Novel nanocapsule of α‐lipoic acid reveals pigmentation improvement: α‐Lipoic acid stimulates the proliferation and differentiation of keratinocyte in murine skin by topical application

Abstract

α‐Lipoic acid is amphipathic with low molecular sulphur‐containing fatty acid and has strong antioxidant effects. It has been used at the purposes of anti‐ageing, treatment of diabetic neuropathy, and supplement as antioxidant. Though α‐lipoic acid is normally administered in oral or injection, it has not been used in a topical use via skin because of its bad penetration. We developed the novel nanocapsule of α‐lipoic acid, named α‐lipoactive (nLA), to improve skin permeability. The nLA is constructed as micelles of α‐lipoic acid mixed with the non‐ionic surfactant, and its surface of the micelles was coated with inorganic metal salts. It is water soluble and has a diameter of approximately 8‐15 nm. After nLA was applied to the murine skin, epidermal thickening was observed. It was confirmed that this effect is caused by α‐lipoic acid molecule, but not by the raw material used for encapsulation. In in vivo experiments, it was found that nLA is very effective for improving UV‐induced pigmentation and epidermal thickening. Our findings suggest that nanoencapsulation of α‐lipoic acid is considerably effective for topical application.

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