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At least 271 records · Page 15Linked to original sources
PubMed2004

Synthesis of novel Bi-, Tri-, and tetracyclic nucleosides by reaction of a common cyclic enamine derived from TSAO-T with nucleophiles.

We report here the efficient regio- and stereoselective synthesis of new polycyclic nucleosides using a common cyclic enamine (7) as the starting material. In fact, the reaction of 7, easily prepared by reaction of 5'-O-Tosyl TSAO-T under basic nonnucleophilic conditions (potassium carbonate), with different classes of nucleophiles, for example, nitrogen-, oxygen-, sulfur-, and carbon-based nucleophiles, or with amino acids afforded, with total regio- and stereoselectivity, new bi-, tri-, and tetracyclic nucleosides. This straighforward route represents an original and unambiguously regio- and stereoselective pathway to these compounds. Some of these polycyclic nucleosides may be useful intermediates for a second series of reactions that may lead to the generation of structurally new nucleosides.

Amines↗
PubMed1998

Induction of low-density lipoprotein catabolism in Hep G2 cells by a fungal sesquiterpene ester, FR111142.

A search for agents that can enhance low density lipoprotein (LDL) catabolism in Hep G2 cells has led to the identification of a fungal sesquiterpene ester, FR111142, as an active compound. The treatment of Hep G2 cells with 40 microM FR111142 at 37 degrees C for 18 h caused a 1.9- to 2.2-fold elevation of binding, internalization and degradation of 125I-LDL in the cells. The Scatchard analysis of the specific 125I-LDL binding demonstrated that the agent caused an increase in the maximum LDL binding along with a slight decrease in the apparent dissociation constant value. The effect of FR111142 was not seen in cells treated by the agent for shorter periods or in cycloheximide-treated cells, suggesting that the effect involves an induction of LDL binding sites. Unlike 3-hydroxy-3-methyglutaryl CoA reductase inhibitors, FR111142 affected neither cholesterol synthesis nor the level of LDL receptor in Hep G2 cells. These results suggest that FR111142 enhances LDL catabolism in Hep G2 cells by a mechanism that involves a receptor other than LDL receptor.

Anticholesteremic Agents↗
PubMed1995

RK-682, a potent inhibitor of tyrosine phosphatase, arrested the mammalian cell cycle progression at G1phase.

A specific inhibitor of protein tyrosine phosphatase (PTPase), RK-682 (3-hexadecanoyl-5-hydroxymethyl-tetronic acid) was isolated from microbial metabolites. In vitro, RK-682 inhibited dephosphorylation activity of CD45 and VHR with IC50 54 and 2.0 microM, respectively. In situ, sodium orthovanadate and RK-682 enhanced the phosphotyrosine level of Ball-1 cells, a human B cell leukemia, but not the phosphoserine/threonine level. The PTPase inhibitors, however, had the different arrest point on the cell cycle progression. Sodium orthovanadate inhibited the cell cycle progression at G2/M boundary phase, on the other hand, RK-682 inhibited the G1/S transition.

Aniline Compounds↗
PubMed2004

Synthesis and antimalarial activity of a new series of trioxaquines.

Trioxanes 8a-b, easily accessible in two steps from allylic alcohol 6a-b, on reductive amination with 4-aminoquinolines 4a-c furnish a new series of trioxaquines 9a-b, 10a-b, 11a-b in 32-77% yields. Dicitrate salts of these trioxaquines have been evaluated for antimalarial activity against multidrug resistant Plasmodium yoelii in mice model.

Aminoquinolines↗
PubMed2004

Deoxypreussomerins from Jatropha curcas: are they also plant metabolites?

Three deoxypreussomerins, palmarumycins CP1, JC1 and JC2, have been isolated from a collection of the stems of Jatropha curcas. The second and third compounds are antibacterial constituents which were characterized from spectral evidence. The X-ray crystallographic structure of palmarumycin JC1 was also studied. Deoxypreussomerins have been obtained here from a plant source in appreciable quantities.

Animals↗
PubMed2003

Identification of a broad-spectrum azasordarin with improved pharmacokinetic properties.

The synthesis and antifungal activity of 5'- and 5'-6'-substituted azasordarin derivatives are described. Modification of the 5'-position led to the discovery of the spirocyclopentyl analogue 7g, which is the first azasordarin to register single-digit MIC values versus Aspergillus spp. Further investigation identified the 5'-i-Pr derivative 7b, which displays superior pharmacokinetic properties compared to other azasordarins.

Administration, Oral↗
PubMed2002

Highly diastereoselective nitrone cycloaddition onto a chiral ketene equivalent: asymmetric synthesis of cispentacin.

[reaction: see text] A highly diastereoselective intramolecular nitrone cycloaddition onto a chiral ketene equivalent, obtained by Horner-Wadsworth-Emmons olefination of either enantiomer of bis-sulfinyl phosphonate 6, is described. Cycloaddition gave 5,5-disubstituted isoxazolidine 10 in good yield as a single diastereomer. Catalytic hydrogenolysis of 10 furnished either enantiomer of optically pure cis-2-aminocyclopentane-1-carboxylic acid.

Antifungal Agents↗