Search results for "cyclic"
showing 10 items of 2439 documents
"Sweet Chemistry": a Green Way for Obtaining Selenium Nanoparticles Active against Cancer Cells
2017
We present an environment friendly synthesis of selenium nanoparticles and the study of their cytotoxic activity against uterine sarcoma cancer and fibroblasts cells. Amorphous selenium (a-SeNPs) and trigonal selenium (t-SeNPs) were synthesized using D-fructose as the reducing agent and characterized by high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction analysis (XRD), inductively coupled plasma optical emission spectrometry (ICP OES), dynamic light scattering (DLS) to obtain zeta potential values and cyclic voltammetry (CV). Particularly, a-SeNPs presented high toxicity toward the resistant cancer cell line MES-SA/…
Stereoselective synthesis of 2-amino-1-hydroxy-3-phenylpropylphosphonic acid
1996
Abstract A highly stereoselective synthesis of 2-amino-1-hydroxy-3-phenylpropylphosphonic acid was achieved by simple addition of diethyl phosphite to enantiomeric N-blocked phenylalaninals. These compouds exhibit significant herbicidal activity.
Enantioselective Synthesis of Unsymmetrical Benzoins from (S)-Mandelic Acid Enolate and Aromatic Aldehydes.
2004
The reaction of the lithium enolate of the 1,3-dioxolan-4-one derived from optically active (S)-mandelic acid and pivalaldehyde with aromatic aldehydes proceeds readily to give the corresponding aldol products in good yields and diastereoselectivities. Subsequent hydroxyl protection, basic hydrolysis of the dioxolanone, oxidative decarboxylation of the α-hydroxyacid moiety, and hydroxyl deprotection provides chiral unsymmetrical benzoins with high enantiomeric excesses.
ChemInform Abstract: Stereoselective Synthesis of 2-Amino-1-hydroxy-3- phenylpropylphosphonic Acid.
2010
Abstract A highly stereoselective synthesis of 2-amino-1-hydroxy-3-phenylpropylphosphonic acid was achieved by simple addition of diethyl phosphite to enantiomeric N-blocked phenylalaninals. These compouds exhibit significant herbicidal activity.
Cationic mono- and bi-nuclear iron complexes as Lewis acid catalysts in Mukaiyama reactions
1992
Organometallic Lewis acids derived from photolysis of mono- and bi-nuclear cationic iron carbonyl complexes function as excellent catalysts for the Mukaiyama aldol reaction.
Anti-inflammatory drimane sesquiterpene lactones from an Aspergillus species
2014
Abstract IFN-γ inducible protein 10 (IP-10, CXCL10) is a 10 kDa chemokine, which is secreted from various cell types after exposure to pro-inflammatory stimuli. This chemokine is a ligand for the CXCR3 receptor and regulates immune responses by activating and recruiting leukocytes such as T cells, eosinophils, monocytes, and NK cells to sites of inflammation. Altered expression of CXCL10 has been associated with chronic inflammatory and infectious diseases and therefore CXCL10 represents a promising target for the development of new anti-inflammatory drugs. In a search for inhibitors of CXCL10 promoter activity, three structurally related drimane sesquiterpene lactones (compounds 1–3) were …
The fungal lactone oxacyclododecindione is a potential new therapeutic substance in the treatment of lupus-associated kidney disease.
2013
Recently oxacyclododecindione (Oxa), a macrocyclic lactone isolated from the imperfect fungus Exserohilum rostratum, has been described as a potent transcription inhibitor of inducible proinflammatory and profibrotic genes in cell culture models. As kidney disease in systemic lupus erythematosus is characterized by aberrant expression of inflammatory mediators and infiltration of immune cells, we investigated the effect of Oxa in MRL-Fas(lpr) mice, a model of systemic lupus erythematosus. These mice develop a spontaneous T-cell and macrophage-dependent autoimmune disease including severe glomerulonephritis that shares features with human lupus. Comparable to the results of in vitro models, …
Zidovudine (AZT) causes an oxidation of mitochondrial DNA in mouse liver
1999
Zidovudine (3′-azido-2′,3′-dideoxythymidine [AZT]) inhibits human immunodeficiency virus replication and delays progression of acquired immune deficiency syndrome. We have recently found that, in muscle, AZT causes oxidative damage to mitochondrial DNA (mtDNA) and other signs of mitochondrial oxidative damage. The aim of this work was to test if AZT causes oxidative damage to liver mtDNA. In our study, an experimental mouse model was used in which mice were administered AZT (10 mg/kg body weight/d) in drinking water. Liver mtDNA of mice treated with AZT had 40% more of the oxidized, mutagenic nucleoside, 8-oxo-7,8-dihydroxy-2′deoxyguanosine (8-oxo-dG) than untreated controls. This oxidative…
Solution-, solid-phase, and fluorous synthesis of beta,beta-difluorinated cyclic quaternary alpha-amino acid derivatives: a comparative study.
2008
The diastereoselective synthesis of cyclic beta,beta-difluorinated alpha-amino acid derivatives bearing a quaternary stereocenter is described. The process relies on the chemo- and diastereoselective addition of allylic organometallic reagents to fluorinated alpha-imino esters and a subsequent ring-closing metathesis reaction (RCM). Complete selectivity in the nucleophilic addition was achieved with (R)-phenylglycinol methyl ether as a chiral auxiliary. The resulting amino acids were introduced into peptide chains, which could facilitate the preparation of potentially bioactive dipeptide derivatives. In addition, the solution synthesis of these cyclic fluorinated alpha-amino acids was succe…
Cross-Metathesis Reactions as an Efficient Tool in the Synthesis of Fluorinated Cyclic β-Amino Acids
2009
The synthesis of enantiomerically pure, cyclic, gamma,gamma-difluorinated beta-amino acids with various ring sizes has been carried out with a cross-metathesis (CM) reaction being one of the key steps, followed by a Dieckmann-type condensation to bring about the cyclization. Subsequent catalytic hydrogenation under microwave irradiation with (-)-8-phenylmenthol as a chiral auxiliary led to the successful chemo- and diastereoselective chemical reduction of the resulting cyclic beta-enamino esters. The efficiency and scope of the CM reaction with different types of fluorinated imidoyl chlorides and unsaturated esters has also been studied in order to determine the optimal reaction conditions …