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Technetium-Labeled Compounds
Published in Garimella V. S. Rayudu, Lelio G. Colombetti, Radiotracers for Medical Applications, 2019
Suresh C. Srivastava, Powell Richards
Colorimetric methods are also suitable for tin analysis especially when relatively small amounts are to be determined. Reagents such as dithiol,147 hematoxylin,148 phen-ylfluorone,149 8-hydroxyquinoline,150 dithizone,151 heteropolymolybdates/52,154 cupfer-ron,116 flavonol,155 Cationic Pink 2S,156 etc. have been proposed and developed, but they all lack sensitivity and specificity and with most, a prior separation of tin from various ions is required. Dithiol perhaps is the best among all these reagents. Two simple modified methods for determining Sn(II) in Tc-99m-labeling kits were described recently.157 The first method using Potentiometrie titrations with iodate (based on the classical iodometric techniques) was modified to be useful over a wide range of Sn(II) concentration, 15 μg to 4 mg or more in 10 mi. The second method involves spectro-photometrically measuring the blue complex produced upon reduction of phospho-molybdate with Sn(II).152 Determinations in the range of 2 to 10 μg/mí Sn(II) are possible with this method. After suitable modifications these methods can be used in the presence of many ligands of radiopharmaceutical interest.
The Toxicology and Biological Properties of Organotin Compounds*
Published in Nate F. Cardarelli, Tin as a Vital Nutrient:, 2019
Early work demonstrated that this group of compounds are irritant when externally applied and cause tissue necrosis in a similar way to organoarsenicals when systemically administered. Poisoning can be treated by 2,3-dimercaptopropanol and their in vitro effects can be explained on the basis of high affinity for dithiols. For example, the keto acid oxidases requiring the dithiol, lipoic acid, as an essential cofactor are inhibited at low concentrations.23 It seems likely that all enzymatic systems requiring vicinal dithiol groups will be inhibited by low concentrations of diorganotins and may have toxicological consequences. This area has not been fully explored.
Biological Effects and Medical Treatment
Published in Alan Perkins, Life and Death Rays, 2021
If the patient has been exposed to radioactive iodine such as iodine-131, a thyroid-blocking agent should be given to reduce the internal uptake of radioiodine in the thyroid gland. Potassium iodide is the drug of choice and should be administered within a few hours to be effective. If a metal radioactive poison has entered the circulation, it may be possible to give an agent to bind the metal and increase the speed of elimination from the body. The more quickly a radioactive poison is removed, the lower the radiation dose and the less serious the health effects will be. Prussian blue (ferric hexacyanoferrate) will increase the elimination of caesium and thallium radionuclides from the bowels. This has been used to treat casualties in the past and is considered to be a good standby in possible terrorist incidents using stolen or abandoned radiation therapy sources or industrial sources containing caesium-137. Chelating agents are also used as scavengers of radiometals and are most effective when they are given shortly after radioactive materials or poisons have entered the body. During the Second World War, dimercaprol, an organic dithiol compound, was developed as an experimental antidote against the arsenic-based poison gas lewisite. After the Second World War, lead poisoning became a major problem in naval personnel as a result of their jobs of repainting the hulls of ships. The medical use of a salt of ethylene diamine tetra-acetate (EDTA) known as sodium calcium edetate was introduced as a therapeutic chelating agent to treat lead poisoning. In the 1960s a further compound meso-2,3-dimercaptosuccinic acid (DMSA), a related dithiol with far fewer side effects, was introduced. A further chelating agent diethylenetriaminepentaacetate (DTPA) was introduced and found to be a more powerful metal sequestering agent. DTPA comes in two forms: calcium (Ca-DTPA) and zinc (Zn-DTPA). In 2004 the US Food and Drug Administration determined zinc-DTPA and calcium-DTPA to be safe and effective for the treatment of internal poisoning with plutonium, americium or curium. When given within the first day after internal contamination has occurred, calcium-DTPA is about 10 times more effective than zinc-DTPA, but after 24 hours have passed, calcium-DTPA and zinc-DTPA are equally effective in chelating these radioactive materials.1
The new H2S-releasing compound ACS94 exerts protective effects through the modulation of thiol homoeostasis
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2018
Daniela Giustarini, Valerio Tazzari, Ivan Bassanini, Ranieri Rossi, Anna Sparatore
The trityl deprotection of the thiol was performed by dissolving 2-(4-(3-thioxo-3H-1,2-dithiol-4-yl)benzamido)-3-(tritylthio)propanoic acid ethyl ester (240 mg; 0.38 mmol) in 4 N HCl in dioxane (10 ml) at 0 °C; water (1 ml) was added, and the mixture was stirred at 0 °C for 30 min. The solvent was evaporated to dryness, and the residue was taken up with ether and then evaporated. This procedure was repeated several times to ensure the complete elimination of HCl and dioxane. After rinsing the residue, first with CH2Cl2 and then with ether, pure ACS94 (117 mg; yield 80%) was obtained. M.p. 109–111 °C. 1H-NMR (DMSO-d6): δ = 9.22 (s, 1H); 8.84 (d, J = 7.63 Hz, 1H); 7.93 (d, J = 8.21 Hz, 2H); 7.68 (d, J = 8.21 Hz, 2H) 4.56–4.50 (m,1H); 4.11 (q, J = 7.03 Hz, 2H); 2.99–2.83 (m,1H); 2.68 (t, J = 7.92 Hz, 1H); 1.18 (t, J = 7.03 Hz, 3H). 13C-NMR (75 MHz, DMSO- d6): δ = 214.0, 170.8, 166.7, 160.4, 137.0, 133.0, 127.8, 129.3, 61.1, 56.1, 25.5, 14.5. HRMS (ESI) m/z calcd for C15H15NO3S4Na [M + Na]+: 407.98270; found: 407.98251.
The clinical potential of thiol redox proteomics
Published in Expert Review of Proteomics, 2020
The glutaredoxin (Grx) family of oxidoreductases also play a functional role in the regulation of redox-sensitive proteins (Figure 2) [6]. Dithiol Grx’s such Grx1 and Grx2 contain a Trx motif CXXC but the family also include a number of monothiolic Grx’s (Grx3-7 containing a CXXS motif) that have been identified in the biogenesis of Fe-S clusters [21,22]. Dithiol Grx’s are thought to function in a similar manner to Trx’s reducing protein disulfides and glutathionylated proteins. However, these proteins use GSH to complete their catalytic cycle with the formation of GSSG which is subsequently reduced by glutathione reductase using NADPH+ (Figure 2).
α-Lipoic acid, functional fatty acid, as a novel therapeutic alternative for central nervous system diseases: A review
Published in Nutritional Neuroscience, 2019
Fatemeh Seifar, Mohammad Khalili, Habib Khaledyan, Shirin Amiri Moghadam, Azimeh Izadi, Amirreza Azimi, Seied Kazem Shakouri
The existence of dithiol ring in the oxidized (LA) and reduced (DHLA) forms of LA makes them natural and potent antioxidants.17 They deal with reactive oxygen species (ROS) such as hydroxyl, peroxyl, and superoxide radicals18 as well as reactive nitrogen species (RNS), so their functions are regarded as part of cellular protective mechanisms against stress conditions, where oxidative stress is the main part of the underlying etiology.19 Although the effect of LA and its reduced form DHLA on ROS is proven,13 it is not well known whether they can scavenge free radicals directly.