Radioiodination of 3-amino-2-quinoxalinecarbonitrile 1,4-dioxide and its biological distribution in Erhlich ascites cancer bearing mice as a preclinical tumor imaging agent

Abstract

3-Amino-2-quinoxalinecarbonitrile 1,4-dioxide (QN) was labeled with 125I, and the biological distribution of the product was studied. 125I-QN was prepared by direct electrophilic substitution reaction using N-bromosuccinimide (NBS) as an oxidizing agent. The radiochemical yield of 92% was reached under the following optimum conditions: pH 7, 15 min, 100 μg of QN, and 75 μg of NBS. The labeled QN was stable for up to 12 h post labeling. Biodistribution study of 125I-QN in tumor-bearing mice reflected that it accumulated in tissues with high proliferation rate with preferential accumulation in tumor sites. 125I-QN was incorporated rapidly in the tumor site (T/NT = 4 at 2 h post injection), and then its content slowly decreased, whereas in the other tissues it decreased rapidly. The results obtained encourage the use of 123I-QN as a tumor imaging agent.