Radioiodination of 5-amino isoquinoline for poly (ADP-ribose) polymerase targeting: an in vitro evaluation in colorectal carcinoma cells

The isoquinoline derivative, 5-amino isoquinoline (5-AIQ), is a potent inhibitor of poly (ADP-ribose) polymerase (PARP) activity; the DNA repairing protein frequently derivative, 5-amino isoquinoline (5-AIQ), is a potent inhibitor of over expressed in various carcinoma cells. The current study is dedicated for developing a highly specific radioiodinated PARP-1 binding tracer namely, [¹³¹I] 5-amino isoquinoline. The radioiodination of 5-amino isoquinoline with ¹³¹I was carried out via electrophilic substitution reaction. In order to achieve the maximum radioiodination, the parameters including 5-amino isoquinoline concentration, oxidizing agent, reaction time, temperature and type of solvent were optimized. the radiochemical purity was determined by high performance liquid chromatography (HPLC) using Reversed phase lichrosorb column 250 Multiplication Sign 4.6 mm, C-18 5 mu m. The maximum radiochemical yield was 80% with radiochemical purity reached 98%. The log P value for [¹³¹I] 5-amino isoquinoline was found to be 2.08 ± 0.79. Data presented from Cell viability (MTT) cytotoxicity assay on Caco-2 cells showed matched IC₅₀ values with the selected drug concentrations profile for either labeled or unlabeled 5-amino isoquinoline. Likewise, the radioiodinated 5-amino isoquinoline elucidated a higher cell uptake compared to free I-131