99m Tc-D-Penicillamine-Glucuronide: Synthesis, Radiolabeling, In Vitro and In Vivo Evaluation Serap Tekso ¨ z, 1 C ¸ig˘ dem Acar Ic ¸ hedef, 1 Seniha O ¨ zyu ¨ ncu ¨, 1 Fazilet Zu ¨ mru ¨ t Biber Mu ¨ ftu ¨ ler, 1 Perihan U ¨ nak, 1 _ Ilker Emin Medine, 1 Tu ¨ rkan Ertay, 2 and Mine S xencan Eren 2 Abstract The current study was aimed at synthesizing a glucuronide derivative of D-penicillamine (D-PA) to be used for imaging purposes. First of all, D-PA-glucuronide (D-PA-Glu) was synthesized by experimental treatments starting with uridine 5¢-diphospho-glucuronosyltransferase enzyme rich microsome preparate. Then, the synthesized compound was labeled with technetium ( 99m Tc) by using a reduction method with stannous chloride. Quality controls were performed by using high-performance liquid chromatography and thin-layer radio chromatography (TLRC). Radiolabeling yield of 99m Tc-D-PA-Glu was more than 98% according to TLRC results. In vitro evaluations of radiolabeled complexes were investigated on PC-3 human prostate cancer cells. 99m Tc-D-PA-Glu exhibited more accumulation on PC-3 cells versus 99m Tc-D-PA at 240 minutes. In order to determine its radiopharmaceutical potential, biodistribution studies were carried out in male Albino Wistar rats. The biodistribution results of 99m Tc- D-PA-Glu, showed the highest uptake in prostate at 120 minutes postinjection with the main excretion route being through kidneys and bladder. 99m Tc-D-PA-Glu and 99m Tc-D-PA have exhibited different biodistribution results. Key words: glucuronidation, PC-3 cell line, penicillamine, radiolabeling, scintigraphy, 99m Tc Introduction G lucuronides are common soluble conjugates formed as a step in the metabolism and excretion of many toxins and drugs, such as phenols and alcohols. Uridine 5¢-diphospho- glucuronosyltransferase (UDP-glucuronosyltransferase or UGT) enzymes produce products that are more water soluble, usually less biologically active, and more readily excreted than the parent compounds. The glucuronides can be excreted by renal and biliary elimination. 1 Due to the deglucuronida- tion of a glucuronide conjugate on the cell membrane by b- glucuronidase, they have become interesting as targeting entities in cancer research. 2–4 Fishman et al. reported that b- glucuronidase was a component of the tumor cells and that some types of normal cells (such as fibroblasts and leukocytes) also contained the enzyme. 5 In other words, cancer cells have the enzyme of b-glucuronidase at an elevated ratio. The compounds of different glucuronide derivatives when con- jugated with toxic aglycons can be used as prodrugs for cancer therapy. 6 Glucuronide-based prodrugs can be used in prodrug monotherapy for selective cancer therapy. Therefore, the glucuronide prodrugs are useful for application in the antibody-directed enzyme prodrug therapy strategy such that b-glucuronidase can be targeted to tumor cells by adminis- tration of antibody- b-glucuronidase conjugates. 7 Ertay et al. studied a peptide glucuronide, Exorphin C glucuronide, labeled with technetium ( 99m Tc) to image opi- oid receptor-expressing tissues and tumor cells containing higher enzyme b-glucuronidase activity. 3 They reported that the radiolabeled peptide is rapidly cleared via the urinary system, thus showing much lower liver uptake. Mu ¨ ftu ¨ ler et al. synthesized an antiestrogen glucuronide compound radiolabeled with 99m Tc, 99m Tc-TOR-G, as a new anti estro- gen glucuronide imaging agent for ovary tumors. 8 It is known that 99m Tc is one of the most important ra- dioisotopes used in diagnostic imaging. Nowadays, radi- olabeled compounds labeling with 99m Tc have been used for bone scintigraphy as well as myocardial perfusion scin- tigraphy, and they have been started to be used with the aim of tumor imaging in recent years. In addition, radiolabeled 1 Ege University Institute of Nuclear Sciences, Bornova, Izmir, Turkey. 2 Dokuz Eylul University, School of Medicine, Department of Nuclear Medicine, Inciralti, _ Izmir, Turkey. Address correspondence to: Serap Tekso ¨ z; Ege University Institute of Nuclear Sciences; Ankara Street, Bornova 35100, Izmir, Turkey E-mail: serap.teksoz@ege.edu.tr CANCER BIOTHERAPY AND RADIOPHARMACEUTICALS Volume 26, Number 5, 2011 ª Mary Ann Liebert, Inc. DOI: 10.1089/cbr.2010.0854 623