Chronic diseases and ageing phenome

Chronic diseases and ageing phenomena are relevant to the
imbalance of free radical levels in the body. An excess of free radicals
can cause lethal cellular damage through oxidising cellular
proteins, enzymes, membrane lipids, and DNA; thus arresting cellular
respiration (Urso & Clarkson, 2003). When the damage cannot
be repaired diseases, such as cancer, cardiovascular diseases and
diabetes, can arise (Collins, 2005). Their presence in foods, in addition
to lipolytic and peroxidative changes, can cause sensory and
nutritional value deterioration (Spitzer, Doucet, & Buettner,
2010). Therefore, it becomes essential to inhibit the peroxidation
of lipids and the generation of free radicals in the living cells and
foodstuffs.
Although artificial antioxidants, such as butylated hydroxytoluene,
butylated hydroxyanisole, and n-propyl gallate, display strong
activity against various oxidation systems, the use of these antioxidants
in food is prohibited in some countries due to the potential
risks to human health (Kahl & Kappus, 1993). This leads to a growing
interest towards natural antioxidants for chemotherapeutic
and preservation properties. In addition to the functional and
physiological properties, antioxidants from protein hydrolysates
may confer nutritional value (Pownall, Udenigwe, & Aluko, 2010).
Consequently, the search for natural antioxidants becomes a subject
of interest to replace artificial antioxidants.
Kudoh, Matsuda, Igoshi, and Oki (2001) identified a j-casein derived
peptide, which displayed 2,2-diphenyl-1-picrylhydrazyl radical
scavenging activity, from the milk fermented with Lactobacillus
delbrueckii subsp. bulgaricus. Sabeena Farvin, Baron, Nielsen, Otte,
and Jacobsen (2010) also found antioxidant peptides comprised
of several fragments from b-casein and a few N-terminal fragments
of as1-, as2- and j-casein from yogurt. Korhonen and Pihlanto
(2006) concluded that most of the peptides are encrypted within
the native protein, and can be released during several food processes,
or during gastrointestinal activities. Moreover, Gupta,
Mann, Kumar, and Sangwan (2009) found that degree of proteolysis,
which depends on the strain used in cheese making, is directly
related to antioxidant activity. Donkor, Henriksson, Vasiljevic, and
Shah (2007) reported that a large number of oligopeptides are generated
by extracellular proteinases, and further breakdown into
peptides by intracellular peptidases