Percorrer por autor "Marques, Mariana Isabel Gonçalves"
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- Polyphenol encapsulation and skin models: a comparative in vitro and ex vivo approach to cosmetic safety testingPublication . Marques, Mariana Isabel Gonçalves; Rodrigues, Francisca; Vieira, MónicaPolyphenols are bioactive compounds with skin antioxidant and anti-aging potential, yet their cosmetic application remains limited due to instability and poor solubility, so encapsulation offers a promising strategy to improve their stability and controlled release (1). This thesis aimed to develop a novel cosmetic ingredient by enhancing the stability and safety of polyphenols through encapsulation, while employing physiologically relevant 3D in vitro and ex vivo skin models for toxicity and permeation testing. Catechin, epicatechin, chlorogenic acid (CGA), neochlorogenic acid (NCGA), and their mixture were microencapsulated in sodium alginate by spray-drying, achieving encapsulation efficiencies between 19 and 27% and product yields from 37 to 53%. The microparticles displayed enhanced thermal stability and physical entrapment of the phenolic compounds. Moreover, microencapsulation enhanced the antioxidant and antiradical activities, and synergistic effects were detected in the phenolic mix. In vitro biocompatibility assays revealed viabilities above 60% in keratinocytes (HaCaT) and over 80% in fibroblasts (HDF), whereas pure polyphenols displayed dose-dependent reductions in viability. A 3D in vitro co-culture model composed by dermal (HDF) and epidermal (HaCaT) cell lines at air-liquid interface conditions was constructed. The permeability assays revealed compound-dependent permeation. Encapsulation reduced the overall permeation but provided a gradual and controlled release, particularly for catechin and epicatechin. MTT assays demonstrated that catechin and epicatechin-loaded microparticles increased the cell viability in the 3D co-culture and the commercial SkinEthicTM Reconstructed Human Epidermis (RHE) model, whereas NCGA reduced the viability only in the 3D co-culture model (82.55%). Histological analysis of SkinEthicTM RHE model confirmed the absence of phenotypical alterations in keratinocytes with exposure to alginate microparticles. Discrepancies were noted between the monocultures and the 3D co-culture skin model, highlighting the critical role of epidermal-dermal communication in safety evaluations. Permeation studies with Franz diffusion cells in ex vivo human explants revealed negligible permeation of catechin and epicatechin, while CGA, NCGA, and the mix permeated up to 50% and displayed more than 60% of skin retention. Overall, this work demonstrates that alginate-based encapsulation enhances the stability, antioxidant activity, and safety profile of polyphenols, while enabling their controlled release and modulating their skin permeation. The integration of advanced 3D in vitro and ex vivo skin models provided valuable mechanistic insights into skin interactions, underscoring their potential as effective and safe cosmetic ingredients. These findings contribute to the development of alternative testing strategies and highlight the relevance of encapsulation for translating bioactive compounds into cosmetically applicable formulations.