Boosting the cosmetic potential of polyphenols via sodium alginate microencapsulation

Polyphenols are bioactive compounds with strong antioxidant and anti-aging potential, yet their cosmetic application is limited by their poor instability, solubility, and restricted skin permeation. Encapsulation has emerged as an effective approach to overcome these limitations, while enabling controlled delivery. This study aimed to develop and characterize sodium alginate microparticles encapsulating catechin, epicatechin, chlorogenic acid (CGA), neochlorogenic acid (NCGA), and their mixture to improve their suitability for cosmetic delivery. Microparticles were produced by spray-drying using inlet and outlet temperatures of 115°C and 70°C, respectively, selected to minimize thermal degradation. Under these conditions, the product yields ranged from 37 to 53% and the encapsulation efficiencies varied from 19 to 27%, due to the hydrophilicity of the selected compounds. Scanning electron microscopy (SEM) revealed spherical microparticles with characteristic surface indentations and sizes in the range of 6.4–7.0 μm. Encapsulated polyphenols displayed enhanced thermal stability according to Differential Scanning Calorimetry (DSC) results and the Fourier-Transform Infrared Spectroscopy (FTIR) analysis suggested the physical entrapment of the bioactive compounds. Moreover, encapsulation enhanced the antioxidant/antiradical properties. Synergistic effects were detected for the phenolic mixture, with Ferric Reducing Antioxidant Power (FRAP) values increasing from 109.08 to 262.23 μmol Fe 2+ /g after encapsulation. In vitro biocompatibility assays revealed viabilities above 60% in keratinocytes and 80% in fibroblasts, whereas pure polyphenols displayed dose-dependent reductions. These findings demonstrate that the encapsulation by spray-drying improves the stability, bioactivity, and safety of polyphenols. This work provides the first comparative assessment of four chemically related polyphenols, individually and combined, providing preliminary data on their application for topical delivery. • Polyphenols and their mix were successfully encapsulated by spray-drying; • Polyphenols encapsulation improved the thermal stability of alginate carriers; • Polyphenol encapsulation improved antioxidant and antiradical activities; • Polyphenols mixture displayed synergistic effects; • Microparticles with high biocompatibility in HaCaT and HDF skin cell lines.