title: Enantiomeric and diastereoisomeric (mixed) L/ D-octaarginine derivatives - a simple way of modulating the properties of cell-penetrating peptides.
abstract: Cell-penetrating peptides (CPPs) are promising vehicles for delivery of drugs, antibiotics, proteins, nucleic acid derivatives, etc. into eukaryotic and prokaryotic target cells. To prevent premature degradation, CPPs consisting of D- or β-amino acid residues have been used. We present simple models for the various modes of delivery of physiologically active cargoes by CPPs, depending on the nature of their conjugation (Fig. 1), and we describe the plasma stability of oligoarginines (OAs) 1-4, the most common unnatural CPPs. Fluorescein-labeled L-octaarginine 1 was found to have a half-life (t1/2 ) of <0.5 min, the D-enantiomer (2) of >7 d (Fig. 2). For possible medicinal applications, the former type of derivative would be too unstable, and the latter one undesirably persistent. Thus, seven of the 256 possible 'mixed' Flua-L/D-octaarginine amides, 4a-4g, were synthesized and shown to have half-lives in heparine-stabilized human plasma between 8 min and 5.5 h (Figs. 3 and 4). The cell penetration of the new OAs was investigated with 'healthy' and with apoptotic HEK cells (Figs. 5-8), and their interactions with phospholipid bilayers were studied, using anionic lipid vesicles (Figs. 9 and 10). There are surprisingly large differences in the rates of cell penetration and binding to vesicle walls between the various stereoisomeric octaarginine derivatives 1, 2, and 4a-4g (Figs. 5 and 7). - The role of D-amino acids and D-peptides in nature and in drug design is briefly discussed and referenced.
authors.affiliation: Laboratorium für Organische Chemie, Departement Chemie und Angewandte Biowissenschaften, ETH-Zürich, Hönggerberg HCI, Wolfgang-Pauli-Strasse 10, CH-8093 Zürich.
authors.forename: Nirupam
authors.initials: N
authors.lastname: Purkayastha
authors.forename: Klaus
authors.initials: K
authors.lastname: Eyer
authors.forename: Tom
authors.initials: T
authors.lastname: Robinson
authors.forename: Petra S
authors.initials: PS
authors.lastname: Dittrich
authors.forename: Albert K
authors.initials: AK
authors.lastname: Beck
authors.forename: Dieter
authors.initials: D
authors.lastname: Seebach
authors.forename: Beata
authors.initials: B
authors.lastname: Kolesinska
authors.forename: Riccardo
authors.initials: R
authors.lastname: Cadalbert
mesh_terms: D000595:Amino Acid Sequence; D002463:Cell Membrane Permeability; D057846:Cell-Penetrating Peptides / Q000097:blood / Q000737:chemistry* / Q000378:metabolism; D019793:Fluorescein / Q000737:chemistry; D057809:HEK293 Cells; D006207:Half-Life; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry; D018613:Microscopy, Confocal; D009842:Oligopeptides / Q000097:blood / Q000737:chemistry* / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: D057846:Cell-Penetrating Peptides; D008051:Lipid Bilayers; D009842:Oligopeptides; C448619:octaarginine; D019793:Fluorescein
keywords: Amino acids; Cell penetration; HEK Cells; Microfluidic devices; Oligoarginines; Peptides; Phospholipid vesicles