Search results for "NOAC"
showing 10 items of 144 documents
Ionic liquids as solvents for the Knoevenagel condensation: understanding the role of solvent–solute interactions
2015
The Knoevenagel condensation in ionic liquids has been demonstrated as a strongly solvent-dependent process. The objective of this study was to establish a simple and descriptive trend of solvent–solute interactions that favour the Knoevenagel condensation in ionic liquid media. The reaction between 4-(dimethylamino)benzaldehyde and ethyl cyanoacetate in several imidazolium- and pyrrolidinium-based ionic liquids and one ionic liquid mixture was studied. The rate constants were rationalised by studying the change in the 1H NMR chemical shift of representative starting materials in the ionic liquids and the measurement and consideration of the Kamlet–Taft descriptors for each solvent. The hyd…
Presence and coding properties of 2'-O-methyl-5-carbamoylmethyluridine (ncm5Um) in the wobble position of the anticodon of tRNA(Leu) (U*AA) from brew…
1992
AbstractThe unknown modified nucleoside U* has been isolated by enzymatic and HPLC protocols from tRNALeu(U*AA) recently discovered in brewer's yeast. The pure U* nucleoside has been characterized by electron impact mass spectroscopy, and comparison of its chromatographic and UV-absorption properties with those of appropriate synthetic compounds. The structure of U* was established as 2′-O-methyl-5-carbamoylmethyluridine (ncm5Um). The yeast tRNALeu (U*AA) is the only tRNA so far sequenced which has been shown to contain ncm5Um. The location of such a modified uridine at the first position of the anticodon restricts the decoding property to A of the leucine UUA codon.
1,2,4-Oxadiazole topsentin analogs as staphylococcal biofilm inhibitors targeting the bacterial transpeptidase sortase A
2020
The inhibition or prevention of biofilm formation represents an emerging strategy in the war against antibiotic resistance, interfering with key players in bacterial virulence. This approach includes the inhibition of the catalytic activity of transpeptidase sortase A (Srt A), a membrane enzyme responsible for covalently attaching a wide variety of adhesive matrix molecules to the peptidoglycan cell wall in Gram-positive strains. A new series of seventeen 1,2,4-oxadiazole derivatives was efficiently synthesized and screened as potential new anti-virulence agents. The ability of inhibiting biofilm formation was evaluated against both Gram-positive and Gram-negative pathogens. Remarkably, all…
Reacciones de cicloadición formal enantioselectivas con isocianoacetatos
2020
En la presente tesis doctoral se ha llevado a cabo el estudio de la cicloadición formal [3+2] enantioselectiva de isocianoacetatos a diferentes electrófilos para la formación de nuevas estructuras cíclicas nitrogenadas. Para ello, se ha desarrollado un método catalítico cooperativo consistente en un organocatalizador bifuncional de tipo escuaramida y óxido de plata como ácido de Lewis. En el primer capítulo se ha estudiado la reacción de adición de isocianoacetatos a trifluoroacetofenonas para la obtención de 2-oxazolinas con dos centros estereogénicos consecutivos, siendo uno de ellos cuaternario y estando sustituido con un grupo trifluorometilo. Se ha estudiado el alcance y las limitacion…
Benzaldehīda kondensācijas reakcijas ar etilciānoacetātu un malonskābi jonu šķidrumos
2015
Benzaldehīda kondensācijas reakcijas ar etilciānoacetātu un malonskābi jonu šķidrumos. Kolesnikova K., zinātniskais vadītājs Dr.h.ķīm., prof. Zicmanis A. Maģistra darbs, 79 lappuses, 53 attēli, 24 tabulas, 69 literatūras avoti. Latviešu valodā. Maģistra darbā ir apkopota vispārīga informācija par jonu šķidrumiem: iegūšanas metodēm, to īpašībām un izmantošanas iespējām, kā arī aplūkota literatūra par Knēvenāgela kondensāciju un tās Dēbnera modifikāciju. Darbā ir veikta vairāku jonu šķidrumu sintēze. Iegūto jonu šķidrumu struktūras tika pieradītas ar 1H KMR spektroskopijas metodi, tad JŠ tika izmantoti kā šķīdinātāji Knēvenāgela kondensācijas reakcijā un Knēvenāgela-Dēbnera kondensācijas reak…
Dažu karbonilsavienojumu kondensācija ar etilcianoacetātu jonu šķidrumu vidēs
2017
Dažu karbonilsavienojumu kondensācija ar etilcianoacetātu jonu šķidrumu vidēs. Kuļikovska L., darba vadītājs Dr.h.ķīm., prof. Zicmanis A. Bakalaura darbs, 55 lappuses, 20 attēli, 6 tabulas, 52 literatūras avoti, 18 pielikums. Latviešu valodā. Literatūras apskata daļa satur vispārīgu informāciju par jonu šķidrumu iegūšanu, to uzbūvi, īpašībām, attīrīšanu, kā arī literatūras apskatu par jonu šķidrumu izmantošanu Knēvenāgela kondensācijas reakcijās. Laboratorijā tika iegūti vairāki 1,3-dialkilimidazolija un 1,2,3-tiralkilimidazolija rindas jonu šķidrumu ar hlorīda un dimetilfosfāta anjoniem, izmantojot dažādas metodes. Iegūto savienojumu struktūras raksturotas ar 1H KMR metodi un noteiktas to …
2,4-Dimetoksibenzaldehīda kondensācija ar etilcianoacetātu jonu šķidrumu vidēs
2019
2,4-Dimetoksibenzaldehīda kondensācija ar etilcianoacetātu jonu šķidrumu vidēs. Maševska Z., zinātniskais vadītājs prof., Dr.h.ķīm. Zicmanis A. Maģistra darbs, 54 lappuses, 14 attēli, 10 tabulas, 66 literatūras avoti, 19 pielikumi. Latviešu valodā. Darbā apkopota literatūra par jonu šķidrumu iegūšanas metodēm, to attīrīšanu, toksiskajām īpašībām, fizikāli-ķīmiskajām īpašībām. Apkopota informācija par Knēvenāgela kondensācijas reakcijas principiem. Sintezēti 17 strukturāli atšķirīgi jonu šķidrumi. Veiktas Knēvenāgela kondensācijas reakcijas jonu šķidrumu vidēs, izvērtēti iegūtie rezultāti. Iegūtie rezultāti salīdzināti ar citiem līdzīgiem pētījumiem.
Elevated levels of 2-arachidonoylglycerol promote atherogenesis in ApoE-/- mice.
2018
Background The endocannabinoid (eCB) 2-arachidonoylglycerol (2-AG) is a known modulator of inflammation and ligand to both, pro-inflammatory cannabinoid receptor 1 (CB1) and anti-inflammatory CB2. While the role of both receptors in atherogenesis has been studied extensively, the significance of 2-AG for atherogenesis is less well characterized. Methods The impact of 2-AG on atherogenesis was studied in two treatment groups of ApoE-/- mice. One group received the monoacylglycerol lipase (MAGL)-inhibitor JZL184 [5 mg/kg i.p.], which impairs 2-AG degradation and thus causes elevated 2-AG levels, the other group received vehicle for four weeks. Simultaneously, both groups were fed a high-chole…
An in vitro and in vivo study of peptide-functionalized nanoparticles for brain targeting: The importance of selective blood-brain barrier uptake
2017
Targeted delivery of drugs across endothelial barriers remains a formidable challenge, especially in the case of the brain, where the blood-brain barrier severely limits entry of drugs into the central nervous system. Nanoparticle-mediated transport of peptide/protein-based drugs across endothelial barriers shows great potential as a therapeutic strategy in a wide variety of diseases. Functionalizing nanoparticles with peptides allows for more efficient targeting to specific organs. We have evaluated the hemocompatibilty, cytotoxicity, endothelial uptake, efficacy of delivery and safety of liposome, hyperbranched polyester, poly(glycidol) and acrylamide-based nanoparticles functionalized wi…
Influence of leucine on intestinal baclofen absorption as a model compound of neutral α-aminoacids
1995
The inhibitory effect of the essential alpha-aminoacid L-leucine on the intestinal absorption of the antispastic drug baclofen was examined by means of an in situ rat gut perfusion technique. When 0.5 mM baclofen solutions were perfused in the presence of increasing concentrations of the aminoacid (5-100 mM), the apparent absorption rate constant of the drug decreased as the initial leucine concentration increased. Higher leucine concentrations however did not completely abolish the absorption of the drug (at 100 mM of leucine, only 76% inhibition was observed). The interaction can be mathematically described as a complete competitive inhibition with a second component, K = 0.35 (+/- 0.08)h…