71774-08-8Relevant articles and documents
A chemoenzymatic approach to hydroperoxyeicosatetraenoic acids. Total synthesis of 5(S)-HPETE
Dussault,Lee
, p. 218 - 226 (2007/10/02)
A new synthetic approach to enantiomerically pure hydroperoxyeicosatetraenoic acids (HPETEs) is described in which the tetraene skeleton is assembled through chemoselective olefination of a protected hydroperoxy aldehyde. Soybean lipoxygenase-mediated dioxygenation of both natural and unnatural fats produces hydroperoxy dienes in high enantiomeric excess; the observed regioselectivity supports a revised hypothesis for substrate specificity. Protection of the diene hydroperoxides as peroxy ketals is followed by regioselective ozonolysis to afford enantiomerically pure 4-peroxy 2,3-enals which undergo olefination to produce peroxytetraenoates. Removal of the monoperoxy ketal and the methyl ester affords enantiomerically pure HPETEs. The generality of the strategy is illustrated with the first chemical synthesis of 5(S)-HPETE.
Stereochemistry and Mechanism of the Biosynthesis of Leukotriene A4 from 5(S)-Hydroperoxy-6(E),8,11,14(Z)-eicosatetraenoic Acid. Evidence for an Organoiron Intermediate
Corey, E. J.,Wright, Stephen W.,Matsuda, Seiichi P. T.
, p. 1452 - 1455 (2007/10/02)
The pathway of biosynthesis of leukotriene A4 (LTA4, 2) from 5(S)-hydroperoxy-6(E),8,11,14(Z)-eicosatetraenoic acid (5-S-HPETE, 1) has been explored by the comparative study of (S)- and (R)-lipoxygenase (LO) enzymes as catalysts.The purified LO from potato, an S-lipoxygenase, converts (anaerobically) 1 to 2 (determined as the characteristic hydrolysis mixture of two epimeric 5,6-diols and two epimeric 5,12-diols), as previously reported by Samuelsson et al.However, the 8-R-LO from the coral Plexaura homomalla transforms 1 (anaerobically) into 6-epi-LTA4 (6).Theobserved divergence of stereopathways agrees with predictions based on the intermediacy of organoiron intermediates in enzymic lipoxygenation (Scheme I) and detailed in Schemes II and III.Further evidence for the intervention of such intermediates has been obtained by trapping experiments under pure O2 at pressures of 1-60 atm.Under O2 pressure 1 is converted by the potato LO to a new product, the bis(hydroperoxide) 7, whereas the coral LO converts 1 to the diastereomeric bis(hydroperoxide) 9.
Unified Mechanism for Polyunsaturated Fatty Acid Autooxidation. Competition of Peroxy Radical Hydrogen Atom Abstraction, β-Scission, and Cyclization
Porter, Ned A.,Lehman, Laura S.,Weber, Bruce A.,Smith, Karl J.
, p. 6447 - 6455 (2007/10/02)
The autooxidation of linoleic (18:2) and arachidonic (20:4) acids with several cosubstrates was investigated.Cumene, tetralin, 1,4-cyclohexadiene, and 9,10-dihydroanthracene in benzene were used as cosubstrates for the oxidation of linoleic acid.The distribution of products, trans,cis diene hydroperoxides and trans,trans diene hydroperoxides, was dependent on the ability of cosubstrates to donate hydrogen atoms to linoleate peroxy radicals.Arachidonic acid was oxidized in mixtures of benzene/1,4-cyclohexadiene with linoleic acid internal standard.Product distribution of six hydroperoxyeicosatetraenoic acids (HPETE) derived from arachidonic acid was established at different concentrations of 1,4-cyclohexadiene in the solvent mixture.A kinetic expression is derived that is useful in describing polyunsaturated fatty acid oxidation product mixtures.By the use of this kinetic derivation, the rate of cyclization of peroxy free radicals derived from arachidonic acid was determined.
