Their Structures (their + structure)

Distribution by Scientific Domains

Selected Abstracts

Electrochemistry of Mitochondria: A New Way to Understand Their Structure and Function

Jing Zhao
Abstract In this article, electrochemistry of mitochondria is achieved. Cyclic voltammograms of freshly prepared mitochondria were obtained by immobilizing mitochondria together with glutaraldehyde and bovine serum albumin on the surface of a pyrolytic graphite electrode. Two pairs of redox peaks could be observed which were ascribed to the electron transfer reactions of cytochrome c and FAD/FADH2. Study of submitochondrial particles was also conducted, which could confirm the results of the study of the entire mitochondria. The redox wave of NADH could be obtained due to the destruction of the membrane of mitochondria. We have also checked the function of succinate in mitochondria by employing the electrochemical method. This work is not only the first to be able to obtain the direct electrochemistry of mitochondria, but is also beneficial to the further understanding of the structure and function of mitochondria in vitro. [source]

An Alternative Approach to Constructing Solution Processable Multifunctional Materials: Their Structure, Properties, and Application in High-Performance Organic Light-Emitting Diodes

Shanghui Ye
Abstract A new series of full hydrocarbons, namely 4,4,-(9,9,-(1,3-phenylene)bis(9H -fluorene-9,9-diyl))bis(N,N -diphenylaniline) (DTPAFB), N,N,-(4,4,-(9,9,-(1,3-phenylene)bis(9H -fluorene-9,9-diyl))bis(4,1-phenylene))bis(N -phenylnaphthalen-1-amine) (DNPAFB), 1,3-bis(9-(4-(9H -carbazol-9-yl)phenyl)-9H -fluoren-9-yl)benzene, and 1,3-bis(9-(4-(3,6-di- tert -butyl-9H -carbazol-9-yl)phenyl)-9H -fluoren-9-yl)benzene, featuring a highly twisted tetrahedral conformation, are designed and synthesized. Organic light-emitting diodes (OLEDs) comprising DNPAFB and DTPAFB as hole transporting layers and tris(quinolin-8-yloxy)aluminum as an emitter are made either by vacuum deposition or by solution processing, and show much higher maximum efficiencies than the commonly used N,N,-di(naphthalen-1-yl)- N,N,-diphenylbiphenyl-4,4,-diamine device (3.6 cd A,1) of 7.0 cd A,1 and 6.9 cd A,1, respectively. In addition, the solution processed blue phosphorescent OLEDs employing the synthesized materials as hosts and iridium (III) bis[(4,6-di-fluorophenyl)-pyridinato-N, C2] picolinate (FIrpic) phosphor as an emitter present exciting results. For example, the DTPAFB device exhibits a brightness of 47 902 cd m,2, a maximum luminescent efficiency of 24.3 cd A,1, and a power efficiency of 13.0 lm W,1. These results show that the devices are among the best solution processable blue phosphorescent OLEDs based on small molecules. Moreover, a new approach to constructing solution processable small molecules is proposed based on rigid and bulky fluorene and carbazole moieties combined in a highly twisted configuration, resulting in excellent solubility as well as chemical miscibility, without the need to introduce any solubilizing group such as an alkyl or alkoxy chain. [source]

ChemInform Abstract: A Novel Synthesis of 2-Arylpyrrolo[1,2-a]pyrimid-7-ones and Their Structure,Activity Relationships as Potent GnRH Receptor Antagonists.

CHEMINFORM, Issue 24 2002
Yun-Fei Zhu
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Synthesis of 9,9-Dialkyl-4,5-diazafluorene Derivatives and Their Structure,Activity Relationships Toward Human Carcinoma Cell Lines

CHEMMEDCHEM, Issue 4 2010
Qiwei Wang
Abstract A homologous set of 9,9-dialkyl-4,5-diazafluorene compounds were prepared by alkylation of 4,5-diazafluorene with the appropriate alkyl bromide and under basic conditions. The structures of these simple organic compounds were confirmed by spectroscopic techniques (FTIR, NMR, and FABMS). Their biological effects toward a panel of human carcinoma cells, including Hep3B hepatocellular carcinoma, MDAMB-231 breast carcinoma, and SKHep-1 hepatoma cells, were investigated; a structure,activity correlation was established with respect to the length of the alkyl chain and the fluorene ring structure. The relationship between the mean potency [log(1/IC50)] and alkyl chain length was systematically studied. The results show that compounds with butyl, hexyl, and octyl chains exhibit good growth inhibitory effects toward these three human carcinoma cell lines, and the 9,9-dihexyl-4,5-diazafluorene further exhibits antitumor activity in athymic nude mice Hep3B xenograft models. For the structurally related dialkylfluorenes that lack the diaza functionality, in,vitro cytotoxicity was not observed at clinically relevant concentrations. [source]

Copper Complexes with Neutral N4 Tripodal Ligands: Influence of the Number of Nitrogen Donors on Their Structures, Properties, and Reactivity,

Kiyoshi Fujisawa
Abstract Copper coordination complexes of the neutral tetradentate nitrogen-containing ligands tris(3,5-dimethylpyrazol-1-ylmethyl)amine (L0N4) and tris(3,5-diisopropylpyrazol-1-ylmethyl)amine (L1N4), namely the copper(II) chlorido complexes [CuII(L0N4)Cl2] (1) and [CuII(L1N4)Cl2] (2), the copper(II) nitrato complexes [CuII(L0N4)(NO3)](NO3) (3) and [CuII(L1N4)(NO3)](NO3) (4), and the copper(II) sulfato complexes [CuII(L0N4)(SO4)] (5) and [CuII(L1N4)(SO4)] (6), and the copper(I) complexes [CuI(L0N4)](PF6) (7) and [CuI(L0N4)(PPh3)](ClO4) (8), have been systematically synthesized in order to investigate the influence of the number of nitrogen donors on their structures, properties, and reactivity. All copper(II) complexes were fully characterized by X-ray crystallography and by IR/far-IR, UV/Vis absorption, and ESR spectroscopy. Although the structure of 7 was not determined by X-ray crystallography, this complex and the structurally characterized copper(I) triphenylphosphane complex 8 were fully characterized by IR/far-IR and NMR spectroscopy. A comparison of the copper(II) complexes with two tris(pyrazol-1-ylmethyl)amine ligands with different bulkiness of the pyrazolyl rings has allowed us to evaluate the second coordination sphere effects of the ligands. Moreover, the structures and physicochemical properties of these complexes are compared with those of related complexes containing the neutral tridentate tris(pyrazolyl)methane ligand and the neutral bidentate bis(pyrazolyl)methane ligand. Finally, the relative stability of the copper(I) complexes is discussed. The influence of the number of nitrogen donors in copper complexes is observed from these systematic results.( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

New Triterpenoidal Saponins from Gypsophila repens

Mohamed Elbandy
Abstract Six new triterpene glycosides, repensosides A,F (1,6, resp.), were isolated from the roots of Gypsophila repens L. Their structures, established by extensive 1D- and 2D-NMR spectroscopic experiments as well as MS analyses, were found to be based on gypsogenic acid (or gypsogenin) as aglycone, with three to nine branched or unbranched sugar moieties. [source]

Three New Polyketide Metabolites from the Endophytic Fungal Strain Cladosporium tenuissimum LR463 of Maytenus hookeri

Huan-Qin Dai
Abstract Three new polyketide metabolites, the twelve-membered macrolides (6R,12S)-6-hydroxy-12-methyloxacyclodoecane-2,5-dione (1), (10S,12S)-10-hydroxy-12-methyloxacyclododecane-2,5-dione (2), and 4,5-dihydroxy-12-methyloxacyclododecan-2-one (3), were isolated from the endophytic fungal strain Cladosporium tenuissimum LR463 of Maytenus hookeri, together with three known compounds, cladospolide A, cladospolide B, and isocladospolide B. Their structures were elucidated by spectroscopic analysis including 1D- and 2D-NMR experiments, and the absolute configurations of 1 and 2 were determined by the Mosher ester method. [source]

Cyclopeptides and Amides from Pseudostellaria heterophylla (Caryophyllaceae)

Ya-bin Yang
From the roots of Pseudostellaria heterophylla, three cyclopeptides and three amides were isolated, besides heterophyllin A and B. Their structures were determined as cyclo (Ala-Gly-Pro-Val-Tyr-) (heterophyllin J; 1), cyclo (Ala-Gly-Pro-Tyr-Leu-) (pseudostellarin A; 2), cyclo (Gly-Gly-Gly-Pro-Pro-Phe-Gly-Ile-) (pseudostellarin B; 3), methyl , -hydroxypyroglutamate (4), methyl pyroglutamate (5), and pyroglutamic acid (6) on the basis of spectral data, especially 2D-NMR data. Among them, compounds 1 and 4 are new compounds. [source]

Polyprenylated Phloroglucinol Derivatives from Hypericum sampsonii

Yun-Lian Lin
Six new prenylated phloroglucinol derivatives, hypersampsones A,F (1,6), were isolated from the aerial part of Hypericum sampsonii, together with 2,4,6-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone 4- O -geranyl ether, 2,4,6-trihydroxybenzophenone 3- C -geranyl ether, sampsoniones D and H. Their structures were elucidated by spectroscopic methods, mainly 1D- and 2D-NMR spectroscopy and mass spectrometry. [source]

Novel azapeptide inhibitors of cathepsins B and K. Structural background to increased specificity for cathepsin B

E. Wieczerzak
Abstract:, We have designed and synthesized a new series of azapeptides which act as potential inhibitors of cathepsin B and/or cathepsin K. Their structures are based upon the inhibitory sites of natural cysteine protease inhibitors, cystatins. For the synthesized azapeptides, the equilibrium constants for dissociation of inhibitor,enzyme complex, Ki, were determined. Comparison of these values indicated that all of the azainhibitors act much stronger toward cathepsin B. Z-Arg-Leu-His-Agly-Ile-Val-OMe (7) proved to be approximately 500 times more potent for cathepsin B than for cathepsin K. To be able to explain the obtained experimental values we used the molecular dynamics procedures to analyze the interactions between cathepsin B and compound 7. We also determined the structure of the most potent and selective cathepsin B azainhibitor by means of NMR studies and theoretical calculations. In this report, we describe SAR studies of azapeptide inhibitors indicating the influence of the conformational flexibility of the examined compounds on inhibition of cathepsins B and K. [source]