Stress In Human Keratinocytes Research Articles

Intracellular Mg2+ protects mitochondria from oxidative stress in human keratinocytes

Reactive oxygen species (ROS) are harmful for the human body, and exposure to ultraviolet irradiation triggers ROS generation. Previous studies have demonstrated that ROS decrease mitochondrial membrane potential (MMP) and that Mg2+ protects mitochondria from oxidative stress. Therefore, we visualized the spatio-temporal dynamics of Mg2+ in keratinocytes (a skin component) in response to H2O2 (a type of ROS) and found that it increased cytosolic Mg2+ levels. H2O2-induced responses in both Mg2+ and ATP were larger in keratinocytes derived from adults than in keratinocytes derived from newborns, and inhibition of mitochondrial ATP synthesis enhanced the H2O2-induced Mg2+ response, indicating that a major source of Mg2+ was dissociation from ATP. Simultaneous imaging of Mg2+ and MMP revealed that larger Mg2+ responses corresponded to lower decreases in MMP in response to H2O2. Moreover, Mg2+ supplementation attenuated H2O2-induced cell death. These suggest the potential of Mg2+ as an active ingredient to protect skin from oxidative stress.

An alkaloid-rich phytopharmaceutical prepared from Qing Dai against IL-17A-induced psoriasis

Ethnopharmacological relevancePsoriasis is a chronic inflammatory disease due to immune dysregulation that cannot be cured. The skin conditions of psoriasis negatively impact patients’ quality of life worldwide. Qing Dai (Indigo Naturalis), a traditional Chinese medicine (TCM) processed from Strobilanthes cusia is a clinical medicine used for psoriasis patient in Taiwan and the gene overexpression of interleukin (IL)-17A could be notably reduced in skin lesions after using Qing Dai ointment and its alkaloid ingredients. Aim of the studyTo develop a potential anti-psoriatic phytopharmaceutical, an alkaloid-rich fraction named INM-A was prepared from Qing Dai. The chemical profile and anti-psoriatic activity of INM-A were analyzed and evaluated to define its in vitro mechanism and in vivo efficacy for psoriasis therapy. Materials and methodsDowex® 50WX4 hydrogen form resin was used for column chromatography to prepare INM-A. To track alkaloids, INM-A was conducted with Dragendorff's, Mayer's, and Wagner's reagents. HPLC and UV–Vis spectrophotometer were applied to analyze the chemical profile and relative total alkaloid content in INM-A. A psoriatic mouse model induced by imiquimod (IMQ) was performed to verify in vivo efficacy of INM-A. IL-17A-dominated cellular oxygen consumption rate, oxidative stress, and cytokines in keratinocytes were measured to clarify in vitro mechanism of INM-A. ResultsAn alkaloid-rich fraction, INM-A, consisted of seven active alkaloid compounds 1–7 was obtained from Qing Dai. INM-A improved the skin condition severities in IMQ-induced psoriatic mice and decreased IL-17A in not only psoriatic mice but also polarized Th17 cells. In addition, INM-A targeted IL-17A to inhibit inflammation and OXPHOS-driven oxidative stress in human keratinocytes. ConclusionAccordingly, INM-A manufactured from Qing Dai may be a promising lead phytopharmaceutical for further IL-17A-related inflammatory disease studies such as psoriasis.

NRF2-ARE signaling is responsive to haloacetonitrile-induced oxidative stress in human keratinocytes

Humans are exposed to disinfection by-products through oral, inhalation, and dermal routes, during bathing and swimming, potentially causing skin lesions, asthma, and bladder cancer. Nuclear factor E2-related factor 2 (NRF2) is a master regulator of the adaptive antioxidant response via the antioxidant reaction elements (ARE) orchestrating the transcription of a large group of antioxidant and detoxification genes. Here we used an immortalized human keratinocyte model HaCaT cells to investigate NRF2-ARE as a responder and protector in the acute cytotoxicity of seven haloacetonitriles (HANs), including chloroacetonitrile (CAN), bromoacetonitrile (BAN), iodoacetonitrile (IAN), bromochloroacetonitrile (BCAN), dichloroacetonitrile (DCAN), dibromoacetonitrile (DBAN), and trichloroacetonitrile (TCAN) found in drinking water and swimming pools. The rank order of cytotoxicity among the HANs tested was IAN ≈ BAN ˃ DBAN ˃ BCAN ˃ CAN ˃ TCAN ˃ DCAN based on their LC50. The HANs induced intracellular reactive oxygen species accumulation and activated cellular antioxidant responses in concentration- and time-dependent fashions, showing elevated NRF2 protein levels and ARE activity, induction of antioxidant genes, and increased glutathione levels. Additionally, knockdown of NRF2 by lentiviral shRNAs sensitized the HaCaT cells to HANs-induced cytotoxicity, emphasizing a protective role of NRF2 against the cytotoxicity of HANs. These results indicate that HANs cause oxidative stress and activate NRF2-ARE-mediated antioxidant response, which in turn protects the cells from HANs-induced cytotoxicity, highlighting that NRF2-ARE activity could be a sensitive indicator to identify and characterize the oxidative stress induced by HANs and other environmental pollutants.

Nrf2-Are Signaling is Responsive to Haloacetonitrile-Induced Oxidative Stress in Human Keratinocytes

Nrf2-Are Signaling is Responsive to Haloacetonitrile-Induced Oxidative Stress in Human Keratinocytes

Jabuticaba (Myrciaria jaboticaba) Peel as a Sustainable Source of Anthocyanins and Ellagitannins Delivered by Phospholipid Vesicles for Alleviating Oxidative Stress in Human Keratinocytes.

The Brazilian berry scientifically known as jabuticaba is a fruit covered by a dark purple peel that is still rich in bioactives, especially polyphenols. Considering that, this work was aimed at obtaining an extract from the peel of jabuticaba fruits, identifying its main components, loading it in phospholipid vesicles specifically tailored for skin delivery and evaluating their biological efficacy. The extract was obtained by pressurized hot water extraction (PHWE), which is considered an easy and low dissipative method, and it was rich in polyphenolic compounds, especially flavonoids (ortho-diphenols and condensed tannins), anthocyanins (cyanidin 3-O-glucoside and delphinidin 3-O-glucoside) and gallic acid, which were responsible for the high antioxidant activity detected using different colorimetric methods (DPPH, FRAP, CUPRAC and metal chelation). To improve the stability and extract effectiveness, it was incorporated into ultradeformable phospholipid vesicles (transfersomes) that were modified by adding two different polymers (hydroxyethyl cellulose and sodium hyaluronate), thus obtaining HEcellulose-transfersomes and hyaluronan-transfersomes. Transfersomes without polymers were the smallest, as the addition of the polymer led to the formation of larger vesicles that were more stable in storage. The incorporation of the extract in the vesicles promoted their beneficial activities as they were capable, to a greater extent than the solution used as reference, of counteracting the toxic effect of hydrogen peroxide and even of speeding up the healing of a wound performed in a cell monolayer, especially when vesicles were enriched with polymers. Given that, polymer enriched vesicles may represent a good strategy to produce cosmetical and cosmeceutical products with beneficial properties for skin.

(-)-Loliolide Isolated from Sargassum horneri Protects against Fine Dust-Induced Oxidative Stress in Human Keratinocytes.

The emergence of fine dust (FD) among air pollutants has taken a toll during the past few decades, and it has provided both controversy and a platform for open conversation amongst world powers for finding sustainable solutions and effective treatments for health issues. The present study emphasizes the protective effects of (–)-loliolide (HTT) isolated from Sargassum horneri against FD-induced oxidative stress in human HaCaT keratinocytes. The purification of (–)-loliolide was carried out by centrifugal partition chromatography. HTT did not show any cytotoxicity, and it further illustrated the potential to increase cell viability by reducing the reactive oxygen species (ROS) production in FD-stimulated keratinocytes. Furthermore, HTT suppressed FD-stimulated DNA damage and the formation of apoptotic bodies, and it reduced the population of cells in the sub-G1 apoptosis phase. FD-induced apoptosis was advancing through the mitochondria-mediated apoptosis pathway. The cytoprotective effects of the HTT against FD-stimulated oxidative damage is mediated through squaring the nuclear factor E2-related factor 2 (Nrf2)-mediated heme oxygenase-1 (HO-1) pathway, dose-dependently increasing HO-1 and NAD(P)H dehydrogenase (quinone) 1 (NQO1) levels in the cytosol while concomitantly improving the nuclear translocation of Nrf2. Future studies could implement the protective functionality of HTT in producing pharmaceuticals that utilize natural products and benefit the diseased.

Cytoprotective effects of a proprietary red maple leaf extract and its major polyphenol, ginnalin A, against hydrogen peroxide and methylglyoxal induced oxidative stress in human keratinocytes.

Phytochemicals from functional foods are common ingredients in dietary supplements and cosmetic products for anti-skin aging effects due to their antioxidant activities. A proprietary red maple (Acer rubrum) leaf extract (Maplifa™) and its major phenolic compound, ginnalin A (GA), have been reported to show antioxidant, anti-melanogenesis, and anti-glycation effects but their protective effects against oxidative stress in human skin cells remain unknown. Herein, we investigated the cytoprotective effects of Maplifa™ and GA against hydrogen peroxide (H2O2) and methylglyoxal (MGO)-induced oxidative stress in human keratinocytes (HaCaT cells). H2O2 and MGO (both at 400 μM) induced toxicity in HaCaT cells and reduced their viability to 59.2 and 61.6%, respectively. Treatment of Maplifa™ (50 μg mL-1) and GA (50 μM) increased the viability of H2O2- and MGO-treated cells by 22.0 and 15.5%, respectively. Maplifa™ and GA also showed cytoprotective effects by reducing H2O2-induced apoptosis in HaCaT cells by 8.0 and 7.2%, respectively. The anti-apoptotic effect of Maplifa™ was further supported by the decreased levels of apoptosis associated enzymes including caspases-3/7 and -8 in HaCaT cells by 49.5 and 19.0%, respectively. In addition, Maplifa™ (50 μg mL-1) and GA (50 μM) reduced H2O2- and MGO-induced reactive oxygen species (ROS) by 84.1 and 56.8%, respectively. Furthermore, flow cytometry analysis showed that Maplifa™ and GA reduced MGO-induced total cellular ROS production while increasing mitochondria-derived ROS production in HaCaT cells. The cytoprotective effects of Maplifa™ and GA in human keratinocytes support their potential utilization for cosmetic and/or dermatological applications.

Protective effect of kudzu root vinegar and adenosine against UVB-induced oxidative stress in human keratinocytes

Ultraviolet (UV) irradiation generates reactive oxygen species (ROS) in cells, which induces sunburn cell formation, melanoma, photoaging, and skin cancer. This study examines the anti-photodamage effects of kudzu root vinegar and adenosine in UVB-exposed human keratinocytes (HaCaT cells). UVB significantly decreased HaCaT cell viability, whereas kudzu root vinegar and adenosine did not exhibit cytotoxic effects and increased the viability of HaCaT cells. To investigate the protective effects of kudzu root vinegar and adenosine on UVB-induced oxidative stress in HaCaT cells, ROS, matrix metalloproteinases (MMPs), and mitogen-activated protein kinase (MAPK) were analyzed. UVB-induced treatment reduced the activity of antioxidant enzymes; however, kudzu root vinegar and adenosine increased their activity. These results indicated that kudzu root vinegar and adenosine exert cytoprotective activity against UVB-induced oxidative stress in HaCaT cells. Moreover, they suppressed the UVB-induced downregulation of MMPs and inhibited the phosphorylation of MAPK induced by UVB-irradiation. Therefore, kudzu root vinegar and adenosine offer anti-oxidative effects, via lowering ROS production, suppressing JNK activation, and downregulating expression of MMPs. Our findings suggest that kudzu root vinegar and adenosine have potential application in preventing skin damage owing to UVB exposure. Keywords: reactive oxygen species (ROS), HaCaT cell, UVB, skin damage, anti-aging

Voriconazole enhances UV‐induced DNA damage by inhibiting catalase and promoting oxidative stress

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer and is associated with cumulative UV exposure. Studies have shown that prolonged voriconazole use promotes cSCC formation; however, the biological mechanisms responsible for the increased incidence remain unclear. Here, we show that voriconazole directly increases oxidative stress in human keratinocytes and promotes UV-induced DNA damage as determined by comet assay, 8-oxoguanine immunofluorescence and mass spectrometry. Voriconazole treatment of human keratinocytes potentiates UV-induced apoptosis and activation of the p38 MAP kinase and 53BP1 UV stress response pathways. The p38 MAP kinase activation promoted by voriconazole exposure can be mitigated by pretreating keratinocytes with N-acetylcysteine. Voriconazole increases oxidative stress in keratinocytes by directly inhibiting catalase leading to lower intracellular NADPH levels and the triazole moieties in voriconazole are critical for inhibiting catalase. Furthermore, voriconazole is shown to promote UV-induced dysplasia in an in vivo model. Together, these data demonstrate that voriconazole potentiates oxidative stress in UV-irradiated keratinocytes through catalase inhibition. Use of antioxidants may mitigate the pro-oncogenic effects of voriconazole.

Carbon Monoxide Partially Mediates Protective Effect of Resveratrol Against UVB-Induced Oxidative Stress in Human Keratinocytes.

Based on the antioxidative effect of resveratrol (RES) in mitigating reactive oxygen species (ROS) production through the induction of nuclear factor-erythroid 2-related factor-2 (Nrf2)/heme oxigenase-1 (HO-1) signaling pathway, we investigated whether the protective activity of RES against ROS-mediated cytotoxicity is mediated by intracellular carbon monoxide (CO), a product of HO-1 activity, in ultraviolet B (UVB)-irradiated human keratinocyte HaCaT cells. The cells were exposed to UVB radiation following treatment with RES and/or CO-releasing molecule-2 (CORM-2). RES and/or CORM-2 upregulated HO-1 protein expression, accompanied by a gradual reduction of UVB-induced intracellular ROS levels. CORM-2 reduced intracellular ROS in the presence of tin protoporphyrin IX, an HO-1 inhibitor, indicating that the cytoprotection observed was mediated by intracellular CO and not by HO-1 itself. Moreover, CORM-2 decreased RES-stimulated mitochondrial quantity and respiration and increased the cytosolic protein expressions of radical-scavenging superoxide dismutases, SOD1 and SOD2. Taken together, our observations suggest that RES and intracellular CO act independently, at least partly, in attenuating cellular oxidative stress by promoting antioxidant enzyme expressions and inhibiting mitochondrial respiration in UVB-exposed keratinocytes.

449 Measuring activation of the NLRP inflammasomes in vitro via Active Caspase-1 Release: Implications in understanding epidermal inflammatory responses

In 2002, a key component of cellular inflammatory response was discovered when the NLRP Inflammasomes were isolated and identified [1]. When skin cells are attacked by endogenous threats, the NLRP proteins oligomerize to form Inflammasomes. The Inflammasomes release Active Caspase-1 (ACase-1), which cleaves Pro-IL-1β and Pro-IL-18 present in the skin cells creating active interleukin cytokines. Activated IL-1β and IL-18 initiate a process of inflammation response that leads to accumulation of downstream curative moieties [2]. NLRP Inflammasomes have been linked to many skin abnormalities such as acne, dandruff, atopic dermatitis, and other skin problems. Inflammasomes are also linked to inflammation caused by external insults like UV radiation, chemical and allergenic agents, and bacterial and fungal attacks. The NLRP1 Inflammasome appears to be the key sensor for UV stress in human keratinocytes, while the NLRP3 Inflammasome has been implicated in wound healing in skin [3,4]. We describe in vitro studies examining the role of various NLRP activators on Normal Human Epidermal Keratinocytes (NHEKs) to elicit upregulation of ACase-1. Two key activators, UVB energy and ATP, cause significant upregulation of the NLRP Inflammasomes measured by release of ACase-1. The release of ACase-1 is delayed from the time of exposure to both NLRP activators. Various external topical treatments that include polysaccharide- and antioxidant-based ingredients were examined for their impact on the expression of ACase-1 in Inflammasome-activated NHEKs. [1] Martinon F et al., The inflammasomes: guardians of the body. Nature 2002. [2] Groslambert M et al., Spotlight on the NLRP3 inflammasome pathway. J Inflamm Res 2018. [3] Burian M et al., NLRP1 is the key inflammasome in primary human keratinocytes. J Invest Dermatol 2018. [4] Ito H. et al., activation of NLRP3 signaling accelerates skin wound healing. Ex Dermatol 2018.

Tectorigenin, a Flavonoid-Based Compound of Leopard Lily Rhizome, Attenuates UV-B-Induced Apoptosis and Collagen Degradation by Inhibiting Oxidative Stress in Human Keratinocytes.

Ultraviolet (UV) light, a major risk factor for external skin photoaging, induces oxidative stress in skin. UV causes a breakdown of skin homeostasis by impairing the extracellular matrix and inducing cell death. Tectorigenin, a constituent of leopard lily (Belamcanda chinensis L.) rhizome, has been reported to possess antioxidant, hair-darkening, and anti-inflammatory activities; however, the effect of tectorigenin on UV-B-induced skin damage is unknown. Here, we investigated the anti-skin-damage effects of tectorigenin against UV-B-stimulated oxidative stress in human keratinocytes. We irradiated HaCaT cells with UV-B (25 mJ/cm2), followed by treatment with tectorigenin for 24 h. We found that tectorigenin decreased the levels of intracellular reactive oxygen species by increasing the expression of anti-oxidative enzymes, such as glutathione and catalase. Furthermore, tectorigenin inhibited apoptosis by reducing caspase-3- and Bcl-2-associated protein-X levels, and increasing Bcl-2 protein levels. Tectorigenin also decreased matrix metalloproteinase-1 levels and increased type 1 collagen levels, thus preventing collagen degradation. These data demonstrate that tectorigenin exerts anti-skin-damage effects in human keratinocytes by attenuating UV-B-induced hyper-oxidation, apoptosis, and collagen degradation.

Hypo-osmotic Stress Drives IL-33 Production in Human Keratinocytes—An Epidermal Homeostatic Response

Although inflammation has traditionally been considered a response to either exogenous pathogen-associated signals or endogenous signals of cell damage, other perturbations of homeostasis, generally referred to as stress, may also induce inflammation. The relationship between stress and inflammation is, however, not well defined. Here, we describe a mechanism of IL-33 induction driven by hypo-osmotic stress in human keratinocytes and also report interesting differences when comparing the responsiveness of other inflammatory mediators. The induction of IL-33 was completely dependent on EGFR and calcium signaling, and inhibition of calcium signaling not only abolished IL-33 induction but also dramatically changed the transcriptional pattern of other cytokines upon hypo-osmotic stress. IL-33 was not secreted but instead showed nuclear sequestration, conceivably acting as a failsafe mechanism whereby it is induced by potential danger but released only upon more extreme homeostatic perturbations that result in cell death. Finally, stress-induced IL-33 was also confirmed in an exvivo human skin model, translating this mechanism to a potential tissue-relevant signal in the human epidermis. In conclusion, we describe hypo-osmotic stress as an inducer of IL-33 expression, linking cellular stress to nuclear accumulation of a strong proinflammatory cytokine.

Phytochemicals and anti-aging potentials of the extracts from Lagerstroemia speciosa and Lagerstroemia floribunda

Skin aging is caused by oxidative stress and the enhanced activation of proteolytic enzymes. Inhibition of these mechanisms by natural plants might be a promising approach to prevent skin aging. The flowers of Lagerstroemia speciosa and Lagerstroemia floribunda are unused parts of agricultural products. They have been reported to possess antioxidant activity and inhibitory properties against matrix metalloproteinase enzymes. In the present study, the ethanolic flowers extracts of L. speciosa and L. floribunda were studied for their total phenolic, flavonoid, and anthocyanin contents, and antioxidant properties. Additionally, the active compounds were identified using high performance liquid chromatography (HPLC). The extracts were also evaluated for their inhibitory effects against hyaluronidase, elastase and tyrosinase. Finally, the extracts were investigated for their protective effects on hydrogen peroxide-induced oxidative stress in human keratinocytes. Results showed that antioxidant activities of the flowers extracts of L. speciosa and L. floribunda were equal to that of ascorbic acid. Both plants also inhibited hyaluronidase, elastase and tyrosinase activity. In addition, these flower extracts showed remarkable inhibitory potential against hyaluronidase, which was higher than that of the standard oleanolic acid. Furthermore, these extracts were found to inhibit hydrogen peroxide-induced cell death in human keratinocytes. L. speciosa extract exhibited higher antioxidant properties, enzymatic inhibitory activities and cytoprotective effects compared with that of L. floribunda. HPLC analysis had revealed that ellagic acid, epicatechin gallate, and quercetin were the major compounds in both extracts, but with higher contents in L. speciosa than in L. floribunda. Taken together, the results suggest that these flower extracts can be considered as new natural sources to be potentially used as anti-aging ingredients in skin care formulations.

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.

Remifentanil reduced the effects of hydrogen peroxide-induced oxidative stress in human keratinocytes via autophagy

ABSTRACTPurpose: Excess reactive oxygen species are detrimental to wound repair. Remifentanil decreases reactive oxygen species generation and inflammatory response; however, its effects on oxidative cell injury are not completely understood. Therefore, we investigated the effects of remifentanil on human keratinocytes under hydrogen peroxide-induced oxidative stress and the correlation of these effects with autophagy. Materials and Methods: Human keratinocytes (HaCaT cell line) were randomly assigned to four groups: control, hydrogen peroxide, remifentanil pretreatment + hydrogen peroxide, and 3-methyladenine + remifentanil pretreatment + hydrogen peroxide. The MTT assay was performed to analyze cell viability. Apoptotic cell death was measured by Hoechst staining. A scratch assay was used to measure cell migration. The role of autophagy was ascertained by autophagosome staining and western blot analysis of autophagy-related proteins. Results: Compared with the control group, the hydrogen peroxide group showed decreased cell viability, which was improved by remifentanil pretreatment. Hydrogen peroxide-induced apoptotic cell death and delayed cell migration were also improved by remifentanil pretreatment. Western blot analysis showed that the expression of autophagy-related proteins significantly increased in the remifentanil pretreatment + hydrogen peroxide group compared with that in the hydrogen peroxide group. Conclusions: This study demonstrated that remifentanil pretreatment ameliorates hydrogen peroxide-induced oxidative injury in human keratinocytes. In addition, our results show that the antioxidative effect of remifentanil against hydrogen peroxide-induced oxidative injury was mediated by autophagy.

Fucoidan reduces oxidative stress by regulating the gene expression of HO‑1 and SOD‑1 through the Nrf2/ERK signaling pathway in HaCaT cells.

Fucoidan, a sulfated polysaccharide, is found in edible brown algae. In the present study, the molecular mechanisms of fucoidan against mild oxidative stress in human keratinocytes were investigated. The current study indicated that fucoidan significantly augmented the antioxidants heme oxygenase‑1 (HO‑1) and superoxide dismutase‑1 (SOD‑1) via the upregulation of nuclear factor erythroid 2‑related factor2 (Nrf2) and markedly reduced the cytoplasmic stability of kelch‑like ECH‑associated protein 1. The upregulation of HO‑1 and SOD‑1 detected in the fucoidan‑treated cells may be responsible for the increased resistance to mild oxidative stress, indicating that fucoidan may augment the activities of antioxidant enzymes via stimulating Nrf2. This is the first report, to the best of our knowledge, to demonstrate that fucoidan attenuates oxidative stress by regulating the gene expression of SOD‑1 and HO‑1 via the Nrf2/extracellular signal‑regulated kinase signaling pathway.

Hesperidin Attenuates Ultraviolet B-Induced Apoptosis by Mitigating Oxidative Stress in Human Keratinocytes.

Human skin cells undergo pathophysiological processes via generation of reactive oxygen species (ROS) upon excessive exposure to ultraviolet B (UVB) radiation. This study investigated the ability of hesperidin (C28H34O15) to prevent apoptosis due to oxidative stress generated through UVB-induced ROS. Hesperidin significantly scavenged ROS generated by UVB radiation, attenuated the oxidation of cellular macromolecules, established mitochondrial membrane polarization, and prevented the release of cytochrome c into the cytosol. Hesperidin downregulated expression of caspase-9, caspase-3, and Bcl-2-associated X protein, and upregulated expression of B-cell lymphoma 2. Hesperidin absorbed wavelengths of light within the UVB range. In summary, hesperidin shielded human keratinocytes from UVB radiation-induced damage and apoptosis via its antioxidant and UVB absorption properties.

Photo-protective effect of sargachromenol against UVB radiation-induced damage through modulating cellular antioxidant systems and apoptosis in human keratinocytes.

The aim of this study was to evaluate the photo-preventive effects of sargachromenol (SC) against ultraviolet B (UVB)-induced oxidative stress in human keratinocytes via assessing the antioxidant properties and underlying molecular mechanisms. SC exhibited a significant scavenging effect on UVB-induced intracellular reactive oxygen species (ROS). SC attenuated UVB-induced oxidative macromolecular damage, including the protein carbonyl content, DNA strand break, and 8-isoprostane level. Furthermore, SC decreased UVB-induced Bax, cleaved caspase-9, and cleaved caspase-3 protein levels, but increased that of Bcl-2, which are well-known key mediators of apoptosis. Moreover, SC increased superoxide dismutase, catalase, and heme oxygenase-1 protein expression. Pre-treatment with SC upregulated the main transcription factor of antioxidant enzymes, erythroid 2-related factor 2 level, which was reduced by UVB irradiation. Extracellular signal-regulated kinase (ERK) and Jun N-terminal kinases (JNK) are involved in the regulation of many cellular events, including apoptosis. SC treatment reversed ERK and JNK activation induced by UVB. Collectively, these data indicate that SC can provide remarkable cytoprotection against the adverse effects of UVB radiation by modulating cellular antioxidant systems, and suggest the potential of developing a medical agent for ROS-induced skin diseases.

Suppressive effects of ethanol extract of Aralia elata on UVB-induced oxidative stress in human keratinocytes

Purpose: Ultraviolet (UV)-induced oxidative stress contributes to several adverse biological effects on skin. Many phenolic phytochemicals have been shown to have antioxidant properties and protect skin cells from UV-induced oxidative damage. In this study, we investigated whether or not Aralia elata (AE) has a protective effect against UVB-induced reactive oxygen species (ROS), ultimately leading to photoaging. Methods: Phenolic content of dried AE and antioxidant properties of AE extract in 70% ethanol weredetermined by measuring DPPH and ABTS radical scavenging activities and ferric reducing antioxidant power (FRAP). The effect of AE extract on cellular ROS generation and expression levels of oxidative stress-response proteins such as superoxide dismutase (SOD)-1, catalase, nuclear factor-erythroid 2-related factor (Nrf)-2,and heme oxygenase (HO)-1 in UVB-irradiated (75 mJ/㎠) human keratinocytes (HaCaT) were further determined by 2-7-dichlorofluoresceine diacetate assay and Western blotting, respectively. Results: The total phenolic and flavonoid contents of dried AE were 20.15 mg tannic acid/g and 18.75 mg rutin/g, respectively. The IC 50 of AE extract against DPPH radical was 98.5 μg/mL, and ABTS radical scavenging activity and FRAP upon treatment with 1,000 μg/mL of AE extract were 41.8 μg ascorbic acid (AA) eq./mL and 29.7 μg AA eq./mL,m respectively. Pretreatment with AE extract significantly reduced (p < 0.05) ROS generation compared to that in UVB-irradiated control HaCaT cells. Pretreatment with AE extract reversed reduction of Nrf-2 and SOD-1 protein expression and induction of HO-1 protein expression caused by UVB exposure in HaCaT cells, whereas it did not affect catalase expression. Conclusion: AE extract in 70% ethanol demonstrated a protective effect against UVB-induced oxidative stress and decreased expression of Nrf-2 and SOD-1 in human keratinocytes. These findings suggest that AE ethanol extract might have potential as a natural resource for a skin anti-photoaging product in the food and cosmetic industry.