Preparation of 18F Labeled Octreotide Derivatives18F-Ta-Gluc-TOCA byClick Chemistry and its Biological Evaluation
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Abstract
The preparation of 18F labeled peptides usually needmany reaction steps, long time, harsh reaction conditions, which greatly limitsthe application of 18Flabeled PET probe. Using click chemistry for the synthesis of 18F labeled peptides make thereaction conditions more reliable, efficient and selective. The reactionconditions are mild, low cost, and fast. The purpose of this research was tosynthetize the glycosylated octreotide derivative quickly and easily, todevelop a method of 18Flabeled peptides by click chemistry. We also discussed the exploration of thefeasibility with 18Flabeled glycosylated octreotide derivatives as a somatostatin receptor positivetumor probe. This work prepared 2-18F-azide ethane precursor compounds by nucleophilic substitution and then labeledPr-Gluc-TOCA by click chemistry, finally we got the product 18F-Ta-Gluc-TOCA by purification.In addition, the in vitro stability and octanolwater partition coefficient of 18F-Ta-Gluc-TOCA were measured.The biodistribution studies of 18F-Ta-Gluc-TOCAin normal mice and tumor bearing nude mice were investigated. The radiochemicalpurity of 18F-Ta-Gluc-TOCAwas 91%. The vitro stability was good. The octanol-water partition coefficientwas -0.43±0.05.The results of biodistribution in normal mice showed rapid clearance fromblood, and excreted mainly through the hepatobiliary metabolism, and also throughthe renal metabolism. The results of the biodistribution in tumor bearing nudemice showed high uptake in the tumor (4.34±0.47%ID/g, 60 min). The findings suggest that 18F-Ta-Gluc-TOCA is a potentialradiotracer for PET imaging of somatostatin receptor positive tumors.
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