TY - JOUR
T1 - Tryptophan-containing milk protein-derived dipeptides inhibit xanthine oxidase
AU - Nongonierma, Alice B.
AU - Fitzgerald, Richard J.
N1 - Copyright © 2012 Elsevier Inc. All rights reserved.
PY - 2012/10
Y1 - 2012/10
N2 - Of twelve dipeptides tested, only the Trp containing peptides Val-Trp and its reverse peptide Trp-Val showed a xanthine oxidase (XO) inhibitory activity. Studies with Val and Trp revealed that XO inhibition was mainly attributed to the Trp residue. No significant difference (P ≥ 0.05) was found for the XO inhibitory potency (IC50) values for Trp, Val-Trp and Trp-Val, which were about 200 times higher than that for Allopurinol. Lineweaver and Burke analysis demonstrated that Trp, Val-Trp and Trp-Val were non-competitive inhibitors while Allopurinol was a competitive inhibitor. Of the different milk-protein substrates hydrolyzed with gastro-intestinal enzyme activities, only lactoferrin (LF) hydrolyzates displayed XO inhibition. Peptides present in a LF hydrolyzate (GLF-240 min) were adsorbed onto activated carbon followed by subsequent desorption with stepwise elution using acetonitrile (ACN). Separation and detection of Trp containing peptides within the different fractions were achieved using RP-HPLC coupled with fluorescence detection. The desorbed fractions displayed different XO inhibitory properties, with no inhibition in the unbound fraction and highest inhibition in fractions eluted with 30, 40 and 70% ACN. The fraction eluting at 40% ACN was significantly more potent (19.1 ± 2.3% inhibition at 1.25 mg mL-1) than the GLF-240 min hydrolyzate (13.4 ± 0.4% inhibition at 1.25 mg mL-1), showing the potential for enrichment of the bioactive peptides on fractionation with activated carbon.
AB - Of twelve dipeptides tested, only the Trp containing peptides Val-Trp and its reverse peptide Trp-Val showed a xanthine oxidase (XO) inhibitory activity. Studies with Val and Trp revealed that XO inhibition was mainly attributed to the Trp residue. No significant difference (P ≥ 0.05) was found for the XO inhibitory potency (IC50) values for Trp, Val-Trp and Trp-Val, which were about 200 times higher than that for Allopurinol. Lineweaver and Burke analysis demonstrated that Trp, Val-Trp and Trp-Val were non-competitive inhibitors while Allopurinol was a competitive inhibitor. Of the different milk-protein substrates hydrolyzed with gastro-intestinal enzyme activities, only lactoferrin (LF) hydrolyzates displayed XO inhibition. Peptides present in a LF hydrolyzate (GLF-240 min) were adsorbed onto activated carbon followed by subsequent desorption with stepwise elution using acetonitrile (ACN). Separation and detection of Trp containing peptides within the different fractions were achieved using RP-HPLC coupled with fluorescence detection. The desorbed fractions displayed different XO inhibitory properties, with no inhibition in the unbound fraction and highest inhibition in fractions eluted with 30, 40 and 70% ACN. The fraction eluting at 40% ACN was significantly more potent (19.1 ± 2.3% inhibition at 1.25 mg mL-1) than the GLF-240 min hydrolyzate (13.4 ± 0.4% inhibition at 1.25 mg mL-1), showing the potential for enrichment of the bioactive peptides on fractionation with activated carbon.
KW - Activated carbon
KW - Antioxidant
KW - Bioactive peptides
KW - Lactoferrin
KW - Tryptophan
KW - Xanthine oxidase inhibition
UR - http://www.scopus.com/inward/record.url?scp=84865324339&partnerID=8YFLogxK
U2 - 10.1016/j.peptides.2012.07.030
DO - 10.1016/j.peptides.2012.07.030
M3 - Article
C2 - 22910190
AN - SCOPUS:84865324339
SN - 0196-9781
VL - 37
SP - 263
EP - 272
JO - Peptides
JF - Peptides
IS - 2
ER -