Authors:Imre Klebovich, György Morovján, István Hazai and Emil Mincsovics
Glyceryl trinitrate (nitroglycerin), useful in the prevention and treatment of acute anginal attacks characteristic of ischemic heart disease, has been used as a model compound to evaluate the applicability of overpressured layer chromatography (OPLC) coupled with several radioactivity detection methods in metabolism research. Radioactivity detection methods studied included digital autoradiography (DAR), flow-cell solid scintillation radioactivity detection (RD), and the phosphor-imaging technique.After treatment of rats with
C-labeled glyceryl trinitrate, glyceryl trinitrate and its metabolites 1,2- and 1,3-glyceryl dinitrate and 1- and 2-glyceryl mononitrate were isolated from plasma by liquid-liquid extraction. OPLC separation of metabolites and glyceryl trinitrate was performed on fine-particle silica gel-coated TLC plates with acetonitrile-dibutyl ether mixtures as mobile phases and stepwise gradient elution.Detection of radiocarbon-labeled parent drug and its metabolites was performed off-line by digital autoradiography and the phosphor-imaging technique. On-line detection was performed by flow-cell solid scintillation radioactivity detection.OPLC coupled with RD combines the selectivity of radiochemical detection with the separation efficiency of overpressured liquid chromatography (OPLC); this is of great importance during metabolite screening and isolation. After sample extraction and application to the plate the selectivity of the system could be optimized. The optimization could be monitored by DAR, which could be chosen as detection method for the off-line analysis of multiple samples simultaneously separated on a single plate. Isolation of separated sample constituents could be performed after applying the sample as a single band to the plate and elution of metabolites of interest followed by their detection by use of on-line RD. Strongly retained compounds could be detected by DAR and removed mechanically, with the adsorbent, and extracted with a strong solvent.The recently developed on-line OPLC-RD method and the previously reported OPLC-DAR and HPLC-RD techniques are rapid, economic, and effective separation systems for application in metabolism research.
Authors:A. Martínez-Alonso, J. Bermejo and J. M. D. Tascón
Characterization of pitches by thermal analysis techniques is highly relevant to the practical use of these materials, as they undergo heat treatments in all of their utilization processes. The aim of this work was to improve the interpretation of the complex DTA curves of pitches by comparison with model compounds. For this, TG/DTG/DTA was used to study under identical conditions the pyrolysis of a petroleum pitch and a coal tar pitch as well as a number of polycyclic aromatic hydrocarbons. Results were interpreted as a function of the molecular structure, pyrolysis reactivity and graphitizability of cokes from the hydrocarbons. It is concluded that condensation and polymerization, which are the most likely exothermal reactions predominant in petroleum pitches, indicate the presence therein of reactive molecules. Alternatively, endothermal phenomena such as distillation, depolymerization and cracking, predominant in coal tar pitches, suggest the presence of light, little reactive aromatic molecules.
lignin substructure modelcompound by laccase of Corioluc versicolor. Mokuzai Gakkaishi 33 , 792-797.
CαaL-CβbT-cleavage of phenolic βbT-1 lignin substructure modelcompound by laccase of Corioluc versicolor
Authors:Şule Seçkin, Şeyda Alsancak, Canan Başaran-Küçükgergin and Müjdat Uysal
Barriere, M., Piriou, A., Tallineau, C., Boulard, M., Mura, P., Guettier, A., Pourrat, O. (1983) Intoxication by benzodiazepines: studies with diazepam used as a modelcompound suggest an interaction with red
Authors:Khaja W. Ahmed, Syed A. Ali, Shakeel Ahmed and Muhammad A. Al-Saleh
results indicate that the HDS of BT is significantly higher compared to DBT, especially at lower temperatures. This result showed that DBT is far more difficult to desulfurize and hence it is considered as a relatively refractory modelcompound
Authors:Y. Li, Z. Yingyuan, L. Yonghui, J. Jing and W. Xiaoqing
these modelcompounds in aqueous solution can provide information about the various contributions to the interaction between hydrated molecules and help us understand the important interactions that determine protein stability.
As amino acids are
Authors:Blaž Likozar, Romana Cerc Korošec, Ida Poljanšek, Primož Ogorelec and Peter Bukovec
combination of literature band assignments, a study of the Raman spectra of modelcompounds and well characterized MF adducts and resins. Modelcompound studies by Jones et al. [ 4 ] suggested that >N–CH 2 –N< bridges are less stable than widely thought unless