1077-28-7Relevant academic research and scientific papers
Catalytic Oxidation of Dithiols by a Semisynthetic Enzyme
Stewart, Kent D.,Radziejewski, Czestaw,Kaiser, E. T.
, p. 3480 - 3483 (1986)
The semisynthetic enzyme flavopapain (1C), obtained from the alkylation of Cys-25 of papain with 8α-(bromoacetyl)-10-methylisoalloxazine (1B), was found to be an effective catalyst for the oxidation of dithiols to disulfides.The k2/Ks values for the oxidation of d,l-dihydrolipoamide and d,l-dihydrolipoic acid determined from anaerobic single-reaction stopped-flow kinetics were 4400 and 3400 M-1 s-1, respectively.These values were, respectively, 126 and 200 times larger than the second-order rate constants for oxidation of d,l-dihydrolipoamide and d,l-dihydrolipoic acid by the model flavin 8-acetyl-10-methylisoalloxazine (1A).Under aerobic turnover conditions using the synthetic dye MTT as an electron acceptor, the kcat and Km values for the oxidation of d,l-dihydrolipoamide by 1C were in approximate agreement with the k2 and Ks values, indicating that the rate-limiting step of catalytic cycle is substrate oxidation rather than oxidation of dihydroflavopapain.When compared with flavopapains 2C and 3C , flavopapain 1C is the most efficient catalyst.The circular dichroic spectra of flavopapains 1C, 2C and 3C were recorded, and the dissociation constants of the sulfite addition complexes of 1C and 2C were determined.From these kinetic and physical studies, the differences in catalytic activity of 1C, 2C, and 3C were judged to be due to changes in the flavin orientation within the active site and the ability to fit the substrate into a productive reaction conformation.
A Reagent for Reduction of Disulfide Bonds in Proteins That Reduces Disulfide Bonds Faster Than Does Dithiothreitol
Singh, Rajeeva,Whitesides, George M.
, p. 2332 - 2337 (1991)
We have synthesized a new reagent - N,N'-dimethyl-N,N'-bis(mercaptoacetyl)hydrazine (DMH) - for the reduction of disulfide bonds in proteins.DMH reduces disulfide bonds 7 times faster than does dithiothreitol (DTT) in water at pH 7.DMH reduces mixed disulfides of cysteine proteases (papain and ficin) especially rapidly (30 times faster than DTT).DMH (ε0 = -0.300 V) reduces noncyclic disulfides completely, although it is less strongly reducing than DTT (ε0 = -0.356 V).
Equilibrium Constants for Thiol-Disulfide Interchange Reactions: A Coherent, Corrected Set
Lees, Watson J.,Whitesides, George M.
, p. 642 - 647 (1993)
Equilibrium constants (Keq) for the thiol-disulfide interchange reactions between dithiothreitol (DTT) and lipoic acid (14.2 +/- 0.7), lipoic acid (Lip) and mercaptoethanol (13.3 M +/- 1.0 M), and mercaptoethanol (ME) and glutathione (GSH or GSSG) (1.20 +/- 0.10) were measured in D2O at pD 7.0 by 1H NMR spectroscopy.Two of these equilibrium constants were also measured in D2O/CD3OD.These values are compared with those obtained by other methods.A coherent set of values for the equilibrium constants between DTT or ME and thiols having a range of structures was assembled (Table III).The recommended value for the equilibrium constant between DTT and GSH is 210 M (Keq = ox>2/(red>)).
Thiolates of arsenic(III), antimony(III), and bismuth(III) with dl-α-dihydrolipoic acid
Ioannou, Panayiotis V.,Tsivgoulis, Gerasimos M.
, p. 897 - 909 (2014)
Lipoic acid can be reduced to dihydrolipoic acid free of lipoic acid without using deoxygenated solvents. Dihydrolipoic acid reacted with phenylarsine oxide, As2O3, and AsCl3, SbCl 3 but not Sb2O3, and Bi2O 3, BiCl3, and Bi(NO3)3· 5H2O in various solvents giving thiolates. When the reactions were done in methanol, the HCl and HNO3 released caused esterification of the -COOH group. The reaction with As(III) compounds was sensitive to dioxygen, leading to production of lipoic acid derivatives as well, arsenite being particularly active for the autoxidation. Physical (1H NMR) and chemical [reactivity of >M-Cl and >Bi(NO3)] properties of the adducts are described. The six-membered dihydrolipoic acid complexes reacted with stoichiometric amounts of British Anti-Lewisite releasing the dihydrolipoic acid by forming the corresponding complexes of British Anti-Lewisite. Graphical Abstract: [Figure not available: see fulltext.]
A lipoic acid injection and its preparation method (by machine translation)
-
Paragraph 0076-0081, (2019/07/04)
The present invention to provide a high safety of the thioctic acid preparation, including lipoic acid, the solvent component, characterized in that the vinyl octoate in preparation, containing lipoic acid ethylenediamine double-substituent, wherein the lipoic acid ethylenediamine double-substituent content are not higher than 0.2%. The lipoic acid preparation high safety, low toxicity, can be better clinical efficacy of lipoic acid. (by machine translation)
Preparation method of R-(+)-lipoic acid
-
Paragraph 0038; 0043; 0044; 0046; 0050; 0052; 0054, (2018/06/23)
The invention discloses a preparation method of R-(+)-lipoic acid. The method comprises the following steps: performing salt formation on a raw material of racemic lipoic acid and a resolving agent ofR-phenylethylamine, so as to obtain diastereoisomeric R-phenylethylamine racemic lipoic acid salt; performing recrystallization separation on a raw material of the salt, so as to obtain a single enantiomer of R-phenylethylamine R-(+)-lipoic acid salt; finally, acidizing the single enantiomer of R-phenylethylamine R-(+)-lipoic acid salt, so as to obtain the target compound R-(+)-lipoic acid in a structure of the formula (I) at a yield of 40%. The method is simple in operation, lower in requirements on equipment, mild in conditions and higher in yield, so that the method is suitable for industrial production.
Oxidation-triggered aggregation of gold nanoparticles for naked-eye detection of hydrogen peroxide
Wu, Shaojue,Tan, Si Yu,Ang, Chung Yen,Luo, Zhong,Zhao, Yanli
, p. 3508 - 3511 (2016/03/04)
Naked-eye detection of H2O2 was realized based on the color change of gold nanoparticles upon aggregation. The removal of polyethylene glycol chains from the nanoparticle surface under H2O2 treatment let to the exposure of inner hydrophobic ligands, causing the nanoparticle aggregation in aqueous medium. This detection system shows a wide dynamic range in the μM scale and a distinguishable limit of 10 μM.
Chirality induction and chiron approaches to enantioselective total synthesis of α-lipoic acid
Chavan, Subhash P.,Pawar, Kailash P.,Praveen, Ch.,Patil, Niteen B.
, p. 4213 - 4218 (2015/06/02)
Abstract An efficient, short and convenient asymmetric synthesis of (R)-(+)-lipoic acid in seven steps from chiral hydroxy aldehyde with 32.5% overall yield is described. Synthesis of S and R enantiomers of α-lipoic acid from cis-1,4-butene diol derived chiral lactone is reported with 34 % overall yield. The present synthesis involves use of simple reaction conditions making it a convenient synthesis.
Polyphenolic Bioprecursors
-
Page/Page column 9-10, (2009/09/07)
Cosmetic and therapeutic, in particular dermatological bioprecursors have the formula [A]n—PP—[B]m wherein PP is a polyphenol radical in which each hydroxyl function is protected by a group A or a group B, A is a saturated or unsaturated, substituted or unsubstituted alkyl radical having 1 to 20 carbon atoms which is bonded to the polyphenol, n is an integer not less than 1, and B is a precursor of a biologically active molecule, which is also bonded to the polyphenol, and m is an integer also not less than 1.
Process For Purifying Thioctic Acid in Water
-
Page/Page column 2, (2008/12/07)
Process for purifying thioctic acid in water comprising the following steps: a) dissolving the thioctic acid in an aqueous alkaline solution or alternatively dissolving a thioctic acid salt, if necessary adjusting the pH to alkaline values, b) acidifying the solution from step (a) with an acid chosen from the class consisting of sulfuric acid, phosphoric acid, methanesulfonic acid to a pH between 5.4 and 5.8. c) isolating the thioctic acid precipitated in step (b) by conventional methods.
