Squalene from Silphium perfoliatum: A Novel Source with Long-Term Stability and Applicability in Topical Formulations

Background: Squalene is a key sebum lipid that plays an important role in skin barrier function, suppleness, and antioxidant protection. Age-related or disease-associated reductions in squalene levels—for example, in atopic dermatitis—reduce skin resilience and increase susceptibility to environmental stressors. However, its oxidation products can have inflammatory, comedogenic, and pro-aging effects on the skin, which is why adequate stabilization is essential when used in topical formulations. Objective: Therefore, identifying sustainable sources of stable squalene with beneficial skin-care properties is of considerable interest. Methods: This review employed an application-focused literature search and comparative analysis of established and new squalene sources, evaluating chemical composition, manufacturing processes, stability, and biological effects following topical applications based on predefined analytical criteria across peer-reviewed studies. Results: Silphium oil appears to be a promising novel source of highly concentrated, sustainable, and stable squalene with potential skin-conditioning properties at concentrations typically used in cosmetic products (2.1–12.6%) while preliminary formulation tests indicate emulsifiability even at concentrations up to 15%. It contains over 3% squalene, a fatty acid profile with over 66% PUFA, and negligible levels of oxidation byproducts (hexanal < 3 ppm) even after years of storage in various types of packaging. Although independent validation and broader comparative studies are limited, these results reveal new possibilities for the use of previously underutilized plant sources in skin care applications.