Identification and Quantification of Inhibitors for Angiotensin-Converting Enzyme in Hypoallergenic Infant Milk Formulas

Abstract

The potential of hypoallergenic (HA) infant milk formulas containing hydrolyzed milk proteins as main constituents to inhibit angiotensin-converting enzyme (ACE) in vitro was investigated. Seven commercially available HA products designed for babies up to 4 months showed a potent inhibition of ACE in vitro, with IC 50 values ranging between 3.2 and 68.5 mg of nitrogen/L. For six samples of conventional milk-based infant formulas and three breast milk samples, no inhibition was observed. Inhibitory potential did not correlate with the degree of hydrolysis. Using reversed-phase high-pressure liquid chromatography (RP-HPLC) coupled to electrospray ionization-time of flight-mass spectrometry (ESI-TOF-MS), 15 peptides known to inhibit ACE were identified. Among them, the highly potent ACE inhibitor Ile-Trp (IC 50 = 0.7 microM) was detected and quantified for the first time in the HA samples, representing the most effective ACE-inhibiting peptide that has ever been detected in food items. The overall inhibitory potential of the HA infant milk formulas could partly be explained by Ile-Trp.

Milk proteins as a source of tryptophan-containing bioactive peptides

“…-CN (f163-164)), IW (α-La (f 59-60) and LF (f 267-268)) and VW (LF (f 346-347) and 50 LF (f 548-549)) were shown to be competitive inhibitors of human ACE 62,63 . The -La-derived peptides, IW and WL (α-La (f 104-105) and α-La (f 118-119)) were identified in milk proteinbased infant formulae 64 and in a whey protein hydrolysate generated with a combination of chymotrypsin and thermolysin 55 62 . The yield for the release of IW was estimated between 4-19% in the infant formulae 64 and at 50% (w/w) in a whey protein hydrolysate 62 .…”

“…The -La-derived peptides, IW and WL (α-La (f 104-105) and α-La (f 118-119)) were identified in milk proteinbased infant formulae 64 and in a whey protein hydrolysate generated with a combination of chymotrypsin and thermolysin 55 62 . The yield for the release of IW was estimated between 4-19% in the infant formulae 64 and at 50% (w/w) in a whey protein hydrolysate 62 . While that of WL was 4% (w/w) in a whey protein hydrolysate 62 .…”

Identification of bioactive peptides in hypoallergenic infant milk formulas by capillary electrophoresis–mass spectrometry

“…Immunostimulating, antimicrobial, opioid, angiotensinconverting enzyme inhibition, mineral binding, antithrombotic, allergenic are, among others, the described bioactivities [1][2][3][4][5][6][7]. However, identification and quantification of bioactive peptides in milk protein hydrolysates, fermented dairy products or, in general, in functional dairy foods with health-promoting or diseasepreventing peptide ingredients is a challenging task because these highly complex samples can contain up to hundreds of different peptides at different levels of concentration [8][9][10][11][12][13][14][15]. These difficulties limit the knowledge about the formation of bioactive peptides, release from the precursor proteins or resistance to gastrointestinal enzymes in vivo.…”

“…These difficulties limit the knowledge about the formation of bioactive peptides, release from the precursor proteins or resistance to gastrointestinal enzymes in vivo. This is the case of hypoallergenic infant milk formulas (IF) that are formulated from different types of bovine milk protein hydrolysates, in order to prevent protein allergy, which is the most common food allergy in the early childhood [11][12][13].…”

Novel Angiotensin I-Converting Enzyme Inhibitory Peptides Found in a Thermolysin-Treated Elastin with Antihypertensive Activity

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18] Many ACE inhibitory peptides have been isolated from the thermolysin (TLN) hydrolysate of dried bonito, 9,19,20) sesame, 7) and soy bean protein. 10) In particular, supplements containing dried bonito peptide LKPNM (IC 50 ¼ 17 mM) and sesame peptide LVY (IC 50 ¼ 1:8 mM) are commercially available in Japan.…”