Search results for "DISCOVERY"
showing 10 items of 4119 documents
Synthesis of tritiated derivatives of the diphenylether herbicides acifluorfen and acifluorfen methyl
1992
Acifluorfen 1 and acifluorfen methyl 2, two herbicides of the diphenylether family, are inhibitors of protoporphyrinogen oxidases. Two tritiated derivatives of these compounds, namely 3-[3H]-5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid [3H]-1, and methyl 3-[3H]-5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid [3H]-2, have been synthesised from 3-[3H]-5-hydroxybenzoic acid, in order to probe their interactions with the target enzymes.
N-Benzyl Residues as the P1′ Substituents in Phosphorus-Containing Extended Transition State Analog Inhibitors of Metalloaminopeptidases
2020
Peptidyl enzyme inhibitors containing an internal aminomethylphosphinic bond system (P(O)(OH)-CH2-NH) can be termed extended transition state analogs by similarity to the corresponding phosphonamidates (P(O)(OH)-NH). Phosphonamidate pseudopeptides are broadly recognized as competitive mechanism-based inhibitors of metalloenzymes, mainly hydrolases. Their practical use is, however, limited by hydrolytic instability, which is particularly restricting for dipeptide analogs. Extension of phosphonamidates by addition of the methylene group produces a P-C-N system fully resistant in water conditions. In the current work, we present a versatile synthetic approach to such modified dipeptides, based…
Anti-inflammatory and antiallergic activity in vivo of lipophilic Isatis tinctoria extracts and tryptanthrin.
2006
The effects of a supercritical CO2 (SFE) extract, a dichloromethane (DCM) extract from Isatis tinctoria leaf and the alkaloidal constituent tryptanthrin were studied in acute and subchronic experimental models of inflammation. The SFE and DCM extracts showed anti-inflammatory activity in the carrageenan-induced acute mouse paw oedema (ED50 values of 78 mg/kg and 165 mg/kg P. O., respectively) and in the acute tetradecanoylphorbol acetate (TPA)-induced mouse ear oedema in oral (62% and 32% oedema reduction at 100 and 125 mg/kg, respectively) and topical application (37% and 33% reduction of oedema at 0.5 mg/ear). In contrast, tryptanthrin showed no significant anti-inflammatory effect. The D…
Anti-Inflammatory Activity of Unusual Lupane Saponins fromBupleurum fruticescens
1998
Extracts from Bupleurum fruticescens were examined for oral and topical anti-inflammatory activities. The BuOH extract proved to be active against carrageenan and tetradecanoylphorbol acetate acute edemas and allowed the isolation of three saponins identified by spectroscopic techniques as 3 beta-O-(O-alpha-L-rhamnopyranosyl-(1-->4)-O-[beta-D-glucopyranosyl- (1-->6)]-O-beta-D-glucopyranosyl)lup-20(29)-ene-23,28-dioic acid (fruticesaponin A), 3 beta-O-(O-alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl) lup-20(29)-ene-23,28-dioic acid 28-O-beta-D-glucopyranosyl ester (fruticesaponin B), and 3 beta-O-(O-alpha-L-rhamnopyranosyl-(1-->4)-O-[beta-D-glucopyranosyl- (1-->6)]-O-beta-D-glucopy…
Design, synthesis and biological evaluation of new oligopyrrole carboxamides linked with tricyclic DNA-intercalators as potential DNA ligands or topo…
2007
In the context of the design and synthesis of minor groove binding and intercalating DNA ligands some new oligopyrrole carboxamides were synthesized. These hybrid molecules (combilexins) possess a variable and conformatively flexible spacer at the N-terminal end. As intercalating tricyclic systems acridone, acridine, anthraquinones and in a special case iminostilbene terminate the N-terminal end of the pyrrole chain. The cytotoxicity was examined by the NCI antitumor screening, furthermore, biophysical as well as biochemical studies were performed in order to get some information about the DNA binding properties and topoisomerase inhibition effect of this new series of molecules.
Steroidal saponins from Chlorophytum orchidastrum.
2009
Six new spirostane-type saponins (1−6), named orchidastrosides A−F, and chloromaloside D were isolated from an ethanol extract of the roots of Chlorophytum orchidastrum. The saponins have neotigogenin or neogitogenin as the aglycon and oligosaccharidic chains possessing seven to nine sugar units. Their structures were elucidated mainly by 2D NMR spectroscopic analyses (COSY, TOCSY, NOESY, HSQC, and HMBC) and FABMS and HRESIMS. Compounds 1−6 were tested for cytotoxicity against two human colon cancer cell lines, HCT 116 and HT-29.
Zur Acetylierung von Spironolacton, Canrenon und 2-Methylencanrenon
1995
Bei der Umsetzung der Titelverbindungen mit Acetanhydrid und Acetylchlorid werden das 3,5-Dien-3-yl-acetat 2, die isomeren 2,4,6- und 3,5,7-Trien-3-yl-acetate 3 und 4 sowie das 2,4,6,8(14)-Tetraen-3-yl-acetat 7 erhalten. Hydrolyse von 7 liefert das 2α-Methl-8,14-didehydro-canrenon (9). 7 und 9 wurden auf ihre Bindungsfahigkeit gegenuber Hormon-Rezeptoren sowie den Serumproteinen SHBG und CBG gepruft: Die Substanzen erwiesen sich als inaktiv. Acetylation of Spironolactone, Canrenone, and 2-Methylene Canrenone Reaction of the title compounds with acetic anhydride and acetyl chloride yields the 3,5-dien-3-yl acetate 2 the isomeric 2,4,6- and 3,5,7-trien-3-yl acetates 3 and 4 as well as the 2,4…
Experimental and theoretical investigations for the tandem alkylation–isomerization reactions between unsaturated carboxylic acids and allyl halides
2003
Abstract—Alkylation of dienediolates from unsaturated carboxylic acids with allylic halides when followed by solventless thermaltreatment at 150 to 2008C afford rearranged products on a trend highly dependent on the acarbon substitution. Thus, 2,2-bisallylated acidswith H atoms at C-2 lead to its 1,3-shift, whereas 2-methyl-2,2-bisallylated acids lead to the corresponding Cope rearrangement product. Inthe latter case, this tandem allylation-Cope reaction lead, in a highly regio and diastereoselective way, to products not accessible from directalkylation. B3LYP/6-31G p energies for the compounds involved at these isomerizations are in reasonable agreement with the experiments,allowing to exp…
Mbandakamine-Type Naphthylisoquinoline Dimers and Related Alkaloids from the Central African Liana Ancistrocladus ealaensis with Antiparasitic and An…
2018
Four new dimeric naphthylisoquinoline alkaloids, michellamine A5 (2) and mbandakamines C–E (4–6), were isolated from the Congolese plant Ancistrocladus ealaensis, along with the known dimer mbandakamine A (3). They represent constitutionally unsymmetric dimers, each consisting of two 5,8′-coupled naphthylisoquinoline monomers. While the molecular halves of michellamine A5 (2) are linked via C-6′ of both of the naphthalene moieties, i.e., via the least-hindered positions, so that the central biaryl axis is configurationally unstable and not an additional element of chirality, the mbandakamines 3–6 possess three consecutive stereogenic axes. Their monomeric units are linked through an unprece…
Einfluß sterischer Hinderung auf den Abbau von Ciclacillin und Ampicillin
1981
Kinetische Untersuchungen der Reaktivitat von Aminopenicillinen belegen bei Ciclacillin eine sterische Hinderung der α-Aminogruppe der Phenylacetamido-Seitenkette. Vergleichende Haltbarkeitsuntersuchungen an Arzneizubereitungen von Ciclacillin und Ampicillin ergaben, das die aus der sterischen Hinderung resultierende hohere Stabilitat von Ciclacillin auch bei Injektions-Losungen, Suspensionen sowie eingeschrankt bei Pulvern und Tabletten nachweisbar ist. Influence of Steric Hindrance on the Degradation of Ciclacillin and Ampicillin Kinetic measurements of the reactivity of aminopenicillins demonstrated steric hindrance of the side chain amino group of ciclacillin. Comparative stability meas…