- Reaction of dihydrolipoic acid with juglone and related naphthoquinones: unmasking of a spirocyclic 1,3-dithiane intermediate en route to naphtho[1,4]dithiepines
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The reaction of dihydrolipoic acid (DHLA) with 5-hydroxy-1,4-naphthoquinone (juglone) gives rise to the novel naphtho[1,4]dithiepine derivatives through ring expansion of an unstable spirocyclic 1,3-dithiane intermediate, which was isolated and completely characterized. Reported herein is also the characterization of novel reaction products of DHLA with other naphthoquinones and the extension of the study to the spirocyclic adduct formed by reaction with a representative 2-substituted naphthoquinone.
- Greco, Giorgia,Panzella, Lucia,Pezzella, Alessandro,Napolitano, Alessandra,d'Ischia, Marco
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- STEREOSELECTIVE REDUCTION OF RACEMIC N-HYDROXYAMINO ACIDS BY OPTICALLY ACTIVE THIOLS-IRON(II)
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Kinetic resolution of racemic N-hydroxyamino acids by the reduction with optically active thiols and a catalytic amount of ferrous ion gave optically active amino acids presumably through enantiodifferentiating coordination of substrates to thiol-Fe(II) complexes.
- Nambu, Yoko,Endo, Takeshi
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- Physicochemical Profiling of α-Lipoic Acid and Related Compounds
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Lipoic acid, the biomolecule of vital importance following glycolysis, shows diversity in its thiol/disulfide equilibria and also in its eight different protonation forms of the reduced molecule. In this paper, lipoic acid, lipoamide, and their dihydro derivatives were studied to quantify their solubility, acid–base, and lipophilicity properties at a submolecular level. The acid–base properties are characterized in terms of six macroscopic, 12 microscopic protonation constants, and three interactivity parameters. The species-specific basicities, the pH-dependent distribution of the microspecies, and lipophilicity parameters are interpreted by various intramolecular effects, and contribute to understanding the antioxidant, chelate-forming, and enzyme cofactor behavior of the molecules observed.
- Mirzahosseini, Arash,Szilvay, András,Noszál, Béla
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- METHOD FOR PRODUCING DIHYDROLIPOIC ACID AND SALT THEREOF
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PROBLEM TO BE SOLVED: To provide a production method that is suitable for industrial production, and makes it possible to obtain dihydrolipoic acid with high purity and high optical purity or a salt thereof. SOLUTION: A method for producing dihydrolipoic acid or a salt thereof includes the step of reducing α-lipoic acid or a salt thereof in an aqueous or organic liquid phase by an electrode reaction. SELECTED DRAWING: Figure 1 COPYRIGHT: (C)2018,JPO&INPIT
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Paragraph 0017; 0074
(2018/08/09)
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- Circularly polarized luminescence in chiral silver nanoclusters
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Silver nanoclusters (NCs) capped with enantiomeric bidentate ligands exhibited mirror image circularly polarized luminescence (CPL) spectra with an anisotropy factor of 0.2%. Chirality in the ligand staples is most likely responsible for the induction of optical activity in the emissive state.
- Kumar, Jatish,Kawai, Tsuyoshi,Nakashima, Takuya
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supporting information
p. 1269 - 1272
(2017/02/05)
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- Shikonin thioctic ester derivatives as well as synthetic method and application thereof
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The invention belongs to the technical field of chemical pharmaceuticals and in particular relates to shikonin thioctic ester derivatives and an application thereof in tumor suppression. Corresponding thioctic ester derivatives are connected with shikonin through synthetic means so as to obtain corresponding ester derivatives. In-vitro anti-tumor activity study proves that the shikonin thioctic ester derivatives have excellent inhibitory activities on tumor cell strains.
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Paragraph 0020
(2017/11/30)
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- METHOD FOR THE PURIFICATION OF LIPONIC ACID
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The invention relates to a method for the purification of liponic acid wherein at least O.1 times the amount of an adsorption agent is added to a solution of liponic acid in relation to the mass of liponic acid to be purified and the adsorption agent is then separated. As a result, it is possible to produce racemic or non-racemic liponic acid with less than 1 wt. % oligomers, e.g. 0.11 wt. %.
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Page/Page column 4-5
(2008/06/13)
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- A short and productive synthesis of (R)-α-Lipoic acid
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(R)-α-Lipoic acid is synthesized in seven steps from the base chemicals methyl acetoacetate or Meldrum's acid and monomethyl adipate. The key steps are the introduction of the stereogenic center by fermentative or homogeneously catalyzed hydrogenation of 3-oxooctanedioic acid diester to (3S)-3-hydroxyoctanedioic acid diester and its regioselective reduction to (6S)-6,8-dihydroxyoctanoic acid ester. The overall yield of (R)-α-lipoic acid, starting from 3-oxooctanedioic acid diester, is 40%.
- Bringmann, Gerhard,Herzberg, Daniela,Adam, Geo,Balkenhohl, Friedhelm,Paust, Joachim
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p. 655 - 661
(2007/10/03)
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- Lipase catalyzed regio- and stereospecific hydrolysis: Chemoenzymatic synthesis of both (R)- and (S)-enantiomers of α-lipoic acid
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Native lipase of Candida rugosa (EC 3.1.1.3) enantioselectively and regiospecifically hydrolyses the n-butyl ester of 2,4-dithioacetyl butanoic acid either at the carboxylic acid terminus or at the α-thioacetate to provide enantiomerically pure (R)-2,4-dithioacetyl butyric acid and (S)- butyl 2-thio-4-thioacetyl butyrate (ee >98%) while the lipase modified by treatment with diethyl p-nitrophenyl phosphate attacks only the α- thioacetate giving enantiomerically pure (S)-butyl 2-thio-4-thioacetyl butyrate. These enantiomerically pure intermediates can be used as chiral building blocks to obtain both(S)- and (R)-enantiomers of α-lipoic acid and their analogues.
- Fadnavis,Babu, Ravi Luke,Vadivel, S. Kumara,Deshpande, Ashlesha A.,Bhalerao
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p. 4109 - 4112
(2007/10/03)
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- Interaction of α-Lipoic acid Enantiomers and Homologues with the Enzyme Components of the Mammalian Pyruvate Dehydrogenase Complex
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Lipoic acid (α-lipoic acid, thioctic acid) is applied as a therapeutic agent in various diseases accompanied by polyneuropathia such as diabetes mellitus. The stereoselectivity and specificity of lipoic acid for the pyruvate dehydrogenase complex and its component enzymes from different sources has been studied. The dihydrolipoamide dehydrogenase component from pig heart has a clear preference for R-lipoic acid, a substrate which reacts 24 times faster than the S-enantiomer. Selectivity is more at the stage of the catalytic reaction than of binding. The Michaelis constants of both enantiomers are comparable (Km = 3.7 and 5.5 mM for R- and S-lipoic acid, respectively) and the S-enantiomer inhibits the R-lipoic acid dependent reaction with an inhibition constant similar to its Michaelis constant. When three lipoic acid homologues were tested, RS-1,2-dithiolane-3-caproic acid was one carbon atom longer than lipoic acid, while RS-bisnorlipoic acid and RS-tetranorlipoic acid were two and four carbon atoms shorter, respectively. All are poor substrates but bind to and inhibit the enzyme with an affinity similar to that of S-lipoic acid. No essential differences with respect to its reaction with lipoic acid enantiomers and homologues exist between free and complex-bound dihydrolipoamide dehydrogenase. Dihydrolipoamide dehydrogenase from human renal carcinoma has a higher Michaelis constant for R-lipoic acid (Km = 18 mM) and does not accept the S-enantiomer as a substrate. Both enantiomers of lipoic acid are inhibitors of the overall reaction of the bovine pyruvate dehydrogenase complex, but stimulate the respective enzyme complexes from rat as well as from Escherichia coli. The S-enantiomer is the stronger inhibitor, the R-enantiomer the better activator. The two enantiomers have no influence on the partial reaction of the bovine pyruvate dehydrogenase component, but do inhibit this enzyme component from rat kidney. The implications of these results are discussed.
- Loeffelhardt, Sabine,Bonaventura, Christoph,Locher, Mathias,Borbe, Harald O.,Bisswanger, Hans
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p. 637 - 646
(2007/10/03)
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- Preparation and use of salts of the pure enantiomers of alpha-lipoic acid
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The pure enantiomers of alpha-lipoic acid are obtained by formation of the diastereomeric salt pairs with the optical antipodes of alpha-methylbenzylamine in solution.
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