibroblast vacuolation and nuclear pyknosis, intense TUNEL staining of fibroblasts and increased staining of cells and nuclei for 8-OHdG. Lesser or marginal increases in intensity followed staining for HO-1 and IL-1α. The IL-1α increase was confirmed by ELISA assays of the medium supernatants. Hesperetin and quercetin-3-glucoside reduced changes in H&E, 8-OHdG, TUNEL and IL-1α. Quercetin-3-glucoside reduced the amount of IL-1α in LSE media. These observations support the use of the selected biomarkers to monitor UV-A1 damage and provide evidence that dietary ingredients could reduce ultraviolet-A radiation-induced damage.