LC/MS-guided isolation and GNPS procedures to identify flavonoid of HCoV-OC43 inhibitors.

The screening of based target compounds supported by LC/MS, MS/MS and Global Natural Products Social (GNPS) used to identify the compounds 1-10 of Butea monsperma. They were evaluated in human malignant embryonic rhabdomyoma cells (RD cells) infected with Human coronavirus OC43 (HCoV-OC43) and showed significant inhibitory activity. Target inhibition tests showed that compounds 6 and 8 inhibited the proteolytic enzyme 3CLpro, which is widely present in coronavirus and plays an important role in the replication process, with an effective IC50 value. The study confirmed that dioxymethylene of compound 8 may be a key active fragment in inhibiting coronavirus (EC50 7.2 µM, SI > 139.1). The results have led to identifying natural bioactive compounds for possible inhibiting HCoV-OC43 and developing drug for Traditional Chinese Medicine (TCM).

Protective effects of astaxanthin on particulate matter 2.5­induced senescence in HaCaT keratinocytes via maintenance of redox homeostasis.

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-1ß, matrix metalloproteinases, and ß-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 ß-galactosidase were higher compared with siControl RNA cells exposed to PM2.5. However, ATX inhibited ROS and ß-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.

Naringenin Induces Cellular Apoptosis in Melanoma Cells via Intracellular ROS Generation.

BACKGROUND/AIM: Melanoma is a prevalent malignant tumor that arises from melanocytes. The treatment of malignant melanoma has become challenging due to the development of drug resistance. It is, therefore, imperative to identify novel therapeutic drug candidates for controlling malignant melanoma. Naringenin is a flavonoid abundant in oranges and other citrus fruits and recognized for its numerous medicinal benefits. The objective of the study was to assess the anti-carcinogenic potential of naringenin by evaluating its ability to regulate the cellular production of reactive oxygen species (ROS) and its effect on mitochondrial function and apoptosis in melanoma cells. MATERIALS AND METHODS: Cell viability, intracellular ROS levels, cell apoptosis, and mitochondrial functions were evaluated. RESULTS: Naringenin decreased melanoma cell viability and triggered generation of ROS, leading to cell apoptosis. In addition, it stimulated mitochondrial damage in melanoma cells by elevating the levels of Ca2+ and ROS in the mitochondria and decreasing cellular ATP. Naringenin stimulated the expression of proapoptotic proteins, including phospho p53, B-cell lymphoma-2 (Bcl-2)-associated X protein, cleaved caspase-3, and cleaved caspase-9, in melanoma cells in a time-dependent manner. Furthermore, it reduced the expression of the anti-apoptotic protein Bcl-2. Naringenin triggered cell apoptosis by phosphorylating c-Jun N-terminal kinase and stimulating cellular autophagy. CONCLUSION: Naringenin caused oxidative stress and mitochondrial damage, and activated autophagy in melanoma cells, leading to cell apoptosis. These findings indicate the potential of naringenin as a new therapeutic candidate for melanoma.

Correction: Kang et al. Anticolon Cancer Effect of Korean Red Ginseng via Autophagy- and Apoptosis-Mediated Cell Death. Nutrients 2022, 14, 3558.

In the original publication [...].

3-Bromo-4,5-dihydroxybenzaldehyde Protects Keratinocytes from Particulate Matter 2.5-Induced Damages.

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.

Blockchain Technology Application Challenges in Renewable Energy Supply Chain Management.

With the advent of new technologies and globalization of business, supply chains have turned into indispensable tools for gaining competitive advantage. The application of new technologies like blockchain can benefit sustainable energy supply chains by improving chain and logistics operations in the areas of trust, transparency and accountability, cooperation, information sharing, financial exchanges, and supply chain integration. However, the efforts to adopt such technologies in supply chains tend to face many challenges and challenges, which can seriously threaten their success. Therefore, it is crucial to carefully examine the challenges to blockchain technology application. This research focuses on identifying the criteria and challenges to the application of blockchain in renewable energy supply chains and also ranks the identified challenges in terms of their capacity to disrupt the process. The applicability of the suggested structure is examined in a case study of the renewable energy supply chain of Iran. In this study, the challenges are evaluated and ranked by the hybrid developed methods by the integration of the concept of gray numbers into the gray stepwise weight assessment ratio analysis (SWARA-Gray) and the gray evaluation based on distance from average solution (EDAS-Gray). Another group of hybrid methods including the gray weighted sum method (WSM-Gray), the gray complex proportional assessment (COPRAS-Gray), and the gray technique for order of preference by similarity to ideal solution (TOPSIS-Gray) is used to validate the results. The rankings obtained from all of these techniques show high degree of correlation. Among the identified challenges, "high investment cost" is found to be the most important challenge to the application of blockchain in sustainable energy supply chains.

Anticolon Cancer Effect of Korean Red Ginseng via Autophagy- and Apoptosis-Mediated Cell Death.

Ginseng (Panax ginseng Meyer) has been used in East Asian traditional medicine for a long time. Korean red ginseng (KRG) is effective against several disorders, including cancer. The cytotoxic effects of KRG extract in terms of autophagy- and apoptosis-mediated cell death and its mechanisms were investigated using human colorectal cancer lines. KRG induced autophagy-mediated cell death with enhanced expression of Atg5, Beclin-1, and LC3, and formed characteristic vacuoles in HCT-116 and SNU-1033 cells. An autophagy inhibitor prevented cell death induced by KRG. KRG generated mitochondrial reactive oxygen species (ROS); antioxidant countered this effect and decreased autophagy. KRG caused apoptotic cell death by increasing apoptotic cells and sub-G1 cells, and by activating caspases. A caspase inhibitor suppressed cell death induced by KRG. KRG increased phospho-Bcl-2 expression, but decreased Bcl-2 expression. Moreover, interaction of Bcl-2 with Beclin-1 was attenuated by KRG. Ginsenoside Rg2 was the most effective ginsenoside responsible for KRG-induced autophagy- and apoptosis-mediated cell death. KRG induced autophagy- and apoptosis-mediated cell death via mitochondrial ROS generation, and thus its administration may inhibit colon carcinogenesis.

Hesperidin Protects SH-SY5Y Neuronal Cells against High Glucose-Induced Apoptosis via Regulation of MAPK Signaling.

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.

Hesperidin Exhibits Protective Effects against PM2.5-Mediated Mitochondrial Damage, Cell Cycle Arrest, and Cellular Senescence in Human HaCaT Keratinocytes.

Particulate matter 2.5 (PM2.5) exposure can trigger adverse health outcomes in the human skin, such as skin aging, wrinkles, pigment spots, and atopic dermatitis. PM2.5 is associated with mitochondrial damage and the generation of reactive oxygen species (ROS). Hesperidin is a bioflavonoid that exhibits antioxidant and anti-inflammatory properties. This study aimed to determine the mechanism underlying the protective effect of hesperidin on human HaCaT keratinocytes against PM2.5-induced mitochondrial damage, cell cycle arrest, and cellular senescence. Human HaCaT keratinocytes were pre-treated with hesperidin and then treated with PM2.5. Hesperidin attenuated PM2.5-induced mitochondrial and DNA damage, G0/G1 cell cycle arrest, and SA-ßGal activity, the protein levels of cell cycle regulators, and matrix metalloproteinases (MMPs). Moreover, treatment with a specific c-Jun N-terminal kinase (JNK) inhibitor, SP600125, along with hesperidin markedly restored PM2.5-induced cell cycle arrest and cellular senescence. In addition, hesperidin significantly reduced the activation of MMPs, including MMP-1, MMP-2, and MMP-9, by inhibiting the activation of activator protein 1. In conclusion, hesperidin ameliorates PM2.5-induced mitochondrial damage, cell cycle arrest, and cellular senescence in human HaCaT keratinocytes via the ROS/JNK pathway.

Hesperidin Protects Human HaCaT Keratinocytes from Particulate Matter 2.5-Induced Apoptosis via the Inhibition of Oxidative Stress and Autophagy.

Numerous epidemiological studies have reported that particulate matter 2.5 (PM2.5) causes skin aging and skin inflammation and impairs skin homeostasis. Hesperidin, a bioflavonoid that is abundant in citrus species, reportedly has anti-inflammatory properties. In this study, we evaluated the cytoprotective effect of hesperidin against PM2.5-mediated damage in a human skin cell line (HaCaT). Hesperidin reduced PM2.5-induced intracellular reactive oxygen species (ROS) generation and oxidative cellular/organelle damage. PM2.5 increased the proportion of acridine orange-positive cells, levels of autophagy-related proteins, beclin-1 and microtubule-associated protein light chain 3, and apoptosis-related proteins, B-cell lymphoma-2-associated X protein, cleaved caspase-3, and cleaved caspase-9. However, hesperidin ameliorated PM2.5-induced autophagy and apoptosis. PM2.5 promoted cellular apoptosis via mitogen-activated protein kinase (MAPK) activation by promoting the phosphorylation of extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38. The MAPK inhibitors U0126, SP600125, and SB203580 along with hesperidin exerted a protective effect against PM2.5-induced cellular apoptosis. Furthermore, hesperidin restored PM2.5-mediated reduction in cell viability via Akt activation; this was also confirmed using LY294002 (a phosphoinositide 3-kinase inhibitor). Overall, hesperidin shows therapeutic potential against PM2.5-induced skin damage by mitigating excessive ROS accumulation, autophagy, and apoptosis.

Comparative Study of Autophagy in Oxaliplatin-Sensitive and Resistant SNU-C5 Colon Cancer Cells.

Few studies have evaluated the role of autophagy in the development of oxaliplatin (OXT) resistance in colon cancer cells. In this study, we compared the role of autophagy between SNU-C5 colon cancer cells and OXT-resistant SNU-C5 (SNU-C5/OXTR) cells. At the same concentration of OXT, the cytotoxicity of OXT or apoptosis was significantly reduced in SNU-C5/OXTR cells compared with that in SNU-C5 cells. Compared with SNU-C5 cells, SNU-C5/OXTR cells exhibited low levels of autophagy. The expression level of important autophagy proteins, such as autophagy-related protein 5 (Atg5), beclin-1, Atg7, microtubule-associated proteins 1A/1B light chain 3B I (LC3-I), and LC3-II, was significantly lower in SNU-C5/OXTR cells than that in SNU-C5 cells. The expression level of the autophagy-essential protein p62 was also lower in SNU-C5/OXTR cells than in SNU-C5 cells. In SNUC5/ OXTR cells, the production of intracellular reactive oxygen species (ROS) was significantly higher than that in SNU-C5 cells, and treatment with the ROS scavenger N-acetylcysteine restored the reduced autophagy levels. Furthermore, the expression of antioxidant-related nuclear factor erythroid 2-related factor 2 transcription factor, heme oxygenase-1, and Cu/Zn superoxide dismutase were also significantly increased in SNU-C5/OXTR cells. These findings suggest that autophagy is significantly reduced in SNU-C5/OXTR cells compared with SNU-C5 cells, which may be related to the production of ROS in OXT-resistant cells.

Impact of UHT processing on volatile components and chemical composition of sea buckthorn (Hippophae rhamnoides) pulp: A prediction of the biochemical pathway underlying aroma compound formation.

The effects of ultrahigh-temperature sterilization (UHT) on the volatile components and chemical composition of sea buckthorn pulp (SBP) were evaluated firstly. UHT had significant effects on the volatiles of SBP (mainly occurring at 140 °C for 2 s and 4 s), in which 140 °C for 2 s resulted in a decrease of 3.48% and 14.60% in total volatiles and esters, and an increase of 6.73% in alcohols, while alcohols contents sharply decreased by 6.90% at 140 °C for 4 s. Moreover, 140 °C for 2 s and 4 s decreased the amino acid content by 35.39% and 29.75%, respectively, while UHT significantly promoted the increase of fatty acids, but only a small increase at 140 °C for 4 s. The speculation is that a large number of volatiles were formed during the 140 °C for 2 s and 4 s, mainly from amino acid reactions and lipid oxidation.

Roasting intervention for the volatile composition of three varieties of nuts originating from Torreya yunnanensis.

For the first time, the volatiles of three varieties of fresh and roasted Torreya yunnanensis nuts were investigated by solid-phase microextraction-gas chromatography-mass spectrometry. The results indicated that roasting had the greatest effect on the volatiles of millet capsules. Fresh nuts had many terpenes, esters, and aldehydes, while roasting led to the formation of pyrazines and furans. In subsequent work, short-term low temperature and small sample area exposed to high temperature had a large effect on the increase in some volatiles and was characterized by a green flavor, such as α-pinene, while ultrahigh-temperature (200 and 230°C) resulted in a decrease in the total volatiles with the generation of unpleasant flavors. Finally, the combination of 170°C for 40 min and slight crushing was found to be the best roasting conditions for samples by means of GC-MS and two-dimensional gas chromatography and time-of-flight mass spectrometry (GC × GC/TOF-MS). PRACTICAL APPLICATIONS: Torreya yunnanensis and its nuts have broad development prospects because of their wide use and rich nutrition. However, inappropriate processing and lack of attention to natural materials such as nuts and wood leads to their poor usage. In addition, volatile compounds make a major contribution to the nut aroma, which is an important indicator of their sensory quality. However, no one has applied roasting technology to Torreya yunnanensis nuts or studied the volatile compounds of the roasted nuts. This study revealed the changes in the composition and content of volatile compounds in Torreya yunnanensis nuts before and after roasting, and the influence of different process points, suggesting that they are key contributors to the development of the related products.

Extract of Cornus officinalis Protects Keratinocytes from Particulate Matter-induced Oxidative Stress.

The skin is one of the large organs in the human body and the most exposed to outdoor contaminants such as particulate matter < 2.5 µm (PM2.5). Recently, we reported that PM2.5 induced cellular macromolecule disruption of lipids, proteins, and DNA, via reactive oxygen species, eventually causing cellular apoptosis of human keratinocytes. In this study, the ethanol extract of Cornus officinalis fruit (EECF) showed anti-oxidant effect against PM2.5-induced cellular oxidative stress. EECF protected cells against PM2.5-induced DNA damage, lipid peroxidation, and protein carbonylation. PM2.5 up-regulated intracellular and mitochondrial Ca2+ levels excessively, which led to mitochondrial depolarization and cellular apoptosis. However, EECF suppressed the PM2.5-induced excessive Ca2+ accumulation and inhibited apoptosis. The data confirmed that EECF greatly protected human HaCaT keratinocytes from PM2.5-induced oxidative stress.

Particulate Matter 2.5 Mediates Cutaneous Cellular Injury by Inducing Mitochondria-Associated Endoplasmic Reticulum Stress: Protective Effects of Ginsenoside Rb1.

The prevalence of fine particulate matter-induced harm to the human body is increasing daily. The aim of this study was to elucidate the mechanism by which particulate matter 2.5 (PM2.5) induces damage in human HaCaT keratinocytes and normal human dermal fibroblasts, and to evaluate the preventive capacity of the ginsenoside Rb1. PM2.5 induced oxidative stress by increasing the production of reactive oxygen species, leading to DNA damage, lipid peroxidation, and protein carbonylation; this effect was inhibited by ginsenoside Rb1. Through gene silencing of endoplasmic reticulum (ER) stress-related genes such as PERK, IRE1, ATF, and CHOP, and through the use of the ER stress inhibitor tauroursodeoxycholic acid (TUDCA), it was demonstrated that PM2.5-induced ER stress also causes apoptosis and ultimately leads to cell death; however, this phenomenon was reversed by ginsenoside Rb1. We also found that TUDCA partially restored the production of ATP that was inhibited by PM2.5, and its recovery ability was significantly higher than that of ginsenoside Rb1, indicating that the process of ER stress leading to cell damage may also occur via the mitochondrial pathway. We concluded that ER stress acts alone or via the mitochondrial pathway in the induction of cell damage by PM2.5, and that ginsenoside Rb1 blocks this process. Ginsenoside Rb1 shows potential for use in skin care products to protect the skin against damage by fine particles.

Esculetin Prevents the Induction of Matrix Metalloproteinase-1 by Hydrogen Peroxide in Skin Keratinocytes.

BACKGROUND: Reactive oxygen species (ROS) are involved in various cellular diseases. Excessive ROS can cause intracellular oxidative stress, resulting in a calcium imbalance and even aging. In this study, we evaluated the protective effect of esculetin on oxidative stress-induced aging in human HaCaT keratinocytes. METHODS: Human keratinocytes were pretreated with esculetin for 30 minutes and treated with H2O2. Then, the protective effects on oxidative stress-induced matrix metalloproteinase (MMP)-1 were detected by Flou-4-AM staining, reverse transcription-PCR, Western blotting, and quantitative fluorescence assay. RESULTS: Esculetin prevented H2O2-induced aging by inhibiting MMP-1 mRNA, protein, and activity levels. In addition, esculetin decreased abnormal levels of phospho-MEK1, phospho-ERK1/2, phospho-SEK1, phospho-JNK1/2, c-Fos, and phospho-c-Jun and inhibited activator protein 1 binding activity. CONCLUSIONS: Esculetin prevented excessive levels of intracellular calcium and reduced the expression levels of aging-related proteins.

Eckol Inhibits Particulate Matter 2.5-Induced Skin Keratinocyte Damage via MAPK Signaling Pathway.

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.

Niacinamide Protects Skin Cells from Oxidative Stress Induced by Particulate Matter.

Niacinamide (NIA) is a water-soluble vitamin that is widely used in the treatment of skin diseases. Moreover, NIA displays antioxidant effects and helps repair damaged DNA. Recent studies showed that particulate matter 2.5 (PM2.5) induced reactive oxygen species (ROS), causing disruption of DNA, lipids, and proteins; mitochondrial depolarization, and apoptosis of skin keratinocytes. Here, we investigated the protective effects of NIA on PM2.5-induced oxidative stress in human HaCaT keratinocytes. We found that NIA could inhibit the ROS generation induced by PM2.5, as well blocked the PM2.5-induced oxidation of molecules, such as lipids, proteins, and DNA. Furthermore, NIA alleviated PM2.5-induced accumulation of cellular Ca2+, which caused cell membrane depolarization and apoptosis, and reduced the number of apoptotic cells. Collectively, the findings show that NIA can protect keratinocytes from PM2.5-induced oxidative stress and cell damage.

Luteolin promotes apoptotic cell death via upregulation of Nrf2 expression by DNA demethylase and the interaction of Nrf2 with p53 in human colon cancer cells.

Luteolin, a dietary flavone, modulates various signaling pathways involved in carcinogenesis. In this study, we investigated the molecular mechanism that underlies the apoptotic effects of luteolin mediated by DNA demethylation of the nuclear factor erythroid 2-related factor 2 (Nrf2) promoter and the interaction of Nrf2 and p53, a tumor suppressor, in human colon cancer cells. Luteolin increased the expression of apoptosis-related proteins and antioxidant enzymes. In DNA methylation, luteolin inhibited the expression of DNA methyltransferases, a transcription repressor, and increased the expression and activity of ten-eleven translocation (TET) DNA demethylases, a transcription activator. Methyl-specific polymerase chain reaction and bisulfite genomic sequencing indicated that luteolin decreased the methylation of the Nrf2 promoter region, which corresponded to the increased mRNA expression of Nrf2. In addition, luteolin increased TET1 binding to the Nrf2 promoter, as determined using a chromatin immunoprecipitation (ChIP) assay. TET1 knockdown decreased the percentages of luteolin-treated cells in sub-G1 phase and cells with fragmented nuclei. Furthermore, complex formation between p53 and Nrf2 was involved in the apoptotic effects of luteolin. These results provide insight into the mechanism that underlies the anticancer effects of luteolin on colon cancer, which involve the upregulation of Nrf2 and its interaction with the tumor suppressor.

Horse Oil Mitigates Oxidative Damage to Human HaCaT Keratinocytes Caused by Ultraviolet B Irradiation.

Horse oil products have been used in skin care for a long time in traditional medicine, but the biological effects of horse oil on the skin remain unclear. This study was conducted to evaluate the protective effect of horse oil on ultraviolet B (UVB)-induced oxidative stress in human HaCaT keratinocytes. Horse oil significantly reduced UVB-induced intracellular reactive oxygen species and intracellular oxidative damage to lipids, proteins, and DNA. Horse oil absorbed light in the UVB range of the electromagnetic spectrum and suppressed the generation of cyclobutane pyrimidine dimers, a photoproduct of UVB irradiation. Western blotting showed that horse oil increased the UVB-induced Bcl-2/Bax ratio, inhibited mitochondria-mediated apoptosis and matrix metalloproteinase expression, and altered mitogen-activated protein kinase signaling-related proteins. These effects were conferred by increased phosphorylation of extracellular signal-regulated kinase 1/2 and decreased phosphorylation of p38 and c-Jun N-terminal kinase 1/2. Additionally, horse oil reduced UVB-induced binding of activator protein 1 to the matrix metalloproteinase-1 promoter site. These results indicate that horse oil protects human HaCaT keratinocytes from UVB-induced oxidative stress by absorbing UVB radiation and removing reactive oxygen species, thereby protecting cells from structural damage and preventing cell death and aging. In conclusion, horse oil is a potential skin protectant against skin damage involving oxidative stress.