Anti-skin aging properties of protocatechuic acid in vitro and in vivo

Background Protocatechuic acid has reported containing antioxidant effects. However, information on its other biological activities such as anti-wrinkle properties is limited Aims The objective of this study was to evaluate an antioxidant, collagen synthesis, MMP-1 inhibition (in vitro), and anti-wrinkle (in vivo) effects of protocatechuic acid (PCA) as a potent ingredient for wrinkle-care cosmetic. Methods Antioxidant effect was evaluated based on its scavenging activity for free radicals (DPPH, ABTS+). To evaluate the anti-skin aging potency of PCA, levels of MMP-1 and type I procollagen were measured using an ELISA kit in cultured human dermal fibroblasts. To further investigate if PCA could increase collagen synthesis, full-thickness human skin explants were immunostained with an anti-collagen I antibody. In an in vivo study, 22 female subjects were enrolled in a placebo-controlled trial. Facial wrinkle, especially crow's feet around eyes, was treated with lotion-containing 0.02% PCA for 8 weeks and compared with the placebo. Results In in vitro study, PCA showed high antioxidant activ ity. PCA also showed potential to induce the synthesis of type I collagen in human dermal fibroblast and skin explants. It inhibited MMP-1 secretion from UVA-irradiated human dermal fibroblast. An in vivo study, treatment with lotion-containing 0.02% PCA for 8 weeks significantly reduced the percentage of all skin wrinkle parameters. Conclusion Based on the results of in vitro assays and in vivo skin testing in human subjects, PCA shows potential in anti-wrinkle or anti-skin aging treatments.