Evaluation of tumor affinity of mono‐[123I]iodohypericin and mono‐[123I]iodoprotohypericin in a mouse model with a RIF‐1 tumor

In this study we have compared the tumour‐seeking properties of mono‐¹²³I]iodoprotohypericin and mono‐¹²³I]iodohypericin in C3H mice with a subcutaneous radiation‐induced fibrosarcoma‐1 tumor. After intravenous injection, both tracers were rapidly cleared from all organs and were retained by the tumors. There was no significant difference in tumor uptake of the two tracers at all studied time points (p > 0.05). To study the plausible mechanism of hypericin and mono‐iodohypericin uptake in tumor, their plasma binding profile was investigated. Both agents show high affinity for low‐density lipoproteins and to a lesser extent high‐density lipoproteins and other heavy proteins. Mono‐¹²³I]iodohypericin appears to be more promising as a tumor diagnostic agent, given its faster clearance from all organs. Copyright © 2007 John Wiley & Sons, Ltd.