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All total 4 Articles be found
All total 4 Articles be foundCyclic side-chain-linked opioid analogs utilizing cis- and trans-4-aminocyclohexyl-d-alanine
Piekielna, Justyna,Gentilucci, Luca,De Marco, Rossella,Perlikowska, Renata,Adamska, Anna,Olczak, Jacek,Mazur, Marzena,Artali, Roberto,Modranka, Jakub,Janecki, Tomasz,T?mb?ly, Csaba,Janecka, Anna
, p. 6545 - 6551 (2015/02/19)
Cyclization of linear sequences is a well recognized tool in opioid peptide chemistry for generating analogs with improved bioactivities. Cyclization can be achieved through various bridging bonds between peptide ends or side-chains. In our earlier paper we have reported the synthesis and biological activity of a cyclic peptide, Tyr-c[d-Lys-Phe-Phe-Asp]NH2 (1), which can be viewed as an analog of endomorphin-2 (EM-2, Tyr-Pro-Phe-Phe-NH2). Cyclization was achieved through an amide bond between side-chains of d-Lys and Asp residues. Here, to increase rigidity of the cyclic structure, we replaced d-Lys with cis- or trans-4-aminocyclohexyl-d-alanine (d-ACAla). Two sets of analogs incorporating either Tyr or Dmt (2′,6′-dimethyltyrosine) residues in position 1 were synthesized. In the binding studies the analog incorporating Dmt and trans-d-ACAla showed high affinity for both, μ- and δ-opioid receptors (MOR and DOR, respectively) and moderate affinity for the κ-opioid receptor (KOR), while analog with Dmt and cis-d-ACAla was exceptionally MOR-selective. Conformational analyses by NMR and molecular docking studies have been performed to investigate the molecular structural features responsible for the noteworthy MOR selectivity.
Stereochemical influence on the stability of radio-metal complexes in vivo. Synthesis and evaluation of the four stereoisomers of 2-(p- nitrobenzyl)-trans-CyDTPA
Wu,Kobayashi,Sun,Yoo,Paik,Gansow,Carrasquillo,Pastan,Brechbiel
, p. 1925 - 1934 (2007/10/03)
Distinct differences in in vivo stability of the two diastereomeric C- Functionalized CyDTPA chelating agents, (CHX-A DTPA and CHX-B DTPA, both racemates), as recently reported prompted further investigation as to why differences in configuration produced striking effects on the in vivo stability of their yttrium complexes. To this end, the four individual component stereoisomers of CHX-A and CHX-B were synthesized and ability to bind yttrium was investigated both in vitro and in vivo.
