Photo-Protective and Anti-Inflammatory Effects of Antidesma thwaitesianum Müll. Arg. Fruit Extract against UVB-Induced Keratinocyte Cell Damage

The main cause of most skin cancers is damage from UVB from sunlight, which penetrate the skin surface and induce inflammation. For this reason, this study aims to identify natural products with photo-protection properties and their mode of action by using the UVB-irradiated HaCaT keratinocyte model. Antidesma thwaitesianum fruit extracts at 25, 50, and 100 µg/mL recovered cell viability following UVB exposure in a dose-dependent manner. Cell survival was associated with the reduction in intracellular ROS and NO. In addition, we showed that the pre-treatment with the fruit extract lowered the phosphorylation level of two MAPK-signaling pathways: p38 MAPKs and JNKs. The resulting lower MAPK activation decreased their downstream pro-inflammatory cascade through COX-2 expression and subsequently reduced the PGE₂ proinflammatory mediator level. The photoprotective effects of the fruit extract were correlated with the presence of polyphenolic compounds, including cyanidin, ferulic acid, caffeic acid, vanillic acid, and protocatechuic acid, which have been previously described as antioxidant and anti-inflammation. Together, we demonstrated that the pre-treatment with the fruit extract had photo-protection by inhibiting oxidative stress and subsequently lowered stress-induced MAPK responses. Therefore, this fresh fruit is worthy of investigation to be utilized as a skincare ingredient for preventing UVB-induced skin damage.     

cis-UROCANIC ACID FAILED TO AFFECT in vitro HUMAN LANGERHANS CELL ALLOSTIMULATORY FUNCTION

Abstract— -Urocanic acid (UCA) represents the major ultraviolet B (UVB, 290–320 nm)-absorbing component of the skin. Trans-UCA is naturally produced in the stratum corneum and converts to the cis isomer upon UVB irradiation. In this study, we examined the effect of purified cis -UCA (about 99% of cis isomer) on the human Langerhans cell (LC) allostimulatory function by using the mixed epidermal cell-lymphocyte reaction (MELR). We found that addition of increasing amounts (6.5–400 μg/mL) of purified cis-UCA or (rara-UCA did not modify the T-cell response supported by enriched LC (eLC: 8–25% LC) as well as purified LC (pLC: 70–90% LC) suspensions. Because cis-UCA had no effect on the allostimulatory function of untreated LC, we investigated whether this compound could modify T-cell proliferation induced by UVB-irradiated LC. The UVB exposure of eLC or pLC to 100 J/m² significantly inhibited the capacity of both suspensions to mount a T-cell response. However, addition of cis- UCA did not potentiate this UVB-induced immunosuppression. The eLC or pLC were then incubated with cis-UCA for 18 h at 37°C and washed before adding to allogeneic T cells. The obtained proliferative response was similar to that induced by control LC incubated in medium alone, demonstrating that pretreatment with cis -UCA did not alter human LC function. In conclusion, these results strongly suggest that cis-UCA has no direct effect on human LC antigen-presenting function.     

The role of cholesterol in UV light B-induced apoptosis

Modification of major lipid raft components, such as cholesterol and ceramide, plays a role in regulation of programmed cell death under various stimuli. However, the relationship between cholesterol level modification and the activation of apoptotic signaling cascades upon UVB light has not been established. In this report, we demonstrate that upon UVB irradiation cholesterol levels in membrane rafts of skin cells increase, which leads to Fas-receptor (Fas) aggregation in the rafts. Utilizing a continuous velocity floatation technique, we show that Fas accumulated in the lipid rafts of human melanoma M624 cells after UVB irradiation. The subsequent events of death-inducing signaling complex formation were also detected in the lipid raft fractions. Depletion of cholesterol by methyl-β-cyclodextrin reduces Fas aggregation, while overloading increases. Disruption of lipid rafts also prevents Fas death domain-associated protein (Daxx) from dissociating from Fas in the lipid rafts, which is accompanied with a reduced apoptotic, but increased nonapoptotic death of UVB-irradiated human keratinocytes, HaCaT cells. Results indicate that cholesterol located in the plasma membrane of skin cells is required for lipid raft domain formation and activation of UVB-induced apoptosis.     

In Vitro and In Vivo Photoprotective Effects of (-)-Loliode Isolated from the Brown Seaweed,Sargassum horneri

Skin is the largest organ of humans. Overexposure to ultraviolet (UV) is the primary environmental factor that causes skin damage. The compound, (-)-loliode, isolated from the brown seaweed Sargassum horneri, showed strong antioxidant and anti-inflammatory activities in in vitro and in vivo models. To further explore the potential of (-)-loliode in cosmetics, in the present study, we investigated the photoprotective effect of (-)-loliode in vitro in skin cells and in vivo in zebrafish. The results indicated that (-)-loliode significantly reduced intracellular reactive oxygen species (ROS) level, improved cell viability, and suppressed apoptosis of UVB-irradiated human keratinocytes. In addition, (-)-loliode remarkably attenuated oxidative damage, improved collagen synthesis, and inhibited matrix metalloproteinases expression in UVB-irradiated human dermal fibroblasts. Furthermore, the in vivo test demonstrated that (-)-loliode effectively and dose-dependently suppressed UVB-induced zebrafish damage displayed in decreasing the levels of ROS, nitric oxide, lipid peroxidation, and cell death in UVB-irradiated zebrafish. These results indicate that (-)-loliode possesses strong photoprotective activities and suggest (-)-loliode may an ideal ingredient in the pharmaceutical and cosmeceutical industries.     

Oxidation of guanine in cellular DNA by solar UV radiation: biological role.

The formation of cyclobutane pyrimidine dimers (CPD) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) was investigated in Chinese hamster ovary cells upon exposure to either UVC, UVB, UVA or simulated sunlight (SSL). Two cell lines were used, namely AT3-2 and UVL9, the latter being deficient in nucleotide excision repair and consequently UV sensitive. For all types of radiation, including UVA, CPD were found to be the predominant lesions quantitatively. At the biologically relevant doses used, UVC, UVB and SSL irradiation yielded 8-oxodGuo at a rather low level, whereas UVA radiation produced relatively higher amounts. The formation of CPD was 10(2) and 10(5) more effective upon UVC than UVB and UVA exposure. These yields of formation followed DNA absorption, even in the UVA range. The calculated relative spectral effectiveness in the production of the two lesions showed that efficient induction of 8-oxodGuo upon UVA irradiation was shifted toward longer wavelengths, in comparison with those for CPD formation, in agreement with a photosensitization mechanism. In addition, after exposure to SSL, about 19% and 20% of 8-oxodGuo were produced between 290-320 nm and 320-340 nm, respectively, whereas CPD were essentially (90%) induced in the UVB region. However, the ratio of CPD to 8-oxodGuo greatly differed from one source of light to the other: it was over 100 for UVB but only a few units for UVA source. The extent of 8-oxodGuo and CPD was also compared to the lethality for the different types of radiation. The involvement of 8-oxodGuo in cell killing by solar UV radiation was clearly ruled out. In addition, our previously reported mutation spectra demonstrated that the contribution of 8-oxodGuo in the overall solar UV mutagenic process is very minor.     

Induction of 8-Oxo-7,8-Dihydro-2'-Deoxyguanosine by Ultraviolet Radiation in Calf Thymus DNA and HeLa Cells

Abstract— The levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) in purified calf thymus DNA and HeLa cells were measured following exposure to either UVC, UVB or UVA wavelengths. This DNA damage was quantitated using HPLC coupled with an electrochemical detector. The 8-oxodGuo was induced in purified DNA in a linear dose-dependent fashion by each portion of the UV spectrum at yields of 100, 0.46 and 0.16 8-oxodGuo per 10⁵ 2'-deoxyguanosine (dGuo) per kJ/m² for UVC, UVB and UVA, respectively. However, the amount of 8-oxodGuo in HeLa cells irradiated with these UV sources decreased to approximately 2.0, 0.013 and 0.0034 8-oxodGuo per 10⁵ dGuo per kJ/m², respectively. In contrast, the levels of cyclobutyl pyrimidine dimers were similar in both irradiated DNA and cells. Therefore, 8-oxodGuo is induced in cells exposed to wavelengths throughout the UV spectrum although it appears that protective precesses exist within cells that reduce the UV-induced formation of this oxidative DNA damage. Cell survival was also measured and the number of dimers or 8-oxodGuo per genome per lethal event determined. These calculations are consistent with the conclusion that dimers play a major role in cell lethality for UVC- or UVB-irradiated cells but only a minor role in cells exposed to UVA wavelengths. In addition, it was found that the relative yield of 8-oxodGuo to dimers increased nearly 1000-fold in both UVA-irra-diated cells and DNA compared with cells subjected to either UVC or UVB. These results are supportive of the hypothesis that 8-oxodGuo, and possible other forms of oxidative damage, play an important role in the induction of biological effects caused by wavelengths in the UVA portion of the solar spectrum.     

Observation and quantification of ultraviolet-induced reactive oxygen species in ex vivo human skin

Two-photon fluorescence imaging is used to detect UV-induced reactive oxygen species (ROS) in ex vivo human skin in this study. ROS (potentially H202, singlet oxygen or peroxynitrite [or all]) are detected after reaction with nonfluorescent dihydrorhodamine-123 (DHR) and the consequent formation of fluorescent rhodamine-123 (R123). The cellular regions at each epidermal stratum that generate ROS are identified. R-123 fluorescence is detected predominately in the lipid matrix of the stratum corneum. In contrast, the strongest R123 fluorescence signal is detected in the intracellular cytoplasm of the viable epidermal keratinocytes. A simple bimolecular one-step kinetic model is used for estimating the upper bound of the number of ROS that are generated in the skin and that react with DHR. After ultraviolet-B radiation (280-320 nm) (UVB) equivalent to 2 h of noonday summer North American solar exposure (1600 J m(-2) UVB), the model finds that 14.70 x 10(-3) mol of ROS that react with DHR are generated in the stratum corneum of an average adult-size face (258 cm(-2)). Approximately 10(-4) mol are potentially generated in the lower epidermal strata. The data show that two-photon fluorescence imaging can be used to detect ROS in UV-irradiated skin.     

Daphnia pulex Fed UVB-lrradiated Chlamydomonas reinhardtii Show Decreased Survival and Fecundity†

Abstract The ability to avoid or tolerate UVB radiation (290–320 nm) probably reduces the quality of phytoplankton as food for zooplankton. Ultraviolet avoidance forces motile algae lower in the water column, reducing net primary productivity. Production of UV-absorbing compounds as a tolerance mechanism takes carbon and energy away from cell growth; these compounds are also less useful as food for herbivores. We assessed the food quality of UVB-irradiated Chlamydomonas reinhardtii Dang, by analysis of cohort life tables for the herbivore Daphnia pulex Leydig. Algal cultures were grown under fluorescent lights interspersed with UV bulbs (20°C, 16 h light: 8 h dark) and covered with either cellulose acetate (+UVB) or Mylar D (-UVB). After a 7 day UVB exposure, carotenoid levels of C. reinhardtii were significantly greater than in unexposed cultures; there were no significant differences in chlorophyll, lipid, protein or nonstructural carbohydrate levels. After an initial decrease in growth rate, UVB-exposed algae recovered and final growth rates of both cultures were similar after 7 days. Daphnia neonates were raised under optimal conditions (20°C, 16 h light:8 h dark) and fed either UVB-irradiated or control algae. Daphnia fed UVB-irradiated algae had significantly increased mortality, decreased growth rate at the time of first clutch production, delayed release of the first clutch and decreased overall fecundity (P < 0.05). Daphnia were also less efficient at clearing UVB-irradiated algae from the water column (17% removal in 18 h) when compared with Daphnia that grazed upon nonirradiated algae (85% removal in 18 h). These data suggest that even though UVB-irradiated algal populations can recover from their initial decline, their predators may not be able to utilize them as an effective food source. Therefore, the impacts of UVB radiation within     

Topically applied eicosapentaenoic acid protects against local immunosuppression induced by UVB irradiation, cis-urocanic acid and thymidine dinucleotides

UVB-induced immunosuppression, a promoter of photocarcinogenesis, involves the formation of pyrimidine dimers and cis-urocanic acid (cis-UCA), but reactive oxygen species (ROS) also plays an important role. Eicosapentaenoic acid (EPA) can inhibit photocarcinogenesis, but due to its polyunsaturated nature it is susceptible to oxidative damage by ROS. The antioxidant defense system may therefore be challenged upon ultraviolet-B (UVB) irradiation in the presence of EPA. We investigated whether topically applied EPA in mice could protect against local immunosuppression (contact hypersensitivity response to dinitrofluorobenzene) induced by UVB radiation (1.5 J/cm2), or topically applied cis-UCA (150 nmol/cm2) or thymidine dinucleotides (pTpT) (5 nmol/cm2). The influence of EPA on epidermal lipid peroxidation and antioxidant status was also measured. UVB irradiation, cis-UCA and pTpT all caused 70% immunosuppression. Topical pretreatment of mice with EPA partially protected against immunosuppression; the EPA dose needed to accomplish this was 10 nmol/cm2 for UVB irradiation, 100 nmol/cm2 for cis-UCA and 1000 nmol/cm2 for pTpT. Higher EPA doses caused higher UVB-induced lipid peroxidation and lower vitamin C levels. Glutathione only decreased with the highest EPA dose whereas vitamin E was not decreased after UVB irradiation. In conclusion, topically applied EPA protects against UVB-, cis-UCA- and pTpT-induced immunosuppression and maintenance of an adequate antioxidant defense seems to be an important prerequisite for the protective action by EPA.     

UVB Irradiation Enhances TiO2 Nanoparticle‐induced Disruption of Calcium Homeostasis in Human Lens Epithelial Cells

Currently, titanium dioxide nanoparticles (TiO₂ NPs) have been widely used in various applications including cosmetics, food additives and biomedicine. However, there are few reports available using TiO₂ NPs to treat ocular diseases. Posterior capsular opacification (PCO) is the most frequent complication after cataract surgery, which is induced by the proliferation and migration of lens epithelial cells. Thus, inhibiting the proliferation of lens epithelial cells will efficiently reduce the occurrence of PCO. In this study, we investigated the effects of TiO₂ NPs on HLE B‐3 cells with or without ultraviolet B (UVB) irradiation in vitro. We found that TiO₂ NPs can inhibit HLE B‐3 cell growth, cause the elevation of intracellular [Ca²⁺], produce excessive reactive oxygen species (ROS), further reduce Ca²⁺‐ATPase activity and decrease the expression of plasma membrane calcium ATPase 1 (PMCA1), finally disrupt the intracellular calcium homeostasis and induce cell damage. Importantly, UVB irradiation can apparently enhance these effects on HLE B‐3 cells in the presence of TiO₂ NPs. Taken together, the generation of excessive ROS and the disruption of intracellular calcium homeostasis may be both involved in TiO₂ nanoparticle‐induced HLE B‐3 cell damage under UVB irradiation.     

The Role of Calcium in UVB-lnduced Damage in Irradiated Ocular Lenses

Abstract— The purpose of this study was to evaluate the role of altered calcium homeostasis in the development of irreversible membrane damage in the UVB-irradiated ocular lens. In particular, experiments were designed to determine whether restricting calcium influx could prevent membrane damage that typically leads to ion imbalances and lens opacification following short-term exposure to ultraviolet light (UVB). The influx of calcium was reduced by culturing lenses in a low-calcium culture medium containing 0.3 mM Ca²+ rather than physiological concentrations of 1.6 mM. This low-calcium protocol retarded calcium accumulation in UVB-irradiated lenses for 2 days of culture, and opacification was delayed by 24 h. Loss of transparency did occur during the second day of culture, but more slowly than in irradiated lenses cultured in normal-calcium medium. Membrane damage was assessed by evaluating loss in cation transport activity, assessed by measuring ⁸⁶Rb uptake into cultured lenses. Uptake was markedly inhibited in UVB-irradiated lenses and low-calcium culture did not prevent this inhibition of cation transport, a finding that explains why low-calcium protocol did not help maintain sodium homeostasis in irradiated lenses. Inhibition of cation transport and sodium accumulation eventually caused lens hydration and light scattering during extended culture in the absence of significant calcium elevation. Additional experiments were done to establish whether initial damage sustained by membranes could be repaired through the biosynthesis of new membrane proteins. Incorporation of ¹⁴C-histidine in membranes of the UVB-exposed lens was measured to assess membrane synthesis essential for repairing membrane damage. The rate of membrane protein synthesis, assessed by measuring incorporation of labeled amino acids, declined in UVB cataract, despite the prevention of calcium accumulation. These results suggest that one explanation for irreversible gain in sodium and calcium content accompanying opacification is the inability of lenses to replenish damaged membrane proteins comprising ion channels or transporters.     

Effects of Sphingomyelin-Containing Milk Phospholipids on Skin Hydration in UVB-Exposed Hairless Mice

Reactive oxygen species (ROS) generated by ultraviolet (UV) exposure cause skin barrier dysfunction, which leads to dry skin. In this study, the skin moisturizing effect of sphingomyelin-containing milk phospholipids in UV-induced hairless mice was evaluated. Hairless mice were irradiated with UVB for eight weeks, and milk phospholipids (50, 100, and 150 mg/kg) were administered daily. Milk phospholipids suppressed UV-induced increase in erythema and skin thickness, decreased transepidermal water loss, and increased skin moisture. Milk phospholipids increased the expression of filaggrin, involucrin, and aquaporin3 (AQP3), which are skin moisture-related factors. Additionally, hyaluronic acid (HA) content in the skin tissue was maintained by regulating the expression of HA synthesis- and degradation-related enzymes. Milk phospholipids alleviated UV-induced decrease in the expression of the antioxidant enzymes superoxidase dismutase1 and 2, catalase, and glutathione peroxidase1. Moreover, ROS levels were reduced by regulating heme oxygenase-1 (HO-1), an ROS regulator, through milk phospholipid-mediated activation of nuclear factor erythroid-2-related factor 2 (Nrf2). Collectively, sphingomyelin-containing milk phospholipids contributed to moisturizing the skin by maintaining HA content and reducing ROS levels in UVB-irradiated hairless mice, thereby, minimizing damage to the skin barrier caused by photoaging.     

Susceptibility to Effects of UVB Irradiation on Induction of Contact Sensitivity, Relevance of Number and Function of Langerhans Cells and Epidermal Macrophages

Sensitization on skin exposed to acute low-dose UVB irradiation separates normal humans into two phenotypically distinct groups: One group, following sensitization on UVB-irradiated skin, develops contact sensitivity, designated UVB resistant (UVB-R) and the second group, following sensitization on UVB-irradiated skin, fails to develop contact sensitivity, designated UVB susceptible (UVB-S). To investigate whether UVB susceptibility in humans is related to antigen-presenting activity in the skin we studied the effect of UVB irradiation on the number and function of the epidermal antigen-presenting cells in volunteers identified as UVB-R and UVB-S. Single cell suspensions of epidermal cells from control skin and skin exposed to 3 minimal erythema doses (MED) of UVB 3 days previously were stained for Langerhans cells (CD1a+HLA-DR+) and epidermal macrophages (CD1a-HLA-DR+). The UVB exposure of the skin significantly decreased the percentage of Langerhans cells (UVB-R: n = 7, P < 0.02, UVB-S: n = 6, P < 0.03) and increased the percentage of epidermal macrophages (UVB-R: n = 7, P < 0.03, UVB-S: n = 6, P < 0.03) however to the same degree in both the UVBR and the UVB-S group. To study the effect on Langerhans cell alloreactivity, epidermal cells were harvested immediately after UVB irradiation. However, in both UVB-R and UVB-S subjects the Langerhans cell alloreactivity was blocked to the same degree immediately after UVB irradiation compared to nonirradiated epidermal cells. To determine the effect of UVB irradiation on epidermal macrophages, epidermal cells were harvested 3 days after UVB irradiation. Irradiated epidermal cells from both UVB-R and UVB-S subjects demonstrated a strong antigen-presenting capacity compared to epidermal cells from control skin leading to activation of T cells that mainly secrete interferon (1FN)-γ and not interleukin (IL)-4. In conclusion we found that UVB susceptibility was not correlated with the number of Langerhans cells or epidermal macrophages in the skin at the same time of sensitization. Neither was it correlated with the capacity of Langerhans cells nor UVB-induced epidermal macrophages to activate T cells in vitro.     

IMPACT OF UVB and 03 ON THE OXYGEN FREE RADICAL SCAVENGING SYSTEM IN Arabidopsis thaliana GENOTYPES DIFFERING IN FLAVONOID BIOSYNTHESIS

Abstract— The effect of UVB and ozone (O₃) on growth and ascorbate-glutathione cycle were investigated in Arabidopsis thaliana wild-type Landsberg erecta (LER) and its transparent testa ( tt 5) mutant differing in UVB sensitivity. Ultraviolet-B radiation decreased dry matter production of tt5, while the dry weight of LER remained unaltered. Ozone exposure decreased dry weight of both genotypes. Ultraviolet-B radiation decreased the F_v/F_m ratio in tt5 but not in LER plants, while O₃ exposure decreased the F_v/F_m ratio in both genotypes. Ultraviolet-B radiation enhanced total ascorbic acid, total glutathione and their redox state and superoxide dismutase and glutathione reductase activities in both genotypes and the increases were greater in tt5 compared to UVB-irradiated LER. Although O₃ exposure enhanced total ascorbic acid and total glutathione in both genotypes, the redox state was significantly higher in tt5. Ozone exposure enhanced superoxide dismutase and glutathione reductase activities in tt5 while there were no major changes in LER. These results suggested that (1) plants blocked in flavonoid biosynthesis are sensitive to UVB in spite of their ability to maintain efficient oxygen free radical scavenging systems and (2) plants sensitive to UVB are comparatively tolerant of O₃ compared to UVB-insensitive plants. The differential responses of plants are discussed with reference to their ability to maintain high redox states of ascorbate and glutathione.     

Akt1-mediated intracellular oxidation after UVB irradiation suppresses apoptotic cell death induced by cell detachment and serum starvation

Apoptosis is an important cell death system that deletes damaged and mutated cells to prevent cancer. We have previously reported that a certain dose of UVB irradiation inhibited the apoptosis induced by serum starvation and cell detachment, leading to cell transformation. This antiapoptotic effect was partially inhibited by phosphatidylinositol 3-kinase (PI3-kinase) inhibitors. UVB irradiation is known to cause the phosphorylation of Akt via the activation of PI3-kinase; however, the Akt isoform-specific relationship has not yet been clarified. Notably, the role in antiapoptotic effect of UVB has yet to be elucidated. In this study, the role of Akt1 in the UVB-induced inhibition of apoptosis was examined by Akt1 knockdown using small interfering RNA (siRNA). NIH3T3 cells showed typical apoptotic cell death by serum starvation and cell detachment, which was significantly inhibited by UVB irradiation. Akt1 knockdown decreased the antiapoptotic effect of UVB. Hydrogen peroxide-induced suppression of cell death was also decreased in Akt1 knockdown cells. An antioxidant, N-acetylcysteine, inhibited the antiapoptotic effect by UVB irradiation, whereas no inhibition was observed in Akt1 knockdown cells. Furthermore, UVB-induced intracellular peroxidation was not observed in the knockdown cells, indicating that Akt1 played an important role in mediating the intracellular redox status. Treatment with insulin had a similar antiapoptotic effect as UVB irradiation involving intracellular peroxidation, which was also attenuated in Akt1 knockdown cells. These findings suggest that appropriate intracellular oxidation after UVB irradiation prevented apoptosis, a process which might be partially regulated by the production of reactive oxygen species mediated by Akt1.     

Effect of Fish Bone Bioactive Peptides on Oxidative,Inflammatory and Pigmentation Processes Triggered by UVB Irradiation in Skin Cells

In the present study, we evaluated for the first time the photoprotective effect of fish bone bioactive peptides (FBBP) preparation isolated from silver carp (Hypophthalmichthys molitrix) discarded tissue using in vitro experimental models of skin cells exposed to ultraviolet B (UVB) irradiation and stressing agents. FBBP preparation was obtained by papain treatment of minced bones and centrifugal ultrafiltration, and the molecular weight (MW) distribution was characterized by size exclusion and reversed-phase high performance liquid chromatography (RP-HPLC). In vitro assessment of the effect of FBBP pretreatment in UVB-irradiated L929 fibroblasts and HaCaT keratinocytes revealed their cytoprotective activity. Their capacity to efficiently reduce reactive oxygen species (ROS) production and lipid peroxidation varied in a dose-dependent manner, and it was greater in fibroblasts. A decrease of proinflammatory cytokines secretion, in particular of tumor necrosis factor alpha (TNF-α), was found after FBBP pretreatment of THP-1-derived inflamed macrophages. Melanin production and tyrosinase activity investigated in UVB-irradiated Mel-Juso cells were lowered in direct relation to FBBP concentrations. FBBP fractions with high radical scavenging activity were separated by ion exchange chromatography, and two collagenic sequences were identified. All these results offer new scientific data on aquaculture fish bone-derived peptides confirming their ability to control the antioxidant, anti-inflammatory and pigmentation processes developed during UV irradiation of skin cells and recommend their use as valuable natural ingredients of photoprotective cosmeceutical products.     

SERS纳米探针对电刺激过程中细胞内产生活性氧的检测

电刺激是用于细胞内紊乱电活动引起疾病的一类重要治疗方式. 在电刺激过程中是否会诱导细胞内活性氧(ROS)水平的改变, 以及常规抗氧化抑制药物与电刺激治疗同时运用带来的影响, 目前尚未有相关研究. 本文设计了一种具有较好生物相容性的金/银核壳纳米棒表面增强拉曼(SERS)活性探针, 用于电刺激过程中细胞内产生ROS的检测. 将该探针与细胞共孵育, 使其内化入细胞, 对细胞进行不同时间的电刺激, 利用拉曼光谱对SERS探针的信号进行检测. 实验结果表明, 随着电刺激时间的延长, SERS信号减弱, 说明细胞内产生ROS的量明显增加. 该传感机制是利用ROS能刻蚀金/银核壳纳米棒的银壳, 从而使其变薄引起SERS信号减弱. 抗坏血酸(AA)和谷胱甘肽(GSH)两种抗氧化抑制剂类药物与电刺激同时运用时, 可观察到它们会对电刺激过程产生的ROS有清除作用. 该研究发展了一类用于细胞内ROS检测的光谱方法, 也为异常的氧化应激和肿瘤治疗过程中的组合用药提供了建议.     

Age dependent increase of elastase type protease activity in mouse skin. Effect of UV-irradiation

The effect of chronological aging and photoaging (UV-radiation) on elastase-type enzyme activity of hairless mouse skin was studied. Aging resulted in the increase of elastase type endopeptidase activity extractable from mouse skins. Both chronic UVA and UVB radiation resulted in a significant increase of elastase type activity. PBS extracted only small part of the elastase activity, UV-A produced an increase of about 90-120% according to the type of irradiation (xenon or UV-A SUN) and UV-B produced a 72% increase. Extraction by Triton X-100 suggested that most of the activity is bound to cells and fibrous structures. EDTA inhibited 80-90% of the elastase activity in chronologically aged skin extracts and also the activity induced by UVA radiation suggesting that metallo-elastase(s) are involved. About 30% of the UVB induced activity could only be inhibited by EDTA and about 50% by PMSF suggesting that irradiation by UVB increased more serine endopeptidase activity but also MMP-activity. Chronic UVA radiation produced an increase of skin elastase activity equivalent to that observed after 24 months of aging in non-irradiated animals (approximately 100 weeks) corresponding to approximately 90% of total life span of these mice. The total increase produced by UVB was less, but the strong increase of a serine elastase, presumably from PMN-s, appear to produce a much more pronounced biological activity as shown by the presence of fibronectin degradation products in skin extracts. Such degradation products were shown to exert harmful effects on tissues. These results may well have biological significance and distinguish chronological aging and photoaging.