title: The relationship of physicochemical properties to the antioxidative activity of free amino acids in Fenton system.
abstract: Herein we compared antioxidative activities (AA) of 25 free L-amino acids (FAA) against Fenton system-mediated hydroxyl radical (HO(•)) production in aqueous solution, and examined the relation between AA and a set of physicochemical properties. The rank order according to AA was: Trp > norleucine > Phe, Leu > Ile > His >3,4-dihydroxyphenylalanine, Arg > Val > Lys, Tyr, Pro > hydroxyproline > α-aminobutyric acid > Gln, Thr, Ser > Glu, Ala, Gly, Asn, Asp. Sulfur-containing FAA generated different secondary reactive products, which were discriminated by the means of electron paramagnetic resonance spin-trapping spectroscopy. AA showed a general positive correlation with hydrophobicity. However, when taken separately, uncharged FAA exhibited strong positive correlation of AA with hydrophobicity whereas charged FAA showed negative or no significant correlation depending on the scale applied. A general strong negative correlation was found between AA and polarity. Steric parameters and hydration numbers correlated positively with AA of nonpolar side-chain FAA. In addition, a decrease of temperature which promotes hydrophobic hydration resulted in increased AA. This implies that HO(•)-provoked oxidation of FAA is strongly affected by hydrophobic hydration. Our findings are important for the understanding of oxidation processes in natural and waste waters.
authors.affiliation: †Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Belgrade 11030, Serbia.
authors.forename: Sonja
authors.initials: S
authors.lastname: Milić
authors.affiliation: †Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Belgrade 11030, Serbia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Bogdanović Pristov
authors.affiliation: †Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Belgrade 11030, Serbia.
authors.forename: Dragosav
authors.initials: D
authors.lastname: Mutavdžić
authors.affiliation: †Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Belgrade 11030, Serbia.
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Savić
authors.affiliation: ‡Department of Physiology, Institute for Biological Research 'Siniša Stanković', University of Belgrade, Belgrade 11060, Serbia.
authors.forename: Mihajlo
authors.initials: M
authors.lastname: Spasić
authors.affiliation: †Department of Life Sciences, Institute for Multidisciplinary Research, University of Belgrade, Belgrade 11030, Serbia.
authors.forename: Ivan
authors.initials: I
authors.lastname: Spasojević
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D000975:Antioxidants / Q000737:chemistry*; D055598:Chemical Phenomena; D005618:Fresh Water / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D017665:Hydroxyl Radical / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008962:Models, Theoretical; D062065:Wastewater / Q000737:chemistry
chemical_list: D000596:Amino Acids; D000975:Antioxidants; D006861:Hydrogen Peroxide; D017665:Hydroxyl Radical; D007501:Iron; D062065:Wastewater; C045076:Fenton's reagent