Food Biochemistry and Food Processing (2 edition)

BLBS102-c36 BLBS102-Simpson March 21, 2012 18:47 Trim: 276mm X 219mm Printer Name: Yet to Come

692 Part 6: Health/Functional Foods

protein derived from the blood of arch shell, prolonged the

APTT from a 32 seconds control clotting time to 325 seconds.

(Jung et al. 2001). These marine-derived anticoagulant peptides

have potential for use as functional ingredients in nutraceuticals

or pharmaceuticals.

Immunomodulatory Activity

There has been increased interest in the study of the relation-

ship between nutrition and immunity due to the hypothesis

that consumption of specific foods may reduce susceptibility

for the development and/or progression of immunological dis-

eases. Many immunomodulatory peptides are derived from milk

proteins. Some of these peptides have been found to be im-

munoinhibitory, while others are immunostimulatory in action.

Furthermore, it has been found that oral administration of the

peptides is a highly effective way to induce the desired im-

munomodulatory effect, even in the absence of any transport

agents such as delivery vehicles. In addition, it has also been

found that the amount of peptide required to produce the ther-

apeutic effect by oral delivery can be significantly lower than

that required to produce a similar effect when the peptide is de-

livered by parenteral injection. The immunomodulatory effects

of marine-derived bioactive peptides have rarely been reported.

Gildberg et al. (1996) reported that four acid peptide fractions

from cod stomach hydrolysate were shown to possess an ability

to stimulate leucocyte superoxide anion production in Atlantic

salmon (S. salar). Increasing the production of reactive oxy-

gen metabolites or promoting the phagocytosis and pinocytosis

in macrophages can enhance the nonspecific immune defense

system. It has been suggested that acid-derived cod protein hy-

drolysate peptide fractions might be useful as an adjuvant in fish

vaccine and as an immune stimulant in fish feed. Immunomod-

ulatory effects of marine oligopeptide preparation (MOP) from

Chum Salmon (Oncorhynchus keta) were also reported by Yang

et al. (2009b). Female ICR mice (6–8 weeks old) were admin-

istered the MOP for 4 weeks with the dose of 0, 0.22, 0.45, and

1.35 g/kg/body weight. In comparison with the control group,

MOP could significantly enhance the capacity of lymphocyte

proliferation induced by the mitogen concanavalin A, the num-

ber of plaque-forming cells, natural killer (NK) cell activity, the

percentage of CD4+T helper (Th) cells in spleen and the se-

cretion of Th1 (interleukin (IL)-2, IFN-γ) and Th2 (IL-5, IL-6)

type cell cytokines. Nevertheless, no significant differences in

weight gain, lymphoid organ indices, and phagocytosis capacity

were observed. In irradiation-treated mice (Yang et al. 2010),

MOP significantly increased the survival rate and prolonged the

survival times for 30 days after irradiation, and lessened the

radiation-induced suppression of T- or B-lymphocyte prolifer-

ation, resulting in the recovery of cell-mediated and humoral

immune functions. This effect may be produced by augmen-

tation of the relative numbers of radioresistant CD4+T cells,

enhancement of the level of immunostimulatory cytokine, IL-

12, reduction of the level of total cellular NF-κB through the

induction of IκB in spleen, and inhibition of the apoptosis of

splenocytes. In addition, it is proposed that MOP can be used as

an ideal adjuvant therapy to alleviate radiation-induced injuries

in cancer patients.

The oligopeptide-enriched hydrolysates from oyster (C. gi-

gas), produced using the protease fromBacillussp. SM98011

possessed antitumor activity and immunostimulating effects of

the oyster hydrolysates in BALB/c mice (Wang et al. 2010). The

growth of transplantable sarcoma-S180 was obviously inhibited

in a dose-dependent manner in BALB/c mice given the oys-

ter hydrolysates. Mice receiving 0.25, 0.5, and 1 mg/g of body

weight by oral gavage had 6.8%, 30.6%, and 48% less tumor

growth, respectively. Concurrently, the weight coefficients of the

thymus and the spleen, the activity of NK cells, the spleen prolif-

eration of lymphocytes and the phagocytic rate of macrophages

in S180-bearing mice significantly increased after administra-

tion of the oyster hydrolysates. These results demonstrated that

oyster hydrolysates produced strong immunostimulating effects

in mice, which might result in its antitumor activity. The an-

titumor and immunostimulating effects of oyster hydrolysates

prepared in this study reveal its potential for tumor therapy and

as a dietary supplement with immunostimulatory activity.

Gastrin/CCK-Like Activity

Different authors have reported the presence of gastrin/CCK-

like molecules in protein hydrolysates from fish by-products

(Cancre et al. 1999, Ravallec-Ple and Van Wormhoudt 2003).

These molecules are the only known members of the gastrin

family in humans, and could have a positive effect on food intake

in humans and fish species in aquaculture. Gastrin is a gastric

hormone that stimulates postprandial gastric acid secretion and

epithelial cell proliferation. In humans, there are two different

gastrins, one with 17 and one with 34 amino acids residues.

CCK is a group of peptides that controls the emptying of the

gallbladder, as well as pancreatic enzyme secretion. It is also a

growth factor, and regulates intestinal motility, satiety signaling,

and inhibition of gastric acid secretion (Rehfeld et al. 2001).

Both gastrin and CCK inhibit food intake and share a common

COOH-terminal pentapeptide amide that also includes the se-

quences essential for biological activity. The incorporation of

protein hydrolysates including gastrin/CCK-like molecules in

functional foods could be of interest for controlling appetite,

food intake, and obesity. The production of protein hydrolysates

including CCK-like molecules could also be useful in the treat-

ment of paralytic ileus, for the removal of small concrements

from the common bile duct and also for the improvement of

pancreatic insufficiency caused by long-term parenteral nutrition

or chronic pancreatitis (Rehfeld 2004). Above and beyond the

stimulation of satiety through bioactive peptides, lipid-lowering

effects as well as increasing metabolic rate are also beneficial in

fighting obesity.

PRODUCTION OF BIOACTIVE PEPTIDES

Enzyme Hydrolysis

Marine bioactive peptides have widely been produced by en-

zymatic hydrolysis of proteins derived from marine animals

(Zhao et al. 2007, Je et al. 2008, Sheih et al. 2009,Sliˇ zytˇ ̇e