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Biomedical subjects

Lester A Mitscher

Publications and source records attributed to Lester A Mitscher.

6 recordsLinked to original sources
PubMed2006

Design, synthesis, and antiproliferative and CDK2-cyclin a inhibitory activity of novel flavopiridol analogues.

The design and synthesis of a small library of 8-amidoflavone, 8-sulfonamidoflavone, 8-amido-7-hydroxyflavone, and heterocyclic analogues of flavopiridol is reported. The potential activity of these compounds as kinase inhibitors was evaluated by cytotoxicity studies in MCF-7 and ID-8 cancer cell lines and inhibition of CDK2-Cyclin A enzyme activity in vitro. The antiproliferative and CDK2-Cyclin A inhibitory activity of these analogues was significantly lower than the activity of flavopiridol. Molecular docking simulations were carried out and these studies suggested a different binding orientation inside the CDK2 binding pocket for these analogues compared to flavopiridol.

Adenosine Triphosphate↗
PubMed2006

Further exploration of antimicrobial ketodihydronicotinic acid derivatives by multiple parallel syntheses.

A synthetic reexamination of a series of ketodihydronicotinic acid class antibacterial agents was undertaken in an attempt to improve their therapeutic potential. A convenient new synthesis was developed involving hetero Diels-Alder chemistry producing 74 new analogs in a multiple parallel synthetic manner and these were examined in vitro for their antimicrobial potential. Several compounds demonstrated significant broad-spectrum activity against clinically derived bacterial strains but previously known 1-(2,4-difluorophenyl)-6-(4-dimethylaminophenyl)-4-pyridone-3-carboxylic acid (7) remained the most potent compound in this class. Cross-resistance with ciprofloxacin supported a commonality of mode of action. Permiabilization of Escherichia coli cells by polymyxin B significantly enhanced potency with these agents suggesting that poor cellular uptake was primarily responsible for the disappointing activity against bacteria that some of the analogs exhibited.

Anti-Infective Agents↗
PubMed2005

Chiral DNA gyrase inhibitors. 3. Probing the chiral preference of the active site of DNA gyrase. Synthesis of 10-fluoro-6-methyl-6,7-dihydro-9-piperazinyl- 2H-benzo[a]quinolizin-20-one-3-carboxylic acid analogues.

In pursuit of an apparent literature anomaly, S- and R-6-methyl-6,7-dihydro-2H-benzo[a]quinolizin-2-one-3-carboxylic acids (12 and 22) were synthesized by an unambiguous route from optically active norephedrines, and their antibacterial potencies were measured. Against Gram-negative microorganisms and DNA gyrase a preference for S-absolute configuration was found whereas R-absolute stereochemistry was more active against Gram-positives. These results are in partial conflict with an earlier report. In an attempt to enhance potency, racemic 10-fluoro-9-piperazinyl (35) and related analogues were synthesized by a novel route. The latter analogues were surprisingly unimproved in potency. The implications of these findings are briefly discussed.

Anti-Bacterial Agents↗
PubMed2003

A parallel synthesis demonstration library of tri-substituted indazoles containing new antimutagenic/antioxidant hits related to benzydamine.

A solution phase strategy for the multiple parallel synthesis of a demonstration library of indazoles is described by which regio-selectivity problems inherent to previous syntheses of this nucleus are largely overcome. Synthesis of selected components proceeded satisfactorily indicating that a fully realized library of indazole analogs could readily be produced using this methodology. Simple modifications of the basic nucleophilic aromatic substitution route unambiguously produce a range of N-1 substitutions (alkyl, aryl and aralkyl) in 50-75% yields. Next a range of substituents was introduced at the C-3 position in 50-80% yields by O-alkylation. Careful choice of reagents and reaction conditions were required to prevent by-product formation due to competing alkylation at N-2 (trace to 15% yields). When present, these contaminants were readily removed by chromofiltration. A third diversity site was sketched in at C-5 in 75-90% yield by reductive alkylation or acylation. Screening of some of the demonstration library members in vitro revealed highly active antioxidants suggesting that producing a full library would be worthwhile.

Antimutagenic Agents↗
PubMed2003

Tetraacyldiborates: selective and efficient acylation reagents suitable for multiple parallel synthetic applications.

Boron-based mixed anhydrides are rapidly reactive, easy to prepare, cheap, efficient, and general acylating reagents capable of selectivity when chelation is possible. High yields of various esters, amides and thioesters are quickly obtainable and the products are easy to isolate in high purity. The method is readily used under multiple parallel synthesis conditions and is readily scaleable.

Acylation↗