Skin Hydration Potential of a Fluid Gel-Based Formulation of Kappaphycus alvarezii (Rhodophyta, Gigartinales)

The red alga Kappaphycus alvarezii is a rich source of bioactive compounds with potential applications in the cosmetic industry. This study aimed to characterize a cosmetic serum containing K. alvarezii and evaluate its immediate moisturizing effect on the skin. A randomized, triple-blind, parallel-group clinical trial was conducted with 28 healthy participants, allocated 1:1 to receive either a control formulation with hyaluronic acid or a test formulation with K. alvarezii. The formulations were assessed for stability over 60 days using organoleptic, microbiological, pH, and rheological analyses. Mechanical and bioadhesive properties were assessed using a texture analyzer, while the water content of the stratum corneum on the palms and backs of the hands was measured in vivo using a Corneometer® CM 825 (Courage potential contributions of film formation and barrier modulation remain hypothetical and were not directly assessed in this study.