Iddon L, Leyton J, Indrevoll B, Glaser M, Robins EG, George AJT, Cuthbertson A, Luthra SK, Aboagye EO. Synthesis and in vitro evaluation of [18F]fluoroethyl triazole labelled [Tyr3]octreotate analogues using click chemistry.
Bioorg Med Chem Lett 2011;
21:3122-7. [PMID:
21458258 DOI:
10.1016/j.bmcl.2011.03.016]
[Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 03/02/2011] [Accepted: 03/03/2011] [Indexed: 10/18/2022]
Abstract
A novel class of alkyne linked [Tyr(3)]octreotate analogues have been labelled by a copper catalysed azide-alkyne cycloaddition reaction (CuAAC) to form a 1,4-substituted triazole using the reagent [(18)F]2-fluoroethyl azide. An unexpected variability in reactivity during the CuAAC reaction was observed for each alkyne analogue which has been investigated. Two lead alkyne linked [Tyr(3)]octreotate analogues, G-TOCA (3a) and βAG-TOCA (5a) have been identified to be highly reactive in the click reaction showing complete conversion to the [(18)F]2-fluoroethyl triazole linked [Tyr(3)]octreotate analogues FET-G-TOCA (3b) and FET-βAG-TOCA (5b) under mild conditions and with short synthesis times (5 min at 20 °C). As well as ease of synthesis, in vitro binding to the pancreatic tumour AR42J cells showed that both FET-G-TOCA and FET-βAG-TOCA have high affinity for the somatostatin receptor with IC(50) of 4.0±1.4, and 1.6±0.2 nM, respectively.
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