Design and synthesis of 99mTc-citro-folate for use as a tumor-targeted radiopharmaceutical.

Folate conjugates exhibit high affinity for folate receptor (FR) positive cells and tissues, such as those in tumors, making them attractive candidates and of interest in diagnostic tumor imaging. The aim of study was to synthesize a novel radiopharmaceutical based folate conjugate, (99m)Tc-citro-folate, and to evaluate its efficiency as a targeted agent for imaging tumors that over express FR. TLC, HPLC (1)H NMR and LC-MS/MS methods were used to check and confirm the synthesized citro-folate. Citro-folate was labeled with Tc-99m with high labeling efficiency (97±1.0%). Biodistribution of the radiolabeled conjugate (99m)Tc-citro-folate was investigated in vivo using two groups of rats: FR saturated and unsaturated. These experiments showed high uptake of (99m)Tc-citro-folate in FR rich tissues and demonstrated its sensitivity and specificity in imaging ovary and uterus. Based on the demonstrated good radiolabeling and biodistribution properties, the compound (99m)Tc-citro-folate may potentially be used as a radiopharmaceutical agent for imaging the FR-positive tumors.