Hydroxyl radical adduct of 5-aminosalicylic acid: a potential marker of ozone-induced oxidative stress.
The use of 5-aminosalicylic acid in assessment of reactive oxygen species formation was investigated by in vitro Fenton and ozonation reactions, and by in vivo ozone-exposure experiments. Enzymatic hydroxylation was evaluated by a microsomal assay. Fischer 344 male rats (250 g) injected with 5-aminosalicylic acid (100 mg x kg(-1) i.p.; 30 min) were exposed to ozone (0, 1, 2 ppm; nose only, 2 h); bronchoalveolar lavage, lung homogenates, and plasma were recovered. Oxidation products of 5-aminosalicylic acid were as follows: salicylic acid, by deamination; 2,3-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid, from radical or enzymatic hydroxylation; 5-amino-2-hydroxy-N,N'-bis(3-carboxy-4-hydroxyphenyl)-1,4-benzoquinonediimine, a condensation product of oxidized 5-aminosalicylic acid; and 5-amino-2,3,4,6-tetrahydroxybenzoic acid, attributed to hydroxyl radical attack without deamination, identified by HPLC electrochemical (HPLC-EC) detector system analysis and by GC-MS analysis of trimethylsilyl derivatives. 5-Aminotetrahydroxybenzoic acid was not formed enzymatically. 5-Aminotetrahydroxybenzoic acid, but not 5-aminosalicylic acid, was significantly elevated in bronchoalveolar lavage (+86%) and lung homogenates (+56%) in response to 2 ppm ozone (p < 0.05); no significant changes were detected in plasma. The data indicate that hydroxylation of 5-aminosalicylic acid is a potential specific probe for in vivo oxidative stress.
Environmental Health Directorate, Health Canada, Ottawa, ON, Canada. premkumari_kumarathasan@hc-sc.gc.ca
P
P
Kumarathasan
R
R
Vincent
P
P
Goegan
M
M
Potvin
J
J
Guénette
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D008401:Gas Chromatography-Mass Spectrometry; D017665:Hydroxyl Radical / Q000378:metabolism*; D006900:Hydroxylation; D008297:Male; D019804:Mesalamine / Q000378:metabolism*; D018384:Oxidative Stress; D010126:Ozone / Q000737:chemistry*; D051381:Rats; D011916:Rats, Inbred F344
D017665:Hydroxyl Radical; D019804:Mesalamine; D010126:Ozone