Abstract
In the present work, we establish novel “environmentally-friendly” oil-in-water nanoemulsions to enhance the transdermal delivery of bakuchiol, the so-called “bioretinol” obtained from powdered Psoralea corylifolia seeds via a sustainable process, i.e., using a supercritical fluid extraction approach with pure carbon dioxide (SC-CO2). According to Green Chemistry principles, five novel formulations were stabilized by “green” hybrid ionic surfactants such as coco-betaine—surfactin molecules obtained from coconut and fermented rapeseed meal. Preliminary optimization studies involving three dispersion stability tests, i.e., centrifugation, heating, and cooling cycles, indicated the most promising candidates for further physicochemical analysis. Finally, nanoemulsion colloidal characterization provided by scattering (dynamic and electrophoretic light scattering as well as backscattering), microscopic (transmission electron and confocal laser scanning microscopy), and spectroscopic (UV–Vis spectroscopy) methods revealed the most stable nanocarrier for transdermal biological investigation. In vitro, topical experiments provided on human skin cell line HaCaT keratinocytes and normal dermal NHDF fibroblasts indicated high cell viability upon treatment of the tested formulation with a final 0.02–0.2 mg/mL bakuchiol concentration. This excellent biocompatibility was confirmed by ex vivo and in vivo tests on animal and human skin tissue. The improved permeability and antiaging potential of the bakuchiol-encapsulated rich extract were observed, indicating that the obtained ecological nanoemulsions are competitive with commercial retinol formulations.
Highlights
IntroductionSurfactin exhibits antibacterial, antifungal, antiviral, and even antitumor activities, while demonstrating a supporting role in collagen production [10,11,12]
Surfactin used as an anionic biosurfactant was obtained in a biotechnological manner from Bacillus subtilis natto KB1 strains grown on rapeseed meal, according to the procedure described below
The NHDF cells were cultured in minimum essential medium Eagle (EMEM) with alpha modifications, supplemented with 10% fetal bovine serum (FBS), glutamine (2 mM), penicillin (100 U/mL), and streptomycin (100 μg/mL)
Summary
Surfactin exhibits antibacterial, antifungal, antiviral, and even antitumor activities, while demonstrating a supporting role in collagen production [10,11,12] This unique feature, combined with excellent emulsification properties and its difficult-to-break traditional emulsion, may be beneficial in surfactin, assisting in the nanoemulsion stabilization process of other surface-active compounds; for example, enhancing the moderate emulsifying properties of coco-betaine, and the application of these green formulations in skin care products, for potential delivery of bioactive compounds. Both surfactants are ionic, which is necessary for obtaining highly stable formulations, since the stability of any nanoemulsion is more complex when electrostatic effects are present [13]. To the best of our knowledge, the presented formulations are ple of “vegan-friendly” nanoemulsions with sustainably achieved bakuchiol stabilized by hybrid coco-betaine–surfactin molecules dedicated to topical applications
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