Evaluation of methionine and tryptophan derivatised vehicles: Met-ac-TE3A/Trp-ac-TE3A for tumor imaging?

RSC Advances Pub Date: 2015-04-24 DOI: 10.1039/C5RA07138K

Abstract

Two novel amino acid (methionine and tryptophan) appended 1,4,8,11-tetraazacyclotetradecane triacetate (TE3A) compounds Met-ac-TE3A and Trp-ac-TE3A were synthesized and evaluated for imaging applications. The pharmacokinetics of these compounds was analyzed by 99mTc labeled tracer methods. In vitro human serum stability of 99mTc labeled Met-ac-TE3A/Trp-ac-TE3A was found to be 96.5% and 96.0% after 24 h respectively. Blood kinetics of both the labeled probes on normal rabbits showed biphasic clearance. The tumor (EAT cell line) grafted in balb/c mice were readily identifiable in the gamma images. Biodistribution revealed significant tumor uptake and good contrast in the EAT tumor bearing mice and also showed high tumor/muscles ratio which is a requisite condition to work as SPECT-radiopharmaceutical for tumor imaging. To look its future applicability for therapy using M+2 and M+3 metal ions, we performed thermodynamic stability constants of complexes derived from Met-ac-TE3A and Trp-ac-TE3A with CuII and LnIII metal ions.

Graphical abstract: Evaluation of methionine and tryptophan derivatised vehicles: Met-ac-TE3A/Trp-ac-TE3A for tumor imaging
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