Chemical, Physical, and Functional Characteristics of Dairy Ingredients 53Antitumor peptides have been shown to
inhibit the proliferation of tumors and are
derived from both whey and casein proteins
including lactoferricin, β - lactoferrin f(17 –38), α - casein f(90 – 95), and α (^) s 1 - casein f(1 – 3)
(Mader et al., 2005 ; Otani and Suzuki, 2003 ;
Kampa et al., 1997 ).
Immunomodulatory peptides either sup-
press or stimulate the immune system and
include isradicins derived from α (^) s 1 - casein
and β - casomorphins derived from β - casein
(Maruyama et al., 1987 ; Kayser and Meisel,
1996 ). Antioxidant peptides inhibit the
formation of free radicals or scavenge free
radicals. Antioxidative peptides include α (^) s 1 -
casein f(144 – 149), β - casein f(177 – 183), and
β - casein f(168 – 176) (Suetsana et al., 2000 ;
Kitts and Weiler, 2003 ).
Antihypertensive peptides are the most
extensively studied milk peptides. They have
been shown to alleviate hypertension in vivo
and in vitro , and consequently commercial
products including Evolus (Valio, Finland)
and Calpis Sour Milk (Calpis, Japan) are mar-
keted as products containing antihyperten-
sive peptides with the ability to reduce blood
pressure in individuals with hypertension.
Other bioactive peptides include opioid,
antiviral, mineral - binding (particularly cal-
cium), and antithrombotic peptides. Opioid
by fermentation with bacteria, and by prote-
olysis with enzymes derived from plants
or microorganisms. Table 2.7 shows the
major bioactive peptides derived from milk
proteins.
Bioactive peptides are claimed to provide
various benefi ts to human health and have
various bioactivities including antimicrobial,
antioxidant, antihypertensive, antagonist and
agonist opioid, immunomodulatory, mineral -
binding, and antithrombotic properties. Sev-
eral peptides exhibit multifunctional activities
including lactoferricin, which has antitumor,
immunomodulatory, anti - infl ammatory, anti-
microbial, and opioid properties.
Antimicrobial peptides include lactoferrin
B f(18 – 36), which is derived from the chy-
mosin or pepsin digestion of lactoferrin. It
has been shown to inhibit several Gram -
positive and Gram - negative bacteria (Bellamy
et al., 1992 ; Recio and Visser, 1999 ). The
antimicrobial peptides, caseinglycopeptide
f(106 – 169) and para - κ - casein f(1 – 105), are
derived from κ - casein by hydrolysis using
the digestive enzyme chymosin. They have
been incorporated into various products
including soft drinks, chewing gums, and
toothpaste due to their ability to inhibit car-
iogenic bacteria (Zayas, 1997 ; Rutherford -
Markwick and Moughan, 2005 ).
Table 2.7. Bioactivity of major peptide types.
Bioactive
peptide group
Protein precursor Bioactivity Systems affected
Casomorphins β - and α - casein Opioid agonists, ACE - inhibitory,
immunomodulatory
Nervous, cardiovascular,
immune
α - lactorphin α - lactalbumin ( α - La) Opioid agonists, ACE - inhibitory Nervous, cardiovascular
β - lactorphin β - lactoglobulin ( β - Lg) Opioid agonists, ACE - inhibitory,
smooth muscle contraction (ileum)
Nervous, cardiovascular,
digestive
Lactoferroxins Lactoferrin Opioid antagonists Nervous
Casoxins κ - casein Opioid antagonists, ACE - inhibitory,
some smooth muscle contraction
Nervous, cardiovascular,
digestive
Casokinins β - and α - casein Antihypertensive, immunomodulatory,
cytomodulatory
Immune, cardiovascular
Casoplatelins κ - casein, transferrin Antithrombiotic cardiovascular
Immunopeptides β - and α - casein Immunomodulatory Immune
Phosphopeptides β - and α - casein Mineral carriers Digestive
Lactoferricin Lactoferrin Antimicrobial, immunomodulatory Immune, digestive
Adapted from Korhonen et al. (1998) and Meisel (2004)