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51.
In recent years there has been an increase in use of botanicals with antioxidant properties as skin photoprotective agents. Pomegranate (Punica granatum L.) fruit possesses strong antioxidant and antiinflammatory properties. Recently, we have shown that pomegranate-derived products rich in anthocyanidins and ellagitannins inhibit UVB-mediated activation of nuclear factor kappa B and modulate UVA-mediated cell proliferation pathways in normal human epidermal keratinocytes. In this study, we evaluated the effect of polyphenol-rich pomegranate fruit extract (POMx) on UVB-induced oxidative stress and photoaging in human immortalized HaCaT keratinocytes. Our data show that pretreatment of HaCaT cells with POMx (10-40 microg mL(-1)) inhibited UVB (15-30 mJ cm(-2))-mediated (1) decrease in cell viability, (2) decrease in intracellular glutathione content and (3) increase in lipid peroxidation. Employing immunoblot analysis we found that pretreatment of HaCaT cells with POMx inhibited UVB-induced (1) upregulation of MMP-1, -2, -7 and -9, (2) decrease in TIMP-1, (3) phosphorylation of MAPKs and (iv) phosphorylation of c-jun, whereas no effect was observed on UVB-induced c-fos protein levels. These results suggest that POMx protects HaCaT cells against UVB-induced oxidative stress and markers of photoaging and could be a useful supplement in skin care products. 相似文献
52.
The molecular dipole moment changes upon 1nπ* and 3nπ* excitation of p-methylbenzaldehyde and p-chlorobenzaldehyde isolated in p-dimethoxybenzene host crystals have been determined from measurements of the Stark splittings in phosphorescence excitation and phosphorescence spectra. Within the experimental uncertainty, the changes are identical for the corresponding triplet and singlet states. This result contrasts with similar determinations for formaldehyde, benzophenone, and 4,4′-dichlorobenzophenone and with predictions based on simple molecular orbital and electron correlation arguments. The result is considered to be a consequence of a relatively large mixing of 3nμ* and 3μμ* states. 相似文献
53.
Jaffer SS Ghosh P Purkayastha P 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(5):1587-1591
trans-2-[4-(Dimethylamino)styryl]benzothiazole (DMASBT) is known to have dual emitting states where the locally excited (LE) state is responsible for fluorescence in less polar environment and in polar milieu fluorescence is from the twisted intramolecular charge transfer (TICT) state. This compound also undergoes minor groove binding to herring sperm DNA (hsDNA) evidenced by the absorption spectra before and after the binding process and an effect on DMASBT fluorescence by an anionic quencher. The binding occurs efficiently in a 1:1 manner, i.e. one guest molecule binds to one site on the hsDNA. Instead of following the DNA twist, the aromatic part seems to project outward. Thus, the bound molecule can be successfully extracted out from the DNA in a controlled way by the hydrophobic cavity of α-cyclodextrin (α-CD). The extraction starts even with a low concentration of α-CD and increases as the concentration is increased. Absorption, steady-state and time resolved fluorescence spectroscopic methods have been employed to explore the mechanistic pathway of binding of DMASBT to hsDNA. The mechanistic approach toward controlled extraction of the guest molecules from hsDNA by α-CD is reported and is expected to serve a significant purpose in treatment of drug overdose. 相似文献
54.
Mujtaba SF Dwivedi A Mudiam MK Ali D Yadav N Ray RS 《Photochemistry and photobiology》2011,87(5):1067-1076
The aim of this study was to analyze the photostability and phototoxicity mechanism of anthracene (ANT) in a human skin epidermal cell line (HaCaT) at ambient environmental intensities of sunlight/UV‐R (UV‐A and UV‐B). Photomodification of ANT under sunlight/UV‐R exposure produced two photoproducts, anthrone and 9,10 anthracenedione. Generation of 1O2, O2?? and ?OH was measured under UV‐R/sunlight exposure. Involvement of reactive oxygen species (ROS) was further substantiated by their quenching with free radical quenchers. Photodegradation of 2‐deoxyguanosine and linoleic acid peroxidation showed that ROS were mainly responsible for ANT phototoxicity. ANT generates significant amount of intracellular ROS in cell line. Maximum cell viability (85%) was reduced under sunlight exposure (30 min). Results of MTT assay accord NRU assay. ANT (0.01 μg mL?1) induced cell‐cycle arrest at G1 phase. RT‐PCR demonstrated constitutive inducible mRNA expression of CYP 1A1 and 1B1 genes. Photosensitive ANT upregulates CYP 1A1 (2.2‐folds) and 1B1 (4.1‐folds) genes. Thus, the study suggests that ROS and DNA damage were mainly responsible for ANT phototoxicity. ANT exposure may be deleterious to human health at ambient environmental intensities reaching the earth’s surface through sunlight. 相似文献
55.
The effect of the interior structure of carbon nanomaterials on their electrochemical properties is not well understood. We report here the electron transfer rate (ETR) of ferrocene (Fc) molecules covalently attached to the exposed end of carbon nanofibers (CNFs) in an embedded nanoelectrode array. The ETR in normal DC voltammetry was found to be limited by the conical graphitic stacking structure interior of CNFs. AC voltammetry, however, can cope with this intrinsic materials property and provide over 100 times higher ETR, likely by a new capacitive pathway. This provides a new method for high‐performance electroanalysis using CNF nanoelectrodes. 相似文献
56.
Syed?Qaiser?ShahEmail author Muhammad?Rafiullah?Khan 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):307-312
In the current investigation complexation of the gemifloxacin (GIN) with technetium-99 m (99mTc) and its biological evaluation in artificially Streptococcus pneumoniae (S. pneumoniae) infected rats was assessed as potential S. pneumoniae infection radiotracer. Radiochemically the 99mTc-GIN complex was further analyzed in terms of stability in saline, in vitro stability in serum at 37 °C, in vitro binding with S. pneumoniae and biodistribution in artificially S. pneumoniae (living and heat killed) infected rats. The complex was found 97.25 ± 0.25% radiochemically stable in saline at 30 min after reconstitution. The stability of the 99mTc-GIN complex was decreased to 90.50 ± 0.20% within 240 min after reconstitution. In serum the 99mTc-GIN complex showed stable profile with the appearance of 18.85% free tracer within 16 h of incubation. The 99mTc-GIN complex showed saturated in vitro binding with S. pneumoniae after different intervals. Almost five fold uptake was observed in living S. pneumoniae infected muscle of the rats as compared to the inflamed and normal muscle. No significant difference in the uptake of heat killed S. pneumoniae infected, inflamed and normal muscles of the rats. The high RCP yield in saline, in vitro permanence in serum, in vitro binding with living S. pneumoniae and biodistribution in artificially S. pneumoniae infected rats we recommend the 99mTc-GIN as potential S. pneumoniae infection radiotracer. 相似文献
57.
Choudhary MI Siddiqui ZA Musharraf SG Nawaz SA Atta-Ur-Rahman 《Natural product research》2005,19(4):311-317
The microbial transformation of prednisone (17alpha,21-dihydroxy-pregna-1,4-diene-3,11,20-trione) (1) by Cunninghamella elegans afforded two metabolites, 17alpha,21-dihydroxy-5alpha-pregn-1-ene-3,11,20-trione (2) and 17alpha,20S,21-trihydroxy-5alpha-pregn-1-ene-3,11-dione (3), while the fermentation of 1 with Fusarium lini, Rhizopus stolonifer and Curvularia lunata afforded a metabolite 1,4-pregnadiene-17alpha,20S,21-triol-3,11-dione (4). Compound 3 was found to be a new metabolite. Their structures were elucidated on the basis of spectroscopic techniques. Compound 3 showed inhibitory activity against lipoxygenase enzyme. 相似文献
58.
A detailed reaction mechanism for n-heptane oxidation has been compiled and subsequently simplified. The model is based on a kinetic model for C1-C4 fuel oxidation of Hoyermann et al. [Phys. Chem. Chem. Phys., 2004, 6, 3824] and a detailed mechanism for n-heptane oxidation developed by Curran et al. [Combust. Flame, 1998, 114, 149]. The generated mechanism is kept compact by limiting the application of the low temperature oxidation pathways to the fuel molecule. The first reaction steps and the complex low temperature paths in the oxidation process have been simplified and reorganized by linear chemical lumping. The reported procedure allows a decrease in number of species and reactions with only a minor loss of model accuracy. The simplified model is of very compact size and gives an advantageous starting point for further model reduction. By this chemically lumped general mechanism without further adjustments the large set of experimental data for the high and low temperature oxidation (ignition delay times, species concentration profiles, heat release and engine pressure profiles, flame speeds and flame structure data) for conditions ranging from very low to high temperatures (550-2300 K), very lean to extremely fuel rich (0.22 < phi < 3) mixtures and pressures between 1 and 42 bar is consistently described providing a basis for reliable predictions for future applications, (i) building reaction mechanisms for similar but chemically more complex fuels (e.g. iso-octane, n-decane,...) and (ii) calculating complex flow fields ("fluid dynamics") after further simplification with advanced reduction tools. 相似文献
59.
Syed Rasheed Devineni Subba Rao Chennamsettty Subramanyam Shaik Thaslim Basha 《合成通讯》2014,44(20):2988-2998
An expeditious, simple, and green method was developed for the synthesis of privileged aryl/heterocyclicphosphonates, 8(a–c) to 13(a–c) through Michaelis–Arbuzov reaction of aryl/heterocyclic halides (Br), 1–6, and trialkylphosphites, 7(a–c), in room-temperature ionic liquid [bbim]Br using heterogeneous Lewis catalyst, nano-silica-supported boron trifluoride (BF3-SiO2). The advantages of this protocol are simplicity, good yield of the products, less reaction time (20–38 min), mild reaction conditions, easy workup, and reusability of the catalyst and ionic liquid. It is demonstrated that nano-BF3-SiO2 is a recoverable and easy accessible catalyst for the formation of C(sp2)-P bond in an ionic liquid. 相似文献
60.
Syed Mustafa Muhammad Waseem Abdul Naeem Khizar Hussain Shah Tauqeer Ahmad Muhammad Safdar 《中国化学》2010,28(11):2204-2208
The current study focuses on the synthesis and sorption properties of two mixed oxides of iron and silicon prepared by physical mixing (M1) and sequential precipitation methods (M2). Both the mixed oxides were synthesized from equimolar ratios of Fe(OH)3 and SiO2 and characterized for surface area, EDX, XRD and PZC. The surface area, micropore volume and average pore width of the oxide M1 were higher as compared to the oxide M2. However, potentiometric titrations revealed that mixed oxide synthesized by this method had a very high capacity towards Cd2+ ions as compared to the mixed oxide M1. Sorption of Cd2+ ions at pH 5 on mixed oxide, M2 was found to increase with temperature in the range 288 to 318 K. Langmuir equation was found applicable to the sorption data with R2>0.99. Entropy (ΔS?), enthalpy (ΔH?) and free energy changes (ΔG?) were calculated which revealed the process to be endothermic and spontaneous in nature. 相似文献