Dietary polyphenol oleuropein and its metabolite hydroxytyrosol are moderate skin permeable elastase and collagenase inhibitors with synergistic cellular antioxidant effects in human skin fibroblasts

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Oleuropein (OLE) and hydroxytyrosol (HT) are dietary polyphenols with skin beneficial effects but their effects on skin-ageing-related enzymes are not clear. Herein, we evaluated their inhibitory effects on elastase and collagenase. OLE and HT (62.5–1 000 μM) showed moderate anti-elastase and anti-collagenase effects (5.1–26.3%, 5.8–12.2% and 12.6–31.0%, 11.6–31.9% inhibition, respectively). Combinations of OLE and HT (1:1 ratio) exerted synergistic inhibitory effects on elastase, which were supported by their combination index (CI), kinetic assay and computational docking. Moreover, HT (100 μM) reduced hydrogen peroxide (H2O2)-induced cytotoxicity and reactive oxygen species (ROS) in human dermal fibroblast cells by 21.8 and 15.2%, respectively. In addition, combinations of OLE and HT (6.25/6.25–100/100 μM) exerted synergistic cytoprotective effects by reducing ROS levels by 7.6–37.3% with CIs of 0.17–0.44, respectively. The findings from this study support the cosmeceutical activities of OLE and HT but further research is warranted to evaluate their anti-skin-ageing effects using in vivo models.

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International Journal of Food Sciences and Nutrition