Antioxidant Constituents of Hops (Humulus lupulus L.) as Functional Raw Materials for Cosmetic Applications

<i>Humulus lupulus</i> L. (hops) is best known for its application in the brewing industry; however, growing scientific interest has revealed its high content of natural antioxidants, including flavonoids and polyphenols. These compounds exhibit pronounced anti-inflammatory activity, positioning hops as a promising plant-derived ingredient for cosmetic use. The present study evaluates the antioxidant properties of <i>Humulus lupulus</i> L. (HL) extract and cosmetic formulations loaded with hop-based active substances. Antioxidant capacity was determined using ABTS, Folin-Ciocâlteu, and FRAP methods. The hop extract showed limited free radical scavenging activity and reducing power; however, these results still confirm its antioxidant potential. Importantly, cosmetic emulsions enriched with the HL extract maintained substantial antioxidant activity, demonstrating successful incorporation and stability of the bioactive compounds within the formulations. Physicochemical stability tests, including pH monitoring and visual evaluation during storage, indicated good stability under different conditions. In vivo studies confirmed the effectiveness of cosmetics containing HL extracts as natural anti-irritant agents, demonstrated by a 10% reduction in erythema after a three-week application period. These findings provide evidence supporting the use of <i>Humulus lupulus</i> L. in the development of plant-based cosmetic products designed to improve the health of skin prone to irritation.