Document Detail


Tryptophan from Human Milk Induces Oxidative Stress and Upregulates the Nrf-2-Mediated Stress Response in Human Intestinal Cell Lines.
MedLine Citation:
PMID:  21677072     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Chemical screening of digested human milk protein using the oxygen radical absorbance capacity (ORAC(FL)) antioxidant assay confirmed the presence of a peptide fraction (PF23) with high antioxidant activity [5.53 mmol Trolox equivalents (TE)/g] that contained tryptophan as a main component. We evaluated the effects of both PF23 and tryptophan alone on the modulation of oxidative stress in cultured intestinal cells using a dichlorofluorescein diacetate probe. Despite the high ORAC(FL) value, PF23 enhanced (P < 0.05) 2, 2'-azobis (2-amidinopropane) dihydrochloride (peroxyl radical generator)-induced intracellular oxidation in the Caco-2 human adenocarcinoma cell line, suggesting prooxidant activity. Compared to selected peptide fractions with relatively lower ORAC(FL) values, PF23 induced oxidative stress more than all other peptide fractions tested (P < 0.05) and contained more tryptophan than the others (P < 0.05). Similar prooxidant activity was observed for tryptophan when it was added to culture medium for both the Caco-2 cells and FHs 74 Int primary fetal enterocytes, while also exhibiting a high ORAC(FL) value (9.69 mmol TE/g). The effect of tryptophan that involves activation of the Nrf-2 pathway and transcription of antioxidant enzymes was therefore investigated in FHs 74 Int cells. Exposure of infant intestinal cells to tryptophan resulted in Nrf-2 activation and an increase in the gene transcript level of glutathione peroxidase 2. We conclude that tryptophan-induced oxidative stress associated with tryptophan-containing milk peptides induces an adaptive response that involves the activation of the antioxidant responsive signaling pathway in intestinal cells.
Authors:
Ingrid Elisia; Apollinaire Tsopmo; James K Friel; William Diehl-Jones; David D Kitts
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-6-15
Journal Detail:
Title:  The Journal of nutrition     Volume:  -     ISSN:  1541-6100     ISO Abbreviation:  -     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-6-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0404243     Medline TA:  J Nutr     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Food, Nutrition and Health, Vancouver, BC, Canada, V6T 1Z4.
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