107-35-7Relevant articles and documents
Reactivity and the mechanisms of reactions of β-sultams with nucleophiles
Wood, J. Matthew,Hinchliffe, Paul S.,Laws, Andrew P.,Page, Michael I.
, p. 938 - 946 (2002)
Ethane-1,2-sultam has a pKa of 12.12±0.06 at 30 °C and its rate of alkaline hydrolysis shows a pH-dependence reflecting this so that the observed pseudo first-order rate constant at phs above the pKa are pH independent. There is no evidence of neighbouring group participation in the hydrolysis of either N-α-carboxybenzylethane-1,2-sultam or N-(hydroxyaminocarbonylmethyl)-2-benzylethane-1,2-sultam. Oxyanions, but not amines or thiols, react with N-benzoylethane-1,2-sultam in water by a nucleophilic ring opening reaction confirmed by product analysis and kinetic solvent isotope effects. A Bronsted plot for this reaction has two distinct correlations with βnuc = 0.52 and 0.65 for weak and strong bases, respectively, although a statistically corrected plot may indicate a single correlation.
Oxyhalogen sulfur chemistry: Kinetics and mechanism of the oxidation of a Bunte salt 2-aminoethanethiolsulfuric acid by chlorite
Chinake,Mundoma,Olojo,Chigwada,Simoyi
, p. 4957 - 4964 (2001)
Spectrophotometric and 1H NMR methods have been used to study the kinetics and mechanism of oxidation of the Bunte salt, 2-aminoethanethiol sulfuric acid, H2NCH2CH2S-SO3H (AETSA) by chlorite in mildly acidic media. The reaction is characterized by a long quiescent induction period followed by rapid and autocatalytic production of chlorine dioxide. The formation of chlorine dioxide is much more pronounced in stoichiometric excess of chlorite. The stoichiometry of the reaction in excess chlorite just before formation of chlorine dioxide was determined to be: 2ClO2- + H2NCH2CH2S-SO3H → ClNHCH2CH2SO3H + SO4-2 + Cl- + H+, while in excess AETSA the stoichiometry was: 3ClO2- + 2H2NCH2CH2S-SO3H + 2H20 → 2NH2CH2CH2SO3H + 2SO4-2 + 3Cl- + 4H+. Although the products in excess chlorite also included pure taurine and dichlorotaurine, monochlorotaurine was the dominant species at pH 1-3. This Bunte salt showed a facile S-S bond cleavage after a single S-oxygenation step on the inner sulfur atom. The sulfoxide is quite stable but there was no experimental evidence for the existence of the sulfone-sulfonic acid. Sulfate production was almost quantitative for the oxidation of only one of the sulfur atoms. Further reaction of the taurine occurred only on the nitrogen atom with no cleavage of the C-S bond. A 21-reaction kinetics scheme model gave reasonable agreement with experiment.
Nucleophilic substitution reactions of N-chloramines: Evidence for a change in mechanism with increasing nucleophile reactivity
Calvo, Paula,Crugeiras, Juan,Rios, Ana,Rios, Miguel A.
, p. 3171 - 3178 (2007)
(Chemical Equation Presented) Third-order rate constants (kNu)H (M-2 s-1) for the hydronium ion catalyzed reactions of a range of nucleophiles with N-chlorotaurine (1) in water at 25°C and I = 0.5 (NaClO4) are reported. The solvent deuterium isotope effects on hydronium ion catalysis of the reaction with 1 of bromide and iodide ion are (kBr)H/(kBr)D = 0.30 and (k I)H/(kI)D = 0.54, respectively. The inverse nature of these isotope effects and the absence of general acid catalysis are consistent with a stepwise mechanism involving protonation of 1 in a fast preequilibrium step. The appearance of strong catalysis by general acids for the reaction of the more nucleophilic SO32- and HOCH2CH2S- with the chloramine indicates a change to a concerted mechanism, with protonation of the chloramine at nitrogen and chlorine transfer to the nucleophile occurring in a single step. A rough estimate of the lifetime of the protonated chloramine in the presence of the thiolate anion suggests that the concerted mechanism is enforced by the absence of a significant lifetime of the protonated substrate in contact with the nucleophile. Theoretical calculations provide evidence against an electron-transfer mechanism for chlorination of the nucleophiles by protonated 1.
Human flavin-containing monooxygenase 1 and its long-sought hydroperoxyflavin intermediate
Catucci, Gianluca,Cheropkina, Hanna,Fenoglio, Ivana,Gilardi, Gianfranco,Marucco, Arianna,Sadeghi, Sheila J.
, (2021)
Out of the five isoforms of human flavin-containing monooxygenase (hFMO), FMO1 and FMO3 are the most relevant to Phase I drug metabolism. They are involved in the oxygenation of xenobiotics including drugs and pesticides using NADPH and FAD as cofactors. Majority of the characterization of these enzymes has involved hFMO3, where intermediates of its catalytic cycle have been described. On the other hand, research efforts have so far failed in capturing the same key intermediate that is responsible for the monooxygenation activity of hFMO1. In this work we demonstrate spectrophotometrically the formation of a highly stable C4a-hydroperoxyflavin intermediate of hFMO1 upon reduction by NADPH and in the presence of O2. The measured half-life of this flavin intermediate revealed it to be stable and not fully re-oxidized even after 30 min at 15 °C in the absence of substrate, the highest stability ever observed for a human FMO. In addition, the uncoupling reactions of hFMO1 show that this enzyme is 2O2 with no observable superoxide as confirmed by EPR spin trapping experiments. This behaviour is different from hFMO3, that is shown to form both H2O2 and superoxide anion radical as a result of ～50% uncoupling. These data are consistent with the higher stability of the hFMO1 intermediate in comparison to hFMO3. Taken together, these data demonstrate the different behaviours of these two closely related enzymes with consequences for drug metabolism as well as possible toxicity due to reactive oxygen species.
Oxyhalogen-sulfur chemistry: Non-linear oxidation of 2-aminoethanethiolsulfuric acid (AETSA) by bromate in acidic medium
Darkwa, James,Mundoma, Claudius,Simoyi, Reuben H.
, p. 4407 - 4413 (1996)
The reaction between bromate and 2-aminoethanethiolsulfuric acid, H2NCH2CH2S-SO3H (AETSA), has been studied in high acid environments. The stoichiometry in excess AETSA is BrO3- + H2NCH2CH2S-SO3H + H2O → H2NCH2CH2SO3H + SO42- + 2H+ + Br- . In excess BrO3- the stoichiometry is: 7BrO3- + 5H2NCH2CH2S-SO3H → 5Br(H)NCH2CH2SO3H + 5SO42- + Br2 + 3H+ + H2O. The reaction displays clock reaction characteristics in which there is initial quiescence followed by a sudden and rapid formation of Br2(aq). The oxidation proceeds by successive addition of oxygen on the inner sulfur atom followed by cleavage of the S-S bond to form taurine and SO42-. The Br2(aq) and the HOBr in solution oxidize the taurine to form a mixture of monobromotaurine and dibromotaurine. Computer simulations of a proposed 13-step reaction scheme produced a reasonable fit to the experimental data.
Antioxidant chemistry: Hypotaurine-taurine oxidation by chlorite
Martincigh, Bice S.,Mundoma, Claudius,Simoyi, Reuben H.
, p. 9838 - 9846 (1998)
Extensive experimental data have been collected on the oxidation of hypotaurine, H2NCH2CH2SO2H, by chlorite and chlorine dioxide. Hypotaurine is stable and reacts slowly with chlorite to give taurine, hypotaurine sulfonic acid, and monochloro- and dichlorotaurine. However, it reacts rapidly with chlorine dioxide with a second-order rate constant of 801 M-1 s-1 to give taurine. Oxidation occurs simultaneously at the sulfur center (to give the sulfonic acid) and at the nitrogen center (to give the chloramines). The stoichiometry of the reaction was experimentally determined to be ClO2- + H2NCH2CH2SO2H + H+ → ClHNCH2CH2SO3H + H2O. The formation of dichlorotaurine is favored only in high acid environments.
Bioactive metabolites from the Caribbean sponge Aka coralliphagum
Grube, Achim,Assmann, Michael,Lichte, Ellen,Sasse, Florenz,Pawlik, Joseph R.,Koeck, Matthias
, p. 504 - 509 (2007)
The chemistry of the burrowing sponge Aka coralliphagum was investigated to identify chemically labile secondary metabolites. The HPLC-MS analysis of the two growth forms typica and incrustans revealed different metabolites. The previously unknown sulfated compounds siphonodictyals B1 to B3 (6-8), corallidictyals C (9) and D (10), and siphonodictyal G (11) were isolated, and their structures were elucidated by NMR and MS experiments. The compounds were tested in a DPPH assay, in antimicrobial assays against bacteria, yeasts, and fungi, and in antiproliferation assays using cultures of mouse fibroblasts. The biological activity was linked to the presence of the ortho-hydroquinone moiety.
Oxyhalogen-sulfur chemistry: Oxidation of 2-aminoethanethiolsulfuric acid by iodate in acidic medium
Mundoma, Claudius,Simoyi, Reuben H.
, p. 1543 - 1550 (1997)
The oxidation of 2-aminoethanethiolsulfuric acid, AETSA, by iodate has been studied in highly acidic media. The reaction is very slow and shows some clock-reaction characteristics in which iodine is formed after some induction period. The oxidation of AETSA involves the oxidation of only one of the sulfur atoms to SO42-. The other sulfur atom remains attached to the carbon chain as a sulfonic acid (taurine). The stoichiometry of the reaction is: IO3- + H2NCH2CH2S-SO3H + H2O → H2NCH2CH2SO3H + I- + SO42- + 2H+. The reaction of I2 and AETSA was found to be slow and autoinhibitory as the I- formed combines with the remaining I2 to form the relatively unreactive triiodide ion, I3-. The second-order rate constant for the reaction between I2 and AETSA was determined as 16.7 ± 2.3 M-1 s-1.
Oxyhalogen-sulfur chemistry - Kinetics and mechanism of the bromate oxidation of cysteamine
Morakinyo, Moshood K.,Chikwana, Edward,Simoyi, Reuben H.
, p. 416 - 425 (2008)
The kinetics and mechanism of the oxidation of the biologically important molecule, cysteamine. by acidic bromate and molecular bromine have been studied. In excess acidic bromate conditions, cysteamine is oxidized to N-brominated derivatives, and in excess cysteamine the oxidation product is taurine according to the following stoichiometry: BrO3- + H 2NCH2CH2SH → H2NCH 2CH2SO3H + Br-. There is quantitative formation of taurine before N-bromination commences. Excess aqueous bromine oxidizes cysteamine to give dibromotaurine: 5Br2 + H 2NCH2CH2SH + 3H2O → Br 2NCH2CH2SO3H + 8Br- + 8H+, while excess cysteamine conditions gave monobromotaurine. The oxidation of cysteamine by aqueous bromine is effectively diffusion-controlled all the way to the formation of monobromotaurine. Further formation of dibromotaurine is dependent on acid concentrations, with highly acidic conditions inhibiting further reaction towards formation of dibromotaurine. The formation of the N-brominated derivatives of taurine is reversible, with taurine regenerated in the presence of a reducing agent such as iodide. This feature makes it possible for taurine to moderate hypobromous acid toxicity in the physiological environment.
Trofosides A and B and other cytostatic steroid-derived compounds from the far east starfish Trofodiscus ueber
Levina,Kalinovsky,Andriyashchenko,Menzorova,Dmitrenok
, p. 334 - 340 (2007)
Three new polar steroids identified as trofoside A, 20R,24S)-24-O-(3-O- methyl-β-D-xylopyranosyl)-3β,6α,8,15β,24-pentahydroxy- 5α-cholestane, its 22(23)-dehydro derivative (trofoside B), and 15-sulfooxy-(20R,24S)-5α-cholestane-3β,6β,8,15α, 24-pentaol sodium salt, were isolated fromTrofodiscus ueber starfish extracts collected in the Sea of Ohotsk. Two known compounds, trofoside A aglycone, (20R,24S)-3β,6α,8,15β,24-pentahydroxy-5α- cholestane, and triseramide, (20R,24R,25S,22E)-24-methyl-3β6α,8, 15β-tetrahydroxy-5α-cholest-22-en-27-oic acid (2-sulfoethyl)amide sodium salt, were also found. The structures of the isolated polyoxysteroids were established from their spectra. Minimal concentrations causing degradation of unfertilized egg-cells of the sea-urchin Strongylocentrotus intermedius(C min) and terminating the cell division at the stage of the first division (C min embr.), as well as the concentrations causing 50% immobilization of sperm cells (OC50) and inhibiting their ability to fertilize egg-cells by 50% (IC50) were determined for the isolated compounds. Of three compounds highly toxic in embryos and sea-urchin sperm cells, the polyol with a sulfo group in the steroid core was the most active; two glycosides with monosaccharide chains located at C3 and C24 atoms were less toxic. Note that all the compounds with the spermiotoxic activities differently affected the embryo development. The positions of monosaccharide residues in the core considerably influence the compound activity. For example, both mono-and double chained glycosides with the monosaccharide fragment at C3 and fragments at C3 and C4 atoms are active against sea-urchin sperm cells and embryos, whereas the C24 glycosylated trofoside A does not affect embryos and displays a poor spermiotoxicity. Nauka/Interperiodica 2007.
