His-His-Leu, an angiotensin I converting enzyme inhibitory peptide derived from Korean soybean paste, exerts antihypertensive activity in vivo

Design of genetically modified soybean proglycinin A1aB1b with multiple copies of bioactive peptide sequences

The peptide IIAEK derived from beta-lactoglobulin has a hypocholesterolemic activity greater than that of beta-sitosterol. To create food proteins with multiple copies of this valuable peptide sequence, we introduced tandem multimers of the nucleotide sequence encoding the peptide into DNA regions corresponding to the five variable regions of soybean glycinin A1aB1b subunit, and expressed the mutants in Escherichia coli. The expression level and solubility of the five mutants, each containing four IIAEK sequences in each of the variable regions, were compared. Overall, the expression level and solubility of the mutants with four IIAEK sequences in the variable regions IV and V were the best followed by II > III > I. Further, introduction of the fifth IIAEK sequence to the variable region IV did not decrease expression level and solubility. Increasing the number of IIAEK to 7 and 10 slightly decreased expression level, while their solubility decreased to as low as 40 and 1%, respectively. Various mutations were combined to get a mutant containing as many IIAEK sequences as possible. Some of the resulting mutants were expressed in the soluble form. The mutant containing eight IIAEK from the combination of variable regions IV and V (IV-4 + V-4) showed the best balance of the expression level and solubility, followed by the combination of variable regions II and III (II-4 + III-4). The soluble fractions of these mutants were purified by hydrophobic, gel filtration and ion-exchange column chromatography. Yields of IIAEK peptide released by in vitro digestion with trypsin from both mutants were around 80%. This is the first report that a large amount of a physiologically active peptide could be introduced into food protein.

Peptides from Anchovy Sauce Induce Apoptosis in a Human Lymphoma Cell (U937) through the Increase of Caspase-3 and -8 Activities

Various biological activities of peptides have been found. In this study, the induction of apoptosis in a human lymphoma cell line (U937) by peptide fraction separated from anchovy sauce was studied using biochemical and flow cytometric methods. After U937 was treated with a hydrophobic peptide fraction of the anchovy sauce, a sub-G1 peak, which represents apoptosis, was found in the cell cycle analysis. The apoptosis in the peptide-treated U937 cell was also confirmed by apoptotic DNA fragmentation. Furthermore, an increase of caspase-3 and -8 activities was observed. Our results suggest that the peptide fraction separated from the anchovy sauce may have cancer chemopreventive effects through the induction of apoptosis in cancer cells.

Grain legume proteins and nutraceutical properties

Grain legumes are a valuable source of food proteins. Their exploitation is expected to grow in relation of a growing world's food needs. Moreover, it is currently taking place a reappraisal of the beneficial effects of legume seed dietary intake, which are the basis for various health claims. Proteins and peptides concur to the observed biological activities of legume seeds, but their effect(s) has(ve) not completely been disclosed. Aims of this review are: to report the most relevant putative positive effects of grain legumes on human health and to give an account of the current knowledge on the demonstrated legume seed protein biological activities. Specific effects on the prevention and treatment of various diseases, mostly of which are typical of the affluent countries, are reported. Examples of studies at molecular level aimed at elucidating of the underlying mechanism(s) are given. The prospects on targeted legume protein exploitation in the nutraceutical area, including the biotechnological approaches, are also considered.

In vitro intestinal transport and antihypertensive activity of ACE inhibitory pea and whey digests

Angiotensin I converting enzyme (ACE) inhibitory peptides cause an antihypertensive effect if they reach the systemic circulation. This was investigated for the high ACE inhibitory activity present in peas and whey in vitro gastrointestinal digests. The samples retained high ACE inhibitory activity when incubated in Caco-2 homogenates or rat intestinal acetone powder, both sources of small intestine peptidases. Only little ACE inhibitory activity was transported through Caco-2 cell monolayers in 1 h. As the Caco-2 model is tighter than intestinal mammalian tissue, sufficient absorption of these peptides might occur in vivo. After intravenous administration of 50 mg protein kg(-1) BW in spontaneously hypertensive rats (SHR), pea digest exerted a transient, but strong antihypertensive effect of 44.4 mmHg. Whey digest exerted no effect at this dose. These results suggest that pea digest could be a promising source of ACE inhibitory peptides for use in the prevention and treatment of hypertension.

Anti-infection effect of hydrolysates from conglycinin on E.coli in mice

AIM: To elucidate anti-infection effect of hydrolysates from conglycinin on E.coli in mice.

METHODS: Male KM mice were assigned randomly in five treatments. After feeding basal diet three days, E.coliO₁₃₈ was fed in five treatments from 2×10¹¹ to 2×10⁷CFU/L, diluted (in decuple) ordinally. The LD₅₀ of mice feeding E.coliO₁₃₈ after 56 h was 4.73×10¹⁰ CFU/L. Two batch of Male KM mice were randomly assigned to six treatments respectively: normal (NOR) group, feeding-E.coli control (FEC), Basal diet + physiological saline, Basal diet + Hcl-full hydrolysis of conglycinin (HCL-FHC), Basal diet + conglycinin (Conglycinin), Basal diet + pepsin-hydrolysate conglycinin (PTC), and Basal diet + purified fraction B of pepsin hydrolysates of conglycinin (P2-PTC) group. The mice were fed with a dose of 0.2 mL /g (containing equal amount of nitrogen) except the ones in NOR and FEC group. Twenty days after feeding, each mouse in FEC, HCL-FHC, Conglycinin, PTC and P2-PTC group was fed with E.coliO₁₃₈ (2×10⁹ CFU/L and 2×10¹¹ CFU/L for the two batch, respectively, 0.2 mL/g) in the 22^nd day (midday). The actions of the mice were observed until 48 h after feeding with E.coliO₁₃₈. Then all the mice were killed. The blood, spleen and the whole length of intestines were collected. The immune index was determined by radioimmunoassay.

RESULTS: The KM mice reacted differently when infected with different levels of E.coli after feeding the pepsin-hydrolysate conglycinin. In mice fed with 2×10⁹ CFU/L of E.coliO₁₃₈, the pepsin-hydrolysate conglycinin significantly increased the level of spleen IL-2 (19.2±9.6 μg/g vs 11.5±4.7 μg/g in P2-PTC and NOR group respectively, P<0.05; 19.2±9.6 μg/g vs 9.4±3.7 μg/g in P2-PTC and FEC group respectively, P<0.01), the intestinal sIgA concentration, and significantly decreased spleen IL-6 (127.1±52.8 ng/g vs 276.4±60.1 ng/g in P2-PTC and NOR respectively, P<0.01; 127.1±52.8 ng/g vs 224.5±38.9 ng/g in P2-PTC and FEC respectively, P<0.05) and TNF-α (9.1±2.0 μg/g vs 16.3±3.9 μg/g in PTC and NOR group respectively, P<0.05) level, but had no significant effect on serum IL-2. In mice fed with 2×10¹¹ CFU/L of E.coliO₁₃₈, the pepsin-hydrolysate conglycinin significantly increased the levels of spleen IL-6 (480.5±184.7 ng/g vs 206.7±72.3 ng/g in P2-PTC and NOR respectively, P<0.05) and TNF-α (43.3±5.8 μg/g vs 10.5±4.1 μg/g in P2-PTC and NOR group respectively, P<0.01; 43.3±5.8 μg/g vs 19.7±9.0 μg/g in P2-PTC and FEC group respectively, P<0.01), and decreased the serum IL-6 and TNF-α (P2-PTC group 2.8±1.0 μg/L vs FEC group 4.6±2.0 μg/L in P2-PTC and FEC group respectively, P<0.05) concentrations.

CONCLUSION: The hydrolysates from conglycinin with pepsin can increase the immune function in mice, defend the invasion of E.coli and keep the gut healthy.

Induction of apoptosis in a human lymphoma cell line by hydrophobic peptide fraction separated from anchovy sauce

Peptide fractions showing anticancer activity were isolated from anchovy sauce, and their abilities to induce apoptosis in a human lymphoma cell (U937) were determined by biochemical and flow cytometric methods. The butanol extract (fraction Aob) from the desalted hydrophobic peptide fraction (Ao) separated from anchovy sauce by HP-20 adsorption chromatography was found to possess strong antiproliferative activity against U937 by inducing apoptosis. Treatment of U937 with Aob resulted in sub-G1 peak representing apoptosis in the cell cycle analysis, and apoptotic DNA fragmentation. Antiproliferative activity of the peptide fraction further purified successively by silica gel chromatography, TLC, and reversed-phase HPLC increased proportionally with the purification fold. The peptide fraction having antiproliferative activity was found to be composed of Ala and Phe, and its molecular weight was estimated to be 440.9 Da.