80182-99-6Relevant articles and documents
Cyclizing pentapeptides: Mechanism and application of dehydrophenylalanine as a traceless turn-inducer
Le, Diane N.,Riedel, Jan,Kozlyuk, Natalia,Martin, Rachel W.,Dong, Vy M.
, p. 114 - 117 (2017/11/27)
Dehydrophenylalanine is used as a traceless turn-inducer in the total synthesis of dichotomin E. Macrocyclization of the monomer is achieved in high yields and selectivity over cyclodimerization under conditions 100 times more concentrated than previously achieved. The enamide facilitates ring closing, and Rh-catalyzed hydrogenation of the unsaturated cyclic peptide results in selective formation of the natural product or its epimer, depending on our choice of phosphine ligand. NMR analysis and molecular modeling revealed that the linear peptide adopts a left-handed α-turn that preorganizes the N- and C-termini toward macrocyclization.
Dehydrodipeptide Hydrogelators Containing Naproxen N-Capped Tryptophan: Self-Assembly, Hydrogel Characterization, and Evaluation as Potential Drug Nanocarriers
Vila?a, Helena,Hortel?o, Ana C. L.,Castanheira, Elisabete M. S.,Queiroz, Maria-Jo?o R. P.,Hilliou, Loic,Hamley, Ian W.,Martins, José A.,Ferreira, Paula M. T.
, p. 3562 - 3573 (2015/11/17)
In this work, we introduce dipeptides containing tryptophan N-capped with the nonsteroidal anti-inflammatory drug naproxen and C-terminal dehydroamino acids, dehydrophenylalanine (ΔPhe), dehydroaminobutyric acid (ΔAbu), and dehydroalanine (ΔAla) as efficacious protease resistant hydrogelators. Optimized conditions for gel formation are reported. Transmission electron microscopy experiments revealed that the hydrogels consist of networks of micro/nanosized fibers formed by peptide self-assembly. Fluorescence and circular dichroism spectroscopy indicate that the self-assembly process is driven by stacking interactions of the aromatic groups. The naphthalene groups of the naproxen moieties are highly organized in the fibers through chiral stacking. Rheological experiments demonstrated that the most hydrophobic peptide (containing C-terminal ΔPhe) formed more elastic gels at lower critical gelation concentrations. This gel revealed irreversible breakup, while the C-terminal ΔAbu and ΔAla gels, although less elastic, exhibited structural recovery and partial healing of the elastic properties. A potential antitumor thieno[3,2-b]pyridine derivative was incorporated (noncovalently) into the gel formed by the hydrogelator containing C-terminal ΔPhe residue. Fluorescence and F?rster resonance energy transfer measurements indicate that the drug is located in a hydrophobic environment, near/associated with the peptide fibers, establishing this type of hydrogel as a good drug-nanocarrier candidate.
Nitrate esters in the generation of amino acid radicals
Easton, Christopher J.,Ivory, Andrew J.,Smith, Craig A.
, p. 503 - 507 (2007/10/03)
Nitrate esters, prepared by treatment of β-hydroxy-α-amino acid derivatives with nitric acid, react with tributyltin hydride to give the corresponding alkoxyl radicals. These radicals readily undergo β-scission, providing a convenient route for the regiocontrolled production of α-carbon-centred amino acid radicals. By examining the partitioning of the alkoxyl radicals between the β-scission process and the competing hydrogen transfer reaction, it has been possible to evaluate the influence of electronic and steric effects on the β-scission reaction and the formation of the carbon-centred radicals.
