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.

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.

Diphlorethohydroxycarmalol Attenuates Fine Particulate Matter-Induced Subcellular Skin Dysfunction.

The skin, the largest organ in humans, is exposed to major sources of outdoor air pollution, such as fine particulate matter with a diameter ≤ 2.5 µm (PM2.5). Diphlorethohydroxycarmalol (DPHC), a marine-based compound, possesses multiple activities including antioxidant effects. In the present study, we evaluated the protective effect of DPHC on PM2.5-induced skin cell damage and elucidated the underlying mechanisms in vitro and in vivo. The results showed that DPHC blocked PM2.5-induced reactive oxygen species generation in human keratinocytes. In addition, DPHC protected cells against PM2.5-induced DNA damage, endoplasmic reticulum stress, and autophagy. HR-1 hairless mice exposed to PM2.5 showed lipid peroxidation, protein carbonylation, and increased epidermal height, which were inhibited by DPHC. Moreover, PM2.5 induced apoptosis and mitogen-activated protein kinase (MAPK) protein expression; however, these changes were attenuated by DPHC 5. MAPK inhibitors were used to elucidate the molecular mechanisms underlying these actions, and the results demonstrated that MAPK signaling pathway may play a key role in PM2.5-induced skin damage.

Effect of Fermented Fish Oil on Fine Particulate Matter-Induced Skin Aging.

Skin is exposed to various harmful environmental factors such as air pollution, which includes different types of particulate matter (PM). Atmospheric PM has harmful effects on humans through increasing the generation of reactive oxygen species (ROS), which have been reported to promote skin aging via the induction of matrix metalloproteinases (MMPs), which in turn can cause the degradation of collagen. In this study, we investigated the effect of fermented fish oil (FFO) derived from mackerel on fine PM (particles with a diameter < 2.5 µm: PM2.5)-induced skin aging in human keratinocytes. We found that FFO inhibited the PM2.5-induced generation of intracellular ROS and MMPs, including MMP-1, MMP-2, and MMP-9. In addition, FFO significantly abrogated the elevation of intracellular Ca2+ levels in PM2.5-treated cells and was also found to block the PM2.5-induced mitogen-activated protein kinase/activator protein 1 (MAPK/AP-1) pathway. In conclusion, FFO has an anti-aging effect on PM2.5-induced aging in human keratinocytes.

Shikonin Exerts Cytotoxic Effects in Human Colon Cancers by Inducing Apoptotic Cell Death via the Endoplasmic Reticulum and Mitochondria-Mediated Pathways.

The apoptotic effects of shikonin (5,8-dihydroxy-2-[(1R)-1-hydroxy-4-methylpent-3-enyl]naphthalene-1,4-dione) on the human colon cancer cell line SNU-407 were investigated in this study. Shikonin showed dose-dependent cytotoxic activity against SNU-407 cells, with an estimated IC50 value of 3 µM after 48 h of treatment. Shikonin induced apoptosis, as evidenced by apoptotic body formation, sub-G1 phase cells, and DNA fragmentation. Shikonin induced apoptotic cell death by activating mitogen-activated protein kinase family members, and the apoptotic process was mediated by the activation of endoplasmic reticulum (ER) stress, leading to activation of the PERK/elF2α/CHOP apoptotic pathway, and mitochondrial Ca²âº accumulation. Shikonin increased mitochondrial membrane depolarization and altered the levels of apoptosis-related proteins, with a decrease in B cell lymphoma (Bcl)-2 and an increase in Bcl-2-associated X protein, and subsequently, increased expression of cleaved forms of caspase-9 and -3. Taken together, we suggest that these mechanisms, including MAPK signaling and the ER-and mitochondria-mediated pathways, may underlie shikonin-induced apoptosis related to its anticancer effect.

Purpurogallin Protects Keratinocytes from Damage and Apoptosis Induced by Ultraviolet B Radiation and Particulate Matter 2.5.

Purpurogallin, a natural phenol obtained from oak nutgalls, has been shown to possess antioxidant, anticancer, and anti-inflammatory effects. Recently, in addition to ultraviolet B (UVB) radiation that induces cell apoptosis via oxidative stress, particulate matter 2.5 (PM2.5) was shown to trigger excessive production of reactive oxygen species. In this study, we observed that UVB radiation and PM2.5 severely damaged human HaCaT keratinocytes, disrupting cellular DNA, lipids, and proteins and causing mitochondrial depolarization. Purpurogallin protected HaCaT cells from apoptosis induced by UVB radiation and/or PM2.5. Furthermore, purpurogallin effectively modulates the pro-apoptotic and anti-apoptotic proteins under UVB irradiation via caspase signaling pathways. Additionally, purpurogallin reduced apoptosis via MAPK signaling pathways, as demonstrated using MAPK-p38, ERK, and JNK inhibitors. These results indicate that purpurogallin possesses antioxidant effects and protects cells from damage and apoptosis induced by UVB radiation and PM2.5.

7,8-Dihydroxyflavone Protects High Glucose-Damaged Neuronal Cells against Oxidative Stress.

Oxidative stress is considered a major contributor in the pathogenesis of diabetic neuropathy and in diabetes complications, such as nephropathy and cardiovascular diseases. Diabetic neuropathy, which is the most frequent complications of diabetes, affect sensory, motor, and autonomic nerves. This study aimed to investigate whether 7,8-dihydroxyflavone (7,8-DHF) protects SH-SY5Y neuronal cells against high glucose-induced toxicity. In the current study, we found that diabetic patients exhibited higher lipid peroxidation caused by oxidative stress than healthy subjects. 7,8-DHF exhibits superoxide anion and hydroxyl radical scavenging activities. High glucose-induced toxicity severely damaged SH-SY5Y neuronal cells, causing mitochondrial depolarization; however, 7,8-DHF recovered mitochondrial polarization. Furthermore, 7,8-DHF effectively modulated the expression of pro-apoptotic protein (Bax) and anti-apoptotic protein (Bcl-2) under high glucose, thus inhibiting the activation of caspase signaling pathways. These results indicate that 7,8-DHF has antioxidant effects and protects cells from apoptotic cell death induced by high glucose. Thus, 7,8-DHF may be developed into a promising candidate for the treatment of diabetic neuropathy.

Mackerel-Derived Fermented Fish Oil Promotes Hair Growth by Anagen-Stimulating Pathways.

Hair growth is regulated by the interaction between dermal papilla cells (DPC) and other cells inside the hair follicle. Here, we show the effect and action mechanism of mackerel-derived fermented fish oil (FFO) extract and its component docosahexaenoic acid (DHA) in the control of hair growth. The hair growth effect of FFO extract was evaluated by the culture method of vibrissa follicles and in vivo dotmatrix planimetry method. FFO extract increased the length of hair-fibers and enabled stimulated initiation into the anagen phase of the hair cycle. As expected, FFO extract significantly increased DPC proliferation. FFO extract induced the progression of the cell cycle and the activation of extracellular signal-regulated kinase (ERK), p38 and Akt. FFO extract induced nuclear translocation of ß-catenin, a stimulator of anagen phase, through an increase of phospho-glycogen synthase kinase3ß (GSK3ß) level. Since various prostaglandins are known to promote hair growth in humans and mice, we examined the effect of DHA, a main omega-3 fatty acid of FFO, on DPC proliferation. DHA not only increased DPC proliferation but also upregulated levels of cell cycle-associated proteins such as cyclin D1 and cdc2 p34. These results show that FFO extract and DHA promote hair growth through the anagen-activating pathways in DPC.

Shikonin induces mitochondria-mediated apoptosis and attenuates epithelial-mesenchymal transition in cisplatin-resistant human ovarian cancer cells.

Cisplatin-based chemotherapy often results in the development of chemoresistance when used to treat ovarian cancer, which is difficult to overcome. The present study investigated the cytotoxic and anti-migratory effects of shikonin, a naphthoquinone compound, on cisplatin-resistant human ovarian cancer A2780 cells (A2780-CR). Shikonin had a potent dose-dependent cytotoxic effect on A2780-CR cells, with 9 µM shikonin treatment reducing A2780-CR cell viability by 50%, validate using an MTT assay. Shikonin induced apoptosis, as evidenced by the increased number of apoptotic bodies, following staining with Hoechst 33342, and terminal deoxynucleotidyl cell transferase dUTP nick end labeling-positive cells following treatment. Flow cytometry and fluorescent microscope imaging, following JC-1 staining, revealed that shikonin increased mitochondrial membrane depolarization. Also it altered the levels of apoptosis-associated proteins, leading to diminished expression of B cell lymphoma-2 (Bcl-2), enhanced expression of Bcl-associated X, and cleavage of caspase-9 and -3, as revealed using western blot analysis. Shikonin activated mitogen-activated protein kinases; while treatment with specific inhibitors of these kinases attenuated the decline in cell viability induced by shikonin treatment. In addition, the cell migration assay and western blot analysis indicated that shikonin decreased the migratory capacity of A2780-CR cells via the upregulation of epithelial-cadherin and downregulation of neural-cadherin. Taken together, the results of the present study indicated that shikonin induces mitochondria-mediated apoptosis and attenuates the epithelial-mesenchymal transition in A2780-CR cells.

Particulate matter 2.5 damages skin cells by inducing oxidative stress, subcellular organelle dysfunction, and apoptosis.

The skin is the largest organ of the human body and the one mostly exposed to outdoor contaminants. To evaluate the biological mechanisms underlying skin damage caused by fine particulate matter (PM2.5), we analyzed the effects of PM2.5 on cultured human keratinocytes and the skin of experimental animals. PM2.5 was applied to human HaCaT keratinocytes at 50 µg/mL for 24 h and to mouse skin at 100 µg/mL for 7 days. The results indicate that PM2.5 induced oxidative stress by generating reactive oxygen species both in vitro and in vivo, which led to DNA damage, lipid peroxidation, and protein carbonylation. As a result, PM2.5 induced endoplasmic reticulum stress, mitochondrial swelling, and autophagy, and caused apoptosis in HaCaT cells and mouse skin tissue. The PM2.5-induced cell damage was attenuated by antioxidant N-acetyl cysteine, confirming that PM2.5 cellular toxicity was due to oxidative stress. These findings contribute to understanding of the pathophysiological mechanisms triggered in the skin by PM2.5, among which oxidative stress may play a major role.

3-Bromo-4,5-dihydroxybenzaldehyde Enhances the Level of Reduced Glutathione via the Nrf2-Mediated Pathway in Human Keratinocytes.

A natural bromophenol found in seaweeds, 3-bromo-4,5-dihydroxybenzaldehyde (BDB), has been shown to possess antioxidant effects. This study aimed to investigate the mechanism by which BDB protects skin cells subjected to oxidative stress. The effect of BDB on the protein and mRNA levels of glutathione-related enzymes and the cell survival of human keratinocytes (HaCaT cells) was investigated. BDB treatment increased the protein and mRNA levels of glutathione synthesizing enzymes and enhanced the production of reduced glutathione in HaCaT cells. Furthermore, BDB activated NF-E2-related factor 2 (Nrf2) and promoted its localization into the nucleus by phosphorylating its up-stream signaling proteins, extracellular signal-regulated kinase and protein kinase B. Thus, BDB increased the production of reduced glutathione and established cellular protection against oxidative stress via an Nrf2-mediated pathway.

The Red Algae Compound 3-Bromo-4,5-dihydroxybenzaldehyde Protects Human Keratinocytes on Oxidative Stress-Related Molecules and Pathways Activated by UVB Irradiation.

Skin exposure to ultraviolet B (UVB) irradiation leads to the generation of reactive oxygen species (ROS). Excessive ROS cause aging of the skin via basement membrane/extracellular matrix degradation by matrix metalloproteinases (MMPs). We recently demonstrated that 3-bromo-4,5-dihydroxybenzaldehyde (BDB), a natural compound of red algae, had a photo-protective effect against UVB-induced oxidative stress in human keratinocytes. The present study focused on the effect of BDB on UVB-irradiated photo-aging in HaCaT keratinocytes and the underlying mechanism. BDB significantly impeded MMP-1 activation and expression, and abrogated the activation of mitogen-activated protein kinases and intracellular Ca2+ level in UVB-irradiated HaCaT cells. Moreover, BDB decreased the expression levels of c-Fos and phospho-c-Jun and the binding of activator protein-1 to the MMP-1 promoter induced by UVB irradiation. These results offer evidence that BDB is potentially useful for the prevention of UVB-irradiated skin damage.

Luteolin induces apoptotic cell death via antioxidant activity in human colon cancer cells.

The present study determined whether luteolin induces HT-29 colon cancer cell death through an antioxidant effect such as the activation of antioxidant enzymes. Luteolin decreased cell viability in human colon cancer cells (HT-29), whereas it had no effect on normal colon cells (FHC). Luteolin induced apoptosis by activating the mitochondria-mediated caspase pathway in HT-29 cells. Luteolin caused loss of the mitochondrial membrane action potential, increased mitochondrial Ca2+ level, upregulated Bax, downregulated Bcl-2, induced the release of cytochrome c from mitochondria to the cytosol, and increased the levels of the active forms of caspase-9 and caspase-3. Luteolin-induced apoptosis was accompanied by the activation of intracellular and mitochondrial reactive oxygen species scavenging through the activation of antioxidant enzymes, such as superoxide dismutase and catalase in HT-29 cells. Luteolin increased the level of reduced glutathione (GSH) and the expression of GSH synthetase, which catalyzes the second step of GSH biosynthesis. The apoptotic effect of luteolin was mediated by the activation of the mitogen-activated protein kinase signaling pathway. The present results indicate that luteolin induces apoptosis by promoting antioxidant activity and activating MAPK signaling in human colon cancer cells.

A Benzylideneacetophenone Derivative Induces Apoptosis of Radiation-Resistant Human Breast Cancer Cells via Oxidative Stress.

Benzylideneacetophenone derivative (1E)-1-(4-hydroxy-3-methoxyphenyl) hept-1-en-3-one (JC3) elicited cytotoxic effects on MDA-MB 231 human breast cancer cells-radiation resistant cells (MDA-MB 231-RR), in a dose-dependent manner, with an IC50 value of 6 µM JC3. JC3-mediated apoptosis was confirmed by increase in sub-G1 cell population. JC3 disrupted the mitochondrial membrane potential, and reduced expression of anti-apoptotic B cell lymphoma-2 protein, whereas it increased expression of pro-apoptotic Bcl-2-associated X protein, leading to the cleavage of caspase-9, caspase-3 and poly (ADP-ribose) polymerase. In addition, JC3 activated mitogen-activated protein kinases, and specific inhibitors of these kinases abrogated the JC3-induced increase in apoptotic bodies. JC3 increased the level of intracellular reactive oxygen species and enhanced oxidative macromolecular damage via lipid peroxidation, protein carbonylation, and DNA strand breakage. Considering these findings, JC3 is an effective therapy against radiation-resistant human breast cancer cells.

Photoprotective effect of Undaria crenata against ultraviolet B-induced damage to keratinocytes.

Chronic exposure of the skin to ultraviolet B (UVB) radiation induces oxidative stress, which plays a crucial role in the induction of skin cancer. The brown alga Undaria crenata is a potential source of antioxidant and anti-apoptotic compounds due to its capacity to produce protective compounds against environmental factors, including UV radiation. The aim of this study was to investigate the photoprotective properties of an U. crenata ethanol extract (UCE) against UVB-induced cell damage in human HaCaT keratinocytes. UCE exhibited absorbing effect of UVB (280-320 nm) and scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical and intracellular reactive oxygen species induced by hydrogen peroxide and UVB rays. Furthermore, electron spin resonance spectrometry revealed the significant scavenging effect of UCE against superoxide anion and hydroxyl radical. UCE reduced UVB-induced apoptosis, as shown by a decrease in apoptotic bodies and nuclear and DNA fragmentation, resulting in the recovery of cell viability. UCE also decreased the degree of UVB-induced oxidative stress to lipids, proteins, and DNA as shown by a decrease in 8-isoprostane level, protein carbonylation and DNA tails. These results suggest that UCE protects human keratinocytes against UVB-induced oxidative stress.

An ethanol extract derived from Bonnemaisonia hamifera scavenges ultraviolet B (UVB) radiation-induced reactive oxygen species and attenuates UVB-induced cell damage in human keratinocytes.

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.

Chondracanthus tenellus (Harvey) hommersand extract protects the human keratinocyte cell line by blocking free radicals and UVB radiation-induced cell damage.

The aim of this study was to investigate the protective effects of the ethanol extract of the red algae Chondracanthus tenellus (Harvey) Hommersand (CTE) on cultured human keratinocyte cell line. The cellular protection conferred by CTE was evidenced by the ability of the extract to absorb ultraviolet B (UVB; 280-320 nm) and to scavenge the radical 1,1-diphenyl-2-picrylhydrazyl, as well as intracellular reactive oxygen species (ROS), induced by either hydrogen peroxide (H(2)O(2)) or UVB radiation. In addition, both superoxide anion generated by the xanthine/xanthine oxidase system and hydroxyl radical generated by the Fenton reaction (FeSO(4) + H(2)O(2)) were scavenged by CTE, as confirmed using electron spin resonance spectrometry. In the human keratinocyte cell line, CTE decreased the degree of injury resulting from UVB-induced oxidative stress to lipids, proteins, and DNA. CTE-treated cells also showed a reduction in UVB-induced apoptosis, as exemplified by fewer apoptotic bodies and less DNA fragmentation. Taken together, these results suggest that CTE confers protection on the human keratinocyte cell line against UVB-induced oxidative stress by absorbing UVB ray and scavenging ROS, thereby reducing injury to cellular constituents.

Photo-protection by 3-bromo-4, 5-dihydroxybenzaldehyde against ultraviolet B-induced oxidative stress in human keratinocytes.

Exposure of the skin to ultraviolet B (UVB) radiation leads to epidermal damage and the generation of reactive oxygen species (ROS) in skin cells, including keratinocytes. Therefore, the photo-protective effect of 3-bromo-4, 5-dihydroxybenzaldehyde (BDB) against UVB was assessed in human HaCaT keratinocytes exposed to UVB radiation in vitro. BDB restored cell viability, which decreased upon exposure to UVB radiation. BDB exhibited scavenging activity against 1, 1-diphenyl-2-picrylhydrazyl radicals, intracellular ROS induced by hydrogen peroxide (H(2)O(2)) or UVB radiation, the superoxide anion generated by the xanthine/xanthine oxidase system, and the hydroxyl radical generated by the Fenton reaction (FeSO(4)+H(2)O(2)). Moreover, BDB absorbed UVB and decreased injury resulting from UVB-induced oxidative stress to lipids, proteins and DNA. Finally, BDB reduced UVB-induced apoptosis, as exemplified by fewer apoptotic bodies and a reduction in DNA fragmentation. Taken together, these results suggest that BDB protects human keratinocytes against UVB-induced oxidative stress by scavenging ROS and absorbing UVB rays, thereby reducing injury to cellular components.