Upcycling Lemon Peel Waste into Sustainable Bioactive Ingredients.Chemical Characterization and Efficacy Assessment

Abstract

The upcycling of agro-industrial by-products emerged as a sustainable strategy to reduce waste, generating high-value bioactive compounds. In this study, exhausted Citrus limon peels-residues obtained after Limoncello production, a typical liquor of Southern Italy-were subjected to supercritical CO ₂ extraction to recover essential oils. The resulting extracts were chemically characterized by gas chromatography coupled with mass spectrometry, and those with the most promising composition were then evaluated in vitro on human keratinocytes to assess biocompatibility. The essential oils exhibited inhibitory effects on collagenase and elastase, melanogenesis suppression, and activity againstCutibacterium acnes, highlighting their potential for anti-aging, skinbrightening, and antimicrobial applications. Preliminary clinical evaluations indicated improvements in skin hydration, softness, and elasticity. Overall, these findings support the possible use of lemon peel-derived essential oils as multifunctional, eco-sustainable cosmetic ingredients.