Preparation of radioiodinated khellin for the urinary tract imaging

Khellin, 4,9-dimethoxy-7-methyl-5H-furo[3,2-g]chromen-5-one, the most biologically active furochromone present in Ammi visnaga fruits indigenous to Egypt. A procedure for radioiodination of khellin with 125I is carried out via an electrophilic substitution reaction. The reaction parameters studied were khellin amount, pH of the reaction mixture, reaction time, temperature, different oxidizing agents and different organic media to optimize the conditions for the labeling of khellin and to obtain a high radiochemical yield of the 125I-khellin (125I-Khel). Using 3.7 MBq of Na125I, 100 μg (0.96 mM) of khellin as substrate, 100 μg (1 mM) of chloramine-T as oxidizing agent in ethanol at 60 °C for 10 min, a maximum radiochemical yield of 125I-Khel (78 %) was obtained. The specific activity of 125I-Khel was 3 MBq/0.5 mM. The biological distribution in normal mice indicates that radioiodinated khellin is a novel agent for urinary tract infection imaging.