• Journal of Life Science
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• v.22 no.1
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• pp.117-125
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• 2012

This study investigated the potential hepatoprotective benefits of Crassostrea gigas oyster hydrolysates. Oysters are known to have many biofunctional properties. In particular, oyster enzymatic hydrolysates produce substances with beneficial functions. The potential hepatoprotective effects of C. gigas hydrolysates against damage induced by tacrine were evaluated in vitro in HepG2 cells. Peptides were generated from C. gigas by enzymatic hydrolysis with Neutrase, Flavourzyme, or Protamex enzyme preparations. Tacrine treatment induced considerable cell damage in HepG2 cells, as shown by significant leakage of glutamic oxaloacetic transaminase (GOT) and lactate dehydrogenase (LDH). Cells treated with C. gigas hydrolysates showed an increased resistance to oxidative challenge compared to control cells, as revealed by higher cell survival against tacrine-induced hepatotoxicity. In addition, treatment with C. gigas hydrolysates reduced the leakage of GOT and LDH. These findings indicate that enzyme hydrolysates derived from C. gigas may be of benefit for developing hepatoprotective foods and drugs.

• Journal of Life Science
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• v.22 no.2
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• pp.220-225
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• 2012

The peptides of enzymatic hydrolysates from oyster were determined by inhibitory activity against angiotensin-converting enzyme. The ACE inhibitory activity of enzymatic oyster hydrolysates increases with hydrolysis time. Among enzymatic oyster hydrolysates, oyster hydrolysates incubated with Protamex showed the best ACE inhibitory activity after 10 h. Hydrolysates were filtered through a HiSep ultrafiltration membrane (M.W. cut-off 30 kDa, 10 kDa) to obtain the peptide fractions with ACE inhibition activity. These fractions were applied to an HPLC column (watchers 120 ODS-AP $250{\times}4.6$ ($5{\mu}m$)). Six active fractions were collected and the range of ACE inhibition was from 29.56 to 85.85%. Peptide was purified from fraction B, showing the highest ACE inhibitory activity, and its sequence was Leu-Gln-Pro. These results suggest that PEH may be beneficial for developing antihypertensive food and drug.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.3
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• pp.269-277
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• 2006

This study prepared functional oyster hydrolysates using two-step enzymatic hydrolysis and investigated their functional properties. To prepare two-step enzymatic hydrolysates (TSEH), oysters were hydrolyzed using 1% Protamex (PR) at $40^{\circ}C$ and pH 6.0 for 1 hr before sequential treatment with one of the following enzymes for 1 hr: Alcalase (AL), Flavourzyme (FL), Neutrase (NE), pepsin (PE), and trypsin (TR). The PRAL, PRNE and PRTR hydrolysates had significantly greater angiotensin I converting enzyme (ACE) inhibitory activity than did PR and the other TSEHs. Only the antioxidant activity of the PRNE hydrolysate was significantly different (p<0.05), while none of the TSEHs had antimicrobial activity. The oyster hydrolysate prepared by sequential treatment with Protamex and Neutrase (PRNE) had the best ACE inhibitory activity and antioxidant activity, with $IC_{50}$ values of 0.40 and 0.94 mg/mL, respectively. The PRNE hydrolysate was processed through an ultrafiltration (UF) series with molecular weight cut-off (MWCO) membranes of 3, 5, 10, and 30 kDa, and the ACE inhibitory, antioxidant, and antimicrobial activities of the permeates were determined. The permeate through the 3-kDa MWCO membrane had greater ACE inhibitory activity and antioxidant activity than did the other PRNE permeates, with $IC_{50}$ values of 0.11 and 0.40 mg/mL, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.12
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• pp.1940-1948
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• 2013

This study is conducted to investigate the antioxidative effect of oyster hydrolysates in the serum and liver of SD-rats through the determination of lipid content, production of free radicals and antioxidant enzyme activities. Two different hydrolysates, Protamex-treated and Neutrase-treated hydrolysate with the cross-linking of protein by transglutaminase (TGPN group) and without (PN group), were fed for 6 weeks. TGPN hydrolysate in serum and liver significantly decreased the total cholesterol in the range of 26.1% to 28.9%, and triglyceride in the liver of up to 6.3%. Superoxide radical in the serum and lipid peroxide radical in the liver were significantly decreased in SD-rats fed 200 mg TGPN hydrolysate. Superoxide dismutase activity was significantly decreased in the liver of SD-rats. These results indicate that TGPN hydrolysate could scavenge the superoxide and hydroxyl radicals, and reduce the superoxide dismutase and catalase activities. The TGPN is also protected the oxidation of protein by the free radicals.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.791-798
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• 1998

To develop natural flavoring substances. optimal hydrolysis conditions for two stage enzyme hydrolysates (TSEH) using low-utilized shellfishes such as purplish clam and frozen oyster stored at $-20^{\circ}C$ for 60 days. The optimal conditions for TSEH method were revealed in temperature at $50^{\circ}C$ 3 hours digestion with alcalase (Aroase AP-10, $0.3%$ w/v, pH 8.0) at the 1st stage and $45^{\circ}C$ 2 hours digestion with neutrase (Pandidase NP-2, $0.3\%$ w/v, pH 6.0) at the 2nd stage. Among water extracts, autolytic extracts and 4 kinds of enzyme hydrolysates tests, TSEH method was superior to other methods on the aspect of yields, nitrogen contents, taste such as umami and control of off-flayer formation, and transparency of extracts. From the results of chemical experiments and sensory evaluation, we may conclude that TSEH from low-utilized marine products is more flavorable compared the conventional enzyme hydrolysates, it could be commercialized as the seasoning substances.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.799-805
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• 1998

In present paper, we examined the flayer constituents and functionality of two stage enzyme hydrolysates (TSEH) of purplish clam and oyster, and also examined reappearance of oyster flavors through repreparation of individual flayer constituents. Total free amino acid contents in TSEH was $1943.0mg\%$ for purplish clam and was $5066.2 mg\%$ for oyster, respectively, Major free amino acids in purplish clam extracts were taurine, glutamic acid, glycine, alanine, Iysine and arginine, and in oyster extracts were taurine, asparagine, glutamic acid, valine, leucine, alanine, Iysine and arginine. As for nucleotides and related compounds, AMP was the principal component though small amounts in TSEH of purplish clam and oyster, and also contents of TMAO, total creatinine, and betaine were $41.2 mg\%,\;35,9 mg\%$ and $220.9 mg\%$ for that of purplish clam and $3.51 mg\%,\;33.4 mg\%$ and $380.9 mg\%$ that of oyster, respectively. The major inorganic ions in TSEH of both samples were Na, K, P, Cl and $PO_4$, and major non-volatile organic acid was succinic acid. The TSEH of purplish clam and oyster revealed very higher inhibition effect ($84.1\%,\;77.0\%$) in ACE inhibition than that ($0\~44.7\%$) of water and autolytic extract. A synthetic oyster extract prepared from pure chemicals on the basis of the analytical data on the TSEH, satisfactorily reproduced the taste of the natural extract except for a slight lack of mildness and odor. From the omission test the major taste compounds of oyster extract were free amino acid and inorganic ions. The quaternary ammonium bases, nucleotides and related compounds seemed to net an auxiliary role in taste of that.