Rhodium
Cyclization
Catalysis
Effects of a lipoxygenase inhibitor, panaxynol, on vascular contraction induced by angiotensin II. (1/35)
We investigated whether a lipoxygenase inhibitor, panaxynol, affected the vascular contraction induced by angiotensin (Ang) II and the mean arterial pressure in spontaneously hypertensive rats (SHR). Panaxynol suppressed dose-dependently the contractile responses induced by 30 nM Ang II in isolated intact and endothelial cell-denuded aorta in the hamster. IC50 values in the intact and endothelial cell-denuded aorta were 23 and 20 microM, respectively. In SHR, the mean arterial pressure after injection of 30 and 60 mg/kg panaxynol was reduced, and the maximum hypotensive values were 23 and 48 mmHg, respectively. Thus, lipoxygenase products may affect the renin-angiotensin system. (+info)Cerebral microvascular endothelial cell tube formation: role of astrocytic epoxyeicosatrienoic acid release. (2/35)
Cerebral microvascular endothelial cells (CMVEC) form tubes when cocultured with astrocytes (AS). Therefore, it appears that AS may be important in mediating angiogenesis in the brain. We hypothesized that AS modulate CMVEC tube formation by releasing a soluble factor. Thymidine incorporation in cultured CMVEC increased 305% when incubated with 50% conditioned AS medium for 24 h [control: 52,755 +/- 4,838 counts per minute (cpm) per well, conditioned 161,082 +/- 12,099 cpm/well, n = 8]. Because our laboratory has previously shown that AS can produce epoxyeicosatrienoic acids (EETs), which are known mitogens, we investigated whether release of EETs by AS is responsible for tube formation in the CMVEC-AS coculture. AS were seeded on Lab-Tek slides, CMVEC were seeded on the AS the next day, and cultures were allowed to progress for another 5 days with and without cytochrome P-450 epoxygenase blockade by 17-octadecynoic acid (17-ODYA). Tube formation in cocultures receiving 17-ODYA was significantly inhibited compared with control (93.8%). These data suggest that tube formation requires the release of EETs by AS. (+info)Chemical constituents from the colombian medicinal plant Niphogeton ternata. (3/35)
Two coumarins and one polyacetylene, 5-0-(3-chloro-2-hydroxy-3-methylbutyl)-8-methoxypsoralen (1), 2',3'-dihydro-jatamansin (2), and 10-chloro-1-heptadecene-4,6-diyne-3,8,9-triol (3), along with 15 known compounds (4-18), were isolated from the methanol extract of Niphogeton ternata. Their structures were elucidated by spectroscopy. (+info)Synthesis of panax acetylenes: chiral syntheses of acetylpanaxydol, PQ-3 and panaxydiol. (4/35)
Acetylpanaxydol (1-Ac), PQ-3 (2) and panaxydiol (3) and their optical isomers were synthesized from L-(+)-diethyl tartrate. The absolute configurations of 1-Ac, 2 and 3 were determined to be 1-Ac (3R,9R,10S), 2 (9R,10S) and 3 (3R,10S), respectively, by comparisons of their optical rotations and the NMR data of their MTPA esters with those of natural products. (+info)Effects of the polyacetylene capillin on human tumour cell lines. (5/35)
We investigated the effects of capillin, a constituent of Artemisia monosperma, on four human tumour cell lines: colon carcinoma H729, pancreatic carcinoma MIA PaCa-2, epidermoid carcinoma of the larynx HEp-2 and lung carcinoma A549. Cells were treated with capillin to examine both the anti-proliferative and pro-apoptotic effects, as well as the molecular mechanism underlying these effects. Changes in cell proliferation, membrane permeability, macromolecular synthesis, glutathione (GSH), cell cycle and programmed cell death were evaluated. Capillin (1microM-10microM) inhibited cell proliferation and decreased macromolecular synthesis simultaneously, in a dose- and time-dependent manner. Co-incubation with L-buthionine sulfoximine (L-BSO) augmented the efficacy of capillin. Capillin modulated GSH levels, accumulated cells in the S+G2/M-phase of the cell cycle and induced cell death and DNA fragmentation, as indicated by flow cytometry, fluorescence microscopy and DNA fragmentation assay. These findings suggest that capillin has cytotoxic activity and can induce apoptosis in human tumour cell lines. (+info)A small molecule Smac mimic potentiates TRAIL- and TNFalpha-mediated cell death. (6/35)
We describe the synthesis and properties of a small molecule mimic of Smac, a pro-apoptotic protein that functions by relieving inhibitor-of-apoptosis protein (IAP)-mediated suppression of caspase activity. The compound binds to X chromosome- encoded IAP (XIAP), cellular IAP 1 (cIAP-1), and cellular IAP 2 (cIAP-2) and synergizes with both tumor necrosis factor alpha (TNFalpha) and TNF-related apoptosis-inducing ligand (TRAIL) to potently induce caspase activation and apoptosis in human cancer cells. The molecule has allowed a temporal, unbiased evaluation of the roles that IAP proteins play during signaling from TRAIL and TNF receptors. The compound is also a lead structure for the development of IAP antagonists potentially useful as therapy for cancer and inflammatory diseases. (+info)Falcarindiol impairs the expression of inducible nitric oxide synthase by abrogating the activation of IKK and JAK in rat primary astrocytes. (7/35)
The effects of falcarindiol on the expression of inducible nitric oxide synthase (iNOS) induced by lipopolysaccharide/interferon-gamma (LPS/IFN-gamma) in rat primary astrocytes were investigated. The molecular mechanisms underlying falcarindiol that confers its effect on iNOS expression were also elucidated. Falcarindiol abrogated the LPS/IFN-gamma-mediated induction of iNOS by about 80%. Falcarindiol attenuated the induction of iNOS in a concentration-dependent manner. The inhibitory effect of falcarindiol on iNOS induction was attributable to decrease in the protein content and the mRNA level of iNOS. Treatment with 50 microM of falcarindiol for 30 min decreased LPS/IFN-gamma-induced nuclear factor-kappaB (NF-kappaB) activation by 32%. Treatment with 50 microM of falcarindiol for 60 min diminished the LPS/IFN-gamma-mediated activation of IkappaB kinase-alpha (IKK-alpha) and IKK-beta by 28.2 and 29.7%, respectively. Falcarindiol modulated the nuclear translocation of signal transducer and activator of transcription 1 (Stat1) in a time-dependent manner. Falcarindiol (50 microM) decreased the tyrosine phosphorylation of janus kinase 1 (JAK1) by 84.8% at 5 min. Falcarindiol also abrogated the tyrosine phoshorylation of JAK2 by 82.3% at 10 min.The present study demonstrates that falcarindiol attenuated the activation of IKK and JAK contributing to the blockade of activation of NF-kappaB and Stat1, thereby leading to the suppression of iNOS expression. (+info)Electrolyte effects on bilayer tubule formation by a diacetylenic phospholipid. (8/35)
A general effect by dissolved electrolytes to destabilize the curvature of bilayer tubules prepared from the diacetylenic phospholipid, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine is not found. This observation discounts the role of an electrostatic interaction between polarization charges on the edges of a ferroelectric bilayer as a means by which the cylindrical curvature may be stabilized in these structures (de Gennes, P. G. 1987. C. R. Acad. Sci. Paris. 304:259-263). The solution-mediated ionic interactions of electrolytes with this phospholipid appear not to influence significantly the relative stability of the crystalline state of the tubule, but at high levels of a few salts, may affect the nucleation and growth of the crystalline bilayer. Curvature of the bilayer in these tubular structures apparently derives from an interaction that is not very sensitive to the presence of electrolytes. Cylindrical curvature may alternatively arise from a bending force within the bilayer that is intrinsic to the anisotropic packing of the lipid molecules (Helfrich, W., and J. Prost. 1988. Phys. Rev. A38:3065-3068; Chappell, J. S., and P. Yager. 1991. Chem. Phys. Lipids. In press), and may therefore be largely determined by the packing interactions within the hydrophobic region of the tubular bilayer. (+info)Diynes are organic compounds that contain two carbon-carbon triple bonds in their molecular structure. The general chemical formula for diynes is R-C≡C-C≡C-R, where R can be a hydrogen atom or any organic group. Diynes are important building blocks in organic synthesis and have been used to create complex molecules, nanomaterials, and pharmaceuticals. They are also of interest in materials science due to their unique electronic properties and potential applications in optoelectronics and photonics.
I'm sorry for any confusion, but "Rhodium" is not a medical term. It is a chemical element with the symbol Rh and atomic number 45. It is a rare, silvery-white, hard, corrosion-resistant, and chemically inert transition metal. It is found in small quantities in platinum or nickel ores along with some other rare metals.
It's primarily used in industrial applications, such as being a key component in catalytic converters in automobiles, which helps to reduce harmful emissions. It's also used in jewelry, electronics, and scientific instruments due to its properties of resistance to corrosion and heat.
If you have any medical terms or concepts that you would like me to explain, please let me know!
Cyclization is a chemical process that involves forming a cyclic structure or ring-shaped molecule from a linear or open-chain compound. In the context of medicinal chemistry and drug design, cyclization reactions are often used to synthesize complex molecules, including drugs, by creating rings or fused ring systems within the molecule's structure.
Cyclization can occur through various mechanisms, such as intramolecular nucleophilic substitution, electrophilic addition, or radical reactions. The resulting cyclized compounds may exhibit different chemical and biological properties compared to their linear precursors, making them valuable targets for drug discovery and development.
In some cases, the cyclization process can lead to the formation of stereocenters within the molecule, which can impact its three-dimensional shape and how it interacts with biological targets. Therefore, controlling the stereochemistry during cyclization reactions is crucial in medicinal chemistry to optimize the desired biological activity.
Overall, cyclization plays a significant role in the design and synthesis of many pharmaceutical compounds, enabling the creation of complex structures that can interact specifically with biological targets for therapeutic purposes.
Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst, which remains unchanged at the end of the reaction. A catalyst lowers the activation energy required for the reaction to occur, thereby allowing the reaction to proceed more quickly and efficiently. This can be particularly important in biological systems, where enzymes act as catalysts to speed up metabolic reactions that are essential for life.
Molecular structure, in the context of biochemistry and molecular biology, refers to the arrangement and organization of atoms and chemical bonds within a molecule. It describes the three-dimensional layout of the constituent elements, including their spatial relationships, bond lengths, and angles. Understanding molecular structure is crucial for elucidating the functions and reactivities of biological macromolecules such as proteins, nucleic acids, lipids, and carbohydrates. Various experimental techniques, like X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and cryo-electron microscopy (cryo-EM), are employed to determine molecular structures at atomic resolution, providing valuable insights into their biological roles and potential therapeutic targets.