Polynucleotide Mixture Attenuates Ultraviolet B-Induced Skin Pigmentation

Ultraviolet (UV) radiation stimulates melanogenesis, leading to various esthetic problems. UV increases oxidative stress and nuclear factor-kappa B (NF-κB), which increase the nucleotide-binding oligomerization domain (NOD) or leucine-rich repeat and pyrin do-main containing 3 (NLRP3) inflammasome. Given that polydeoxyribonucleotides reduce melanogenesis and polynucleotide (PN) has molecular similarity to polydeoxyribonucleotides, we hypothesized that PN can decrease melanogenesis. We compared the anti-melanogenic effect of PN with that of a PN mixture (PNM) that contained other antioxidants, such as glutathione and hyaluronic acid, in UVB-irradiated keratinocytes and animal skin. PN and PNM both decreased oxidative stress, which was evaluated according to the expression of NADPH oxidase (NOX) 1/2/4, the glutathione (GSH):oxidized glutathione (GSSG) ratio, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in UVB-irradiated keratinocytes. The expression of NLRP3 inflammasome components (NLRP3, ASC, and pro-caspase-1) and IL-18 was increased by UVB radiation and reduced by PN and PNM. When conditioned media from PN or PNM were administered to UVB-radiated keratinocytes, melanogenesis-related signals (MITF, tyrosinase, and tyrosinase-related protein1/2) were decreased. These effects were similar in the UVB-irradiated animal skin. Both PN and PNM decreased melanin accumulation and increased skin lightness in UVB-irradiated skin. The anti-melanogenic effect of PNM was greater than that of PN. In conclusion, PN and PNM decreased melanogenesis by decreasing oxidative stress, NF-κB, and NLRP3 inflammasome activation.