Prevention of UV-Induced Melanin Production by Accumulation of Redox Nanoparticles in the Epidermal Layer <i>via</i> Iontophoresis

Abstract

UV rays induce melanin production in the skin, which, from a cosmetic point of view, is problematic. Reactive oxygen species (ROS) generated in the skin upon UV irradiation are thought to be responsible for melanin production. Thus, effective antioxidants are recognized as useful tools for prevention of UV-induced melanin production. Redox nanoparticles (RNPs) containing nitroxide radicals as free radical scavengers were previously developed, and shown to be effective ROS scavengers in the body. RNPs are therefore expected to be useful for effective protection against UV-induced melanin production. However, as the sizes of RNPs are typically larger than the intercellular spaces of the skin, transdermal penetration is difficult. We recently demonstrated effective transdermal delivery and accumulation of nanoparticles in the epidermal layer via faint electric treatment, i.e., iontophoresis, suggesting that iontophoresis of RNPs may be a useful strategy for prevention of UV-induced melanin production in the skin. Herein, we performed iontophoresis of RNPs on the dorsal skin of hairless mice that produce melanin in response to light exposure. RNPs accumulated in the epidermal layer upon application of iontophoresis. Further, the combination of RNPs with iontophoresis decreased UV-induced melanin spots and melanin content in the skin. Taken together, we successfully demonstrated that iontophoresis-mediated accumulation of RNPs in the epidermis prevented melanin production.

Therapeutic Effect of Seawater Pearl Powder on UV-Induced Photoaging in Mouse Skin

“…These results were dose-dependent in a certain concentration range, and the optimal concentration of seawater pearl powder was 200 mg/g. Research indicates that ROS generated in the skin upon UV irradiation is responsible for melanin production, and effective antioxidants are recognized as useful tools for prevention of UV-induced melanin production [ 27 ]. Therefore, SPP has the ability to reduce melanin content via inhibition of TYR activity after scavenging excess ROS in UV-induced photoaged skin in mice.…”

Photodamage and Photoprotection: An In vivo Approach Using Noninvasive Probes

“…Melanin content in skin increases as a result of sun exposure, and this is due to the defense mechanism as photoprotection of skin against UV radiations . UV radiations induce many alterations in human skin one of which is the development of melanin, which may be due to ROS . Skin erythema level increases in the sun‐exposed site as compared to the photoprotected site.…”

Iontophoresis in dermal delivery: A review of applications in dermato‐cosmetic and aesthetic sciences

“…Astaxanthin (3,3P-dihydroxyl-4,4P-dioxo-L-carotene), a common pigment found in algae, fish and birds, is a potent antioxidative carotenoid, with demonstrated protective effects on UV-mediated skin damage [60]. However, since it is difficult to administer topically to skin, Hama et al, in 2012, prepared a topical astaxanthin liposomal formulation and examined, in vitro and in vivo, its preventive effects on UV-induced skin damage [61].…”

“…The pharmaceutical and cosmetic industries are perpetually searching for topical antioxidants that can be used to avert or treat skin conditions related to oxidative stress, such as skin ageing and UV-mediated melanin production [60,64]. However, some active compounds may have limited antioxidant effects when applied passively, because of their limited capacity to reach the viable epidermis [64].…”

“…However, since their penetration through the skin is hard to achieve, iontophoresis of RNPs has been investigated and found to be a successful strategy for the prevention of UV-induced melanin production in the skin. In 2017, Shiota et al performed anodal iontophoresis of positively charged RNPs on the dorsal skin of hairless mice that produce melanin in response to light exposure [60]. Upon application of iontophoresis, RNPs accumulated in the epidermal layer.…”