Recent advances in the synthesis of (^99mTechnetium) based radio-pharmaceuticals

Abstract

Technetium radionuclide (99mTc) has excellent extent of disintegration properties and occupies a special place in the field of nuclear medicinal chemistry and other health disciplines. Current review describes recent approaches of synthesis in detailed ways for radio-pharmaceuticals of technetium which have been developed to treat and diagnose the biotic disorders. These technetium labeled radio-pharmaceuticals have been established to apply in the field of diagnostic nuclear medicine especially for imaging of different body parts such as brain, heart, kidney, bones and so on, through single photon emission computed tomography (SPECT) that is thought to be difficult to image such organs by using common X-ray and MRI (Magnetic Resonance Imaging) techniques. This review highlights and accounts an inclusive study on the various synthetic routes of technetium labeled radio-pharmaceuticals using ligands with various donor atoms such as carbon, nitrogen, sulphur, phosphorus etc. These compounds can be utilized as next generation radio-pharmaceuticals.

99mTc-exendin-4: Radiolabeling and quality control studies of glucagon-like peptide analog

“…So, before labeling, 99m TcO4is reduced to transform it from a +7-oxidation state to a +4/+5-oxidation state, which allows it to form complexes with the ligand and synthesize the radiopharmaceutical [33]. Various reducing agents have been utilized for this purpose, with stannous chloride being one of the most common [23,24].…”

“…Technetium-99m ( 99m Tc) has recently become the most preferred radionuclide for labeling research [23]. The use of 99m Tc may improve image quality and radiation safety for patients and personnel due to many procedural advantages related to this isotope's physical features [24]. Because 99m Tc is a radionuclide with monoenergetic gamma rays of 140 KeV, a half-life of 6 h, and a diverse chemistry for forming complexes [25].…”

A preliminary study on radiolabeling and quality control of [99mTc]Tc-6-mercaptopurine to develop tumor scintigraphic agent

“…The researchers have used a variety of reduction agents for this purpose, including stannous chloride, stannous tartrate, sulphonic acid, sodium dithionite, sodium borohydride, formamidine, hydrohalic acids, and others. Stannous salts are frequently used as a reductant within them due to its non-toxic and stable characteristics [9,29].…”

Copper-free click bioconjugation of technetium-99m complexes using strained cyclononyne derivatives

“…19 A diverse redox chemistry with oxidation states from −I to +VII is found for technetium. 20,21 Classically, [ 99m Tc]TcO 4 − comprises Tc in the oxidation state +7 and has to be reduced to a lower oxidation state to be conjugated to biomolecules or other carriers with suitable reducing agents, like SnCl 2 ·H 2 O or NaBH 4 . A variety of technetium cores have been used, such as the [TcO] 3+ , [TcN] 2+ , [Tc(CO) 3 ] + , and Tc-HYNIC cores.…”

“…19 A diverse redox chemistry with oxidation states from −I to +VII is found for technetium. 20,21 ] + , and Tc-HYNIC cores. 22,23 In particular, the 99m Tc-tricarbonyl core 24 with Tc in the oxidation state +1 has gained special interest due to its facile one-pot synthesis and water solubility, and the rapid ligand exchange of the water ligands with various suitable ligands and bears the possibility of a kit formulation.…”