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UV Spectra (uv + spectrum)
Selected AbstractsUV Spectra and Excitation Delocalization in DNA: Influence of the Spectral WidthCHEMPHYSCHEM, Issue 7 2005Emanuela Emanuele Abstract The singlet excited states of the model DNA duplex (dA)10.(dT)10 are studied. Calculations are performed in the exciton theory framework. Molecular dynamics calculations provide the duplex geometry. The dipolar coupling is determined using atomic transition charges. The monomer transition energies are simulated by Gaussian functions resembling the absorption bands of nucleosides in aqueous solutions. Most of the excited states are found to be delocalized over at least two bases and result from the mixing of different monomer states. Their properties are only weakly affected by conformational changes of the double helix. On average, the highest oscillator strength is carried by the upper eigenstates. The duplex absorption spectra are shifted a few nanometers to higher energies with respect to the spectra of noninteracting monomers. The states with larger spatial extent are located close to the maximum of the absorption spectrum. [source] Toxicity reduction of metal pyrithiones by near ultraviolet irradiationENVIRONMENTAL TOXICOLOGY, Issue 4 2006Hideo Okamura Abstract Zinc pyrithione (ZnPT) or copper pyrithione (CuPT) have been effectively used as ship-antifouling agents, as an alternative to organotin compounds. Because of their instability in light and a lack of suitable analytical procedures, there is little data on their residue levels in environmental matrices. It is possible to investigate the fate of such compounds by toxicity alteration with certain treatments. The purpose of this study was to evaluate the degradation of pyrithiones through toxicity reduction by near ultraviolet (UV-A) irradiation. Metal pyrithiones dissolved in acetonitrile were irradiated with a UV-A lamp for 0, 0.5, 1, and 2 h, and were subjected to UV spectral measurement and toxicity evaluation using both sea urchin and freshwater rotifer bioassays. For the bioassays, photolyzed samples were dissolved in dimethyl sulfoxide after evaporation of the acetonitrile. The changes in UV spectra of photolyzed ZnPT or CuPT showed a time-dependent degradation, and the UV spectra at 2 h irradiation suggested substantial decomposition. Toxicities of ZnPT and CuPT were 12 and 5 ,g/L as 24 h LC50 to the survival of rotifers and 10,6 ng/L and 2.3 ng/L as 27 h EC50 to normal pluteus formation, respectively. By evaporation of the acetonitrile, the EC50 of ZnPT was 2.2 ng/L, which was the same as that of CuPT. The EC50s of ZnPT or CuPT for both species increased with longer irradiation times. Photolyzed ZnPT or CuPT demonstrated substantial degradation in the UV spectra, but possessed marked toxicity, which is probably due to toxic degradation products. One reason why photolyzed CuPT was toxic to rotifers was explained by the high toxicity of copper ions formed by UV-A irradiation. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 305,309, 2006. [source] Toxicology of a Microcystis ichthyoblabe waterbloom from Lake Oued Mellah (Morocco)ENVIRONMENTAL TOXICOLOGY, Issue 1 2002Brahim Sabour Abstract In the Lake Oued Mellah cyanobacteria waterblooms occur periodically in late spring and summer with Microcystis ichthyoblabe as the main bloom-forming species. In 1999, a heavy waterbloom of M. ichthyoblabe occurred during May June with a maximal biomass of 298 mg/l. During this period, several bloom samples were collected. The toxicity assessment was done by mouse and brine shrimp (Artemia) bioassays. Apart from the sample collected on 15/06/1999, all the other samples were toxic by mouse bioassay. The LD50 determined by intraperitoneal injection to mice during active cyanobacterial growth and decline phases were 518 and 1924 mgDW/kg respectively. Using Artemia bioassay, the 24hLC50 varied from 6.0 to 40.6 mg/ml and the 48hLC50 ranged from 2.8 to 18.2 mg/ml. The separation and identification of microcystin variants was performed by high performance liquid chromatography,photodiode array detection. Eleven toxins were separated and preliminarily identified as microcystin variants as they exhibit a typical UV spectra like the microcystin-LR standard. The quantification of total microcystins determined by enzyme-linked immunosorbent assay showed that the contents were varied between 0.1 and 0.76 ,g/g DW. © 2002 by Wiley Periodicals, Inc. Environ Toxicol 17: 24,31, 2002 [source] Variety of photoluminescence intensity of fluorescent whitening agents introduced into polyacrylonitrile nanofibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Shugang Wang Abstract The major objective in this study was the preparation of polyacrylonitrile (PAN) nanofibers composed of 1,4-bis(o -cyanostyryl)benzene (ER) and 1-(o -cyanostyryl)-4-(p -cyanostyryl)benzene (EB), two kinds of fluorescent whitening agents widely used in the textile industry. The scanning electron microscopy images revealed that the diameters of ER/PAN and EB/PAN fibers ranged from 78 to 154 nm. The IR spectra indicated that the peaks of the CN group blueshift and the generation of a shoulder peak were obviously due to the interaction between ER or EB and PAN. Furthermore, the UV spectra demonstrated that the distributive status of ER or EB tended toward the molecular state in PAN nanofibers. Finally, the most interesting finding in this study was that the photoluminescence intensity of EB/PAN nanofibers increased magnificently, whereas that of ER/PAN nanofibers decreased remarkably. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2382,2386, 2007 [source] HPLC-DAD in identification and quantification of selected coumarins in crude extracts from plant cultures of Ammi majus and Ruta graveolensJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2003Marian Kami Abstract This paper describes a method for the separation and determination of selected coumarins and furanocoumarins in the crude extracts from plant tissue cultures of Ammi majus hairy roots and Ruta graveolens cell suspensions, cultured in vitro, separately or together as co-cultures. The usefulness of the three main components of the eluent used in reversed-phase high performance liquid chromatographic analysis, namely: methanol (MeOH), acetonitrile (ACN), and tetrahydrofuran (THF), and different elution programs, was assessed. In the optimal analytical method a Lichrospher® RP-18e 5-,m column, a THF-MeOH elution gradient, and a UV/VIS DAD detector were used. Due to the presence of many different compounds in the investigated plant extracts, the use of a UV/VIS DAD detector was essential. Coumarins were identified by comparison of their UV spectra with those of the analytical standards, and characterization of peak purity. [source] HPLC flavonoid profiles as markers for the botanical origin of European unifloral honeysJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 5 2001Francisco A Tomás-Barberán Abstract The HPLC phenolic profiles of 52 selected unifloral honey samples produced in Europe were analysed to detect possible markers for the floral origin of the different honeys. Lime-tree (five markers), chestnut (five markers), rapeseed (one marker), eucalyptus (six markers) and heather (three markers) honeys had specific markers with characteristic UV spectra. In addition, the flavanone hesperetin was confirmed as a marker for citrus honey, as well as kaempferol for rosemary honey and quercetin for sunflower honey. Abscisic acid, which had been reported to be a possible marker for heather honey, was also detected in rapeseed, lime-tree and acacia honeys. Ellagic acid in heather honey and the hydroxycinnamates caffeic, p -coumaric and ferulic acids in chestnut, sunflower, lavender and acacia honeys were also detected. The characteristic propolis-derived flavonoids pinocembrin, pinobanksin and chrysin were present in most samples in variable amounts. © 2001 Society of Chemical Industry [source] An Improved Algorithm for Satellite-derived UV Radiation,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2003Sigrid Wuttke ABSTRACT The improved algorithm surface irradiance derived from a range of satellite-based sensors (SIDES) is presented in this article. It calculates various types of surface UV intensities, such as biologically weighted or unweighted UV spectra, integrated doses or irradiance at specific wavelengths, using data from satellite instruments. These surface UV data are mainly useful for environmental impact or process studies where high accuracy or a high temporal resolution is required. In contrast to several previous studies, SIDES has been validated with spectral measurements. By this method an averaging of positive or negative deviations over the complete wavelength range is avoided. This is especially important for UV wavelengths around 300 nm where biological effectiveness is highest. The results of SIDES deviate less than 7% from ground-based observations for wavelengths between 295 and 400 nm. In contrast, the corresponding deviations of the joint research center algorithm escalate for shorter wavelengths, reaching 35% at 295 nm. This large deviation is due to an inaccurate interpolation procedure that has been detected by spectral analysis. Thus, spectral validation is demonstrated to be an appropriate tool to detect weaknesses in such an algorithm and provides information essential for improvement. [source] Sunscreens containing the broad-spectrum UVA absorber, Mexoryl® SX, prevent the cutaneous detrimental effects of UV exposure: a review of clinical study resultsPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 4 2008Anny Fourtanier Background: UVA exposure of human skin mainly produces reactive oxygen species (ROS) leading to DNA, cell and tissue damage. It alters immune function, pigmentation and it is certainly responsible for a large part of photoaging changes. Moreover UVA is implicated in the etiology of several photodermatoses. As a consequence, to provide adequate protection, sunscreens or skin care products for daily use protective products need UVA absorbers combined with UVB ones. Aim: To assess the efficacy of sunscreens containing a broad-spectrum UVA absorber the Mexoryl® SX or ecamsule and to compare formulations with and without it through a large number of clinical studies in human volunteers and patients. Methods: The following assessments were conducted: ,Prevention of excessive pigmentation induced by UV exposure in Caucasian and Asian skins using a method that measures pigmentation protection factors (PPF). ,Efficacy against DNA damage by measurement of pyrimidine dimer formation and p53 protein accumulation. ,Protection of immune system using delayed type hypersensitivity (DTH) reactions to recall antigens, isomerization of urocanic acid (UCA), alteration of Langerhans cells (LC) density, morphology and function. ,Reduction of epidermal and dermal alterations induced by repeated UVA or UV solar simulated radiation (SSR) using histology or immunohistology. ,Prevention of the polymorphous light eruption (PMLE) in patients prone to develop this disease. Results: Mexoryl® SX-containing formulations showed a dose-dependent level of protection against pigmentation. For a same sun protection factor (SPF) the higher the UVA protection was, the higher was the PPF. Pyrimidine dimer formation and p53 accumulation were significantly reduced by formulations with Mexoryl® SX. In the studies looking at the suppression of DTH reactions to recall antigens by the different UV spectra, the LC alterations and the cis UCA formation, Mexoryl® SX formulations always showed a higher protective potency than sunscreen without it even when the protection against erythema was similar (products with same SPF). Mexoryl® SX formulations also prevented or significantly decreased to minimal, ferritin, tenascin and lysozyme expression induced by repeated UVA or SSR exposure. It also reduced the enhancement of collagenase 2 mRNA expression induced by SSR exposure. Finally PMLE study demonstrated that UVA protection was essential for the prevention of this photodermatose. Conclusion: Mexoryl® SX formulated in sunscreens or daily use products have been shown to be an effective UV absorber, leading to an increased efficacy of these products against a large number of biological damage induced by UVA, SSR or sun exposure. [source] Calycopterin, an immunoinhibitory compound from the extract of Dracocephalum kotschyiPHYTOTHERAPY RESEARCH, Issue 9 2008Najme Faham Abstract Medicinal plants have been widely investigated for their various effects. Dracocephalum kotschyi Boiss (Labiatae) is used in Iranian traditional medicine for the treatment of rheumatoid diseases. The inhibitory effect of D. kotschyi on the lectin-induced cellular immune response has been demonstrated previously. In this study, mitogen-treated lymphocytes were exposed to the extract of D. kotschyi and analysed for the induction of apoptosis using flow cytometry and gel electrophoresis. The data obtained indicated a dose-dependent increase of cells in the sub-G1 phase of cell cycle. Study of internucleosomal DNA fragmentation showed a typical DNA laddering in agarose gels. A bioactivity-guided fractionation assay to find the active components responsible for the inhibitory effect of D. kotschyi on mitogen-induced lymphocyte proliferation led to the isolation of calycopterin from the ethyl acetate extract of D. kotschyi. Its structure was identified by spectroscopic methods including 1H-NMR, 13C-NMR, MS and UV spectra. Calycopterin inhibited lymphocyte proliferation in a dose-dependent manner with an IC50 value of 1.7 µg/mL. In conclusion, the results of this study suggest that D. kotschyi extract has the capacity to induce apoptosis in the lymphocytes and that isolated calycopterin is responsible for the inhibitory effect of D. kotschyi on lymphocyte proliferation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Study of the Daughter Products of Akardite-IIPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 4 2006Louis-Simon Lussier Abstract In this work, five akardite-II (AK-II) daughter products were produced and isolated. Their respective MS, NMR, IR and UV spectra were recorded. These five products were positively identified as: N-NO-AK-II, 2-NO2 -AK-II, 4-NO2 -AK-II, N-NO-2-NO2 -AK-II and N-NO-4-NO2 -AK-II. An HPLC method giving baseline separation of 6 AK-II family products and 10 diphenylamine (DPA) family products is also described. Finally, preliminary results concerning the stability of AK-II daughter products are discussed. [source] Probing protein structure and dynamics by second-derivative ultraviolet absorption analysis of cation,, interactionsPROTEIN SCIENCE, Issue 10 2006Laura H. Lucas Abstract We describe an alternate approach for studying protein structure using the detection of ultraviolet (UV) absorbance peak shifts of aromatic amino acid side chains induced by the presence of salts. The method is based on the hypothesis that salt cations (Li+, Na+, and Cs+) of varying sizes can differentially diffuse through protein matrices and interact with benzyl, phenyl, and indole groups through cation,, interactions. We have investigated the potential of this method to probe protein dynamics by measuring high resolution second-derivative UV spectra as a function of salt concentration for eight proteins of varying physical and chemical properties and the N -acetylated C -ethyl esterified amino acids to represent totally exposed side chains. We show that small shifts in the wavelength maxima for Phe, Tyr, and Trp in the presence of high salt concentrations can be reliably measured and that the magnitude and direction of the peak shifts are influenced by several factors, including protein size, charge, and the local environment and solvent accessibility of the aromatic groups. Evaluating the empirical UV spectral data in light of known protein structural information shows that probing cation,, interactions in proteins reveals unique information about the influence of structure on aromatic side chain spectroscopic behavior. [source] Structural characterization and identification of ecdysteroids from Sida rhombifolia L. in positive electrospray ionization by tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2008Yan-Hong Wang Seven ecdysteroids isolated from Sida rhombifolia L. were studied by electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn) in the positive ion mode using an ion trap analyzer and high-performance liquid chromatography coupled with a diode-array detector (HPLC/DAD). The HPLC experiments were performed by means of a reversed-phase C18 column and a binary mobile phase system consisting of water (containing 0.05% formic acid) and acetonitrile (containing 0.05% formic acid) under gradient elution conditions. According to mass spectral features and the substitution at C-2, C-20, C-24 and C-25, ecdysteroids in S. rhombifolia were classified into three sub-groups. Structural identification of these three sub-groups of ecdysteroids was established by LC/multi-stage ion trap mass spectrometry on-line or off-line. The fragmentation patterns of ecdysteroids yielded ions of successive loss of 1,4 water molecules. Furthermore, ions corresponding to the complete loss of the side chain at C-17 will help to identify the sub-groups of ecdysteroids in addition to containing a hydroxyl moiety at one of the above-mentioned positions. Based on the HPLC retention behavior, the diagnostic UV spectra and the molecular structural information provided by ESI-MSn spectra, a total of nine naturally occurring ecdysteroids were identified, of these two are identified for the first time in S. rhombifolia. Copyright © 2008 John Wiley & Sons, Ltd. [source] Characterization of compounds in the Chinese herbal drug Mu-Dan-Pi by liquid chromatography coupled to electrospray ionization mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2006Shun-jun Xu Cortex Moutan is a well-known traditional Chinese medicine derived from Paeonia suffruticosa ANDREWS. However, root cortices of P. delavayi and P. decomposita also are used under the name of this drug in some regions such as Yunnan and Sichuan Provinces, respectively. In order to make a comparison of their chemical constituents, the compounds of the three Paeonia species were analyzed by high-performance liquid chromatography-diode array detection/electrospray ionization and quadrupole-time-of-flight tandem mass spectrometry (HPLC-DAD/ESI-MS2). A total of 50 compounds were observed in the 50% (v/v) methanolic extracts, including 17 monoterpenes, 14 galloyl glucoses, 10 acetophenones, 5 phenolic acids, 3 flavonoids and 1 triterpene. These chemical constituents were separated on a C18 column and identified or tentatively characterized based on UV spectra and MS fragmentation behavior. The chemical compositions of the three Paeonia species were found to have many differences. Paeonol was the predominant constituent of P. suffruticosa and P. decomposita, while P. delavayi contained albiflorin and more galloyl glucoses than the other two Paeonia species. Most of these identified compounds have been reported from P. delavayi and P. decomposita for the first time. The ESI-MS fragmentation behavior of monoterpene glycosides, acetophenones and galloyl glucoses was also investigated successively, and appropriate characteristic pathways were proposed. The large differences in chemical compounds among the three Paeonia species strongly encouraged further comparison of the bioactivities of these three species. Copyright © 2006 John Wiley & Sons, Ltd. [source] Characterization of phenolic compounds in the Chinese herbal drug Tu-Si-Zi by liquid chromatography coupled to electrospray ionization mass spectrometry,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2005Min Ye Phenolic compounds are the major bioactive constituents of the Chinese herbal drug Tu-Si-Zi, which is prepared from the seeds of Cuscuta chinensis. However, seeds of C. australis also are offered under the name of this drug in the herb market. In order to make a comparison of their chemical constituents, the phenolic compounds of these two Cuscuta species were analyzed by high-performance liquid chromatography/diode-array detection/electrospray ion trap tandem mass spectrometry (HPLC/DAD/ESI-MSn). A total of 50 compounds were observed in the methanol extracts, including 23 flavonoids, 20 lignans and 7 quinic acid derivatives. These compounds were separated on a C18 column and identified or tentatively characterized based on UV spectra and MS fragmentation behavior. In contrast to previous reports, the phenolic patterns of these two Cuscuta species were found to be very different. Kaempferol and astragalin were the predominant constituents of C. australis, while hyperoside was the major compound in C. chinensis. Most of the identified compounds, especially the acylated flavonoid glycosides, have not previously been reported from Cuscuta species. In addition, a 30,Da neutral loss observed for flavonols was investigated and could be used to differentiate flavonoid isomers such as kaempferol and luteolin. The ESI-MS fragmentation behavior of furofuran lignans was also investigated, and a characteristic pathway is proposed. The large differences observed between the phenolic constituents of C. chinensis and C. australis strongly encouraged further comparison of the bioactivities of these two species. Copyright © 2005 John Wiley & Sons, Ltd. [source] Phenol, chlorobenzene and chlorophenol isomers: resonant states and dissociative electron attachment,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 20 2003Roustem V. Khatymov This paper reports a study of resonant dissociative electron attachment (DEA) to the phenol, chlorobenzene, p- , m- , and o- chlorophenol molecules. On the basis of spectroscopic and thermochemical approaches the resonant states of the molecular negative ions (NIs) and the structures of some dissociative decay products are assigned. In the electron energy range up to 3,eV, DEA processes are determined by the two 2[,*]-shape resonances resulting mainly in formation of [MH], and/or Cl, ions. At higher electron energies the energy correlation between peaks in the negative ion effective yield curves and bands of UV spectra allowed identification of the core-excited resonances. The peculiarities of Cl, ion formation and the vibrational fine structure on the effective yield curves of the [MH], ions are discussed. The mass spectrometric procedures for measurement of relative cross sections for NI formation are described. Copyright © 2003 John Wiley & Sons, Ltd. [source] Synthesis, characterization and biological studies of alkenyl-substituted titanocene(IV) carboxylate complexesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 9 2010Goran N. Kalu, erovi Abstract The carboxylate compounds [Ti(,5 -C5H5)(,5 -C5H4{CMe2(CH2CH2CHCH2)})(O2CCH2SXyl)2] (2; Xyl = 3,5-Me2C6H3) and [Ti(,5 -C5H5)(,5 -C5H4{CMe2(CH2CH2CHCH2)})(O2CCH2SMesl)2] (3; Mes 1 = 2,4,6-Me3C6H2) were synthesized by the reaction of [Ti(,5 -C5H5)(,5 -C5H4{CMe2(CH2CH2CHCH2)})Cl2] (1) with 2 equivalents of xylylthioacetic acid or mesitylthioacetic acid, respectively. Compounds 2 and 3 were characterized by spectroscopic methods. The cytotoxic activity of 1,3 was tested against human tumor cell lines from four different histogenic origins,8505C (anaplastic thyroid cancer), DLD-1 (colon cancer) and the cisplatin sensitive A253 (head and neck cancer) and A549 (lung carcinoma),and compared with those of the reference complex [Ti(,5 -C5H5)2Cl2] (R1) and cisplatin. Surprisingly, the cytotoxic activities of the carboxylate derivatives were lower than those of their corresponding dichloride analogue (1). However, complexes 1,3 were more active than titanocene dichloride against all the studied cells with the exception of complex 2 against A253 and A549 cell lines. DNA-interaction tests were also carried out. Solutions of all the studied complexes were treated with different concentrations of fish sperm DNA, observing modifications of the UV spectra with intrinsic binding constants of 2.99 × 105, 2.45 × 105, and 2.35 × 105M,1 for 1,3. Structural studies based on density functional theory calculations of 2 and 3 were also carried out. Copyright © 2010 John Wiley & Sons, Ltd. [source] In vitro Metabolism of Genistein and Tangeretin by Human and Murine Cytochrome P450sBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 1 2003Vibeke M. Breinholt Analysis of the metabolic profile from incubations with genistein and human liver microsomes revealed the production of five different metabolites, of which three were obtained in sufficient amounts to allow a more detailed elucidation of the structure. One of these metabolites was identified as orobol, the 3,-hydroxylated metabolite of genistein. The remaining two metabolites were also hydroxylated metabolites as evidenced by LC/MS. Orobol was the only metabolite formed after incubation with CYP1A2. The two major product peaks after incubation of tangeretin with human microsomes were identical with 4,-hydroxy-5,6,7,8-tetramethoxyflavone and 5,6-dihydroxy-4,,7,8-trimethoxyflavone, previously identified in rat urine in our laboratory. By comparison with UV spectra and LC/MS fragmentation patterns of previously obtained standards, the remaining metabolites eluting after 14, 17 and 20 min. were found to be demethylated at the 4,,7-, 4,,6-positions or hydroxylated at the 3,- and demethylated at the 4,-positions, respectively. Metabolism of tangeretin by recombinant CYP1A2, 3A4, 2D6 and 2C9 resulted in metabolic profiles that qualitatively were identical to those observed in the human microsomes. Inclusion of the CYP1A2 inhibitor fluvoxamine in the incubation mixture with human liver microsomes resulted in potent inhibition of tangeretin and genistein metabolism. Other isozymes-selective CYP inhibitors had only minor effects on tangeretin or genistein metabolism. Overall the presented observations suggest major involvement of CYP1A2 in the hepatic metabolism of these two flavonoids. [source] Simultaneous determination of ten amphetamine designer drugs in human whole blood by capillary electrophoresis with diode array detectionBIOMEDICAL CHROMATOGRAPHY, Issue 10 2005Maria Nieddu Abstract In recent years, a number of new designer drugs have entered the illicit drug market. The methylenedioxyderivatives of amphetamine represent the largest group of designer drugs. This paper describes a method for screening for and simultaneously quantifying 10 2,5-methylenedioxy-derivatives of amphetamine and phenethylamine in human whole blood, using capillary electrophoresis (CE) with diode array detection (DAD). Using an aqueous pH 2.5 phosphate buffer, CE analysis gave peaks with good symmetry and reproducible migration times. Under these experimental conditions, the 10 amphetamines were resolved in 15 min and without interference from biological matrices (blood). Their identification by migration time was confirmed by their UV spectra recorded with a DAD (190,350 nm). The main advantages of the present method lie in its simplicity, clean and reliable extraction from human whole blood and simultaneous detection and quantification by CE-DAD. The applicability of the method was demonstrated by analysis of in vivo rat blood samples. The method was validated according to international guidelines. Copyright © 2005 John Wiley & Sons, Ltd. [source] Development of the second-order derivative UV spectrophotometric method for direct determination of paracetamol in urine intended for biopharmaceutical characterisation of drug productsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 7 2003Jelena Paroj Abstract Paracetamol is a widely used nonsalicylate analgesic and antipyretic drug. The existing methods for the determination of paracetamol in biological fluids are mainly HPLC techniques, although there are some reported methods based on spectrophotometric determinations. However, all these methods involve some extraction or derivatisation procedures. In the present study the UV spectra of investigated samples were recorded over the wavelength range 220,400 nm (, step 0.21 nm; scan speed 60 nm/min) and second-order derivative spectra were calculated. Second-order derivative spectra of different blank urine samples displayed the presence of a zero-crossing point at 245,247 nm defined as ,zc. The zero-order absorption spectra of paracetamol in water displays maximum absorbance at 243 nm, while in second derivative spectra, a minimum peak at 246 nm was observed. Therefore, the application of zero-crossing technique to the second-derivative UV absorption spectrum should be useful for the determination of paracetamol using 2D,zc. The proposed method enables determination of total paracetamol in urine directly and simply by reading the 2D,zc of the diluted samples. The obtained results were in good accordance with published data on cumulative urinary excretion after per oral administration of paracetamol obtained applying different spectrophotometric methods of determination. It could be useful for biopharmaceutical characterisation of drug products (monitoring of the levels of paracetamol in urine in bioavailability testing, for the evaluation of in vitro,in vivo correlation and screening of different formulations during drug product development). Copyright © 2003 John Wiley & Sons, Ltd. [source] Structural Diversity in the Self-Assembly of Pseudopeptidic MacrocyclesCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2010Ignacio Alfonso Dr. Abstract The self-assembling abilities of several pseudopeptidic macrocycles have been thoroughly studied both in the solid (SEM, TEM, FTIR) and in solution (NMR, UV, CD, FTIR) states. Detailed microscopy revealed large differences in the morphology of the self-assembling micro/nanostructures depending on the macrocyclic chemical structures. Self-assembly was triggered by the presence of additional methylene groups or by changing from para to meta geometry of the aromatic phenylene backbone moiety. More interestingly, the nature of the side chain also plays a fundamental role in some of the obtained nanostructures, thus producing structures from long fibers to hollow spheres. These nanostructures were obtained in different solvents and on different surfaces, thus implying that the chemical information for the self-assembly is contained in the molecular structure. Dilution NMR studies (chemical shift and self-diffusion rates) suggest the formation of incipient aggregates in solution by a combination of hydrogen-bonding and ,,, interactions, thus implicating amide and aryl groups, respectively. Electronic spectroscopy further supports the ,,, interactions because the compounds that lead to fibers show large hypochromic shifts in the UV spectra. Moreover, the fiber-forming macrocycles also showed a more intense CD signature. The hydrogen-bonding interactions within the nanostructures were also characterized by attenuated total-reflectance FTIR spectroscopy, which allowed us to monitor the complete transition from the solution to the dried nanostructure. Overall, we concluded that the self-assembly of this family of pseudopeptidic macrocycles is dictated by a synergic action of hydrogen-bonding and ,,, interactions. The feasibility and geometrical disposition of these interactions finally render a hierarchical organization, which has been rationalized with a proposal of a model. The understanding of the process at the molecular level has allowed us to prepare hybrid soft materials. [source] Synthesis and Thermal Decomposition Kinetics of the Complex of Samarium p -Methylbenzoate with 1,10-PhenanthrolineCHINESE JOURNAL OF CHEMISTRY, Issue 1 2007Jian-Jun Zhang Abstract The complex [Sm(p -MBA)3phen]2 (p -MBA, p -methylbenzoate; phen, 1,10-phenanthroline) was prepared and characterized by elemental analysis, IR and UV spectra. The thermal decomposition process of [Sm(p - MBA)3phen]2 was studied under a static air atmosphere by TG-DTG and IR techniques. Thermal decomposition kinetics was investigated employing a newly proposed method, together with the integral isoconversional non-linear method. Meanwhile, the thermodynamic parameters (,H,, ,G, and ,S,) were also calculated. The lifetime equation at mass-loss of 10% was deduced as ln ,=,24.7825+18070.43/T by isothermal thermogravimetric analysis. [source] The electronically excited states of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine): Vertical excitationsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 11 2009Itamar Borges Jr Abstract The RDX molecule, hexahydro-1,3,5-trinitro-1,3,5-triazine, is a key component for several energetic materials, which have important practical applications as explosives. A systematic study of the electronic excited states of RDX in gas phase using time-dependent density functional theory (TDDFT), algebraic diagrammatic construction through second order method [ADC (2)], and resolution of the identity coupled-cluster singles and doubles method (RI-CC2) was carried out. Transition energies and optical oscillator strengths were computed for a maximum of 40 transitions. RI-CC2 and ADC (2) predict a spectrum shaped by three intense ,-,* transitions, two with charge transfer and one with localized character. TDDFT fails in the description of the charge transfer states. The low-energy band of the experimental UV spectrum of RDX is assigned to the first charge transfer state. Two alternative assignments of the high-energy band are proposed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Poly(O -anisidine) coatings electrodeposited onto AL-2024: Synthesis, characterization, and corrosion protection evaluationADVANCES IN POLYMER TECHNOLOGY, Issue 4 2004Kunal Shah Abstract Poly(O -anisidine) coating was successfully electrodeposited onto Al-2024. Cyclic voltammetry and reflection absorption infrared spectroscopy (RAIR) analysis were carried out in order to fully understand the formation and structure of the resulting polymer coating. RAIR spectrum showed the characteristics peaks of poly(O -anisidine). As the reaction time was varied, the CV peak shifted from 0.75 to 0.81 V vs. SCE suggesting that a change in structure of the polymer from a reduced state to a partially oxidized form has occurred. UV spectrum showed two peaks at 320 and 620 nm suggesting the presence of conjugation on the polymer backbone. The deposition of the poly(O -anisidine) onto the substrate was controlled by nucleation and growth mechanism. DC polarization technique was used to evaluate the corrosion protection offered by poly(O -anisidine) coatings. Preliminarily data shows that these coatings help to ennoble the surface of the substrate. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 291,297, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20024 [source] Phenothiazine photosensitizers for onium salt photoinitiated cationic polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 8 2001Zaza Gomurashvili Abstract Phenothiazine compounds bearing a wide range of different substituents are excellent photosensitizers for onium salt cationic photoinitiators. These photosensitizers are generally operative in the mid- and long-range regions of the UV spectrum and are especially useful for enhancing the rate of photoinitiated cationic polymerization carried out utilizing both filtered and broadband UV emission sources. In this article, the syntheses of several different substituted phenothiazines are described and the ability of these compounds to photosensitize the photolysis of different onium salt photoinitiators is evaluated. Attempts were made to correlate the structure and spectral characteristics of the phenothiazines with their efficiency of photosensitization in the cationic photopolymerizations of several typical epoxide and vinyl ether monomers. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1187,1197, 2001 [source] In vitro and in vivo identification of ,pseudocatalase' activity in Dead Sea water using Fourier transform Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2002Karin U. Schallreuter Balneotherapy with Dead Sea water has been reported as a successful treatment modality for psoriasis, atopic eczema and vitiligo, but the precise mode of action has escaped definition so far. The saturating salt concentration (346 g/litre) together with the unique UV spectrum have been suggested to trigger the release of pro-inflammatory and chemotactic mediators. The results of our study show for the first time a high content of transition metal ions (manganese, iron and copper) in Dead Sea water. Using in vitro Fourier transform (FT) Raman spectroscopy, we were able to identify ,pseudocatalase' activity by observing the decomposition of hydrogen peroxide (H2O2) over time by Dead Sea water. Since patients with vitiligo accumulate millimolar levels of H2O2 in their skin, we followed the degradation of H2O2in vivo again utilizing the same technique. The results of this in vitro and in vivo study show for the first time a ,pseudocatalase' activity of Dead Sea water and provide evidence that the antioxidant properties of Dead Sea water bathing could play an important role in this unique treatment modality. Furthermore, the use of non-invasive in vivo FT-Raman spectroscopy introduces an excellent biomedical application in investigative dermatology. Copyright © 2002 John Wiley & Sons, Ltd. [source] Straightforward Determination of the Degree of N -Acetylation of Chitosan by Means of First-Derivative UV SpectrophotometryMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 14 2008Ricardo M. P. da Silva Abstract First-derivative UV spectrophotometry is shown to be a reliable method for the determination of the degree of N- acetylation of chitosan samples. A mathematical expression is derived that allows to determine the DA directly from the mass concentration of a chitosan solution and the first derivative of its UV spectrum at 202 nm, thus eliminating the need for empiric correction curves for highly deacetylated samples. A procedure is proposed for the accurate mass determination of the hygroscopic chitosan. The proposed approach facilitates the routine determination of the DA, especially when using potent multiwell microplate readers, which allow hundreds of samples to be measured in just a few minutes. [source] Assessment of UV Biological Spectral Weighting Functions for Phenolic Metabolites and Growth Responses in Silver Birch SeedlingsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2009Titta Kotilainen In research concerning stratospheric ozone depletion, action spectra are used as biological spectral weighting functions (BSWFs) for describing the effects of UV radiation on plant responses. Our aim was to evaluate the appropriateness of six frequently used BSWFs that differ in effectiveness with increasing wavelength. The evaluation of action spectra was based on calculating the effective UV radiation doses according to 1,2) two formulations of the generalized plant action spectrum, 3) a spectrum for ultraviolet induced erythema in human skin, 4) a spectrum for the accumulation of a flavonol in Mesembryanthemum crystallinum, 5) a spectrum for DNA damage in alfalfa seedlings and 6) the plant growth action spectrum. We monitored effects of UV radiation on the concentration of individual UV absorbing metabolites and chlorophyll concentrations in leaves and growth responses of silver birch (Betula pendula) seedlings. Experiments were conducted outdoors using plastic films attenuating different parts of the UV spectrum. Chlorophyll concentrations and growth were not affected by the UV treatments. The response to UV radiation varied between and within groups of phenolics. In general, the observed responses of phenolic groups and individual flavonoids were best predicted by action spectra extending into the UV-A region with moderate effectiveness. [source] A full-UV spectrum absorbing daily use cream protects human skin against biological changes occurring in photoagingPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 4 2000S. Seité Background: There is overwhelming evidence that exposure of human skin to ultraviolet radiations (UVR) leads to the development of cutaneous photoaging and eventually to neoplasia. This study was designed to evaluate in humans the protection afforded by a daily use cream containing a photostable combination of UVB and UVA absorbers (Uvinul® N539, Parsol® 1789 and Mexoryl® SX) providing a continuous absorption through the entire UV spectrum, against damages induced by repeated daily exposure to solar simulated radiation (SSR). Methods: Buttock skin of 12 healthy volunteers was exposed 5 days per week for 6 weeks to one minimal erythema dose of solar simulated radiation per exposure. The following parameters in treated and untreated skin were evaluated: erythema, pigmentation, skin hydration, skin microtopography, histology and immunochemistry, and collagen and metalloproteinase (MMP) mRNA levels. Results: In SSR exposed unprotected skin sites, we observed melanization and changes in the skin hydration and microtopography. The epidermis revealed a significant increase in stratum corneum and stratum granulosum thickness. In the dermis, an enhanced expression of tenascin and a reduced expression of type I pro-collagen were evidenced just below the dermal epidermal junction. Although we were unable to visualize any change in elastic fibers in exposed buttock skin, a slightly increased deposition of lysozyme and alpha 1 antitrypsin on these fibers was observed using immunofluorescence techniques. Furthermore, types I and III collagen mRNA were slightly increased and a significant enhancement (up to 2.8-fold) of MMP-2 mRNA level was observed. The daily use cream was shown to prevent all these biological changes. Conclusion: Our results show in vivo that an appropriate full-UV spectrum product significantly reduces the solar-UV-induced skin damage, demonstrating the benefit of daily photoprotection. [source] Gas-Phase Watson,Crick and Hoogsteen Isomers of the Nucleobase Mimic 9-Methyladenine,2-PyridoneCHEMPHYSCHEM, Issue 7 2006Jann A. Frey Abstract 2-Pyridone (pyridin-2-one) is a mimic of the uracil and thymine nucleobases, with only one NH and CO group. It provides a single H-bonding site, compared to three for the canonical pyrimidine nucleobases. Employing the supersonically cooled 9-methyladenine,2-pyridone (9MAd,2PY) complex, which is the simplest base pair to mimic adenine-uracil or adenine-thymine, we show that its gas-phase UV spectrum consists of contributions from two isomers. Based on the H-bonding sites of 9-methyladenine, these are the Watson,Crick and Hoogsteen forms. Combining two-color two-photon ionisation (2C-R2PI), UV-UV depletion and laser-induced fluorescence spectroscopies allows separation of the two band systems, revealing characteristic intermolecular in-plane vibrations of the two isomers. The calculated S0 and S1 intermolecular frequencies are in good agreement with the experimental ones. Ab initio calculations predict the Watson,Crick isomer to be slightly more stable (D0=,16.0 kcal,mol,1) than the Hoogsteen isomer (D0=,15.0 kcal,mol,1). The calculated free energies ,fG0 of the Watson,Crick and Hoogsteen isomers agree qualitatively with the experimental isomer concentration ratio of 3:1. 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