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This study investigated the mechanism of silver nanoparticle (AgNP) cytotoxicity from a mitochondrial perspective. The effect of AgNP on manganese superoxide dismutase (MnSOD), a mitochondrial antioxidant enzyme, against oxidative stress has not been studied in detail. We demonstrated that AgNP decreased MnSOD mRNA level, protein expression, and activity in human Chang liver cells in a time-dependent manner. AgNP induced the production of mitochondrial reactive oxygen species (mtROS), particularly superoxide anion. AgNP was found to increase mitochondrial calcium level and disrupt mitochondrial function, leading to reduced ATP level, succinate dehydrogenase activity, and mitochondrial permeability. AgNP induced cytochrome c release from the mitochondria into the cytoplasm, attenuated the expression of the anti-apoptotic proteins phospho Bcl-2 and Mcl-1, and induced the expression of the pro-apoptotic proteins Bim and Bax. In addition, c-Jun N-terminal kinase (JNK) phosphorylation was significantly increased by AgNP. Treatment with elamipretide (a mitochondria-targeted antioxidant) and SP600125 (a JNK inhibitor) showed the involvement of MnSOD and JNK in these processes. These results indicated that AgNP damaged human Chang liver cells by destroying mitochondrial function through the accumulation of mtROS.

Physiological stress such as excessive reactive oxygen species (ROS) production may contribute normal fibroblasts activation into cancer‑associated fibroblasts, which serve a crucial role in certain types of cancer such as pancreatic, breast, liver and lung cancer. The present study aimed to examine the cytoprotective effects of luteolin (3',4',5,7‑tetrahydroxyflavone) against hydrogen peroxide (H 2 O 2 )‑generated oxidative stress in lung fibroblasts. To examine the effects of luteolin against H 2 O 2 ‑induced damages, cell viability, sub‑G 1 cell population, nuclear staining with Hoechst 33342, lipid peroxidation and comet assays were performed. To evaluate the effects of luteolin on the protein expression level of apoptosis, western blot assay was performed. To assess the antioxidant effects of luteolin, detection of ROS using H 2 DCFDA staining, O 2 ‑ and ·OH using electron spin resonance spectrometer and antioxidant enzyme activity was performed. In a cell‑free chemical system, luteolin scavenges superoxide anion and hydroxyl radical generated by xanthine/xanthine oxidase and the Fenton reaction (FeSO 4 /H 2 O 2 ). Furthermore, Chinese hamster lung fibroblasts (V79‑4) treated with H 2 O 2 showed a significant increase in cellular ROS. Intracellular ROS levels and damage to cellular components such as lipids and DNA in H 2 O 2 ‑treated cells were significantly decreased by luteolin pretreatment. Luteolin increased cell viability, which was impaired following H 2 O 2 treatment and prevented H 2 O 2 ‑mediated apoptosis. Luteolin suppressed active caspase‑9 and caspase‑3 levels while increasing Bcl‑2 expression and decreasing Bax protein levels. Additionally, luteolin restored levels of glutathione that was reduced in response to H 2 O 2 . Moreover, luteolin enhanced the activity and protein expressions of superoxide dismutase, catalase, glutathione peroxidase, and heme oxygenase‑1. Overall, these results indicated that luteolin inhibits H 2 O 2 ‑mediated cellular damage by upregulating antioxidant enzymes.

Particulate matter 2.5 (PM 2.5 ) poses a serious threat to human health and is responsible for respiratory disorders, cardiovascular diseases, and skin disorders. 3-Bromo-4,5-dihydroxybenzaldehyde (3-BDB), abundant in marine red algae, exhibits anti-inflammatory, antioxidant, and antidiabetic activities. In this study, we investigated the protective mechanisms of 3-BDB against PM 2.5 -induced cell cycle arrest and autophagy in human keratinocytes. Intracellular reactive oxygen species generation, DNA damage, cell cycle arrest, intracellular Ca 2+ level, and autophagy activation were tested. 3-BDB was found to restore cell proliferation and viability which were reduced by PM 2.5 . Furthermore, 3-BDB reduced PM 2.5 -induced reactive oxygen species levels, DNA damage, and attenuated cell cycle arrest. Moreover, 3-BDB ameliorated the PM 2.5 -induced increases in cellular Ca 2+ level and autophagy activation. While PM 2.5 treatment reduced cell growth and viability, these were restored by the treatment with the autophagy inhibitor bafilomycin A1 or 3-BDB. The findings indicate that 3-BDB ameliorates skin cell death caused by PM 2.5 via inhibiting cell cycle arrest and autophagy. Hence, 3-BDB can be exploited as a preventive/therapeutic agent for PM 2.5 -induced skin impairment., Competing Interests: Declaration of Competing Interests The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Particulate matter (PM) increases levels of pro-inflammatory cytokines, but its effects on the skin remain largely unknown. We investigated the signal transduction pathway and epigenetic regulatory mechanisms underlying cellular inflammation induced by PM with a diameter of ≤ 2.5 (PM 2.5 ) in vitro and in vivo. PM 2.5 -treated skin keratinocytes produced various inflammatory cytokines, including IL-6. The binding of PM 2.5 to TLR5 initiated intracellular signaling through MyD88, and led to the translocation of NFκB to the nucleus, where it bound the NFκB site within IL-6 promoter. Furthermore, PM 2.5 induced a direct interaction between TLR5 and NOX4, and in turn induced the production of ROS and activated NFκB-IL-6 downstream, which was prevented by siRNA-mediated knockdown of NOX4 or antioxidant treatment. Furthermore, expression of TLR5, MyD88, NOX4, phospho-NFκB, and IL-6 was increased in skin tissue of PM 2.5 -treated flaky tail mice. PM 2.5 -induced increased transcription of IL-6 was regulated via DNA methylation and histone methylation by epigenetic modification; the binding of DNA demethylase and histone methyltransferase to the IL-6 promoter regions resulted in increased IL-6 mRNA expression. Our findings provide deep insight into the pathogenesis of PM 2.5 exposure and can be used as a therapeutic strategy to treat inflammatory skin diseases caused by PM 2.5 exposure., (Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: This study aimed to investigate whether luteolin, a flavonoid, induces apoptosis in human melanoma cells via endoplasmic reticulum (ER) stress., Materials and Methods: To investigate the effects of luteolin in human melanoma cells, the anti-proliferation, apoptosis, ER stress induction and reactive oxygen species (ROS) generation were evaluated using MTT, Hoechst 33342, ER-tracker Blue White DPX and DCF-DA staining assays, respectively., Results: Luteolin inhibited cell proliferation and increased apoptotic body formation. Luteolin induced ER stress, as shown by ER staining and mitochondrial Ca(2+) overloading. Luteolin increased expression of the ER stress-related proteins; protein kinase RNA-like ER kinase, phospho eukaryotic translation initiation factor 2α, activating transcription factor (ATF) 6, CCAAT/enhancer-binding protein-homologous protein (CHOP), and cleaved caspase 12. Furthermore, luteolin increased the level of intracellular ROS, leading to ROS-mediated apoptosis and ER stress. However, N-acetyl cysteine, a ROS scavenger, decreased ROS levels, apoptosis, and ER stress induced by luteolin treatment. In addition, knockdown of CHOP and ATF6 by small-interfering RNA inhibited luteolin-induced cell death., Conclusion: Luteolin induces apoptosis by ER stress via increasing ROS levels., (Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

The present study investigated the apoptotic effects of esculetin, a coumarin derivative, on the human colon cancer cell line HT-29. Esculetin had cytotoxic effects on HT-29 cells in a dose- and time-dependent manner; treatment with 55 μg/mL esculetin reduced cell viability by 50%. Esculetin induced apoptosis, as evidenced by apoptotic body formation, an increased percentage of cells in sub-G1 phase, and DNA fragmentation. Moreover, esculetin increased mitochondrial membrane depolarization, released cytochrome c into cytosol, and modulated the expression of apoptosis-associated proteins, resulting in reduced expression of B cell lymphoma-2, increased expression of Bcl-2-associated X protein, and activation of caspase-9 and caspase-3. Esculetin induced the formation of reactive oxygen species; however, treatment with an antioxidant reduced the apoptotic cell death induced by esculetin treatment. In addition, esculetin activated mitogen-activated protein kinases and specific inhibitors of these kinases abrogated the reduction in cell viability induced by esculetin treatment., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In this study, we evaluated the hypothesis that a marine brown algae, Dictyopteris undulata ethanol extract (DUE), provokes apoptosis in a human melanoma cell line, A2058, via reactive oxygen species (ROS) and endoplasmic reticulum (ER) stress. DUE inhibited A2058 cell proliferation and increased apoptotic body formation, as indicated by the presence of fragmented nuclei and the activation of caspase-3. Moreover, DUE-treated cells showed elevated ER staining, mitochondrial calcium cation (Ca2+) overloading, augmented levels of ER stress-related and cell death modulatory proteins, including RNA-dependent protein kinase-related ER kinase, phospho-inositol-requiring enzyme 1α, phospho-eukaryotic translation initiation factor 2α, and CCAAT/enhancer-binding protein-homologous protein, as well as increased intracellular ROS levels. However, the antioxidant N-acetyl cysteine reversed the elevated ROS levels, decreased apoptosis, and mitigated ER stress in A2058 cells following DUE treatment. These findings suggest that DUE treatment triggers apoptosis in human melanoma cells through a mechanism involving ER stress and ROS.

Purpose: Previously we demonstrated that phloroglucinol (1,3,5-trihydroxybenzene) protected human HaCaT keratinocytes against ultraviolet B (UVB, 280-320 nm)-induced oxidative stress in vitro by scavenging intracellular reactive oxygen species (ROS). The current study investigated whether phloroglucinol could similarly protect the mouse skin against UVB-induced oxidative tissue damage in vivo., Materials and Methods: Male 7-week-old Balb/c mice were divided into the following untreated normal control, phloroglucinol only-treated, vehicle plus UVB (30 or 60 mJ/cm(2))-exposed, and phloroglucinol (10 or 50 mg/ml) plus UVB (30 or 60 mJ/cm(2))-treated groups. Following UVB exposure, phloroglucinol or phosphate buffered saline vehicle was applied to the dorsal skin of each mouse daily for 3 days. Studies were conducted at 24 h after the last of the UVB exposures. Histopathological analyses of dorsal skin lesions were performed on all mice. In addition, the levels of UVB-provoked injury to cellular components, including DNA, proteins, and lipids were detected by levels of 8-oxoguanine (8-oxoG), protein carbonyls, and 8-isoprostane. Apoptosis were assessed by using western blot for B-cell lymphoma-2-associated X protein (Bax) and activated caspase-3 expression, by using immunohistochemistry., Results: UVB radiation increased the thickness of the epidermis and the dermis, and also stimulated the accumulation of mast cells in the irradiated skin. However, treatment with phloroglucinol significantly decreased all of these parameters. Furthermore, phloroglucinol decreased UVB-provoked injury to cellular components, including DNA, proteins, and lipids; down-regulated the expression of phospho-histone H2A.X in the injured skin; and reduced the UVB-generated levels of 8-oxoG, protein carbonyls, and 8-isoprostane, which are all markers of oxidative stress. In addition, phloroglucinol attenuated the UVB-induced expression of the pro-apoptotic proteins, Bax protein, and activated caspase-3., Conclusion: These results suggest that phloroglucinol safeguards the mouse skin against UVB-induced oxidative stress and apoptosis.

The aim of this study was to investigate the antioxidant properties of the ethanol extract of the flower of Camellia japonica (Camellia extract). Camellia extract exhibited 1,1-diphenyl-2-picrylhydrazyl radical and intracellular reactive oxygen species (ROS) scavenging activity in human HaCaT keratinocytes. In addition, Camellia extract scavenged superoxide anion generated by xanthine/xanthine oxidase and hydroxyl radical generated by the Fenton reaction (FeSO(4) + H(2)O(2)) in a cell-free system, which was detected by electron spin resonance spectrometry. Furthermore, Camellia extract increased the protein expressions and activity of cellular antioxidant enzymes, such as superoxide dismutase, catalase and glutathione peroxidase. These results suggest that Camellia extract exhibits antioxidant properties by scavenging ROS and enhancing antioxidant enzymes. Camellia extract contained quercetin, quercetin-3-O-glucoside, quercitrin and kaempferol, which are antioxidant compounds.

This study investigated the cytoprotective effect of butin, a flavonoid, on hydrogen peroxide (H(2)O(2))-induced mitochondrial dysfunction. Electron spin resonance (ESR) spectrometry revealed butin's significant scavenging effects on superoxide radicals and hydroxyl radicals. When H(2)O(2) was used to induce an increase in mitochondrial reactive oxygen species (ROS) in Chinese hamster lung fibroblast (V79-4) cells, butin treatment decreased high level of ROS. Butin also attenuated intracellular Ca(2+) levels that have been induced by H(2)O(2). Furthermore, butin recovered ATP levels and succinate dehydrogenase activity that had been decreased by H(2)O(2) treatment. We conclude these results suggest butin decreased mitochondrial ROS accumulation, balanced intracellular Ca(2+) levels, and improved mitochondrial energy production, thus recovering mitochondrial function., (Copyright (c) 2010 Elsevier Ltd. All rights reserved.)

Aim: To investigate the anti-oxidant properties of esculetin (6,7-dihydroxycoumarin) against H2O2-induced Chinese hamster lung fibroblast (V79-4) damage., Methods: The radical scavenging activity was assessed by 1,1-diphenyl- 2-picrylhydrazyl (DPPH) radical, hydroxyl radical, and intracellular reactive oxygen species (ROS). In addition, lipid peroxidation was assayed by the measure of related substances which react with thiobarbituric acid. The amount of carbonyl formation in protein was determined using a protein carbonyl ELISA kit. As well, cellular DNA damage was detected by Western blot and immunofluorescence image. Cell viability was assessed by 3-(4,5-dimethylthiazole-2- yl)-2,5-diphenyltetrazolium bromide assay., Results: Esculetin exhibited DPPH radical scavenging, hydroxyl radical scavenging, and intracellular ROS scavenging activities. The radical scavenging activity of esculetin resulted in the protection of cells from lipid peroxidation, protein carbonyl, and DNA damage induced by H2O2. Therefore, esculetin recovered cell viability exposed to H2O2., Conclusion: Esculetin efficiently attenuated the oxidative stress induced cell damage via its anti-oxidant properties. As a result, esculetin may be useful in the development of functional food and raw materials of medicine.

The radioprotective effect of eckol against gamma-ray radiation-induced oxidative stress and its possible protective mechanisms were investigated. Eckol was found to reduce the intracellular reactive oxygen species generated by gamma-ray radiation. Moreover, eckol also protected against radiation-induced cellular DNA damage and membrane lipid peroxidation, which are the main targets of radiation-induced damage. In addition, eckol recovered the cell viability damaged by radiation via the inhibition of apoptosis. Irradiated cells with eckol treatment reduced the expression of bax, the activation of caspase 9 and caspase 3, which were induced by radiation. However, irradiated cells with eckol recovered the expression of bcl-2 and mitochondrial cytochrome c which were decreased by radiation. The anti-apoptotic effect of eckol exerted via the inhibition of mitogen-activated protein kinase kinase-4 (MKK4/SEK1)-c-Jun NH(2)-terminal kinase (JNK)-activator protein 1 (AP-1) cascades induced by radiation. In summary, the results suggest that eckol protects cells against the oxidative stress induced by radiation via the reduction of reactive oxygen species and the attenuation of activation in SEK1-JNK-AP-1 pathway.

The present study investigated the cytoprotective properties of glycitein, a metabolite formed by the transformation of glycitin by intestinal microflora, against oxidative stress. Glycitein was found to scavenge intracellular reactive oxygen species (ROS), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and thereby preventing lipid peroxidation and DNA damage. Glycitein inhibited apoptosis of Chinese hamster lung fibroblast (V79-4) cells exposed to hydrogen peroxide (H(2)O(2)) via radical scavenging activity. Glycitein abrogated the activation of c-Jun N-terminal kinase (JNK) induced by H(2)O(2) treatment and inhibited DNA binding activity of activator protein-1 (AP-1), a downstream transcription factor of JNK. Taken together, these findings suggest that glycitein protected H(2)O(2) induced cell death in V79-4 cells by inhibiting ROS generation and JNK activation.

Exposure to fine particulate matter with an aerodynamic diameter of less than 2.5 μm (PM2.5) can cause oxidative damage and apoptosis in the human skin. Chlorogenic acid (CGA) is a bioactive polyphenolic compound with antioxidant, antifungal, and antiviral properties. The objective of this study was to identify the ameliorating impact of CGA that might protect human HaCaT cells against PM2.5. CGA significantly scavenged the reactive oxygen species (ROS) generated by PM2.5, attenuated oxidative cellular/organelle damage, mitochondrial membrane depolarization, and suppressed cytochrome c release into the cytosol. The application of CGA led to a reduction in the expression levels of Bcl‐2‐associated X protein, caspase‐9, and caspase‐3, while simultaneously increasing the expression of B‐cell lymphoma 2. In addition, CGA was able to reverse the decrease in cell viability caused by PM2.5 via the inhibition of extracellular signal‐regulated kinase (ERK). This effect was further confirmed by the use of the mitogen‐activated protein kinase kinase inhibitor, which acted upstream of ERK. In conclusion, CGA protected keratinocytes from mitochondrial damage and apoptosis via ameliorating PM2.5‐induced oxidative stress and ERK activation. [ABSTRACT FROM AUTHOR]

Cellular senescence can be activated by several stimuli, including ultraviolet radiation and air pollutants. This study aimed to evaluate the protective effect of marine algae compound 3-bromo-4,5-dihydroxybenzaldehyde (3-BDB) on particulate matter 2.5 (PM2.5)-induced skin cell damage in vitro and in vivo. The human HaCaT keratinocyte was pre-treated with 3-BDB and then with PM2.5. PM2.5-induced reactive oxygen species (ROS) generation, lipid peroxidation, mitochondrial dysfunction, DNA damage, cell cycle arrest, apoptotic protein expression, and cellular senescence were measured using confocal microscopy, flow cytometry, and Western blot. The present study exhibited PM2.5-generated ROS, DNA damage, inflammation, and senescence. However, 3-BDB ameliorated PM2.5-induced ROS generation, mitochondria dysfunction, and DNA damage. Furthermore, 3-BDB reversed the PM2.5-induced cell cycle arrest and apoptosis, reduced cellular inflammation, and mitigated cellular senescence in vitro and in vivo. Moreover, the mitogen-activated protein kinase signaling pathway and activator protein 1 activated by PM2.5 were inhibited by 3-BDB. Thus, 3-BDB suppressed skin damage induced by PM2.5. [ABSTRACT FROM AUTHOR]

Toxicity of particulate matter (PM) towards the epidermis has been well established in many epidemiological studies. It is manifested in cancer, aging, and skin damage. In this study, we aimed to show the mechanism underlying the protective effects of eckol, a phlorotannin isolated from brown seaweed, on human HaCaT keratinocytes against PM2.5-induced cell damage. First, to elucidate the underlying mechanism of toxicity of PM2.5, we checked the reactive oxygen species (ROS) level, which contributed significantly to cell damage. Experimental data indicate that excessive ROS caused damage to lipids, proteins, and DNA and induced mitochondrial dysfunction. Furthermore, eckol (30 μM) decreased ROS generation, ensuring the stability of molecules, and maintaining a steady mitochondrial state. The western blot analysis showed that PM2.5 promoted apoptosis-related protein levels and activated MAPK signaling pathway, whereas eckol protected cells from apoptosis by inhibiting MAPK signaling pathway. This was further reinforced by detailed investigations using MAPK inhibitors. Thus, our results demonstrated that inhibition of PM2.5-induced cell apoptosis by eckol was through MAPK signaling pathway. In conclusion, eckol could protect skin HaCaT cells from PM2.5-induced apoptosis via inhibiting ROS generation.

The present study investigated the photoprotective properties of an ethanol extract derived from the red alga Bonnemaisonia hamifera against ultraviolet B (UVB)-induced cell damage in human HaCaT keratinocytes. The Bonnemaisonia hamifera ethanol extract (BHE) scavenged the superoxide anion generated by the xanthine/xanthine oxidase system and the hydroxyl radical generated by the Fenton reaction (FeSO4 + H2O2), both of which were detected by using electron spin resonance spectrometry. In addition, BHE exhibited scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical and intracellular reactive oxygen species (ROS) that were induced by either hydrogen peroxide or UVB radiation. BHE reduced UVB-induced apoptosis, as shown by decreased apoptotic body formation and DNA fragmentation. BHE also attenuated DNA damage and the elevated levels of 8-isoprostane and protein carbonyls resulting from UVB-mediated oxidative stress. Furthermore, BHE absorbed electromagnetic radiation in the UVB range (280–320 nm). These results suggest that BHE protects human HaCaT keratinocytes against UVB-induced oxidative damage by scavenging ROS and absorbing UVB photons, thereby reducing injury to cellular components.

The aim of this study was to investigate the cytoprotective properties of the ethyl acetate fraction of Sargassum muticum (SME) against ultraviolet B (UVB)-induced cell damage in human keratinocytes (HaCaT cells). SME exhibited scavenging activity toward the 1,1-diphenyl-2-picrylhydrazyl radicals and hydrogen peroxide (H2O2) and UVB-induced intracellular reactive oxygen species (ROS). SME also scavenged the hydroxyl radicals generated by the Fenton reaction (FeSO4 + H2O2), which was detected using electron spin resonance spectrometry. In addition, SME decreased the level of lipid peroxidation that was increased by UVB radiation, and restored the level of protein expression and the activities of antioxidant enzymes that were decreased by UVB radiation. Furthermore, SME reduced UVB-induced apoptosis as shown by decreased DNA fragmentation and numbers of apoptotic bodies. These results suggest that SME protects human keratinocytes against UVB-induced oxidative stress by enhancing antioxidant activity in cells, thereby inhibiting apoptosis.

The aim of this study was to investigate the antioxidant properties of the ethanol extract of the flower of Camellia japonica (Camellia extract). Camellia extract exhibited 1,1-diphenyl-2-picrylhydrazyl radical and intracellular reactive oxygen species (ROS) scavenging activity in human HaCaT keratinocytes. In addition, Camellia extract scavenged superoxide anion generated by xanthine/xanthine oxidase and hydroxyl radical generated by the Fenton reaction (FeSO4 + H2O2) in a cell-free system, which was detected by electron spin resonance spectrometry. Furthermore, Camellia extract increased the protein expressions and activity of cellular antioxidant enzymes, such as superoxide dismutase, catalase and glutathione peroxidase. These results suggest that Camellia extract exhibits antioxidant properties by scavenging ROS and enhancing antioxidant enzymes. Camellia extract contained quercetin, quercetin-3-O-glucoside, quercitrin and kaempferol, which are antioxidant compounds.

Neurodegenerative diseases are associated with neuronal cell death through apoptosis. Apoptosis is tightly associated with the overproduction of reactive oxygen species (ROS), and high glucose levels contribute to higher oxidative stress in diabetic patients. Hesperidin, a natural active compound, has been reported to scavenge free radicals. Only a few studies have explored the protective effects of hesperidin against high glucose−induced apoptosis in SH−SY5Y neuronal cells. Glucose stimulated neuronal cells to generate excessive ROS and caused DNA damage. In addition, glucose triggered endoplasmic reticulum stress and upregulated cytoplasmic as well as mitochondrial calcium levels. Hesperidin inhibited glucose−induced ROS production and mitigated the associated DNA damage and endoplasmic reticulum stress. The downregulation of antiapoptotic protein Bcl−2 following glucose treatment was reversed by a hesperidin treatment. Furthermore, hesperidin repressed the glucose−induced Bcl−2−associated X protein, cleaved caspase−9, and cleaved caspase−3. Hesperidin also suppressed the glucose−induced phosphorylation of extracellular signal−regulated kinase and c−Jun N−terminal kinase. The current results confirmed that hesperidin could protect neuronal cells against glucose−induced ROS. Mechanistically, hesperidin was shown to promote cell viability via attenuation of the mitogen−activated protein kinase signaling pathway. [ABSTRACT FROM AUTHOR]

Particulate matter 2.5 (PM2.5) imposes a heavy burden on the skin and respiratory system of human beings, causing side effects such as aging, inflammation and cancer. Astaxanthin (ATX) is a well-known antioxidant widely used for its anti-inflammatory and anti-aging properties. However, few studies have investigated the protective effects of ATX against PM2.5-induced senescence in HaCaT cells. In the present study, the levels of reactive oxygen species (ROS) and antioxidant enzymes were measured after treatment with PM2.5. The results revealed that PM2.5 generated excessive ROS and reduced the translocation of nuclear factor erythroid 2-related factor 2 (NRF2), subsequently reducing the expression of antioxidant enzymes. However, pretreatment with ATX reversed the ROS levels as well as the expression of antioxidant enzymes. In addition, ATX protected cells from PM2.5-induced DNA damage and rescued PM2.5-induced cell cycle arrest. The levels of senescence-associated phenotype markers, such as interleukin-1β, matrix metalloproteinases, and β-galactosidase, were increased by exposure to PM2.5, however these effects were reversed by ATX. After interfering with NRF2 mRNA expression and exposing cells to PM2.5, the levels of ROS and β-galactosidase were higher compared with siControl RNA cells exposed to PM2.5. However, ATX inhibited ROS and β-galactosidase levels in both the siControl RNA and the siNRF2 RNA groups. Thus, ATX protects HaCaT keratinocytes from PM2.5-induced senescence by partially inhibiting excessive ROS generation via the NRF2 signaling pathway. [ABSTRACT FROM AUTHOR]

Shikonin, an herbal naphthoquinone, demonstrates a broad spectrum of pharmacological properties. Owing to increasingly adverse environmental conditions, human skin is vulnerable to harmful influences from dust particles. This study explored the antioxidant capabilities of shikonin and its ability to protect human keratinocytes from oxidative stress induced by fine particulate matter (PM2.5). We found that shikonin at a concentration of 3 µM was nontoxic to human keratinocytes and effectively scavenged reactive oxygen species (ROS) while increasing the production of reduced glutathione (GSH). Furthermore, shikonin enhanced GSH level by upregulating glutamate‐cysteine ligase catalytic subunit and glutathione synthetase mediated by nuclear factor‐erythroid 2‐related factor. Shikonin reduced ROS levels induced by PM2.5, leading to recovering PM2.5‐impaired cellular biomolecules and cell viability. Shikonin restored the GSH level in PM2.5‐exposed keratinocytes via enhancing the expression of GSH‐synthesizing enzymes. Notably, buthionine sulphoximine, an inhibitor of GSH synthesis, diminished effect of shikonin against PM2.5‐induced cell damage, confirming the role of GSH in shikonin‐induced cytoprotection. Collectively, these findings indicated that shikonin could provide substantial cytoprotection against the adverse effects of PM2.5 through direct ROS scavenging and modulation of cellular antioxidant system. [ABSTRACT FROM AUTHOR]