Preventive effects of dietary fucoxanthin on ultraviolet A induced photoaging in hairless mice.

BACKGROUND: Repeated exposure to ultraviolet A (UVA) irradiation, which can penetrate the epidermis and reach the dermis, is one of the major causes of skin photoaging. Photoaged skin is characterized clinically by generalized wrinkling, a dry and loose appearance, and seborrheic keratoses, along with skin barrier dysfunction. Fucoxanthin, a xanthophyll carotenoid with a specific allenic bond and 5,6-monoepoxide in its structure, has been found to serve various functions as a food supplement. In the present study, the protective effects of orally administered fucoxanthin at relatively low concentrations (0.001% and 0.01%) against UVA induced photoaging were evaluated in vivo using hairless mice. RESULTS: Oral supplementation of 0.001% fucoxanthin was sufficient for its metabolites to accumulate in the skin, thereby inhibiting pathological changes induced by UVA irradiation, including impaired skin barrier function and accelerated wrinkle formation. Analysis of gene expression revealed that dietary fucoxanthin exerted antiphotoaging effects, possibly by modulating natural moisturizing factor (NMF) synthesis, desquamation, and ceramide composition in the epidermis, and by inhibiting the UVA induced degradation of collagen fibers and inflammation in the dermis. CONCLUSION: Taken together, our data indicate the potential application of dietary fucoxanthin as a novel ingredient in nutricosmetics for skin care against photoaging. © 2024 Society of Chemical Industry.

Expression profiles and functional analysis of transfer RNA-derived small RNAs (tsRNAs) in photoaged human dermal fibroblasts.

Transfer RNA-derived small RNAs (tsRNAs) refer to a newly established family of non-coding RNAs that regulate a diverse set of biological processes. However, the function of tsRNAs in skin photoaging remains unclear. This research aims to investigate the potential correlation between tsRNAs and skin photoaging. Human dermal fibroblasts (HDFs) were irradiated with UVA at 10 J/cm2 once a day lasting for 14 days, resulting in the establishment of a photoaging model induced by UVA. To identify the expression profiles and functions of tsRNAs, tsRNA sequencing and bioinformatics analysis were conducted. qPCR was employed to validate the results of differentially expressed (DE) tsRNAs. A total of 34 tsRNAs exhibited significant differential expression between the UVA and control groups (n = 3), with nine upregulated and 25 downregulated (log2 fold change >1.5, p-value <0.05). Six tsRNAs were selected at random and validated by qRT-PCR. The enrichment analysis of DE tsRNAs target genes indicated that the dysregulated tsRNAs appeared to be connected with cell cycle, DNA replication and the AGE-RAGE signaling pathway. The expression of tsRNAs was found to be aberrant in UVA-HDF. These findings provide insights into the UVA-induced damage and potential target genes for skin photoaging.

Tapinarof and its structure-activity relationship for redox chemistry and phototoxicity on human skin keratinocytes.

Tapinarof (3,5-dihydroxy-4-isopropylstilbene) is a therapeutic agent used in the treatment of psoriasis (VTAMA®). In this study, we examined the redox behaviour, (photo)stability, (photo)toxicity and (bio)transformation of tapinarof in the context of a structure-activity relationship study. Selected derivatives of the structurally related tapinarof were investigated, namely resveratrol, pterostilbene, pinosylvin and its methyl ether. Tapinarof undergoes electrochemical oxidation in a neutral aqueous medium at a potential of around +0.5 V (vs. Ag|AgCl|3M KCl). The anodic reaction of this substance is a proton-dependent irreversible and adsorption-driven process. The pKa value of tapinarof corresponds to 9.19 or 9.93, based on empirical and QM calculation approach, respectively. The oxidation potentials of tapinarof and its analogues correlate well with their HOMO (highest occupied molecular orbital) energy level. The ability to scavenge the DPPH radical decreased in the order trolox ≥ resveratrol > pterostilbene > tapinarof > pinosylvin â‰« pinosylvin methyl ether. It was also confirmed that tapinarof, being a moderate electron donor, is able to scavenge the ABTS radical and inhibit lipid peroxidation. The 4'-OH group plays a pivotal role in antioxidant action of stilbenols. During the stability studies, it was shown that tapinarof is subject to spontaneous degradation under aqueous conditions, and its degradation is accelerated at elevated temperatures and after exposure to UVA (315-399 nm) radiation. In aqueous media at pH 7.4, we observed an ∼50 % degradation of tapinarof after 48 h at laboratory temperature. The main UVA photodegradation processes include dihydroxylation and hydration. In conclusion, the phototoxic effect of tapinarof on a human keratinocytes cell line (HaCaT) was evaluated. Tapinarof exhibited a clear phototoxic effect, similar to phototoxic standard chlorpromazine. The IC50 values of the cytotoxicity and phototoxic effects of tapinarof correspond to 27.6 and 3.7 µM, respectively. The main HaCaT biotransformation products of tapinarof are sulfates and glucuronides.

Association between SPRY1 and TET3 in skin photoaging and natural aging mechanisms.

BACKGROUND: SPRY1 is associated with the invasiveness and prognosis of various tumors, and TET3 affects aging by regulating gene expression. AIMS: We investigated the roles of SPRY1 and TET3 in natural skin aging, replicative aging, and photoaging, along with the effect of UVA on genome-wide DNA methylation in HaCaT cells. METHODS: TET3 and SPRY1 expression were measured in the skin of patients of different age groups, as well as in vitro human skin, HaCaT cell replicative senescence, and HaCaT and HaCaT-siTET3 cell photoaging models. Senescence was verified using ß-galactosidase staining, and DNA damage was detected using immunofluorescence staining for γ-H2A.X. 5-Methyl cytosine (5-mC) content in the genome was determined using ELISA. RESULTS: SPRY1 expression increased with age, whereas TET3 expression decreased. Similarly, SPRY1 was upregulated and TET3 was downregulated with increasing cell passages. TET3-siRNA upregulated SPRY1 expression in HaCaT cells. UVA irradiation promoted HaCaT cell senescence and induced cellular DNA damage. SPRY1 was upregulated and TET3 was downregulated upon UVA irradiation. Genome-wide 5-mC content increased upon TET3 silencing and UVA irradiation, indicating a surge in overall methylation. CONCLUSIONS: SPRY1 and TET3 are natural skin aging-related genes that counteract to regulate replicative aging and UVA-induced photoaging in HaCaT cells. The cell photoaging model may limit experimental bias caused by different exposure times of skin model samples.

Screening of Adapalene Microsponges Fabrication Parameters with Insight on the In vitro Biological Effectiveness.

Purpose: The objective of the present study was to scrutinize the microsponges (MS) as a carrier system using Adapalene (ADA) as a model drug. Methods: Data modelling was implemented using Plackett-Burman design to identify the main variables affecting the formulation of ADA-MS. The adopted method of preparation for MS was quasi-emulsion solvent diffusion method. The nominated independent variables were volume of organic phase, sonication time, stirring speed, drug percent, polymer type, emulsifier concentration, and method of organic phase addition. As for the dependent variables, they included entrapment efficiency (E.E.%), production yield (P.Y.%), particle size (P.S.) and morphology. Furthermore, selected ADA loaded microsponges (ADA-MS) were in vitro assayed for their biological activities via cytotoxicity, UVA irradiation and cell viability, and antimicrobial activity. Results: The study indicated that the drug percent, polymer type and surfactant concentration have the key significant effect on E.E.% and P.Y.%, while, the drug percent, stirring speed and volume of organic phase have had a significant effect on P.S. and their morphology. Furthermore, ADA-MS had a momentous cytotoxic effect on A431 and M10 cell-lines with exceptional enrichment when the polymer Eudragit RS100 was used. Also, the ADA-MS increased the cell viability after UVA irradiation on HFB-4 cell-line by 14% to 43%, especially when using Ethyl Cellulose as a polymer. Lastly, the antimicrobial activity of ADA against Propionibacterium acnes was boosted when incorporated into MS. Conclusion: The Plackett-Burman design proved its impact in discerning preparation variables affecting the quality of ADA-MS formulation, with heightening of the in vitro biological activities of ADA. Thus, MS was presumed to be an auspicious carrier system for ADA.

Acacetin resists UVA photoaging by mediating the SIRT3/ROS/MAPKs pathway.

Ultraviolet A (UVA) radiation is a major contributor to the pathogenesis of skin photoaging, and the aim of this study was to investigate the effect of Acacetin on skin photoaging in UVA-irradiated mice and human dermal fibroblasts (HDF). Healthy dorsal depilated rats were irradiated with UVA 30 J/cm2 daily, every other day, for 1 month. Acacetin (40, 80 mg kg/day) was coated to the bare skin of the rats' backs 1 h before UVA irradiation. HDF were treated different concentrations of Acacetin (5, 10, 20 µg/ml) and then irradiated with UVA (20 J/cm2 ). Acacetin was found to be effective in ameliorating UVA-induced oxidative stress and cell death. Acacetin also prevented the UVA-induced decrease of SIRT3, reduced the activation of mitogen-activated protein kinases (MAPKs, p-38 and p-JNK) and blocked the down-regulated activation of oxidative stress in matrix metalloproteinases (MMPs). In addition, Acacetin increased the expressions of collagen-promoting proteins (TGF-ß and Smad3). Finally, the SIRT3 inhibitor 3-TYP blocked all protective effects of Acacetin, indicating that the protective effect of Acacetin against UVA photoaging is SIRT3-dependent. Acacetin effectively mitigated photoaging by targeting the promotion of SIRT3, inhibiting the UVA-induced increases in MMPs and pro-inflammatory factors, and promoting TGF-ß and Smad3.

Urolithin A protects human dermal fibroblasts from UVA-induced photoaging through NRF2 activation and mitophagy.

Photoaging, caused by exposure to sunlight and especially UVA, has been identified as one of the culprits for age-related skin deterioration. Here, we initially demonstrated that urolithin A (UroA), a metabolite derived from intestine microflora, possessed sufficient photoprotective capacity and attenuated UVA-induced senescent phenotypes in human fibroblasts, such as growth inhibition, senescence-associated ß-galactosidase activity, breakdown of extracellular matrix, synthesis of senescence-associated secretory phenotypes and cell cycle arrest. Furthermore, UroA lessened the accumulation of intracellular reactive oxygen species, which promoted the phosphorylation and afterwards nuclear translocation of NRF2, subsequently driving the activation of downstream antioxidative enzymes. In parallel, we proved that UroA restored mitochondrial function by induction of mitophagy, which was regulated by the SIRT3-FOXO3-PINK1-PARKIN network. Taken together, our results showed that UroA protected dermal fibroblast from UVA damage through NRF2/ARE activation and mitophagy process, thus supporting UroA as a potential therapeutic agent for photoaging.

In vivo method to evaluate antioxidative activity using UVA-induced carbonylated protein on human skin.

BACKGROUND: Skin is continuously exposed to oxidative stress caused by reactive oxygen species (ROS) produced by the ultraviolet (UV) light, and it is important to evaluate the antioxidant activity. Carbonylated proteins (CPs) are candidate markers of oxidative modification as a result from the ROS. We aimed to develop the CP-based method to assess the efficacy of antioxidants in human skin. METHODS: Ten healthy females were enrolled in the study to determine the UVA dosage for CP production, and another 10 females were included to evaluate the antioxidative activity. The stratum corneum was collected from test skin using D-Squame tape, and CPs from the SC were stained by fluorescence labeling and observed using a fluorescence microscope. RESULTS: CP level significantly increased with UVA irradiation from 15J/cm2 to 50J/cm2 compared to the control (non-UVA) area. CP production significantly increased by 34.38% and 35.22% in UVA irradiation and squalene (vehicle) areas. 5% α-tocopherol and ß-carotene significantly increased the CP production by 20.77% and 19.34% after 2 hours of 30J of UVA irradiation compared to control area. Inhibition rate of CPs in 5% α-tocopherol and 5% ß-carotene showed 41.45% and 45.37% after 2 hours of UVA irradiation. CONCLUSION: This study developed the simple, visual, and direct in vivo method to evaluate the antioxidative activity for products in human skin by measuring the CP level as an oxidative modification caused by UVA-induced ROS generation.

Synergistic interaction of tap water-based neutral electrolyzed water combined with UVA irradiation to enhance microbial inactivation on stainless steel.

As an emerging electrolyzed water (EW) technology, tap water-based neutral electrolyzed water (TNEW) is an attractive alternative to other types of conventional EW for sterilization of food contact surfaces. In this study, we sought to identify strategies for improving TNEW inactivation efficiencies of major foodborne pathogenic bacteria. We investigated the synergistic antimicrobial effect of TNEW and ultraviolet-A light (UVA) combination treatment against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on stainless steel. The data confirmed that simultaneous TNEW and UVA treatment for 60 min reduced E. coli O157:H7, S. Typhimurium, and L. monocytogenes population by 2.15, 1.55, and 2.65 log CFU/cm2, respectively. The synergistic cell count reductions in E. coli O157:H7, S. Typhimurium, and L. monocytogenes in the combination treatment group were 1.17, 0.59, and 1.62 log units, respectively. Additionally, the mechanisms of the synergistic bactericidal effects of TNEW and UVA were identified through several approaches. Mechanistic investigations suggested that the synergistic effect was associated with intracellular reactive oxygen species generation, bacterial cell membrane damage, and inactivation of dehydrogenase. These findings demonstrate that treatment with TNEW and UVA light can enhance the microbiological safety of food contact surfaces during food processing.

Microplastics aged in various environmental media exhibited strong sorption to heavy metals in seawater.

To date, the degradation of microplastics (MPs; <5 mm) in different environments, particularly their adsorption characteristics for coexisted metal pollutants remains to be elucidated. Thus, this study investigated the effects of aging MPs, including polyamide (mPA), polyethylene terephthalate (mPET), polystyrene (mPS), and polyvinyl chloride (mPVC) for 3 months under UVA irradiation in four environmental media (air, seawater, sand, and soil) and adsorption of heavy metals (Cu, Cd) onto seawater-aged mPS and mPVC. The results showed that surface morphological changes, including cracks, oxidized particles, and wrinkles, appeared on aged MPs. The heavy metal adsorption capacity decreased in the order aged mPVC > aged mPS > unaged mPS > unaged mPVC, and the Cu2+ and Cd2+ ions competed for active adsorption sites on the MPs surfaces. Overall, the aging environment affected the physical and chemical properties of MPs and the aging of MPs enhanced their adsorption of coexisting metals tested.

Switching from healthy to unhealthy oxidative stress - does the radical type can be used as an indicator?

Ultraviolet (UV) radiation leads to the formation of free radicals, which may cause immunological modulations, skin aging or skin cancer. Sunlight exposure in the UVA region according to CIE 85 promotes almost 46% of radical formation in skin. A critical radical concentration characterized by the inversion of the domination of primary ROS (reactive oxygen species) to an excess of secondary LOS (lipid oxygen species) is proven for the spectral regions UV and or VIS light and is intended to be a marker for an imbalance in the redox system, which can no longer compensate harmful effects. To investigate whether this transition point is also universally valid for one spectral region, the radical formation during and after targeted UVA in situ-irradiation at 365 ± 5 nm and three different irradiances (31, 94 and 244 mW/cm2) was investigated in ex vivo porcine skin using x-band electron paramagnetic resonance (EPR) spectroscopy. The quantification was performed with the spin probe 3-(carboxy)-2,2,5,5-tetramethylpyrrolidin-1-oxyl (PCA), the spin trap 5,5-Dimethyl-1-Pyrroline-N-Oxide (DMPO) was used to characterize the radical species. Furthermore, the viability of the skin cells after irradiation was controlled by an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, skin integrity was examined by histological analysis. A significant dose dependence in the radical formation is given at higher irradiance. The transition point was detected in the range of 0.5 MED after irradiation with the highest irradiance. From this point on the proportion of LOS increases with increasing dose and the proportion of ROS decreases. After switching off the UVA irradiation no further quantitative changes were detected, but rapid changes in the radical pattern were observed demonstrating the importance of in situ irradiation during the use of spin traps. Heat-pre-stressed skin showed more LOS than ROS already at the beginning of the irradiation, leading to the assumption that the transition point to the distress-level has already been reached. In summary, a postulated transition point could be verified for the UVA spectral region using only one spin trap combined with in-situ irradiation. A certain degree of stress is necessary to detect an inversion of the ratio of ROS to LOS. This reversal indicates an imbalance in the redox status. However, at low intensities no changes at all in radical pattern appeared over time (dose), probably it can be compensated by adaptation processes of the skin.

The dual effects of riboflavin and kelp polyphenol extracts on the gel properties of myofibrillar protein from Scomberomorus Niphonius under UVA irradiation.

In the present study, effects of riboflavin (RF) and kelp polyphenol extracts (KPE) on mackerel (Scomberomorus Niphonius) myofibrillar protein (MP) gel were studied with or without ultraviolet A (UVA) irradiation treatment. The gel strength was increased with the addition of RF and KPE under UVA irradiation. Analysis of the proteins in the gel indicated that the carbonyl content increased, while the contents of total sulfhydryl and amino groups decreased. The proteins appeared to have no α-helix structures, and the endogenous tryptophan content appeared to decrease. The results of SDS-PAGE indicated that the RF and KPE treated samples under UVA irradiation showed massive MP cross-linking by covalent bonds. Electron spin resonance (ESR) results indicated that UVA irradiation generated free radicals in RF and KPE, which ultimately led to an improvement in MP gel properties. It also indicated that KPE could prevent the occurrence of peroxidation to improve the gel properties.

Repeat UVA exposure of human skin fibroblasts induces both a transitionary and recovery DNA methylation response.

Aim: UVA radiation drives skin photoaging in the dermis, plausibly via persistent changes to DNA methylation in dermal fibroblasts. Methods: Genome-wide DNA methylation changes after five repeated daily UVA doses were determined at 48 h (transitionary) and 1 week (recovery) post final irradiation. Results: Differential methylation was found at the transitionary time point in active chromatin states near genes that are highly expressed in fibroblasts and are involved in cellular defensive mechanisms; the majority of these methylation differences were restored to control levels after 7 day recovery. At the recovery time point, new differential methylation occurred at repressed regions near developmental genes, normally weakly expressed in fibroblasts. Conclusion: UVA irradiation induces transitionary and recovery-associated DNA methylation responses in fibroblasts with contrasting functional characteristics.

Microplastics release precursors of chlorinated and brominated disinfection byproducts in water.

Microplastics (MPs) are prevalent global pollutants that are being detected in aquatic ecosystems and drinking water sources around the world. In addition to plastic polymers, MPs contain various chemical substances (known as "additives") that can leach and risk water quality. In this paper, we investigated for the first time the potential release of disinfection byproducts (DBPs) precursors when MPs are exposed to hydrolysis and/or degradation by simulated sunlight. Seventeen MPs with seven different polymer types were collected either as commercial products (e.g. drinking water bottles, shopping bags, recycled plastics, etc.) or pure/virgin polymers. Results showed high release of dissolved organic carbon (DOC) from five MP samples and a significant increase in bromide concentrations from four MPs. DBPs formation potential (DBPFP) experiments with MPs' leachates showed higher concentrations of chlorinated trihalomethanes (THMs), haloacetonitriles (HANs), and total organic halogens (TOX) in three samples, while a significant shift to brominated DBPs was observed in samples containing bromide. Extending the leaching experiments to four consecutive cycles showed that the leaching of DOC and DBPs' precursor significantly decreased after the second leaching cycle. Further analysis revealed that the reactivity of the leached DOC - indicated by THMFP yields - was comparable to those of several raw waters that supply drinking water treatment plants. The leached THMs and TOX from MPs that were exposed to UVA irradiation were in general higher than MPs that were run under dark conditions.

Improvement of myofibrillar protein gel strength of Scomberomorus niphonius by riboflavin under UVA irradiation.

In this study, effects of different concentrations of riboflavin (0, 0.02, and 0.1 µmol/g protein) on myofibrillar protein (MP, Scomberomorus niphonius) gel were characterized. The gel structure and properties were studied with or without Ultraviolet A (UVA) irradiation. Electron spin resonance results showed that riboflavin produced ·OH under UVA irradiation, which subsequently oxidized the MP. Compared with the control group, the addition of riboflavin with UVA irradiation increased the strength of the MP gel. The rheological results showed that under UVA irradiation, addition of riboflavin facilitated the sol-gel transition between 45 and 52°C, indicating that oxidation led to significant structural changes which in turn resulted in a more compact and uniform gel network. The presence of riboflavin led to increased carbonyl content and decreased sulfhydryl and free amino groups, which decreased the protein solubility and promoted alpha-helical conformational loss in the secondary structure of the MP. These results all indicated that the MP has been oxidized. Electrophoresis revealed that myosin heavy chains were aggregated in the UVA-treated riboflavin-added MP gel, indicating that protein cross-linking has been induced. All the results indicated that the ·OH produced by riboflavin under UVA irradiation oxidized the MP, and improved protein crosslinking and gel properties.

Improvement of gel properties of mackerel mince by phlorotannin extracts from sporophyll of Undaria pinnatifidai and UVA induced cross-linking.

The effects of phlorotannin extracts (PTE) (from sporophyll of Undaria pinnatifida) added at different concentration (0, 1.6, 8, and 40 mg/g protein) with and without ultraviolet A (UVA) irradiation treatment on gel properties of mackerel (Scomberomorus niphonius) mince (MM) were investigated. The results indicated that both the breaking force and water-holding capacity (WHC) of the MM gel increased with addition of PTE, and the highest breaking force and WHC were observed with 40 mg/g PTE under UVA irradiation. Low-field nuclear magnetic resonance revealed that free water significantly decreased in this PTE-MM gel as well. UVA irradiation treatment led to reduction of total sulfhydryls and free amines in the PTE-MM gel, indicating more cross-linking between proteins. Electrophoresis results indicated that myosin heavy chains were aggregated in the UVA-treated PTE-MM gel. The microstructure of the UVA-treated PTE-MM gel showed that protein formed more evenly distributed cross-linked structures and was more compact than the untreated control gel. As a conclusion, PTE addition with UVA irradiation is shown to improve gelling properties of mackerel mince.

Thermal and irradiation resistance of folic acid encapsulated in zein ultrafine fibers or nanocapsules produced by electrospinning and electrospraying.

The objectives of this study were to characterize zein fibers and capsules prepared by electrospinning and electrospraying techniques, respectively, and then use them to encapsulate folic acid. Folic acid containing fibers and capsules (0.5, 1.0, and 1.5%, w/v) were submitted to thermal treatment (100, 140, and 180 °C) and ultraviolet A light (UVA) irradiation to evaluate the resistance of folic acid. Zein fibers and capsules containing folic acid showed high encapsulation efficiency (>80%). Unencapsulated folic acid showed a reduction in folic acid content from 17.17 µg/mL to 5.44 µg/mL (approximately 70%) when exposed to 180 °C. Photodegradation of unencapsulated folic acid lowered its concentration from 17.17 µg/mL to 12.58 µg/mL (~26% of reduction), when exposed for 1 h to UVA irradiation. However, folic acid concentration when encapsulated in fibers (1.5%) was maintained or only slightly reduced from 9.73 µg/mg to 8.88 µg/mg after thermal treatment at 180 °C. The capsules containing 1.5% of folic acid also presented a slight reduction in folic acid concentration from 8.84 µg/mg to 7.88 µg/mg when exposed to 24 h of UVA irradiation. Zein fibers and capsules containing folic acid present promising characteristics for application in foods that require thermal processing or exposure to irradiation.

UVA irradiation strengthened an interaction between UBF1/2 proteins and H4K20 di-/tri-methylation.

Repair of ribosomal DNA (rDNA) is a very important nuclear process due to the most active transcription of ribosomal genes. Proper repair of rDNA is required for physiological biogenesis of ribosomes. Here, we analyzed the epigenetics of the DNA damage response in a nucleolar compartment, thus in the ribosomal genes studied in nonirradiated and UVA-irradiated mouse embryonic fibroblasts (MEFs). We found that the promoter of ribosomal genes is not abundant on H4K20me2, but it is densely occupied by H4K20me3. Ribosomal genes, regulated via UBF1/2 proteins, were characterized by an interaction between UBF1/2 and H4K20me2/me3. This interaction was strengthened by UVA irradiation that additionally causes a focal accumulation of H4K20me3 in the nucleolus. No interaction has been found between UBF1/2 and H3K9me3. Interestingly, UVA irradiation decreases the levels of H3K9me3 and H4K20me3 at 28S rDNA. Altogether, the UVA light affects the epigenetic status of ribosomal genes at 28S rDNA and strengthens an interaction between UBF1/2 proteins and H4K20me2/me3.

Use of laterite as a sustainable catalyst for removal of fluoroquinolone antibiotics from contaminated water.

Although there is a growing interest in Fenton oxidation processes based on natural catalysts, the use of laterite soil to promote sequential adsorption/oxidation treatments of fluoroquinolone antibiotics has been scarcely investigated. In this work, the ability of an african laterite containing goethite and hematite to remove flumequine (FLU), used as a representative compound of fluoroquinolone antibiotics, was evaluated under dark and UVA irradiation. Batch experiments and liquid chromatography analyses showed that the presence of laterite can enhance FLU removal from heavily contaminated water through both sorption and oxidation reactions (up to 94% removal of 77 µmol L-1 of FLU and 72% of mineralization). The heterogeneous reaction rate is dominated by the rate of intrinsic surface chemical reactions including sorption and oxidation of FLU, and light-induced reduction of FeIII sites to produce FeII. Based on the probe and scavenging experiments, OH radicals were mainly involved in the heterogeneous oxidation reaction. The photo-assisted Fenton process showed a high efficiency of FLU removal even in the presence of a second fluoroquinolone antibiotic, norfloxacin (NOR), which can be co-found with FLU in affected environments. Determinations of kinetic rate constants and total organic carbon (TOC) for five sequential adsorption/oxidation cycles showed that laterite exhibited no deactivation of surface sites and an excellent catalytic stability. This cost-effective and environmentally friendly remediation technology may appear as a promising way for the removal of fluoroquinolone antibiotics from multi-contaminated waters.

Zerumbone protects human skin keratinocytes against UVA-irradiated damages through Nrf2 induction.

Ultraviolet A (UVA) irradiation is toxic to skin as it penetrates deep into the dermis and damages cellular components through excessive reactive oxygen species (ROS) production, which accelerates photoaging and skin cancer. We evaluated the dermato-protective efficacies of zerumbone (natural sesquiterpene of Zingiber zerumbet) in UVA-irradiated human skin keratinocyte (HaCaT) cells and mouse epidermis. Zerumbone pretreatment (2-10 µM) substantially suppressed UVA (15 J/cm2)-induced HaCaT cell death and lactate dehydrogenase release in a dose-dependent manner. UVA-induced excessive ROS production, DNA single-strand breaks, apoptotic DNA fragmentation and a dysregulated Bax/Bcl-2 ratio were remarkably reversed by zerumbone in keratinocytes. Zerumbone-mediated cytoprotective properties were associated with increased nuclear translocation of nuclear factor-E2-related factor-2 (Nrf2) and elevated antioxidant response element (ARE) luciferase activity. Activation of Nrf2/ARE signaling was accompanied by induction of heme oxygenase-1 (HO-1) and γ-glutamyl cysteine ligase (γ-GCLC) genes in zerumbone-treated keratinocytes. Zerumbone-induced Nrf2 transcriptional activation was mediated by the p38 MAPK, PI3K/AKT and PKC signaling cascades. Notably, silencing of Nrf2 (siRNA transfection) significantly diminished zerumbone-mediated cytoprotective effects, as evidenced by impaired antioxidant genes, uncontrolled ROS/apoptotic DNA fragmentation and keratinocytes death, following UVA irradiation. In vivo evidence demonstrated that zerumbone treatment to nude mice (55 and 110 µg/day) significantly ameliorated UVA (15 J/cm2/every 2-day/14-day) cytotoxicity via increased nuclear localization of Nrf2 and Nrf2-dependent antioxidant genes (HO-1 and γ-GCLC) in UVA-treated skin tissues. Our findings emphasized the significance of Nrf2/ARE-signaling in zerumbone-mediated induction of antioxidant genes against UVA-toxicity. The molecular evidence suggests zerumbone can be a natural medicine to treat/prevent UVA-induced skin damage/photoaging.