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Identification of the Structural Determinants for Anticancer Activity of a Ruthenium Arene Peptide Conjugate
Author(s) -
Meier Samuel M.,
Novak Maria,
Kandioller Wolfgang,
Jakupec Michael A.,
Arion Vladimir B.,
MetzlerNolte Nils,
Keppler Bernhard K.,
Hartinger Christian G.
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201300889
Subject(s) - ruthenium , moiety , chemistry , peptide , linker , bioconjugation , stereochemistry , conjugate , click chemistry , combinatorial chemistry , alkyne , medicinal chemistry , organic chemistry , catalysis , biochemistry , mathematical analysis , mathematics , computer science , operating system
Organometallic Ru(arene)–peptide bioconjugates with potent in vitro anticancer activity are rare. We have prepared a conjugate of a Ru(arene) complex with the neuropeptide [Leu 5 ]‐enkephalin. [Chlorido( η 6 ‐ p ‐cymene)(5‐oxo‐ κO ‐2‐{(4‐[( N ‐tyrosinyl‐glycinyl‐glycinyl‐phenylalanyl‐leucinyl‐NH 2 )propanamido]‐1 H ‐1,2,3‐triazol‐1‐yl)methyl}‐4 H ‐pyronato‐ κO )ruthenium(II)] ( 8 ) shows antiproliferative activity in human ovarian carcinoma cells with an IC 50 value as low as 13 μ M , whereas the peptide or the Ru moiety alone are hardly cytotoxic. The conjugation strategy for linking the Ru(cym) (cym= η 6 ‐ p ‐cymene) moiety to the peptide involved N‐terminal modification of an alkyne‐[Leu 5 ]‐enkephalin with a 2‐(azidomethyl)‐5‐hydroxy‐4 H ‐pyran‐4‐one linker, using Cu I ‐catalyzed alkyne–azide cycloaddition (CuAAC), and subsequent metallation with the Ru(cym) moiety. The ruthenium‐bioconjugate was characterized by high resolution top‐down electrospray ionization mass spectrometry (ESI‐MS) with regard to peptide sequence, linker modification and metallation site. Notably, complete sequence coverage was obtained and the Ru(cym) moiety was confirmed to be coordinated to the pyronato linker. The ruthenium‐bioconjugate was analyzed with respect to cytotoxicity‐determining constituents, and through the bioconjugate models [{2‐(azidomethyl)‐5‐oxo‐ κO ‐4 H ‐pyronato‐ κO }chloride ( η 6 ‐ p ‐cymene)ruthenium(II)] ( 5 ) and [chlorido( η 6 ‐ p ‐cymene){5‐oxo‐ κO ‐2‐([(4‐(phenoxymethyl)‐1 H ‐1,2,3‐triazol‐1‐yl]methyl)‐4 H ‐pyronato‐ κO }ruthenium(II)] ( 6 ) the Ru(cym) fragment with a triazole‐carrying pyronato ligand was identified as the minimal unit required to achieve in vitro anticancer activity.