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      Inhibitive action of some plant extracts on the corrosion of steel in acidic media

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      Corrosion Science

      Elsevier BV

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          Most cited references 31

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          Studying single living cells and chromosomes by confocal Raman microspectroscopy.

          Many indirect methods have been developed to study the constitution and conformation of macromolecules inside the living cell. Direct analysis by Raman spectroscopy is an ideal complement to techniques using directly labelled fluorescent probes or of indirect labelling with mono- and polyclonal antibodies. The high information content of Raman spectra can characterize biological macromolecules both in solution and in crystals. The positions, intensities and linewidths of the Raman lines (corresponding to vibrational energy levels) in spectra of DNA-protein complexes yield information about the composition, secondary structure and interactions of these molecules, including the chemical microenvironment of molecular subgroups. The main drawback of the method is the low Raman scattering cross-section of biological macromolecules, which until now has prohibited studies at the level of the single cell with the exception of (salmon) sperm heads, in which the DNA is condensed to an exceptionally high degree. Ultraviolet-resonance Raman spectroscopy has been used to obtain single cell spectra (and F. Sureau and P. Y. Turpin, personal communication), but in this method absorption of laser light may impair the integrity of the sample. We have avoided this problem in developing a novel, highly sensitive confocal Raman microspectrometer for nonresonant Raman spectroscopy. Our instrument makes it possible to study single cells and chromosomes with a high spatial resolution (approximately less than 1 micron 3).
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            Fixed oil of Nigella sativa and derived thymoquinone inhibit eicosanoid generation in leukocytes and membrane lipid peroxidation.

            Samples of the expressed fixed oil from different sources of Nigella sativa seeds were examined by thin-layer and gas chromatography for content of fixed oils and thymoquinone, and these substances were tested as possible inhibitors of eicosanoid generation and membrane lipid peroxidation. The crude fixed oil and pure thymoquinone both inhibited the cyclooxygenase and 5-lipoxygenase pathways of arachidonate metabolism in rat peritoneal leukocytes stimulated with calcium ionophore A23187, as shown by dose-dependent inhibition of thromboxane B2 and leukotriene B4, respectively. Thymoquinone was very potent, with approximate IC50 values against 5-lipoxygenase and cyclo-oxygenase of < 1 microgram/ml and 3.5 micrograms/ml, respectively. Both substances also inhibited non-enzymatic peroxidation in ox brain phospholipid liposomes, but thymoquinone was about ten times more potent. However, the inhibition of eicosanoid generation and lipid peroxidation by the fixed oil of N. sativa is greater than is expected from its content of thymoquinone (ca. 0.2% w/v), and it is possible that other components such as the unusual C20:2 unsaturated fatty acids may contribute also to its anti-eicosanoid and antioxidant activity. These pharmacological properties of the oil support the traditional use of N. sativa and its derived products as a treatment for rheumatism and related inflammatory diseases.
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              High performance liquid chromatographic analysis of the pharmacologically active quinones and related compounds in the oil of the black seed (Nigella sativa L.).

              An HPLC method for quantifying the putative pharmacologically active constituents: thymoquinone (TQ), dithymoquinone (DTQ), thymohydroquinone (THQ), and thymol (THY), in the oil of Nigella sativa seed is described. Extraction of the constituents from the oil was carried out using C18 PrepSep mini columns followed by quantification of the recovered constituents by HPLC on a reversed-phase muBondapak C18 analytical column, using an isocratic mobile phase of water:methanol:2-propanol (50:45:5% v/v) at a flow rate of 2 ml min(-1). UV detection was at 254 nm for TQ, DTQ, and THY, and at 294 nm for THQ. The above four compounds were separated with good resolution, reproducibility, and sensitivity under these conditions. This analytical method was used to quantify the above four constituents in a commercial sample of N. sativa seed oil, and provides a good quality control methodology for the pharmacologically active components in this widely used natural remedy.
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                Author and article information

                Journal
                Corrosion Science
                Corrosion Science
                Elsevier BV
                0010938X
                September 2006
                September 2006
                : 48
                : 9
                : 2765-2779
                Article
                10.1016/j.corsci.2005.09.017
                © 2006

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