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Chemical Constitution (chemical + constitution)
Selected AbstractsANTIBACTERIAL ACTIVITY AND CHEMICAL CONSTITUTIONS OF OLEA EUROPAEA L. LEAF EXTRACTSJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2010MIHRIBAN KORUKLUOGLU ABSTRACT The in vitro antimicrobial activity of aqueous, acetone, diethyl ether and ethyl alcohol extracts of olive leaves (Olea europaea L.) was studied. The aqueous extract of olive leaves had no antibacterial effect against the test microorganisms, whereas acetone extract showed inhibitory effect on Salmonella enteritidis, Bacillus cereus, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, Streptococcus thermophilus and Lactobacillus bulgaricus. Furthermore, the antimicrobial activities of some phenolic compounds against microorganisms were tested. The most effective compound was found to be oleuropein while syringic acid was found ineffective. The characterization of phenolic compounds in different extracts determined by high performance liquid chromatography-air pressure chemical ionization-mass spectrometry detector (HPLC-APCI-MSD GC-MS) gas chromatography-mass spectrometry (GC-MS). The acetone and the ethyl alcohol extracts had the most and the least oleuropein content, respectively. PRACTICAL APPLICATIONS In recent years the extracts of many plant species have become popular, and attempts to characterize their bioactive principles have gained speed for many pharmaceutical and food-processing applications. Especially, antimicrobial properties of plants have revived as a consequence of current problems associated with the use of chemical preservatives. Because of consumers' negative perspectives of synthetic preservatives, attention is shifting toward natural alternatives. The findings suggest that olive leaf extracts and their phenolic compounds have good potential as antibacterial substances in food preservation as they may be more acceptable to consumers and the regulatory agencies in comparison with synthetic chemical compounds. [source] In situ study of growth and dissolution kinetics of ammonium oxalate monohydrate single crystals from aqueous solutions containing cationic impuritiesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2007K. Sangwal Abstract The results of an in situ investigation of the effect of four different bi- and trivalent cations (Fe(III), Cu(II), Mn(II) and Cr(III)) on the displacement velocity of individual growth steps on the (110) face of ammonium oxalate monohydrate crystals as a function of supersaturation are described and discussed. It was observed that: (1) at a particular temperature of pure solutions and solutions containing impurities, the velocity v of movement of the [110] growth steps is always greater than that of the [111] steps, (2) fluctuations in the velocity of individual growth steps occur in all solutions containing similar concentrations of different impurities, (3) the value of kinetic coefficient , for growth steps decreases with an increase in the concentration ci of Cu(II) impurity, but that for dissolution steps does not depend on ci; moreover, the value of kinetic coefficient , for growth steps is higher than that of dissolution steps, and (4) in the presence of Mn(II) and Cr(III) impurities, the kinetic coefficient , for dissolution steps is several times greater than that for growth steps. The results are explained from the standpoint of Kubota-Mullin model of adsorption of impurities at kinks in the steps and the stability of dominating complexes present in solutions. Analysis of the results revealed that: (1) the effectiveness of different impurities in inhibiting growth increases in the order: Fe(III), Cu(II), Mn(II), and Cr(III), and this behavior is directly connected with the stability and chemical constitution of dominating complexes in saturated solutions, (2) fluctuations in the velocity of growth steps is associated with the effectiveness of an impurity for adsorption; the stronger the adsorption of an impurity, the higher is the fluctuation in step velocity v, and (3) depending on the nature of the impurity, the kinetic coefficient for the dissolution steps can remain unchanged or can be higher than that of the growth steps. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Survey of the year 2005: literature on applications of isothermal titration calorimetryJOURNAL OF MOLECULAR RECOGNITION, Issue 1 2007Adessamad Ababou Abstract Isothermal titration calorimetry (ITC) can provide a full thermodynamic characterization of an interaction. Its usage does not suffer from constraints of molecular size, shape or chemical constitution. Neither is there any need for chemical modification or attachment to solid support. This ease of use has made it an invaluable instrumental resource and led to its appearance in many laboratories. Despite this, the value of the thermodynamic parameterization has, only quite recently, become widely appreciated. Although our understanding of the correlation between thermodynamic data and structural details continues to be somewhat naïve, a large number of publications have begun to improve the situation. In this overview of the literature for 2005, we have attempted to highlight works of interest and novelty. Furthermore, we draw attention to those works which we feel have provided a route to better analysis and increased our ability to understand the meaning of thermodynamic change on binding. Copyright © 2006 John Wiley & Sons, Ltd. [source] Evaluation of Baccharis trimera and Davilla rugosa in tests for adaptogen activityPHYTOTHERAPY RESEARCH, Issue 6 2007Fúlvio Rieli Mendes Abstract Baccharis trimera (Asteraceae) and Davilla rugosa (Dilleniaceae) are used popularly as tonics, aphrodisiacs and for stomach ailments, among other uses. Hydroalcohol extracts of the aerial parts of both plants were investigated with regard to their chemical constitution and their pharmacological activity in tests that evaluate adaptogen activity. Alkaloids, flavonoids, saponins, polyphenols/tannins and coumarins were identified in both extracts, while lignans were found only in the extract of Davilla rugosa. This extract presented also a marked antioxidant activity and exerted a moderate antiulcer effect in rats submitted to cold immobilization stress. It did not, however, inhibit the increase in the levels of ACTH and corticosterone induced by stress. Moreover, the Davilla rugosa did not improve the physical performance of mice submitted to forced exercise and the learning time of old rats in the T-maze, neither did it reduce the blood viscosity of the old animals. Conversely, the Baccharis trimera extract only presented a moderate antioxidant activity, without any positive effect on the other tests. These results point to the absence of an adaptogen activity of Baccharis trimera, with some effects that could be related to such an activity as regards the Davilla rugosa. Copyright © 2007 John Wiley & Sons, Ltd. 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