Synthesis of 99mTc-labeled 2-Mercaptobenzimidazole as a novel radiotracer to diagnose tumor hypoxia

Abstract

Discovery of 99m Tc-labeled imidazole derivatives as a potential radiotracer for hypoxic tumor imaging is considered to be of great interest because of non-invasive detection capabilities. 2-Mercaptobenzimidazole (2-MBI) was successfully synthesized, characterized and radiolabeled with [ 99m Tc (CO) 3 (H 2 O) 3 ] + intermediate to form 99m Tc-2-MBI complex with radiochemical purity of ≥95% yield as observed by instant-thin layer chromatography (ITLC) and radio-high performance liquid chromatography (radio-HPLC). The 99m Tc-2-MBI complex was observed to be stable in saline and serum with no noticeable decomposition at room temperature and 37 °C, respectively, over a time period of 24 h. Biodistribution results in Balb/c mice bearing S180 tumor show that 99m Tc-2-MBI highly internalized in tumor tissue, also possess preferably high tumor/muscle and tumor/blood ratios 4.14 ± 0.77 and 3.91 ± 0.63, respectively at 24 h incubation. Scintigraphic imaging study shows 99m Tc-2-MBI is visibly accumulated in hypoxic tumor tissue, suggesting it would be a promising radiotracer for early stage diagnosis of tumor hypoxia.

Preclinical assessment of Alzheimer's disease using novel designed 99mTc‐labeled RGD‐based pro‐apoptotic cyclic peptide as a promising SPECT agent

“…Various amounts of SnCl 2 .2H 2 O and NaBH 4 were used as reducing agents by following the protocols reported in the literature. [ 19,20 ]…”

“…For this purpose, the above‐collected samples including liver, blood, and urine of mice model sacrificed at 60‐min postinjection were processed as reported in the literature. [ 20 ] In brief, the blood sample was centrifuged at 1409 × g for 5 min and the supernatant was isolated and treated with acetonitrile to get protein precipitates as a result of centrifugation. The urine sample was directly diluted with normal saline and passed through a 0.22 μm Millipore filter.…”

“…Various amounts of SnCl 2 .2H 2 O and NaBH 4 were used as reducing agents by following the protocols reported in the literature. [19,20] For direct labeling of DTPA-peptide conjugates, varying concentrations of SnCl 2 .2H 2 O (0.5-5 μg/10 μl in 0.1-M HCl) were used. The freshly prepared solution of SnCl 2 .2H 2 O with a concentration of 0.75 and 0.5 μg/μl (from 1 mg/ml in 0.1-M HCl/water) was taken in Eppendorf tubes containing DTPA-cPT and DTPA-L PT (10 μg/200 μl Na-PBS, pH 6.5), respectively.…”

Radioiodination and biological evaluation of irbesartan as a tracer for cardiac imaging

“…The biological distribution of radiotracer, [ 125 I]IodoIrbesartan and the extent of is uptake in the heart muscle compared to its concentration of blood was studied through empirical animals like mice [9][10][11]. Additionally, in recent study [12] a novel 18 F-labeled derivative of irbesartan was made for in vivo positron emission tomography (PET). To measure a angiotensin II type 1 receptor expression.…”

“…Additionaly, [ 125 I]IodoIrbesartan was examined in saline medium. At time intervals, the stability was determined using TLC technique[15,16,18].…”