Document Detail

Salivary uric acid at the acidic pH of the stomach is the principal defense against nitrite-derived reactive species: sparing effects of chlorogenic acid and serum albumin.
MedLine Citation:
PMID:  17157178     Owner:  NLM     Status:  MEDLINE    
A complex antioxidant system is present in human saliva, with uric acid being the most concentrated component. Ascorbic acid, present at low concentrations in saliva, is actively secreted into the gastric lumen. We report that ascorbic acid added to human saliva at pH 2 was consumed within a few minutes, regenerating HNO(2), whereas uric acid was consumed relatively slowly in a nitrite-dependent manner. The consumption of uric acid was (i) rapid under normoxic conditions and slower at low oxygen tensions, (ii) coupled to *NO release, (iii) linked to the decrease in nitrite consumption and in nitrate formation, and (iv) unaffected by the nitrosation catalyst thiocyanate. Both chlorogenic acid and bovine serum albumin, representative of a phenol- and a protein-rich meal, respectively, were able to spare uric acid, although chlorogenic acid increased, whereas bovine serum albumin inhibited, *NO release. We hypothesize that the major role of uric acid in saliva at pH 2 could be to preserve the stomach from the formation of toxic nitrogen species and that low levels of uric acid, together with ascorbic acid consumption, may contribute to the high occurrence of tumors at the gastroesophageal junction and cardia. The sparing effects of dietary compounds may therefore be an important not fully appreciated effect.
Donatella Pietraforte; Marco Castelli; Alessio Metere; Giuseppe Scorza; Paola Samoggia; Antonio Menditto; Maurizio Minetti
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Publication Detail:
Type:  Comparative Study; Journal Article     Date:  2006-08-22
Journal Detail:
Title:  Free radical biology & medicine     Volume:  41     ISSN:  0891-5849     ISO Abbreviation:  Free Radic. Biol. Med.     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2006-12-12     Completed Date:  2007-04-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8709159     Medline TA:  Free Radic Biol Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1753-63     Citation Subset:  IM    
Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Roma, Italy.
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MeSH Terms
Ascorbic Acid / metabolism
Chlorogenic Acid / pharmacology*
Hydrogen-Ion Concentration
Nitric Oxide / metabolism
Nitrogen Dioxide / metabolism
Oxygen / pharmacology
Reactive Nitrogen Species / adverse effects*
Saliva / chemistry
Serum Albumin, Bovine / pharmacology*
Stomach / drug effects*
Tyrosine / analogs & derivatives,  metabolism
Uric Acid / analysis,  metabolism,  pharmacology*
Reg. No./Substance:
0/Reactive Nitrogen Species; 0/Serum Albumin, Bovine; 10102-43-9/Nitric Oxide; 10102-44-0/Nitrogen Dioxide; 327-97-9/Chlorogenic Acid; 3604-79-3/3-nitrotyrosine; 50-81-7/Ascorbic Acid; 55520-40-6/Tyrosine; 69-93-2/Uric Acid; 7782-44-7/Oxygen
Comment In:
Free Radic Biol Med. 2006 Dec 15;41(12):1747-9   [PMID:  17157176 ]

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