The influence of stereoisomerism on the biological behavior of 99mTc labeled penicillamine

The aim of this study is to investigate stereoisomeric behavior of penicillamine and the effect of temperature on labeling. In addition, it was explored how stereoisomerism affected biological behavior of them. In the present work, D- and L-enantiomers of penicillamine(D-PA, L-PA) were labeled with 99mTc using SnCl2 as reducing agent and their radiopharmaceutical potentials were investigated. Quality control procedures were carried out using thin layer radiochromatography (TLRC), electrophoresis and high performance liquid radiochromatography (HPLRC). HPRLC chromatograms showed two peaks for 99mTc-D-PA, while a single peak was observed for 99mTc-L-PA at room temperature. However, the single peak was observed at 90 °C for both isomers. Labeling yields of each isomer were found to be over 98%. Biological activity of these complexes was determined on male Albino Wistar rats by biodistribution studies. While the biodistribution result of 99mTc-D-PA showed high uptake in the liver, maximum uptake of 99mTc-L-PA was observed in the kidneys. Both two complexes were cleared rapidly from the blood, mainly by the renal system. Since the activity concentration of 99mTc-D-PA at the 30th minute in the kidneys and the liver reached a maximum value and at the 120th minute, it was removed by renal and hepatobiliary excretion. As a result, it can be concluded that stereoisomerism affect not only the chemical behavior, but also differs their biological behavior of these compounds. © 2009 Akadémiai Kiadó, Budapest, Hungary

A new 99mtc labeled peptide: 99mtc ß-casomorphin 6, biodistribution and imaging studies on rats [99mTc Bağlı Yeni Bir Peptid: Ratlarda 99m Tc ß-Kazomorfin 6 Molekülünün Biyodağılım ve Görüntüleme çalışması]

Peptide radiopharmaceuticals have an increasing significance in nuclear medicine practice. ß-casomorphin is a digestive peptide with 6 amino acids (Tyr-Pro-Phe-Pro-Gly-Pro). N terminal amino acid chain mainly tyr-pro-phe-pro structured exogen opioid peptid type beta cosomorphin are µ-receptor agonistic activity with priority. Animal studies show that ß-casomorphins can act as opioid receptor agonists. The aim of this study was to label ß-casomorphin with 99m Tc and to examine its usefulness as an opioid receptor binding radiopharmaceutical in Albino Wistar rats and cancer cells. ß-casomorphin was labeled with 99m Tc radionuclide using bifunctional chelating agent. Quality control studies were done by Instant Thin layer chromatography (ITLC) and High performance liquid chromatography (HPLC) methods. Binding efficiency of the compound was more than 99%. It was observed as stable for at least 3 h at room temperature. Lipophilicity was also performed for labeled molecule. Imaging studies for 99m Tc labeled molecule was done in rats by using gamma camera. For biodistribution studies; 99m Tc labeled molecule was injected to the rats from tail vein and radioactivity per gr weight of each organ was measured as count per second (cps). Receptor specificity was evaluated in imaging and biodistribution studies in experimental animals. Cell labeling studies were also performed on breast and ovarien cancer cells. In terms of evaluating the biodistribution of 99m Tc-ß-casomorphin molecule in rats, uterus and ovary displayed high involvement. It was also confirmed by cell labeling studies. If the radiopharmaceutical is radiolabeled with therapeutic radionuclides it would be useful for therapy for uterus, ovary and breast tumors. © 2017, Veteriner Fakultesi Dergisi. All rights reserved

Radiolabeling of morphine with 131I and its biodistribution in rats

PubMed ID: 20707720This study was conducted to determine the possible radiopharmaceutical potential of morphin labeled with 131I. Morphine was extracted from dry capsules of the opium poppy (Papaver somniferum L.), purified by high-performance liquid chromatography, and characterized with nuclear magnetic resonance and infrared spectroscopy. The purified compound was labeled with 131I. Male Albino Wistar rats (18) were used for receptor blockage and unblockage biodistribution studies. Tissue distribution studies showed that radiolabeled morphine had higher uptake in lung, liver, small intestines, large intestines, and stomach than the other tissues. The highest uptake of radiolabeled compounds in rats' brain was found to be in the midbrain and hypothalamus. After receptor blockage with morphine, uptake of 131I-morphine decreased in the lungs, liver, kidney, testis, prostate, spinal cord, cerebellum, hippocampus, striatum, and temporal cortex with respect to receptor unblockage studies of rats. This study concludes that the labeling yield of 131I-morphine was high, high amount of 131I-morphine was found in the hypothalamus, and 131I- morphine has enough stability for diagnostic scanning. © 2010, Mary Ann Liebert, Inc