Selective growth of ZnO nanorods on microgap electrodes and their applications in UV sensors

Selective area growth of ZnO nanorods is accomplished on microgap electrodes (spacing of 6 μm) by using a facile wet chemical etching process. The growth of ZnO nanorods on a selected area of microgap electrode is carried out by hydrothermal synthesis forming nanorod bridge between two electrodes. This is an attractive, genuine, direct, and highly reproducible technique to grow nanowire/nanorod onto the electrodes on selected area. The ZnO nanorods were grown at 90°C on the pre-patterned electrode system without destroying the electrode surface structure interface and geometry. The ZnO nanorods were tested for their application in ultraviolet (UV) sensors. The photocurrent-to-dark (Iph/Id) ratio was 3.11. At an applied voltage of 5 V, the response and recovery time was 72 and 110 s, respectively, and the response reached 2 A/W. The deposited ZnO nanorods exhibited a UV photoresponse that is promising for future cost-effective and low-power electronic UV-sensing applications.     

UVB-Stimulated TNFα Release from Human Melanocyte and Melanoma Cells Is Mediated by p38 MAPK

Ultraviolet (UV) radiation activates cell signaling pathways in melanocytes. As a result of altered signaling pathways and UV-induced cellular damage, melanocytes can undergo oncogenesis and develop into melanomas. In this study, we investigated the effect of UV-radiation on p38 MAPK (mitogen-activated protein kinase), JNK and NFκB pathways to determine which plays a major role in stimulating TNFα secretion in human HEM (melanocytes) and MM96L (melanoma) cells. MM96L cells exhibited 3.5-fold higher p38 activity than HEM cells at 5 min following UVA + B radiation and 1.6-fold higher JNK activity at 15–30 min following UVB+A radiation, while NFκB was minimally activated in both cells. Irradiated HEM cells had the greatest fold of TNFα secretion (UVB: 109-fold, UVA + B: 103-fold & UVB+A: 130-fold) when co-exposed to IL1α. The p38 inhibitor, SB202190, inhibited TNFα release by 93% from UVB-irradiated HEM cells. In the UVB-irradiated MM96L cells, both SB202190 and sulfasalazine (NFκB inhibitor) inhibited TNFα release by 52%. Although, anisomycin was a p38 MAPK activator, it inhibited TNFα release in UV-irradiated cells. This suggests that UV-mediated TNFα release may occur via different p38 pathway intermediates compared to those stimulated by anisomycin. As such, further studies into the functional role p38 MAPK plays in regulating TNFα release in UV-irradiated melanocyte-derived cells are warranted.     

Changes in Phospholipid/Ceramide Profiles and Eicosanoid Levels in the Plasma of Rats Irradiated with UV Rays and Treated Topically with Cannabidiol

Chronic UV radiation causes oxidative stress and inflammation of skin and blood cells. Therefore, in this study, we assessed the effects of cannabidiol (CBD), a natural phytocannabinoid with antioxidant and anti-inflammatory properties, on the phospholipid (PL) and ceramide (CER) profiles in the plasma of nude rats irradiated with UVA/UVB and treated topically with CBD. The results obtained showed that UVA/UVB radiation increased the levels of phosphatidylcholines, lysophospholipids, and eicosanoids (PGE2, TxB2), while downregulation of sphingomyelins led to an increase in CER[NS] and CER[NDS]. Topical application of CBD to the skin of control rats significantly upregulated plasma ether-linked phosphatidylethanolamines (PEo) and ceramides. However, CBD administered to rats irradiated with UVA/UVB promoted further upregulation of CER and PEo and led to significant downregulation of lysophospholipids. This was accompanied by the anti-inflammatory effect of CBD, manifested by a reduction in the levels of proinflammatory PGE2 and TxB2 and a dramatic increase in the level of anti-inflammatory LPXA4. It can therefore be suggested that topical application of CBD to the skin of rats exposed to UVA/UVB radiation prevents changes in plasma phospholipid profile resulting in a reduction of inflammation by reducing the level of LPE and LPC species and increasing antioxidant capacity due to upregulation of PEo species.     

Urolithin and Reduced Urolithin Derivatives as Potent Inhibitors of Tyrosinase and Melanogenesis: Importance of the 4-Substituted Resorcinol Moiety

We previously reported (E)-β-phenyl-α,β-unsaturated carbonyl scaffold ((E)-PUSC) played an important role in showing high tyrosinase inhibitory activity and that derivatives with a 4-substituted resorcinol moiety as the β-phenyl group of the scaffold resulted in the greatest tyrosinase inhibitory activity. To examine whether the 4-substituted resorcinol moiety could impart tyrosinase inhibitory activity in the absence of the α,β-unsaturated carbonyl moiety of the (E)-PUSC scaffold, 10 urolithin derivatives were synthesized. To obtain more candidate samples, the lactone ring in synthesized urolithins was reduced to produce nine reduced urolithins. Compounds 1c (IC₅₀ = 18.09 ± 0.25 μM), 1h (IC₅₀ = 4.14 ± 0.10 μM), and 2a (IC₅₀ = 15.69 ± 0.40 μM) had greater mushroom tyrosinase-inhibitory activities than kojic acid (KA) (IC₅₀ = 48.62 ± 3.38 μM). The SAR results suggest that the 4-substituted resorcinol motif makes an important contribution to tyrosinase inhibition. To investigate whether these compounds bind to human tyrosinase, a human tyrosinase homology model was developed. Docking simulations with mushroom and human tyrosinases showed that 1c, 1h, and 2a bind to the active site of both tyrosinases with higher binding affinities than KA. Pharmacophore analyses showed that two hydroxyl groups of the 4-substituted resorcinol entity act as hydrogen bond donors in both mushroom and human tyrosinases. Kinetic analyses indicated that these compounds were all competitive inhibitors. Compound 2a inhibited cellular tyrosinase activity and melanogenesis in α-MSH plus IBMX-stimulated B16F10 melanoma cells more strongly than KA. These results suggest that 2a is a promising candidate for the treatment of skin pigment disorders, and show the 4-substituted resorcinol entity importantly contributes to tyrosinase inhibition.     

Annealing temperature and environment effects on ZnO nanocrystals embedded in SiO2: a photoluminescence and TEM study

We report on efficient ZnO nanocrystal (ZnO-NC) emission in the near-UV region. We show that luminescence from ZnO nanocrystals embedded in a SiO₂ matrix can vary significantly as a function of the annealing temperature from 450°C to 700°C. We manage to correlate the emission of the ZnO nanocrystals embedded in SiO₂ thin films with transmission electron microscopy images in order to optimize the fabrication process. Emission can be explained using two main contributions, near-band-edge emission (UV range) and defect-related emissions (visible). Both contributions over 500°C are found to be size dependent in intensity due to a decrease of the absorption cross section. For the smallest-size nanocrystals, UV emission can only be accounted for using a blueshifted UV contribution as compared to the ZnO band gap. In order to further optimize the emission properties, we have studied different annealing atmospheres under oxygen and under argon gas. We conclude that a softer annealing temperature at 450°C but with longer annealing time under oxygen is the most preferable scenario in order to improve near-UV emission of the ZnO nanocrystals embedded in an SiO₂ matrix.     

Synthesis and Evaluation of Novel Oxyalkylated Derivatives of 2′,4′-Dihydroxychalcone as Anti-Oomycete Agents against Bronopol Resistant Strains of Saprolegnia sp.

A series of novel oxyalkylchalcones substituted with alkyl groups were designed and synthesized, and the antioomycete activity of the series was evaluated in vitro against Saprolegnia strains. All tested O-alkylchalcones were synthesized by means of nucleophilic substitution from the natural compound 2′,4′-dihydroxychalcone (1) and the respective alkyl bromide. The natural chalcone (1) and 10 synthetic oxyalkylchalcones (2–11) were tested against Saprolegnia parasitica and Saprolegnia australis. Among synthetic analogs, 2-hydroxy,4-farnesyloxychalcone (11) showed the most potent activity against Saprolegnia sp., with MIC and MOC values of 125 µg/mL (similar to bronopol at 150 µg/mL) and 175 µg/mL, respectively; however, 2′,4′-dihydroxychalcone (1) was the strongest and most active molecule, with MIC and MOC values of 6.25 µg/mL and 12.5 µg/mL.     

Content and Color Stability of Anthocyanins Isolated from Schisandra chinensis Fruit

In this work, a multivariate study based on Box-Behnken Design was used to evaluate the influence of three major variables affecting the performance of the extraction process of Schisandra chinensis anthocyanins. The optimum parameters were 5.5 h extraction time; 1:19 solid-liquid ratio and 260 r/min stirring rate, respectively. The extraction yield of anthocyanins was 29.06 mg/g under the optimum conditions. Moreover, many factors on the impact of heating, ultrasound, microwave treatment and ultraviolet irradiation on content and color stability of anthocyanins from Schisandra chinensis fruit were investigated. The results show that thermal degradation reaction of anthocyanins complies with the first order reaction kinetics, and the correlation coefficient is greater than 0.9950 at 40–80 °C. Ultrasound and microwave treatment has little effect on the stability of anthocyanins, and the extraction time of ultrasound and microwave should be no more than 60 min and 5 min, respectively. The anthocyanins degradation effect of UVC ultraviolet radiation is greater than UVA and UVB; after 9 h ultraviolet radiation, the anthocyanins content degradation of UVC is 23.9 ± 0.7%, and the ΔE* was changed from 62.81 to 76.52 ± 2.3. Through LC-MS analysis, the major composition of Schisandra chinensis anthocyanins was cyanidin-3-O-xylosylrutinoside.     

防晒产品抗紫外线效能的研究

采用紫外分光光度法和体外ＳＰＦ测定法分别研究了ＵＶＢ和ＵＶＡ防晒剂紫外光谱特性;ＵＶＢ、ＵＶＡ防晒剂、成膜剂以及防晒时间对防晒产品ＳＰＦ的影响。结果表明：ＵＶＢ和ＵＶＡ复配可明显提高对紫外线的吸收能力;在含ＵＶＢ的防晒产品中加入ＵＶＡ防晒剂可显提高防晒产品ＳＰＦ值;防晒时间对部分防晒产品ＳＰＦ值有一定的影响;成膜剂能使防晒产品ＳＰＦ同线显上升。上述实验结果对进一步探讨防晒产品抗紫外线效能具有重     

Anti-Inflammatory Components from the Root of Solanum erianthum

Two new norsesquiterpenoids, solanerianones A and B (1–2), together with nine known compounds, including four sesquiterpenoids, (−)-solavetivone (3), (+)-anhydro-β-rotunol (4), solafuranone (5), lycifuranone A (6); one alkaloid, N-trans-feruloyltyramine (7); one fatty acid, palmitic acid (8); one phenylalkanoid, acetovanillone (9), and two steroids, β-sitosterol (10) and stigmasterol (11) were isolated from the n-hexane-soluble part of the roots of Solanum erianthum. Their structures were elucidated on the basis of physical and spectroscopic data analyses. The anti-inflammatory activity of these isolates was monitored by nitric oxide (NO) production in lipopolysaccharide (LPS)-activated murine macrophage RAW264.7 cells. The cytotoxicity towards human lung squamous carcinoma (CH27), human hepatocellular carcinoma (Hep 3B), human oral squamous carcinoma (HSC-3) and human melanoma (M21) cell lines was also screened by using an MTT assay. Of the compounds tested, 3 exhibited the strongest NO inhibition with the average maximum inhibition (E_max) at 100 μM and median inhibitory concentration (IC₅₀) values of 98.23% ± 0.08% and 65.54 ± 0.18 μM, respectively. None of compounds (1–9) was found to possess cytotoxic activity against human cancer cell lines at concentrations up to 30 μM.     

Synthesis and Biological Evaluation of Novel Dehydroabietic Acid Derivatives Conjugated with Acyl-Thiourea Peptide Moiety as Antitumor Agents

A series of dehydroabietic acid (DHAA) acyl-thiourea derivatives were designed and synthesized as potent antitumor agents. The in vitro pharmacological screening results revealed that the target compounds exhibited potent cytotoxicity against HeLa, SK-OV-3 and MGC-803 tumor cell lines, while they showed lower cytotoxicity against HL-7702 normal human river cells. Compound 9n (IC₅₀ = 6.58 ± 1.11 μM) exhibited the best antitumor activity against the HeLa cell line and even displayed more potent inhibitory activity than commercial antitumor drug 5-FU (IC₅₀ = 36.58 ± 1.55 μM). The mechanism of representative compound 9n was then studied by acridine orange/ethidium bromide staining, Hoechst 33,258 staining, JC-1 mitochondrial membrane potential staining, TUNEL assay and flow cytometry, which illustrated that this compound could induce apoptosis in HeLa cells. Cell cycle analysis indicated that compound 9n mainly arrested HeLa cells in the S phase stage. Further investigation demonstrated that compound 9n induced apoptosis of HeLa cells through a mitochondrial pathway.     

Dibenzofuran, 4-Chromanone,Acetophenone, and Dithiecine Derivatives: Cytotoxic Constituents from Eupatorium fortunei

Five new compounds, eupatodibenzofuran A (1), eupatodibenzofuran B (2), 6-acetyl-8-methoxy-2,2-dimethylchroman-4-one (3), eupatofortunone (4), and eupatodithiecine (5), have been isolated from the aerial part of Eupatorium fortunei, together with 11 known compounds (6‒16). Compounds 1 and 2 featured a new carbon skeleton with an unprecedented 1-(9-(4-methylphenyl)-6-methyldibe nzo[b,d]furan-2-yl)ethenone. Among the isolates, compound 1 exhibited potent inhibitory activity with IC₅₀ values of 5.95 ± 0.89 and 5.55 ± 0.23 μM, respectively, against A549 and MCF-7 cells. The colony-formation assay demonstrated that compound 1 (5 μM) obviously decreased A549 and MCF-7 cell proliferation, and Western blot test confirmed that compound 1 markedly induced apoptosis of A549 and MCF-7 cells through mitochondrial- and caspase-3-dependent pathways.     

Effect of Artocarpus communis Extract on UVB Irradiation-Induced Oxidative Stress and Inflammation in Hairless Mice

Administration of antioxidants and anti-inflammatory agents is an effective strategy for preventing ultraviolet (UV) irradiation-induced skin damage. Artocarpus communis possesses several pharmacological activities, such as antioxidant, anticancer and anti-inflammation. However, the photoprotective activity of methanol extract of A. communis heartwood (ACM) in ultraviolet irradiation-induced skin damage has not yet been investigated. The present study was performed using ultraviolet absorption, histopathological observation, antioxidant and anti-inflammation assays to elucidate the mechanism of the photoprotective activity of ACM. Our results indicated that ACM displayed a UVA and UVB absorption effect and then effectively decreased scaly skin, epidermis thickness and sunburn cells during ultraviolet irradiation in hairless mice. ACM not only decreased ultraviolet irradiation-mediated oxidative stress, including lowering the overproduction of reactive oxygen species and lipid peroxidation (p < 0.05), but also reduced the levels of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α) and interleukin 1β. Additionally, ACM can decrease the synthesis of cytosolic phospholipase A2, cyclooxygenase, inducible nitric oxide synthase and vascular cell adhesion molecular-1 via inhibiting TNF-α-independent pathways (p < 0.05) in UVB-mediated inflammation and formation of sunburn cells. Consequently, we concluded that ACM extract has a photoprotective effect against UVB-induced oxidative stress and inflammation due to its sunscreen property, and its topical formulations may be developed as therapeutic and/or cosmetic products in further studies.     

Novel Redox-Dependent Esterase Activity (EC 3.1.1.2) for DJ-1: Implications for Parkinson’s Disease

Mutations the in human DJ-1 (hDJ-1) gene are associated with early-onset autosomal recessive forms of Parkinson’s disease (PD). hDJ-1/parkinsonism associated deglycase (PARK7) is a cytoprotective multi-functional protein that contains a conserved cysteine-protease domain. Given that cysteine-proteases can act on both amide and ester substrates, we surmised that hDJ-1 possessed cysteine-mediated esterase activity. To test this hypothesis, hDJ-1 was overexpressed, purified and tested for activity towards 4-nitrophenyl acetate (pNPA) as µmol of pNPA hydrolyzed/min/mg·protein (U/mg protein). hDJ-1 showed maximum reaction velocity esterase activity (V_max = 235.10 ± 12.00 U/mg protein), with a sigmoidal fit (S_0.5 = 0.55 ± 0.040 mM) and apparent positive cooperativity (Hill coefficient of 2.05 ± 0.28). A PD-associated mutant of DJ-1 (M26I) lacked activity. Unlike its protease activity which is inactivated by reactive oxygen species (ROS), esterase activity of hDJ-1 is enhanced upon exposure to low concentrations of hydrogen peroxide (<10 µM) and plateaus at elevated concentrations (>100 µM) suggesting that its activity is resistant to oxidative stress. Esterase activity of DJ-1 requires oxidation of catalytic cysteines, as chemically protecting cysteines blocked its activity whereas an oxido-mimetic mutant of DJ-1 (C106D) exhibited robust esterase activity. Molecular docking studies suggest that C106 and L126 within its catalytic site interact with esterase substrates. Overall, our data show that hDJ-1 contains intrinsic redox-sensitive esterase activity that is abolished in a PD-associated mutant form of the hDJ-1 protein.     

Synthesis and Characterization of Some New Bis-Pyrazolyl-Thiazoles Incorporating the Thiophene Moiety as Potent Anti-Tumor Agents

A new series of 1,4-bis(1-(5-(aryldiazenyl)thiazol-2-yl)-5-(thiophen-2-yl)-4,5-dihydro-1H-pyrazol-3-yl)benzenes 3a–i were synthesized via reaction of 5,5′-(1,4-phenylene)bis(3-(thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide) (1) with hydrazonoyl halides 2a–i. In addition, reaction of 1 with ethyl chloroacetate afforded bis-thiazolone derivative 8 as the end product. Reaction of compound 8 with methyl glyoxalate gave bis-thiazolone derivative 10. The structures of the newly synthesized compounds were established on the basis of spectroscopic evidences and their alternative syntheses. All the synthesized compounds were evaluated for their anti-tumor activities against hepatocellular carcinoma (HepG2) cell lines, and the results revealed promising activities of compounds 3g, 5e, 3e, 10, 5f, 3i, and 3f with IC₅₀ equal 1.37 ± 0.15, 1.41 ± 0.17, 1.62 ± 0.20, 1.86 ± 0.20, 1.93 ± 0.08, 2.03 ± 0.25, and 2.09 ± 0.19 μM, respectively.     

Photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid on TiO2 films under UVA and UVB irradiation

Titanium dioxide (TiO₂) photocatalysis is a possible alternative/complementary technology for water purification. Attempts to increase the overall efficiency of the process include using higher energy UV to gain better quantum efficiency and electrochemically assisting the process by the application of an external electrical potential. In this work, nanocrystalline TiO₂ films, prepared on borosilicate glass and indium-doped tin oxide (ITO) borosilicate glass, were used to investigate the photocatalytic and electrochemically assisted photocatalytic oxidation of formic acid under UVA and UVB irradiation. The experiments were carried out in a stirred tank reactor with high mass transfer characteristics. The rate of formic acid oxidation under UVB irradiation was 30% greater as compared to UVA irradiation. A maximum Φ_app of 9% was obtained under UVA irradiation in 100% O₂ under open circuit or +1.0 V (SCE) applied potential. A maximum Φ_app of 20.3% was obtained under UVB irradiation with 100% O₂ using TiO₂ on borosilicate glass. Φ_app was 19% for +1.0 V, 100% O₂, using TiO₂ on ITO borosilicate glass under UVB irradiation. The increase in oxidation rates and Φ_app with UVB irradiation are due to the higher extinction coefficient of TiO₂ at shorter wavelengths and/or the promotion of conduction band electrons to higher more stable states, thus reducing the rate of recombination of charge carriers. The use of a UVB source as compared to a UVA source results in a significant increase in the rate of oxidation and increased apparent quantum yields, however, a cost analysis of the process would be required to determine the economic viability of employing UVB sources. Electrochemically assisted photocatalysis may prove beneficial in large-scale reactors where mass transfer limitations exist.     

Time-resolved photoluminescence studies of annealed 1.3-μm GaInNAsSb quantum wells

Time-resolved photoluminescence (PL) was applied to study the dynamics of carrier recombination in GaInNAsSb quantum wells (QWs) emitting near 1.3 μm and annealed at various temperatures. It was observed that the annealing temperature has a strong influence on the PL decay time, and hence, it influences the optical quality of GaInNAsSb QWs. At low temperatures, the PL decay time exhibits energy dependence (i.e., the decay times change for different energies of emitted photons), which can be explained by the presence of localized states. This energy dependence of PL decay times was fitted by a phenomenological formula, and the average value of E₀, which describes the energy distribution of localized states, was extracted from this fit and found to be smallest (E₀ = 6 meV) for the QW annealed at 700°C. In addition, the value of PL decay time at the peak energy was compared for all samples. The longest PL decay time (600 ps) was observed for the sample annealed at 700°C. It means that based on the PL dynamics, the optimal annealing temperature for this QW is approximately 700°C.