Preparation of ¹³¹I-23-hydroxybetulinic acid and in vivo evaluations in liver cancer HepA tumor-bearing mice

In this work, preparation of ¹³¹I-labeled 23-hydroxybetulinic acid (¹³¹I-23-HBA) and its pharmacokinetics in mice were studied. 23-HBA was labeled with ¹³¹I using the hydrogen peroxide method. Purity and stability of the ¹³¹I-23-HBA were evaluated by silicon TLC, in which the substratum of V_{dichoromethane}: V_methanol = 9:1 was used as the developing agent. The dynamic distribution in ICR mice and liver cancer HepA tumor-bearing mice were studied. The results showed that the labeling yield of ¹³¹I-23-HBA was 98% and the radiochemical purities were 98.5%, 97.3%, and 95.8% after 1, 4 and 8 days, respectively. In ICR mice, the blood clearance was quick and the profile of the blood concentration-time was fitted with two compartment model. In tumor-bearing mice 0.5 h after intravenous injection, the liver uptake was the highest (9.14% ID·g^-1). The radioisotope was concentrated in kidney, blood, spleen, intestine, lung and tumor, too. The brain uptake was the lowest as 0.28% ID/g at pi. 0.5 h. The tumor-to-muscle ratio was over 3. The labeling yield and purity of ¹³¹I-23-HBA are high and ¹³¹I-23-HBA is stable. The tumor uptake of ¹³¹I-23-HBA is higher than 23-HBA. ¹³¹I-23-HBA is a potent cancer treatment drug.