Metabolite
Chemical structure* Reactive species generated Reactive species scavenged References TRP pKa (COOH) = 2.38 pKa (NH2 ) = 9.34
, H2 O2 , ∙ OH. Increases GSH, TBARS, and DCF fluorescence. Decreases catalase activity.ONOO− and ∙ OH. Chemiluminometric assays. [239 –241 ] KYN pKa (COOH) = 1.9 pKa (anilino group) = 5.1 pKa (NH2 ) = 8.5H2 O2 , OH∙ , ONOO− . Reduces chemiluminescence induced by H2 O2 . Prevents lipid peroxidation and fluorescence of DCF.
, H2 O2 . Cytochrome c reduction.[56 , 60 , 62 , 242 ] KYNA pKa (COOH) < 2 pKa (N) = 3.65 pKa (OH) = 13.9
Potentiates the prooxidants properties of
-aminolevulinic acid [83 , 216 ]. OH∙ , ONOO− ,
. Reduces degradation of 2-desoxyribose in synthetic systems. Reduces TBARS and fluorescence of DCF and prevents protein degradation. [79 , 84 , 243 –245 ] ANA pKa (COOH) = 2.17 pKa (
) = 4.85∙ OH. Creates a complex with copper, increasing Fe reactivity in Fenton reaction.∙ OH. Creates a complex with copper and captures radicals in inflammatory processes.[130 , 131 ] 3-HK pKa (COOH) = 1.9 pKa (alpha NH2 ) = 9.6
, H2 O2 . Reaction with peroxidase. Induces H2 O2 accumulation and generates cell death.ROO∙ ,
. Prevents oxidation of B-phycoerythrin. Decreases lipid peroxidation. [59 , 88 , 101 , 246 ] XA pKa (N) = 1.8 pka (OH1) = 7.3 pKa (OH2) = 12.3
, ∙ OH, O1 . Generates ROS through complex with Fe ions. Inactivates aconitase. Generates
, upon irradiation.∙ OH. Prevents oxidation of ABTS from hematoxylin oxidation. Inhibits lipid peroxidation in low density lipoprotein. Protects NADP isocitrate from oxidation.[106 , 112 , 115 ] 3-HA pKa (NH2 ) = 5.19 pKa (OH) = 10.12
, H2 O2 . Anthraniloyl radical (semiquinone) generated during autooxidation. Inhibits oxygen uptake by mitochondria.ROO∙ . Acts as coantioxidant with alpha-tocopherol. Prevents lipid peroxidation. [118 , 119 , 124 , 247 ] PIC pKa (N) = 1.03 pKa (COOH) = 5.40∙ OH. Chelates Fe2+ and enhances Fenton reaction.Chelates different bivalent metals as Ni2+ , Zn2+ , Cb2+ , Cu2+ , and Pb2+ . [143 , 147 ] QUIN pKa (COOH) = 2.43 pKa (COOH) = 4.78∙ OH. Chelates Fe2+ and enhances Fenton reaction. Generates ROS via excitotoxicity. [162 ]