Phenothiazine-Biaryl-Containing Fluorescent RGD Peptides.

Elmira Ghabraie, Isabell Kemker, Nicolo Tonali, Mohamed Ismail, Veronica I Dodero, Norbert Sewald

Chemistry (Weinheim an der Bergstrasse, Germany) 2020 Sep 16

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Cyclic RGD peptides are well-known ligands of integrins. The integrins αV β3 and α5 β1 are involved in angiogenesis, and integrin αV β3 is abundantly present on cancer cells, thus representing a therapeutic target. Hence, synthetic and biophysical studies continuously are being directed towards the understanding of ligand-integrin interaction. In this context, the development of versatile synthetic strategies to obtain fluorescent building blocks that can add molecular diversity and modular spectral characteristics while not compromising binding affinity or selectivity is a relevant task. An on-resin intramolecular Suzuki-Miyaura cross-coupling (SMC) between l- or d-7-bromotryptophan (7BrTrp) and a phenothiazine (Ptz) boronic acid affords fluorescent cyclic RGD pseudopeptides, c(RGD(W/w)Ptz). Ring closure by SMC establishes a phenothiazine-indole moiety with axial chirality. An array of eight novel compounds has been synthesized, among them one fluorescent compound with good affinity to integrin αV β3 . The fluorescence properties of the analogues can be efficiently tuned depending on the substituents in Ptz moiety even for fluorescence emission in the visible (red) spectral range. © 2020 The Authors. Published by Wiley-VCH GmbH.

Citation

Elmira Ghabraie, Isabell Kemker, Nicolo Tonali, Mohamed Ismail, Veronica I Dodero, Norbert Sewald. Phenothiazine-Biaryl-Containing Fluorescent RGD Peptides. Chemistry (Weinheim an der Bergstrasse, Germany). 2020 Sep 16;26(52):12036-12042