99 m Tc labeled resveratrol, a novel radiopharmaceutical for mammary tumor imaging

Objectives Labeling of resveratrol with 99mTc and elucidation of its efficacy in SPECT imaging of mammary tumors.

Methods Labeling of resveratrol with 99mTc was performed using SnCl2 reduction method. Labeling efficiency for the drug and radio-pharmaceutical stability was assessed by standard radio-chromatographic techniques. Blood kinetics and bio distribution pattern of the labeled radio-pharmaceutical as a function of time was determined in normal female Sprague Dawley (S.D) rats. Mammary tumors were induced to another group of female S.D. rats by single intraperitoneal injection of Methyl nitroso urea. Percentage specific uptake at 60min post i.v injection was determined in mammary tumors. The data observed in bio distribution studies was further confirmed by SPECT imaging.

Results Maximum labeling efficiency (>80%) was observed at 1:1 resveratrol to stannous ratio at pH 5-6. Biodistribution studies showed maximum % specific uptake (30.5%) in the kidneys 1 hr post injection which then decreased to 5.6 % at 3 hrs post injection. Increase in blood activity was observed at 15 sec and 7 min post injection showing biphasic drug release pattern. Radiopharmaceutical uptake in tumorous tissue, was found to be 10 times greater, in comparison to normal mammary tissue.

Conclusions Higher tumor uptake as compared to normal mammary tissue uptake and quick excretion via kidneys, clearly depicts the effectiveness of 99m Tc labeled resveratrol as a potential mammary cancer imaging agent. Further studies to improve its localization in mammary tumors are in progress.