Abstract
Orobol is one of the major soy isoflavones, and has been reported to have various pharmacological activities, including an anti-skin-aging effect. However, since it has low solubility in water and physicochemical instability, the formulation of orobol for delivery into the dermal layer of the skin could be challenging. The objective of this study was to prepare lipid nanoparticles formulations of orobol to enhance its stability as well as its deposition into the skin. Formulations of orobol-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were characterized in terms of their mean particle size, entrapment efficiency, and morphology. The nano-sized spherical NLCs formulations maintained the stability of orobol for up to 28 days. Moreover, the NLCs formulation significantly increased the in vitro deposition of orobol into both Strat-M membranes and human cadaver skin compared with the other formulations. Additionally, the NLCs formulation did not cause significant skin irritation in clinical study. These results demonstrate that a shea butter-based NLC formulation could be a promising and safe carrier system for improving the stability of orobol and enhancing its topical skin delivery.
Highlights
Long-term ultraviolet (UV) exposure is one of the major causes of photoaging of the skin, which results in irreversible and progressive structural changes of the skin [1]
Transcutol and Capmul MCM EP were selected as the surfactant and as the oil, respectively, for the formulation of solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs)
Cocoa butter and shea butter were selected as the solid lipids for the inner phase
Summary
Long-term ultraviolet (UV) exposure is one of the major causes of photoaging of the skin, which results in irreversible and progressive structural changes of the skin [1]. The clinical signs of photoaging include wrinkles, skin roughness, and decreased skin elasticity. Studies have shown that, when exposed to UV light, reactive oxygen species (ROS) are generated in the skin, which activate c-Jun N-terminal kinase and stimulate the expression of matrix metalloproteinase-1 (MMP-1), thereby up-regulating the degradation of collagen, elastin, and hyaluronic acid in the dermis of the skin [2,3,4]. Isoflavones derived from soy beans have been widely used as potential anti-skin-aging compounds [5,6]. Numerous studies have reported that genistein, a major soy isoflavone, could suppress the generation of ROS and expression of MMP-1 and inducible nitrogen oxide synthase (iNOS), thereby exerting anti-wrinkle, skin-protective, and hydration effects against UV-induced photoaging [7,8]. Nano-carrier systems such as microemulsions, liposomes, and lipid nanoparticles have been exploited to enhance topical skin delivery of genistein and reach its therapeutic concentration in target cells of skin [9,10,11]
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