Investigation of Controlled Release Molecular Mechanism of Oil Phase in Spilanthol Emulsion: Development and In Vitro, In Vivo Characterization

Effect of squalane-based emulsion on polyphenols skin penetration: Ex vivo skin study

Polyphenols have gained attractiveness as ingredients in cosmetic formulations as result of their ability to delay the aging process. However, different factors limit their use, including low solubility and poor skin permeability. In this sense, this study describes the potential of squalane to increase the polyphenols ex vivo skin penetration, incorporated into a water-in-oil emulsion. Polyphenols skin permeation followed the Fick's first law and, p-coumaric acid, vitexin, schaftoside and ferulic acid had the higher permeability coefficients (Kp = 6.0-8.0 × 10^-3 cm^-2 h^-1). Addition of squalane to phenolic compounds decreased the permeability coefficients (Kp = 4.1-5.9 × 10^-3 cm^-2 h^-1), indicating that squalane increased the retention of polyphenols in the skin. Gentisic acid, ferulic acid, and p-coumaric acid were the only compounds permeating from water-in-oil emulsion, in the first 8 h of study and, according Krosmeyer-Peppas model, its n value was > 1 indicating a high transport resistance from the formulation and throughout the skin. Results suggest squalane as an efficient vehicle to increase the dermal availability increasing phenolic compounds physiological functions, by enhancing the skin retention time where they should exert antiaging effect.

Neurocosmetics in Skincare—The Fascinating World of Skin–Brain Connection: A Review to Explore Ingredients, Commercial Products for Skin Aging, and Cosmetic Regulation

The “modern” cosmetology industry is focusing on research devoted to discovering novel neurocosmetic functional ingredients that could improve the interactions between the skin and the nervous system. Many cosmetic companies have started to formulate neurocosmetic products that exhibit their activity on the cutaneous nervous system by affecting the skin’s neuromediators through different mechanisms of action. This review aims to clarify the definition of neurocosmetics, and to describe the features of some functional ingredients and products available on the market, with a look at the regulatory aspect. The attention is devoted to neurocosmetic ingredients for combating skin stress, explaining the stress pathways, which are also correlated with skin aging. “Neuro-relaxing” anti-aging ingredients derived from plant extracts and neurocosmetic strategies to combat inflammatory responses related to skin stress are presented. Afterwards, the molecular basis of sensitive skin and the suitable neurocosmetic ingredients to improve this problem are discussed. With the aim of presenting the major application of Botox-like ingredients as the first neurocosmetics on the market, skin aging is also introduced, and its theory is presented. To confirm the efficacy of the cosmetic products on the market, the concept of cosmetic claims is discussed.

Development and Evaluation of Cucurbitacin B Microemulsion: the Effect of Oil Phase and Aqueous Phase on Drug Percutaneous Absorption Based on ATR-FTIR Spectroscopy and Molecular Modeling

The present study aimed to develop a cucurbitacin B microemulsion (CuB-ME) and investigate the mechanism of the enhanced drug skin absorption at the molecular level. Firstly, the pseudo-ternary phase diagrams were developed to evaluate the effect of composition on microemulsion properties systematically. The formulation composition types and ratios of oil phase, surfactant, co-surfactant, and aqueous phase were optimized by an in vitro skin permeation experiment, and the optimized formula was confirmed with the pharmacodynamics study. Furthermore, the molecular mechanism of enhanced skin permeation was investigated using ATR-FTIR and molecular modeling. As a result, the optimized CuB-ME formulation was composed of Azone:Tween 80:ethanol:water = 2.5:16.9:5.6:75.0 (w/w/w/w). The oil phase improved skin permeation by disordering the stratum corneum intercellular liquid, while the aqueous phase impacted the particle size of the microemulsion and permeability coefficient of the drug. Besides, the hydration state of skin lipid also enhanced drug permeation by the interaction of water and the polar head of ceramide. The in vitro skin permeation amount was 45.47 ± 10.39 μg/cm², and no significant skin irritation was observed. The pharmacodynamics study demonstrated that CuB-ME had a significant therapeutic effect on the animal tumor model. In conclusion, the CuB-ME was developed successfully and the effect of the oil phase and aqueous phase on drug skin permeation was clarified at the molecular level.