title: Antioxidant functions of selected allium thiosulfinates and S-alk(en)yl-L-cysteine sulfoxides.
abstract: Pure thiosulfinates, R-S(O)S-R (2), where R = Me (2a), Pr (2b), or All (2c), at levels up to 4 mM were not capable of scavenging hydrogen peroxide or superoxide anion. Relative to standard antioxidants (ascorbic acid, n-propyl gallate, butylated hydroxytoluene, Trolox, and reduced glutathione), these thiosulfinates were 1-3 orders of magnitude less efficient at reducing 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 0.5-2 orders of magnitude less efficient at quenching singlet oxygen, and about equally effective at scavenging hydroxyl radical. Generally, AllS(O)SAll (2c) was the most effective and PrS(O)SPr (2b) was the least effective thiosulfinate in these assays, except that MeS(O)SMe (2a) exhibited no quenching effect toward singlet oxygen. These thiosulfinates were also incapable at levels up to 0.1 mM (where they were toxic) of in vitro induction of quinone reductase (QR) in murine hepatoma (hepa 1c1c7) cells. However, S-1-propenyl-L-cysteine sulfoxide (isoalliin, 1a) and cycloalliin (3) induced QR in this system at 2 mM and 1 mM, respectively, although doubling of QR required levels of 10-15 mM.
authors.affiliation: University of Wisconsin-Madison, Department of Food Science, Babcock Hall, 1605 Linden Drive, Madison, WI 53706, USA.
authors.forename: Hang
authors.initials: H
authors.lastname: Xiao
authors.forename: Kirk L
authors.initials: KL
authors.lastname: Parkin
mesh_terms: D000490:Allium / Q000737:chemistry*; D000975:Antioxidants / Q000494:pharmacology*; D015764:Bepridil / Q000031:analogs & derivatives* / Q000737:chemistry; D001713:Biphenyl Compounds; D003545:Cysteine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D016166:Free Radical Scavengers; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000096:biosynthesis; D010084:Oxidation-Reduction; D010851:Picrates; D026082:Singlet Oxygen / Q000737:chemistry; D013441:Sulfinic Acids / Q000494:pharmacology*; D013481:Superoxides / Q000737:chemistry
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D016166:Free Radical Scavengers; D005609:Free Radicals; D010851:Picrates; D013441:Sulfinic Acids; C100040:thiosulfinic acids; D013481:Superoxides; D026082:Singlet Oxygen; D017665:Hydroxyl Radical; D015764:Bepridil; C006453:alliin; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl; D016660:NAD(P)H Dehydrogenase (Quinone); D003545:Cysteine