title: Isotope-reinforced polyunsaturated fatty acids protect mitochondria from oxidative stress.
abstract: Polyunsaturated fatty acid (PUFA) peroxidation is initiated by hydrogen atom abstraction at bis-allylic sites and sets in motion a chain reaction that generates multiple toxic products associated with numerous disorders. Replacement of bis-allylic hydrogens of PUFAs with deuterium atoms (D-PUFAs), termed site-specific isotope reinforcement, inhibits PUFA peroxidation and confers cell protection against oxidative stress. We demonstrate that structurally diverse deuterated PUFAs similarly protect against oxidative stress-induced injury in both yeast and mammalian (myoblast H9C2) cells. Cell protection occurs specifically at the lipid peroxidation step, as the formation of isoprostanes, immediate products of lipid peroxidation, is drastically suppressed by D-PUFAs. Mitochondrial bioenergetics function is a likely downstream target of oxidative stress and a subject of protection by D-PUFAs. Pretreatment of cells with D-PUFAs is shown to prevent inhibition of maximal uncoupler-stimulated respiration as well as increased mitochondrial uncoupling, in response to oxidative stress induced by agents with diverse mechanisms of action, including t-butylhydroperoxide, ethacrynic acid, or ferrous iron. Analysis of structure-activity relationships of PUFAs harboring deuterium at distinct sites suggests that there may be a mechanism supplementary to the kinetic isotope effect of deuterium abstraction off the bis-allylic sites that accounts for the protection rendered by deuteration of PUFAs. Paradoxically, PUFAs with partially deuterated bis-allylic positions that retain vulnerable hydrogen atoms (e.g., monodeuterated 11-D1-Lin) protect in a manner similar to that of PUFAs with completely deuterated bis-allylic positions (e.g., 11,11-D2-Lin). Moreover, inclusion of just a fraction of deuterated PUFAs (20-50%) in the total pool of PUFAs preserves mitochondrial respiratory function and confers cell protection. The results indicate that the therapeutic potential of D-PUFAs may derive from the preservation of mitochondrial function.
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093-0636, USA.
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Andreyev
authors.affiliation: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA 90095-1569, USA.
authors.forename: Hui S
authors.initials: HS
authors.lastname: Tsui
authors.affiliation: Division of Clinical Pharmacology, Vanderbilt University, Nashville, TN 37232-6602, USA.
authors.forename: Ginger L
authors.initials: GL
authors.lastname: Milne
authors.affiliation: Institute of Physical Organic Chemistry, National Academy of Science of Belarus, Minsk 220072, Belarus.
authors.forename: Vadim V
authors.initials: VV
authors.lastname: Shmanai
authors.affiliation: Department of Chemistry, Belarusian State University, Minsk 220020, Belarus.
authors.forename: Andrei V
authors.initials: AV
authors.lastname: Bekish
authors.affiliation: Institute of Physical Organic Chemistry, National Academy of Science of Belarus, Minsk 220072, Belarus.
authors.forename: Maksim A
authors.initials: MA
authors.lastname: Fomich
authors.affiliation: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA 90095-1569, USA.
authors.forename: Minhhan N
authors.initials: MN
authors.lastname: Pham
authors.affiliation: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA 90095-1569, USA.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Nong
authors.affiliation: Department of Pharmacology, University of California at San Diego, La Jolla, CA 92093-0636, USA.
authors.forename: Anne N
authors.initials: AN
authors.lastname: Murphy
authors.affiliation: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California at Los Angeles, Los Angeles, CA 90095-1569, USA.
authors.forename: Catherine F
authors.initials: CF
authors.lastname: Clarke
authors.affiliation: Retrotope, Inc., Los Altos Hills, CA 94022, USA. Electronic address: misha@retrotope.com.
authors.forename: Mikhail S
authors.initials: MS
authors.lastname: Shchepinov
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002460:Cell Line; D019069:Cell Respiration; D003903:Deuterium; D004734:Energy Metabolism; D004976:Ethacrynic Acid / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013329:Structure-Activity Relationship; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D005231:Fatty Acids, Unsaturated; D020122:tert-Butylhydroperoxide; D003903:Deuterium; D004976:Ethacrynic Acid
keywords: Chain reaction; Coenzyme Q; Free radicals; Kinetic isotope effect; Lipid peroxidation; Mitochondria respiration; Polyunsaturated fatty acid