Ultraviolet B (UVB) irradiation may cause inflammation- and oxidative-stress-dependent skin cancer and premature aging. Naringenin (1) has been reported to have anti-inflammatory and antioxidant properties, but its effects and mechanisms on UVB irradiation-induced inflammation and oxidative stress are still not known. Thus, the present study aimed to investigate the potential of naringenin to mitigate UVB irradiation-induced inflammation and oxidative damage in the skin of hairless mice. Skin edema, myeloperoxidase (neutrophil marker) and matrix metalloproteinase-9 (MMP-9) activity, and cytokine production were measured after UVB irradiation. Oxidative stress was evaluated by 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS) scavenging ability, ferric reducing antioxidant power (FRAP), reduced glutathione levels, catalase activity, lipid peroxidation products, superoxide anion production, and gp91phox (NADPH oxidase subunit) mRNA expression by quantitative PCR. The intraperitoneal treatment with naringenin reduced skin inflammation by inhibiting skin edema, neutrophil recruitment, MMP-9 activity, and pro-inflammatory (TNF-α, IFN-γ, IL-1β, IL-4, IL-5, IL-6, IL-12, IL-13, IL-17, IL-22, and IL-23) and anti-inflammatory (TGF-β and IL-10) cytokines. Naringenin also inhibited oxidative stress by reducing superoxide anion production and the mRNA expression of gp91phox. Therefore, naringenin inhibits UVB irradiation-induced skin damage and may be a promising therapeutic approach to control skin disease.

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Naringenin (NGN) exhibits anti-inflammatory and antioxidant activities, but it remains undetermined its topical actions against ultraviolet B (UVB)-induced inflammation and oxidative stress in vivo. The purpose of this study was to evaluate the physicochemical and functional antioxidant stability of NGN containing formulations, and the effects of selected NGN containing formulation on UVB irradiation-induced skin inflammation and oxidative damage in hairless mice. NGN presented ferric reducing power, ability to scavenge 2,2′-azinobis (3-ethylbenzothiazoline- 6-sulfonic acid) (ABTS) and hydroxyl radical, and inhibited iron-independent and dependent lipid peroxidation. Among the three formulations containing NGN, only the F3 kept its physicochemical and functional stability over 180 days. Topical application of F3 in mice protected from UVB-induced skin damage by inhibiting edema and cytokine production (TNF-α, IL-1β, IL-6, and IL-10). Furthermore, F3 inhibited superoxide anion and lipid hydroperoxides production and maintained ferric reducing and ABTS scavenging abilities, catalase activity, and reduced glutathione levels. In addition, F3 maintained mRNA expression of cellular antioxidants glutathione peroxidase 1, glutathione reductase and transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2), and induced mRNA expression of heme oxygenase-1. In conclusion, a formulation containing NGN may be a promising approach to protecting the skin from the deleterious effects of UVB irradiation.

Skin exposure to ultraviolet B (UVB) irradiation has increased significantly in recent years due to ozone depletion, and it represents the main cause of many skin diseases. Hesperidin methyl chalcone (HMC) is a compound used to treat vascular diseases that has demonstrated anti-inflammatory activities in pre-clinical studies. Herein, we tested the antioxidant activity of HMC in cell free systems and the in vivo effects of a stable topical formulation containing HMC in a mouse model of skin oxidative stress and inflammation induced by UVB irradiation. HMC presented ferric reducing power, neutralized 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and hydroxyl free radicals, and inhibited lipid peroxidation. In hairless mice, a topical formulation containing HMC inhibited UVB irradiation-induced skin edema, depletion of antioxidant capacity (ferric and ABTS reducing abilities and catalase activity), lipid peroxidation, superoxide anion production and mRNA expression of gp91phox (nicotinamide adenine dinucleotide phosphate [NADPH] oxidase 2 sub-unity). In addition, HMC inhibited UVB irradiation-induced depletion of reduced glutathione levels by maintaining glutathione peroxidase-1 and glutathione reductase mRNA expression, prevented down-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) mRNA expression and increased heme oxygenase-1 mRNA expression. Finally, we demonstrated that topical application of the formulation containing HMC inhibited cytokine (TNF-α, IL-1β, IL-6, and IL-10) production induced by UVB irradiation. Therefore, this topical formulation containing HMC is a promising new therapeutic approach to protecting the skin from the deleterious effects of UVB irradiation.

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