Physicochemical Characterization, In Vitro Anti-Aging Enzyme Modulation, and Dermocosmetic Application of Prunus spinosa L. Kernel Oil

Prunus spinosa L. kernel oil (PSKO) is an underexplored natural oil rich in unsaturated fatty acids and minor bioactive constituents with potential dermocosmetic relevance. In this study, PSKO was comprehensively characterized in terms of physicochemical quality parameters, fatty acid composition, phenolic and carotenoid content, and antioxidant capacity. Gas chromatography–mass spectrometry (GC–MS) analysis revealed oleic acid (65.9%) and linoleic acid (18.8%) as the predominant fatty acids. The biological potential of PSKO was further investigated through in vitro anti-aging enzyme assays, showing a concentration-dependent inhibition of key extracellular matrix-degrading enzymes, including matrix metalloproteinase-9 (MMP-9), collagenase, and elastase, thus indicating a multi-target modulation of enzymatic pathways involved in skin aging. Based on its chemical composition and bioactivity profile, PSKO was incorporated into a moisturizing cream formulation. The PSKO-enriched cream exhibited improved physicochemical stability, enhanced occlusive properties, and higher sensory acceptability compared with the control formulation. In addition, UV–visible spectrophotometric analysis demonstrated that both PSKO and the PSKO-enriched cream displayed measurable absorption in the ultraviolet B (UVB) and ultraviolet A (UVA) regions, together with good photostability, supporting a complementary in vitro UV-protective role. Overall, these findings highlight PSKO as a sustainable and multifunctional bioactive ingredient derived from an underutilized agri-food by-product, with promising potential for innovative dermocosmetic applications.