Prevention of UVB radiation-induced oxidative stress in mice by topical administration of Azadirachta indica(neem) extract

Neem tree (Azadirachta indica A. Juss. fam. Meliaceae) has been extensively employed to combat diverse pathologies. Moreover, it has been described that its leaf extract present anticarcinogenic action. Thus, the neem extract (NE) chemical and antioxidant properties was evaluated, and also, the capacity of two dermatological formulations incorporated with neem extract (F1 and F2) to avoid oxidative UVB-induced skin injury in hairless mice. NE constituents were investigated and free radical scavenging ability were determined by different methods in vitro. Skin from mice treated with F1 and F2 and submitted to UVB radiation were tested for different parameters of inflammation and oxidative injury. Results show that the NE polyphenol and flavonoid content were 135.30 and 37.12mg/g, respectively. High performance liquid chromatography (HPLC) results demonstrated the existence of azarachtin, rutin, ursolic acid and tannic acid. NE presented scavenging ability by ABTS radical, ferric-reducing antioxidant power (FRAP), inhibition of lipid peroxidation and iron chelation. In vivo, it was observed that mice treated with F1 and F2 showed amelioration of the inflammation by reducing UVB induced skin edema. However, only samples from animals treated with F1 had lower neutrophil recruitment (measured by myeloperoxidase activity), and returning the oxidative status to baseline levels in parameters such as reduced glutathione level, ferric reducing ability (FRAP), and scavenging of free radical (ABTS). Concluding, NE demonstrated a good antioxidant property in vitro, and the data suggest the use of NE added F1 to prevent skin damage caused by UVB irradiation.(AU)

Adenophora remotiflora protects human skin keratinocytes against UVB-induced photo-damage by regulating antioxidative activity and MMP-1 expression

BACKGROUND/OBJECTIVES: Chronic ultraviolet (UV) exposure-induced reactive oxygen species (ROS) are commonly involved in the pathogenesis of skin damage by activating the metalloproteinases (MMP) that break down type I collagen. Adenophora remotiflora (AR) is a perennial wild plant that inhabits Korea, China, and Japan. The present study investigated the protective effects of AR against UVB-induced photo-damage in keratinocytes. MATERIALS/METHODS: An in vitro cell-free system was used to examine the scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and nitric oxide (NO). The effect of AR on ROS formation, antioxidant enzymes, elastase, MMP-1 level, and mRNA expression of MMP-1 were determined in UVB-irradiated human keratinocyte HaCaT cells. RESULTS: AR demonstrated strong DPPH free radical and NO scavenging activity in a cell-free system exhibiting IC50 values of 1.88 mg/mL and 6.77 mg/mL, respectively. AR pretreatment dose-dependently attenuated the production of UVB-induced intracellular ROS, and antioxidant enzymes (catalase and superoxide dismutase) were enhanced in HaCaT cells. Furthermore, pretreatment of AR prevented UVB-induced elastase and collagen degradation by inhibiting the MMP-1 protein level and mRNA expression. Accordingly, AR treatment elevated collagen content in UVB-irradiated HaCaT cells. CONCLUSION: The present study provides the first evidence of AR inhibiting UVB-induced ROS production and induction of MMP-1 as a result of augmentation of antioxidative activity in HaCaT human keratinocytes. These results suggest that AR might act as an effective inhibitor of UVB-modulated signaling pathways and might serve as a photo-protective agent.

Protective effect of the standardized green tea seed extract on UVB-induced skin photoaging in hairless mice

BACKGROUND/OBJECTIVES: Ultraviolet B (UVB) irradiation on skin can induce production of reactive oxygen species (ROS), which cause expression of matrix metalloproteinases (MMPs) and collagen degradation. Thus, chronic exposure of skin to UVB irradiation leads to histological changes consistent with aging, such as wrinkling, abnormal pigmentation, and loss of elasticity. We investigated the protective effect of the standardized green tea seed extract (GSE) on UVB-induced skin photoaging in hairless mice. MATERIALS/METHODS: Skin photoaging was induced by UVB irradiation on the back of Skh-1 hairless mice three times per week and UVB irradiation was performed for 10 weeks. Mice were divided into six groups; normal control, UVB irradiated control group, positive control (UVB + dietary supplement of vitamin C 100 mg/kg), GSE 10 mg/kg (UVB + dietary supplement of GSE 10 mg/kg), GSE 100 mg/kg (UVB + dietary supplement of GSE 100 mg/kg), and GSE 200 mg/kg (UVB + dietary supplement of GSE 200 mg/kg). RESULTS: The dietary supplement GSE attenuated UVB irradiation-induced wrinkle formation and the decrease in density of dermal collagen fiber. In addition, results of the antioxidant analysis showed that GSE induced a significant increase in antioxidant enzyme activity compared with the UVB irradiation control group. Dietary supplementation with GSE 200 mg/kg resulted in a significant decrease in expression of MMP-1, MMP-3, and MMP-9 and an increase in expression of TIMP and type-1 collagen. CONCLUSIONS: Findings of this study suggest that dietary supplement GSE could be useful in attenuation of UVB irradiation-induced skin photoaging and wrinkle formation due to regulation of antioxidant defense systems and MMPs expression.

Protective effect of the standardized green tea seed extract on UVB-induced skin photoaging in hairless mice

BACKGROUND/OBJECTIVES: Ultraviolet B (UVB) irradiation on skin can induce production of reactive oxygen species (ROS), which cause expression of matrix metalloproteinases (MMPs) and collagen degradation. Thus, chronic exposure of skin to UVB irradiation leads to histological changes consistent with aging, such as wrinkling, abnormal pigmentation, and loss of elasticity. We investigated the protective effect of the standardized green tea seed extract (GSE) on UVB-induced skin photoaging in hairless mice. MATERIALS/METHODS: Skin photoaging was induced by UVB irradiation on the back of Skh-1 hairless mice three times per week and UVB irradiation was performed for 10 weeks. Mice were divided into six groups; normal control, UVB irradiated control group, positive control (UVB + dietary supplement of vitamin C 100 mg/kg), GSE 10 mg/kg (UVB + dietary supplement of GSE 10 mg/kg), GSE 100 mg/kg (UVB + dietary supplement of GSE 100 mg/kg), and GSE 200 mg/kg (UVB + dietary supplement of GSE 200 mg/kg). RESULTS: The dietary supplement GSE attenuated UVB irradiation-induced wrinkle formation and the decrease in density of dermal collagen fiber. In addition, results of the antioxidant analysis showed that GSE induced a significant increase in antioxidant enzyme activity compared with the UVB irradiation control group. Dietary supplementation with GSE 200 mg/kg resulted in a significant decrease in expression of MMP-1, MMP-3, and MMP-9 and an increase in expression of TIMP and type-1 collagen. CONCLUSIONS: Findings of this study suggest that dietary supplement GSE could be useful in attenuation of UVB irradiation-induced skin photoaging and wrinkle formation due to regulation of antioxidant defense systems and MMPs expression.

Aging and UV Irradiation Related Changes of Gene Expression in Primary Human Keratinocytes

The epidermis is a physiological barrier to protect organisms against environment. During the aging process, skin tissues undergo various changes including morphological and functional changes. The transcriptional regulation of genes is part of cellular reaction of aging process. In order to examine the changes of gene expression during the aging process, we used the primary cell culture system of human keratinocytes. Since UV radiation is the most important environmental skin aggressor, causing skin cancer and other problems including premature skin aging, we examined the changes of gene expression in human keratinocytes after UV irradiation using oligonucleotide microarray containing over 10,000 genes. We also compared the gene expression patterns of the senescent and UV treated cells. Expression of the variety of genes related to transcription factors, cell cycle regulation, immune response was altered in human keratinocytes. Some of down-regulated genes are represented in both senescent and UV treated cells. The results may provide a new view of gene expression following UVB exposure and aging process in human keratinocytes.

The Effect of UVB on the NF-kB and AP-1 Activity in Cultured Human Keratinocytes and Fibroblasts / 대한피부과학회지

BACKGROUND: Ultraviolet B(UVB) light, which can cause severe damage like induction and promotion of cancer, cutaneous inflammation and immunosuppression, represents one of the most important environmental impacts for humans. Keratinocytes are natural target cells of UVB in humans. NF-kB plays a role in the cell of the immune system, where it controls the expression of various cytokines and the major histocompatibility complex gene. OBJECTIVE: The purpose of this study was to examine the effect of UVB on the NF-kB and AP-1 activity in cultured human keratinocytes and fibroblasts. METHODS: Keratinocyte and fibroblast cultures were produced with DMEM medium. Cells were irradiated for 100J/m, 200J/m, 300 J/m. and Nuclear proteins were extracted. AP-1 and NF-kB activities were measured by the gel shift mobility assay. RESULTS: Gel shift mobility assay. 1. The NFkB activity was increased upon UVB in a dose dependent manner in the keratinocyte. 2. Enhanced levels of AP-1 binding activity in the radiated extracts frorn human skin keratinocytes were detected. 3. The levels of GRE (glucocorticoid responsive element) binding activity were similar in both radiated and unradiated extracts from fibroblasts and keratinocytes. CONCLUSIONS: The activities of NF-aB and AP-1 are increased following stimulation of a cell with UVB irradiation. Therefore, UV induced skin tumors, abnormal cell proliferation, cutaneous inflammation and immunosuppression, may be due to these transcriptional factors.

The Study on the Ultraviolet-B Blocking Effect of Sunscreens in the Epidermal Langerhans Cells of Hairless Mice

BACKGROUND: Sunscreens have been used widely to prevent the photosensitive skin diseases, skin cancer, and skin aging. However, no sunscreen blocks all kinds of effects caused by ultraviolet light(UVL), and the effect of sunscreens on the impairment of immune function by UVL irradiation is controversial. OBJECTIVE: We try to evaluate the efficiency of sunscreens for blocking the depletion of LC induced by UVB irradiation. METHOD: The ATPase positive LCs were observed in the skin of hairless mice(Hr+/Kud) irradiated by UVB with or without topical application of sunscreens. Two commercially available sunscreens with respective SPF 8 and SPF 30 were applied to the dorsal trunk skin. The mice were irradiated with different increasing doses of UVB at a single time. RESULTS: The ATPase positive LCs in the irradiated dorsal and ear skin were significantly de-creased in densities according to the dosage, and apparently revealed a loss of their dendrites, granulation, and clumping from a UVB dose of more than 60mJ/Cm2. With both sun-screen treatment on the dorsal trunk before irradiation, the densities of LCs on the dorsal skin were significantly higher compared to the un-treated groups at all ranges of UVB doses in spite of a dose dependent decrease in their density. However there was no significant difference on their preventive effect between both sunscreens(SPF 8 and SPF 30) except at high UVB dos-es of more than 240mJ/Cm². CONCLUSION: The LC depletion induced by UVB can be partially protected through the topical application of a sunscreen at a UVB dose dependent fashion. However SPF(sun protective factor) dose not appear to be a good indicator for evaluating sunscreens immunologically.

The Effect of Ultraviolet Irradiation on the Morphological Changes in Epidermal Keratinocytes / 대한피부과학회지

A total of 40 adult black-mice was used and divided into two groups for expeiment. Group A was irradiated by UVB only and Group B had SPF 15 sunscreen a.pplied to the back followed by irradiation by UVB. Each group was divided again into 5 subgroups according to the days of UVB irradiation frcm 2 to 10 days. A Waldmann combination UVA+UVB Radiation Treatment Cabin 8001 was used as the light source and the UVB dosage was 50 mJ/cm2 daily. Skin specimens were taken 24 hours after the last irradiation. Histologic changes in epidermis were reviewed by the light microscope. In group A, the characteristic sunburn cells(SBC) were observed with 100 mJ/ cm2. SBC number was maximum with 400 mJ/cm2. The other epidermal changes were parakerat.osis, crusts, atypical cells, and mitoses of basal cells, which showed graded responses to the UVB doses. Pretreatment with the sunscreen completely prevented these changes.