Search

Quantitative imaging of apoptosis in vivocould enable real-time monitoring of acute cell death pathologies such as traumatic brain injury, as well as the efficacy and safety of cancer therapy. Here, we describe the development and validation of F-18-labeled caspase-3 substrates for PET/CT imaging of apoptosis. Preliminary studies identified the O-benzylthreonine-containing substrate 2MP-TbD-AFC as a highly caspase 3-selective and cell-permeable fluorescent reporter. This lead compound was converted into the radiotracer [18F]-TBD, which was obtained at 10% decay-corrected yields with molar activities up to 149 GBq/μmol on an automated radiosynthesis platform. [18F]-TBD accumulated in ovarian cancer cells in a caspase- and cisplatin-dependent fashion. PET imaging of a Jo2-induced hepatotoxicity model showed a significant increase in [18F]-TBD signal in the livers of Jo2-treated mice compared to controls, driven through a reduction in hepatobiliary clearance. A chemical control tracer that could not be cleaved by caspase 3 showed no change in liver accumulation after induction of hepatocyte apoptosis. Our data demonstrate that [18F]-TBD provides an immediate pharmacodynamic readout of liver apoptosis in mice by dynamic PET/CT and suggest that [18F]-TBD could be used to interrogate apoptosis in other disease states.

Despite being crucial for energy generation in most forms of life, few if any microbial antibiotics specifically inhibit glycolysis. To develop a specific inhibitor of the glycolytic enzyme enolase 2 (ENO2) for the treatment of cancers with deletion of ENO1 (encoding enolase 1), we modeled the synthetic tool compound inhibitor phosphonoacetohydroxamate (PhAH) into the active site of human ENO2. A ring-stabilized analog of PhAH, in which the hydroxamic nitrogen is linked to Cα by an ethylene bridge, was predicted to increase binding affinity by stabilizing the inhibitor in a bound conformation. Unexpectedly, a structure-based search revealed that our hypothesized backbone-stabilized PhAH bears strong similarity to SF2312, a phosphonate antibiotic of unknown mode of action produced by the actinomycete Micromonospora, which is active under anaerobic conditions. Here, we present multiple lines of evidence, including a novel X-ray structure, that SF2312 is a highly potent, low-nanomolar inhibitor of enolase.

Cancers harboring homozygous deletion of the glycolytic enzyme enolase 1 (ENO1) are selectively vulnerable to inhibition of the paralogous isoform, enolase 2 (ENO2). A previous work described the sustained tumor regression activities of a substrate-competitive phosphonate inhibitor of ENO2, 1-hydroxy-2-oxopiperidin-3-yl phosphonate (HEX) (5), and its bis-pivaloyoxymethyl prodrug, POMHEX (6), in an ENO1-deleted intracranial orthotopic xenograft model of glioblastoma [Nature Metabolism2020,2,1423–1426]. Due to poor pharmacokinetics of bis-ester prodrugs, this study was undertaken to identify potential non-esterase prodrugs for further development. Whereas phosphonoamidate esters were efficiently bioactivated in ENO1-deleted glioma cells, McGuigan prodrugs were not. Other strategies, including cycloSal and lipid prodrugs of 5, exhibited low micromolar IC50values in ENO1-deleted glioma cells and improved stability in human serum over 6. The activity of select prodrugs was also probed using the NCI-60 cell line screen, supporting its use to examine the relationship between prodrugs and cell line-dependent bioactivation.

The synthesis of several α-substituted N-Boc-protected prolines has been achieved by cross metathesis (CM) of N-Boc-allylproline 5with terminal long chain alkenes and alkenes bearing hydroxy, silyloxy, ester, and O-acetylglucosamido groups. The CM occurred with good selectivity and short reaction time under microwave heating conditions, affording yields in the range of 40–92 . Addition of Ti(OiPr)4as a Lewis acid allowed a slight increase of the yield in the case of alkenes with Lewis basic substituents. The CM was also successfully applied to allylproline protected with trichloroacetaldehyde 4, but the intermediate products were less practical for further deprotection and elaboration. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The solid-phase synthesis of cyclic pseudopeptides containing the Arg-Gly-Asp recognition sequence and the dipeptide isostere 2-amino-3-oxotetrahydro-1 H-pyrrolizine-7a(5 H)-carboxylic acid (GPTM) was accomplished. N-Fmoc-Asp-OAll was anchored to Wang resin through its side chain and sequentially coupled with N-Fmoc-Gly-OH, N-Fmoc-Arg(Pbf)-OH and N-Fmoc-GPTM-OH. The supported linear pentapeptide smoothly underwent head-to-tail cyclization by activation with TBTU/DIPEA. Finally, TFA treatment released the completely deprotected cyclic pseudopentapeptide. Competition binding assays to purified ? V? 3 and ? V? 5 integrins showed a high inhibitory activity of cyclo[Arg-Gly-Asp-(2 S,7a S)- GPTM].

Derivatization of racemic 2‐hydroxypyrrolizidinones with S‐(+)‐α‐methoxy‐α‐trifluoromethylphenylacetyl chloride (MTPA‐Cl) was successfully used for enantiomer separation and absolute configuration assignment. Chirality 17:149–153, 2005.© 2005 Wiley‐Liss, Inc.

Monocyclic β-lactams were synthesized by a 1,3-cycloaddition/thermal rearrangement process in the presence of a protic acid, starting from methylenecyclopropane derivatives and acyclic nitrones. Five-membered cyclic nitrones failed to give carbapenam structures under the same conditions, affording exclusively the corresponding N-trifluoroacetyl β-amino acid derivatives in the presence of trifluoroacetic acid. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The (3S)-3-alkoxypyrroline N-oxides 7 and 27 were easily prepared from L-malic acid and used as starting materials for enantiospecific syntheses of stereodifferentiated polyhydroxyindolizidines. Selection of the appropriate modality (inter- or intramolecular) for 1,3-dipolar cycloaddition of the cyclic nitrone with 5-hydroxypentenoic acid derivatives gave access to either [1,8a]-trans- or -cis-hydroxyindolizidines 31 and 24, respectively, through elaboration of the primary cycloadducts. Moreover, the choice of the esterification conditions (Ph3P/DEAD or DIC/DMAP) used in linking the nitrone and the dipolarophile moieties in the intramolecular approach determined the absolute configuration of the final product, allowing the selective synthesis of both enantiomers, (−)-24 and (+)-24. This strategy required protection of the nitrone functionality to avoid racemization of the unprotected hydroxy nitrone during the introduction of the dipolarophile moiety. Protection/deprotection were achieved by cycloaddition/retro-cycloaddition reactions. The different propensity of some pyrrolo[1,2-b]isoxazolidines to undergo retro-cycloaddition with regeneration of the nitrone functionality was investigated both experimentally and by semiempirical and ab initio calculations on model compounds. The relative calculated activation energies were qualitatively in good agreement with the experimental observations. Fumaronitrile was found to be a convenient protecting reagent for the nitrone moiety and could be removed by retro-cycloaddition at lower temperatures than styrene and ethyl acrylate. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

A practical synthesis of the necine base (+)-heliotridine (1) is reported here. The present total synthesis is based on the highly selective 1,3-dipolar cycloaddition of (S)-3-tert-butoxypyrroline N-oxide (2) to the commercially available ethyl 4-bromocrotonate, followed by a suitable elaboration of the adduct. The synthesis gives a 17% overall yield from nitrone 2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Acrylate and maleate functionalized resins were used to mask the nitrone moiety of a chiral pyrroline N-oxide to prevent the racemization at the C-3 stereogenic center and to link them to a solid phase. After the elaboration of the linked cycloadducts, the product was disconnected from the resin through a 1,3-dipolar cycloreversion/intramolecular cycloaddition domino process.

ortho‐Amino substituted internal arylalkynes of type (III) are prepared by Sonogashira coupling.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

For Abstract see ChemInform Abstract in Full Text.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.