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Dale L Boger

Publications and source records attributed to Dale L Boger.

80 records · Page 5Linked to original sources
PubMed2002

Synthesis and evaluation of vancomycin and vancomycin aglycon analogues that bear modifications in the residue 3 asparagine.

The synthesis and biological evaluation of a set of residue 3 analogues of vancomycin and its aglycon are described. These investigations follow from the promising biological activity of a protected and synthetically modified vancomycin aglycon analogue in which the asparagine side chain was modified to possess a nitrile, rather than a carboxamide. Although this modification typically was detrimental to antimicrobial activity, hydrophobic vancomycin aglycon analogues that lack a lipid anchor as well as the disaccharide are detailed that exhibit unusual potency against VanB, but not VanA, resistant bacteria.

Anti-Bacterial Agents↗
PubMed2002

Hairpin versus extended DNA binding of a substituted beta-alanine linked polyamide.

A series of alpha-substituted beta-alanine (beta) linked polyamides (DbaPyPyPy-beta*-PyPyPy) were prepared and examined. This resulted in the observation that while most substituents disrupt DNA binding, (R)-alpha-methoxy-beta-alanine (beta((R)-OMe)) maintains strong binding affinity and preferentially adopts a hairpin versus extended binding mode, providing an alternative hairpin linker to gamma-aminobutyric acid (gamma). A generalized variant of a fluorescent intercalator displacement assay conducted on a series of hairpin deoxyoligonucleotides containing a systematically varied A/T-rich binding site size was developed to distinguish between the extended binding of the parent beta-alanine 1 (DbaPyPyPy-beta-PyPyPy) and the hairpin binding of 3 (DbaPyPyPy-beta((R)-OMe)-PyPyPy).

Alanine↗
PubMed2002

Small-molecule antagonists of Myc/Max dimerization inhibit Myc-induced transformation of chicken embryo fibroblasts.

Myc is a transcriptional regulator of the basic helix-loop-helix leucine zipper protein family. It has strong oncogenic potential, mutated or virally transduced forms of Myc induce lymphoid tumors in animals, and deregulated expression of Myc is associated with numerous types of human cancers. For its oncogenic activity, Myc must dimerize with the ubiquitously expressed basic helix-loop-helix leucine zipper protein Max. This requirement for dimerization may allow control of Myc activity with small molecules that interfere with Myc/Max dimerization. We have measured Myc/Max dimerization with fluorescence resonance energy transfer and have screened combinatorial chemical libraries for inhibitors of dimerization. Candidate inhibitors were isolated from a peptidomimetics library. Inhibition of Myc/Max interaction was validated by ELISA and electrophoretic mobility-shift assay. Two of the candidate inhibitors also interfere with Myc-induced oncogenic transformation in chicken embryo fibroblast cultures. Our work provides proof of principle for the identification of small molecule inhibitors of protein-protein interactions by using high-throughput screens of combinatorial chemical libraries.

Animals↗
PubMed2002

The DNA phosphate backbone is not involved in catalysis of the duocarmycin and CC-1065 DNA alkylation reaction.

The rates of DNA alkylation were established for the reaction of (+)-duocarmycin SA (1) with the native duplex d(G(1)TCAATTAGTC(11))*d(G(12)ACTAATTGAC(22)), an 11 bp deoxyoligonucleotide that contains a single high-affinity alkylation site that has been structurally characterized at exquisite resolution, and modified duplexes in which the four backbone phosphates proximal to the C4 carbonyl of bound 1 were replaced with methylphosphonates. All were found to react at comparable rates establishing that these backbone phosphates do not participate in catalysis of the DNA alkylation reaction.

Algorithms↗
PubMed2002

Erythropoietin mimetics derived from solution phase combinatorial libraries.

The erythropoietin receptor (EPOr) is activated by ligand-induced homodimerization, which leads to the proliferation and differentiation of erythroid progenitors. Through the screening of combinatorial libraries of dimeric iminodiacetic acid diamides, novel small molecule binders of EPOr were identified in a protein binding assay. Evaluation of a series of analogues led to optimization of binding subunits, and these were utilized in the synthesis of higher order dimer, trimer, and tetramer libraries. Several of the most active EPOr binders were found to be partial agonists and induced concentration-dependent proliferation of an EPO-dependent cell line (UT-7/EPO) while having no effect on a cell line lacking the EPOr (FDC-P1). An additional compound library, based on a symmetrical isoindoline-5,6-dicarboxylic acid template and including the optimized binding subunits, was synthesized and screened leading to the identification of additional EPO mimetics.

Cell Division↗
PubMed2002

10-Formyl-5,10-dideaza-acyclic-5,6,7,8-tetrahydrofolic acid (10-formyl-DDACTHF): a potent cytotoxic agent acting by selective inhibition of human GAR Tfase and the de novo purine biosynthetic pathway.

The synthesis of 10-formyl-DDACTHF (3) as a potential inhibitor of glycinamide ribonucleotide transformylase (GAR Tfase) and aminoimidazole carboxamide ribonucleotide transformylase (AICAR Tfase) is reported. Aldehyde 3, the corresponding gamma- and alpha-pentaglutamates 21 and 25 and related agents were evaluated for inhibition of folate-dependent enzymes including GAR Tfase and AICAR Tfase. The inhibitors were found to exhibit potent cytotoxic activity (CCRF-CEM IC(50) for 3=60nM) that exceeded their enzyme inhibition potency [K(i) (3)=6 and 1 microM for Escherichia coli GAR and human AICAR Tfase, respectively]. Cytotoxicity rescue by medium purines, but not pyrimidines, indicated that the potent cytotoxic activity is derived from selective purine biosynthesis inhibition and rescue by AICAR monophosphate established that the activity is derived preferentially from GAR versus AICAR Tfase inhibition. The potent cytotoxic compounds including aldehyde 3 lost activity against CCRF-CEM cell lines deficient in the reduced folate carrier (CCRF-CEM/MTX) or folylpolyglutamate synthase (CCRF-CEM/FPGS(-)) establishing that their potent activity requires both reduced folate carrier transport and polyglutamation. Unexpectedly, the pentaglutamates displayed surprisingly similar K(i)'s versus E. coli GAR Tfase and only modestly enhanced K(i)'s versus human AICAR Tfase. On the surface this initially suggested that the potent cytotoxic activity of 3 and related compounds might be due simply to preferential intracellular accumulation of the inhibitors derived from effective transport and polyglutamation (i.e., ca. 100-fold higher intracellular concentrations). However, a subsequent examination of the inhibitors against recombinant human GAR Tfase revealed they and the corresponding gamma-pentaglutamates were unexpectedly much more potent against the human versus E. coli enzyme (K(i) for 3, 14nM against rhGAR Tfase versus 6 microM against E. coli GAR Tfase) which also accounts for their exceptional cytotoxic potency.

Antineoplastic Agents↗
PubMed2002

Inhibitors of cell migration that inhibit intracellular paxillin/alpha4 binding: a well-documented use of positional scanning libraries.

Screening combinatorial libraries for inhibition of Paxillin binding to the cytoplasmic tail of the integrin alpha4 provided the first inhibitors of this protein-protein interaction implicated in enhanced rates of cell migration and chronic inflammation. The preparation of substructure analogs of the lead identified features required for activity, those available for modification, and those that may be removed. The most potent lead structure was shown to inhibit alpha(4)beta(1)-mediated human Jurkat T cell migration in a dose-dependent manner, validating the intracellular Paxillin/alpha4 interaction as a useful and unique target for therapeutic intervention. Moreover, the lead structure emerged from a library that was prepared in two formats: (1) a traditional small mixture format composed of 100 mixtures of 10 compounds and (2) a positional scanning library. Their parallel testing provided the rare opportunity to critically compare two approaches.

Chemotaxis, Leukocyte↗