A simple HPLC-DAD method for determination of adapalene in topical gel formulation

A simple stability indicating high-performance liquid chromatography method for the analysis of adapalene in pharmaceutical gel formulation is developed and validated. An isocratic separation is performed using a Merck RP-8 (150 mm × 4.6 mm i.d., particle size 5 m) column and a mixture of acetonitrile water (67:33, v/v, pH adjusted to 2.5 with phosphoric acid) as the mobile phase. The detection is achieved with a photodiode array detector at 321 nm. The specificity of the method is verified by subjecting both the reference substance and the pharmaceutical form to hydrolytic, oxidative, photolytic, and thermal stress conditions. There is no interference from the excipients of the formulation on the determination of adapalene in gel. The response is linear over the concentration range of 8.0-16.0 μg/mL (r > 0.999) with a limit of detection and quantification of 0.04 and 0.14 μg/mL, respectively. The mean recovery is 100.8%. The RSD values for the intra- and inter-day precision studies are < 1.2%. The method is validated by reaching satisfactory results for linearity, selectivity, specificity, precision, accuracy, robustness, and system suitability.     

The importance of the N-H bond in Ru/TsDPEN complexes for asymmetric transfer hydrogenation of ketones and imines

Ru(II) complexes of TsDPEN containing two alkyl groups on the non-tosylated nitrogen atom are poor catalysts for asymmetric transfer hydrogenation of ketones and imines; this observation provides direct evidence for the importance of the N-H interaction in the transition state for ketone reduction.     

In situ microbial fuel cell-based biosensor for organic carbon

The biological oxygen demand (BOD) may be the most used test to assess the amount of pollutant organic matter in water; however, it is time and labor consuming, and is done ex-situ. A BOD biosensor based on the microbial fuel cell principle was tested for online and in situ monitoring of biodegradable organic content of domestic wastewater. A stable current density of 282±23mA/m(2) was obtained with domestic wastewater containing a BOD(5) of 317±15mg O(2)/L at 22±2°C, 1.53±0.04mS/cm and pH 6.9±0.1. The current density showed a linear relationship with BOD(5) concentration ranging from 17±0.5mg O(2)/L to 78±7.6mg O(2)/L. The current generation from the BOD biosensor was dependent on the measurement conditions such as temperature, conductivity, and pH. Thus, a correction factor should be applied to measurements done under different environmental conditions from the ones used in the calibration. These results provide useful information for the development of a biosensor for real-time in situ monitoring of wastewater quality.     

The influence of patterned nanofiber meshes on human mesenchymal stem cell osteogenesis

A specially designed electroconductive collector enables the electrospinning of P-NFM composed of areas of parallel/uniaxially aligned fibers and areas of random/orthogonal nanofiber distribution. The biological relevance of P-NFM is demonstrated using hBMSCs as an autologous cell source. The structures induce cell orientation along the uniaxially aligned fibers, mainly during earlier culturing periods under basal and osteogenic differentiation conditions. The microtopography of the P-NFM also controls the deposition of mineralized extracellular matrix along the pre-defined fiber direction. Genotypic characterization confirms the successful differentiation into the osteogenic lineage.     

Application of molecularly imprinted polymer solid-phase extraction for salivary cotinine

A method constituted by molecularly imprinted solid-phase extraction (MISPE) with high-performance liquid chromatography coupled to diode array detector (HPLC-DAD) was developed for cotinine analysis in saliva samples. For this purpose, the separation was carried out with a C18 reversed-phase column at 20 °C. The mobile phase which was composed of a mixture of 09:91 (v/v) acetonitrile/phosphate buffer, pH 6.3, was delivered with isocratic flow rate at 1.4 mL min⁻¹. Employing MISPE, the best conditions were achieved with 1.5 mL of saliva plus 1.5 mL of 0.1 mol L⁻¹ of acetate buffer, pH 5.5, which were then passed through a cartridge previously conditioned with 2 mL acetonitrile, 2 mL methanol, and 2 mL of 0.1 mol L⁻¹ sodium acetate buffer, pH 5.5. The washing was carried out with 1 mL deionized water, 1 mL of 0.1 mol L⁻¹ sodium hydroxide, and 1 mL hexane; finally; the cotinine elution was carried out with 3 mL methanol/water (97.5: 2.5, v/v). Linearity ranged from 30 to 500 ng mL⁻¹ with r > 0.99. Intra-assay, interassay precision, and accuracy ranged from 3.1% to 10.1%, 5.2% to 15.9%, and 99.22% to 111.17%, respectively. The detection and quantification limits were 10 and 30 ng mL⁻¹, respectively. This investigation has provided a reliable method for routine cotinine determination in saliva, and it is an important tool for monitoring cigarette smoke exposure in smokers. The method was applied in five smokers’ samples who consumed around five to 20 cigarettes per day and the values of cotinine in saliva were from 66.7 to 316.16 ng mL⁻¹.     

Synthesis, antimicrobial and antiproliferative activity of novel silver(I) tris(pyrazolyl)methanesulfonate and 1,3,5-triaza-7-phosphadamantane complexes

Five new silver(I) complexes of formulas [Ag(Tpms)] (1), [Ag(Tpms)(PPh(3))] (2), [Ag(Tpms)(PCy(3))] (3), [Ag(PTA)][BF(4)] (4), and [Ag(Tpms)(PTA)] (5) {Tpms = tris(pyrazol-1-yl)methanesulfonate, PPh(3) = triphenylphosphane, PCy(3) = tricyclohexylphosphane, PTA = 1,3,5-triaza-7-phosphaadamantane} have been synthesized and fully characterized by elemental analyses, (1)H, (13)C, and (31)P NMR, electrospray ionization mass spectrometry (ESI-MS), and IR spectroscopic techniques. The single crystal X-ray diffraction study of 3 shows the Tpms ligand acting in the N(3)-facially coordinating mode, while in 2 and 5 a N(2)O-coordination is found, with the SO(3) group bonded to silver and a pendant free pyrazolyl ring. Features of the tilting in the coordinated pyrazolyl rings in these cases suggest that this inequivalence is related with the cone angles of the phosphanes. A detailed study of antimycobacterial and antiproliferative properties of all compounds has been carried out. They were screened for their in vitro antimicrobial activities against the standard strains Enterococcus faecalis (ATCC 29922), Staphylococcus aureus (ATCC 25923), Streptococcus pneumoniae (ATCC 49619), Streptococcus pyogenes (SF37), Streptococcus sanguinis (SK36), Streptococcus mutans (UA159), Escherichia coli (ATCC 25922), and the fungus Candida albicans (ATCC 24443). Complexes 1-5 have been found to display effective antimicrobial activity against the series of bacteria and fungi, and some of them are potential candidates for antiseptic or disinfectant drugs. Interaction of Ag complexes with deoxyribonucleic acid (DNA) has been studied by fluorescence spectroscopic techniques, using ethidium bromide (EB) as a fluorescence probe of DNA. The decrease in the fluorescence of DNA-EB system on addition of Ag complexes shows that the fluorescence quenching of DNA-EB complex occurs and compound 3 is particularly active. Complexes 1-5 exhibit pronounced antiproliferative activity against human malignant melanoma (A375) with an activity often higher than that of AgNO(3), which has been used as a control, following the same order of activity inhibition on DNA, i.e., 3 > 2 > 1 > 5 > AgNO(3)? 4.     

Charge carrier mobility and concentration as a function of composition in AgPO3-AgI glasses

Conductivity data of the xAgI(1 - x)AgPO(3) system (0 ≤ x ≤ 0.5) were collected in the liquid and glassy states. The difference in the dependence of ionic conductivity on temperature below and above their glass transition temperatures (T(g)) is interpreted by a discontinuity in the charge carrier's mobility mechanisms. Charge carrier displacement occurs through an activated mechanism below T(g) and through a Vogel-Fulcher-Tammann-Hesse mechanism above this temperature. Fitting conductivity data with the proposed model allows one to determine separately the enthalpies of charge carrier formation and migration. For the five investigated compositions, the enthalpy of charge carrier formation is found to decrease, with x, from 0.86 to 0.2 eV, while the migration enthalpy remains constant at ≈0.14 eV. Based on these values, the charge carrier mobility and concentration in the glassy state can then be calculated. Mobility values at room temperature (≈10(-4) cm(2) V(-1) s(-1)) do not vary significantly with the AgI content and are in good agreement with those previously measured by the Hall-effect technique. The observed increase in ionic conductivity with x would thus only be due to an increase in the effective charge carrier concentration. Considering AgI as a weak electrolyte, the change in the effective charge carrier concentration is justified and is correlated to the partial free energy of silver iodide forming a regular solution with AgPO(3).     

Microwave promoted Suzuki reactions between aroyl chlorides and boronic acids catalyzed by heterogeneous and homogeneous phosphine-free palladium catalysts

Suzuki cross-coupling reactions between arylboronic acids and aroyl chlorides with phosphine-free palladium catalysis under microwave irradiation were performed to obtainment of aromatic ketones in good yields within short times. Heterogeneous and homogeneous catalysts were studied as well as their influence in the reaction selectivity relative to homocoupling of the boronic acids.     

Biomolecule profiles in inedible wild mushrooms with antioxidant value

The use of natural products isolated from mushrooms, included inedible species, against infection, cancer diseases and other oxidative-stress related diseases is one of the cornerstones of modern medicine. In the present work, the antioxidant molecule profiles of inedible mushroom species were evaluated and compared with those of edible species. The order of antioxidant abundance found in inedible wild mushrooms was: phenolics > flavonoids > ascorbic acid > tocopherols > carotenoids, similar to that of edible species. Furthermore the same energetic biomolecules were found including the disaccharide trehalose, the monosaccharide alcohol derivative mannitol and the fatty acids palmitic, oleic and linoleic acids. Fomitopsis pinicola revealed a very high phenolics concentration (388 mg GAE/g extract) and powerful antioxidant properties, mainly reducing power (EC??) value 60 μg/mL similar to the standard Trolox?). It could find applications in the prevention of free radical-related diseases as a source of bioactive compounds.     

Electron transfer processes in potassium collisions with 5-fluorouracil and 5-chlorouracil

Electron transfer to uracil (U), 5-chlorouracil (5-ClU) and 5-fluorouracil (5-FU) yielding anion formation has been investigated in 30-100 eV potassium-molecule collisions. The rich fragmentation patterns of all three molecules suggest that electron transfer in collisions with electronegative neutrals may cause efficient damage to RNA. The main ring fragment anion in all the mass spectra was NCO(-) while the production of X(-) (X = F, Cl) was a strong decomposition of the halouracil temporary negative ions. Cl(-) was the most intense fragment anion in the 5-chlorouracil measurements, whereas NCO(-) production dominated in the U and 5-FU data. Arguments based on energetics and vibrational dynamics have been proposed to explain these differences. Electronic coupling between dipole- and valence-bound states may play a particularly important role in the fragmentation pathways of the 5-ClU parent anion. The stabilizing influence of the potassium cation following electron transfer (ionic scattering) on the observed fragmentation patterns is discussed, notably in the context of comparisons with free electron attachment processes.