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131.
Maddalena Donati Andrea Mondin Zheng Chen Fabricio Mendes Miranda Baraquizio Braga do Nascimento Jr Giulia Schirato 《Natural product research》2015,29(10):939-946
The essential oils (EOs) from the Brazilian species Croton zehntneri, Pterodon emarginatus and Schinopsis brasiliensis were examined for their chemical constituents, and antioxidant and antimicrobial activities. The composition of EOs was determined by using gas chromatography coupled with mass spectrometry analysis, while the antioxidant activity was evaluated through the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays. Furthermore, the antimicrobial activity was investigated against Escherichia coli and Pseudomonas aeruginosa (both Gram-negative), Staphylococcus aureus (Gram-positive) and Candida parapsilosis (fungus). The main components of C. zehntneri, P. emarginatus and S. brasiliensis were identified as estragole, trans-anethole, β-caryophyllene and myrcene. Among the EOs, P. emarginatus showed the highest antioxidant activity, with an IC50 of 7.36 mg/mL and a Trolox equivalent antioxidant capacity of 3748 μmol/g determined by DPPH and ORAC assays, respectively. All EOs showed low activities against the bacterial strains tested, whereas the C. zehntneri oil and its main constituent estragole exhibited an appreciable antifungal activity against C. parapsilosis. 相似文献
132.
Sabatino L Scordino M Gargano M Belligno A Traulo P Gagliano G 《Natural product communications》2011,6(12):1873-1876
The present study evaluated the reliability of the ISO/TS 3632-2 UV-Vis spectrometric method for saffron classification, making experiments on saffron samples to which were added increasing concentrations of common saffron spice adulterants (safflower, marigold and turmeric). The results showed that the ISO/TS 3632-2 method is not able to detect addition of up to 10-20%, w/w, of saffron adulterants. For additions from 20 to 50%, w/w, of the three adulterants, saffron was classified in a wrong category; addition of higher than 50%, w/w, determined variations in the investigated parameters that did not allow identification of the product as "saffron". In all cases, the method did not permit the recognition of the nature of the adulterant. On the contrary, the specificity of the HPLC/PDA/MS technique allowed the unequivocal identification of adulterant characteristic marker molecules that could be recognized by the values of absorbance and mass. The selection of characteristic ions of each marker molecule has revealed concentrations of up to 5%, w/w, for safflower and marigold and up to 2% for turmeric. In addition, the high dyeing power of turmeric allowed the determination of 2%, w/w, addition using exclusively the HPLC/PDA technique. 相似文献
133.
Aggarwal VK Binanzer M de Ceglie MC Gallanti M Glasspoole BW Kendrick SJ Sonawane RP Vázquez-Romero A Webster MP 《Organic letters》2011,13(6):1490-1493
Tertiary allyl- or crotylsilanes have been prepared in high er and dr via the lithiation-borylation reaction of alkyl carbamates with silaboronates. Using a related strategy, quaternary allylsilanes could be accessed in similarly high er. 相似文献
134.
Maddalena Bonanzinga Filippo Cammaroto Bruno A. Pansera 《Central European Journal of Mathematics》2011,9(3):583-592
The definition of monotone weak Lindelöfness is similar to monotone versions of other covering properties: X is monotonically weakly Lindelöf if there is an operator r that assigns to every open cover U a family of open sets r(U) so that (1) ∪r(U) is dense in X, (2) r(U) refines U, and (3) r(U) refines r(V) whenever U refines V. Some examples and counterexamples of monotonically weakly Lindelöf spaces are given and some basic properties such as the behavior with respect to products and subspaces are discussed. 相似文献
135.
We present a quantum reaction approach that unambiguously quantifies the complete and incomplete fusion of weakly-bound few-body nuclei. Calculations carried out within a simple model for \({\text{}^{6}}\)Li + \({\text{}^{209}}\)Bi at energies near the Coulomb barrier show that converged probabilities for the total, complete and incomplete fusion as well as for the scattering process can be obtained with the time-dependent wave-packet dynamics. 相似文献
136.
137.
A capillary GC-flame ionization detection (FID) method to determine volatile compounds (ethyl acetate, 1,1-diethoxyethane, methyl alcohol, 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 1-butanol, and 2-butanol) in wine was investigated in terms of calculation of detection limits and calibration method. The main objectives were: (1) calculation of regression coefficient parameters by ordinary least-squares (OLS) and bivariate least-squares (BLS) regression models, taking into account errors in both axes; (2) estimation of linear dynamic range (LDR) according to International Conference on Harmonization recommendations; (3) performance evaluation of a method by using three different internal standards (ISs) such as acetonitrile, acetone, and 1-pentanol; (4) evaluation of LODs according to the U.S. Environmental Protection Agency (EPA) 3sigma approach and the Hubaux-Vos (H-V) method; (5) application of H-V theory to a gas chromatographic analytical method and to a food matrix; and (6) accuracy assessment of the method relative to methyl alcohol content through a Unione Italiana Vini (UIV) interlaboratory proficiency test. Calibration curves calculated via BLS and OLS show similar slopes, while intercepts are closer to zero in the first case, independent of the chosen IS. The studied ISs show a substantially equivalent behavior, even though the IS closer to the analyte retention time seems to be more appropriate in terms of LDR and LOD. Results indicate an underestimation of LODs using the EPA 3sigma approach instead of the more realistic H-V method, both with OLS and BLS regression models. Methanol contents compared with UIV average values indicate recovery between 90 and 110%. 相似文献