Quantification of Multifunctional Dipeptide YA from Oyster Hydrolysate for Quality Control and Efficacy Evaluation

Antioxidant and protective effects of a peptide (VTAL) derived from simulated gastrointestinal digestion of protein hydrolysates of Magallana gigas against acetaminophen-induced HepG2 cells

Oxidative stress is an automatic mechanism responsible for the commencement and continuance of liver injury. In this study, an antioxidative peptide Val-Thr-Ala-Leu (VTAL) was purified from simulated gastrointestinal digestion of protein hydrolysates of the triploid oyster Magallana gigas. Significant antioxidant activity was identified, as well as a protective effect against acetaminophen (APAP)-induced human liver cancer (HepG2) cells. The results suggested that the antioxidant activity improved in a dose-dependent manner. The highest cell viability (88.105 ± 3.62%) was observed in 15 mM APAP-induced cells when treated with 25 μg/mL M. gigas peptide [M.g (pep)]. The peptide sequences include hydrophobic amino acids, which could be responsible for its chemoprotective and antioxidant activities. Treatment with M.g (pep) significantly promoted the proliferation of HepG2 cells, thus protecting them against APAP and imbuing them with significant antioxidant capacity. M.g (pep) could be beneficial for treating drug-induced oxidative stress and liver damage. Additionally, M.g (pep) could serve as an alternative to synthetic antioxidant drugs.

Bioactive Earthworm Peptides Produced by Novel Protease-Producing Bacillus velezensis PM 35 and Its Bioactivities on Liver Cancer Cell Death via Apoptosis, Antioxidant Activity, Protection Against Oxidative Stress, and Immune Cell Activation

Earthworms have long been used as traditional medicine. The purposes of this research were to create bioactive peptides from the unique Amynthas arenulus earthworm (PAAEs) and test their potentials on liver cancer bioprophylactic activity, antioxidant, oxidative stress protection, and immune cell activation. This earthworm had a high protein content ratio, at 55.39%. Besides, PM 35 is one out of 58 bacteria isolated from the earthworm carcasses that exhibited the highest protease and yield protein production which was chosen as the protease-producing bacteria to hydrolyze the protein. The genera were identified by 16S rRNA and 16S–23S rRNA comparison and confirmed as Bacillus velezensis PM 35. The response surface methodology was applied to optimize these hydrolysis parameters, i.e., the enzyme/substrate (E/S) concentration ratio [1%–3% (v/v)] and time (1–3 h) of the hydrolyzing earthworm’s proteins. The optimal hydrolyzing conditions were 3% (v/v) of E/S concentration ratio and 3 h of hydrolysis time, which found protein-hydrolysate yield (24.62%) and degree of hydrolysis (85.45%) as the highest. After being challenged in the gastrointestinal tract-resistant model, these PAAEs (MW <3 and 3–5 kDa) induced liver cancer cell (HepG2) death via apoptotic action modes (cell morphological change and DNA fragmentation). The PAAEs (MW <3 kDa) exhibited significant antioxidant activity via DPPH, ABTS, and FRAP with IC₅₀ values of 0.94, 0.44, and 6.34 mg/ml, respectively. The PAAEs (MW < 3 kDa) were non-cytotoxic and protected the mouse fibroblast cells (L929) against oxidative stress. These PAAEs (MW < 3 kDa, 0.2 mg/ml) stimulated the B lymphocytes (122.3%), and T lymphocytes (126.7%) proliferation. This research suggests that PAAEs can be used in a variety of applications, especially in the food and pharmaceutical industries.

A Review of Bioactive Compounds in Oyster Shell and Tissues

Oysters are saltwater bivalves with high nutritional and medicinal value that are consumed widely around the world. As well as being highly nutritious, oysters are a low-calorie, low-cholesterol source of protein and an exceptional source of zinc, which strengthens the immune system; and a rich source of bioactive compounds, which comprise various biological activities. The present review summarizes the biological applications and bioactive compounds from oyster shells, whole tissue, gill tissue, and mantle tissue. The various biological compounds present in an oyster shell, and their chemical constituents, have applications in the food, pharmaceutical, and medical industries. Bioactive peptides and proteins obtained from the whole, mantle, and gill tissues of oysters exhibit antioxidant, antimicrobial, antihypertensive, anticancer, antifatigue, anticoagulant, and anti-wrinkle effects, as well as enhance osteoblast differentiation. This review clearly shows that oysters have great potential for functional food production and that various compounds therein can have pharmaceutical applications.

Oyster Hydrolysates Attenuate Muscle Atrophy via Regulating Protein Turnover and Mitochondria Biogenesis in C2C12 Cell and Immobilized Mice

Sarcopenia, also known as skeletal muscle atrophy, is characterized by significant loss of muscle mass and strength. Oyster (Crassostrea gigas) hydrolysates have anti-cancer, antioxidant, and anti-inflammation properties. However, the anti-sarcopenic effect of oyster hydrolysates remains uninvestigated. Therefore, we prepared two different oyster hydrolysates, namely TGPN and PNY. This study aimed to determine the anti-muscle atrophy efficacy and molecular mechanisms of TGPN and PNY on both C2C12 cell lines and mice. In vitro, the TGPN and PNY recovered the dexamethasone-induced reduction in the myotube diameters. In vivo, TGPN and PNY administration not only improved grip strength and exercise endurance, but also attenuated the loss of muscle mass and muscle fiber cross-sectional area. Mechanistically, TGPN and PNY increased the expression of protein synthesis-related protein levels via phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of the rapamycin pathway, and reduced the expression of protein degradation-related protein levels via the PI3K/Akt/forkhead box O pathway. Also, TGPN and PNY stimulated NAD-dependent deacetylase sirtuin-1(SIRT1), peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α), nuclear respiratory factor 1,2, mitochondrial transcription factor A, along with mitochondrial DNA content via SIRT1/PGC-1α signaling. These findings suggest oyster hydrolysates could be used as a valuable natural material that inhibits skeletal muscle atrophy via regulating protein turnover and mitochondrial biogenesis.

Oyster-Derived Tyr-Ala (YA) Peptide Prevents Lipopolysaccharide/D-Galactosamine-Induced Acute Liver Failure by Suppressing Inflammatory, Apoptotic, Ferroptotic, and Pyroptotic Signals

Models created by the intraperitoneal injection of lipopolysaccharide (LPS) and D-galactosamine (D-GalN) have been widely used to study the pathogenesis of human acute liver failure (ALF) and drug development. Our previous study reported that oyster (Crassostrea gigas) hydrolysate (OH) had a hepatoprotective effect in LPS/D-GalN-injected mice. This study was performed to identify the hepatoprotective effect of the tyrosine-alanine (YA) peptide, the main component of OH, in a LPS/D-GalN-injected ALF mice model. We analyzed the effect of YA on previously known mechanisms of hepatocellular injury in the model. LPS/D-GalN-injected mice showed inflammatory, apoptotic, ferroptotic, and pyroptotic liver injury. The pre-administration of YA (10 mg/kg or 50 mg/kg) significantly reduced the liver damage factors. The hepatoprotective effect of YA was higher in the 50 mg/kg YA pre-administered group than in the 10 mg/kg YA pre-administered group. These results showed that YA had a hepatoprotective effect by reducing inflammation, apoptosis, ferroptosis, and pyroptosis in the LPS/D-GalN-injected ALF mouse model. We suggest that YA can be used as a functional peptide for the prevention of acute liver injury.

Systematic screening and structural characterization of dipeptides using offline 2D LC-LTQ orbitrap MS: A case study of Cordyceps sinensis

Cordyceps sinensis (C. sinensis) is a widely used and highly valuable traditional Chinese medicine. Several dipeptides have been detected in C. sinensis, but current scientific knowledge of its chemical makeup remains limited. In this study, an improved approach that integrates offline two-dimensional liquid chromatography (2D LC) separation, precursor ion list, library screening, and diagnostic ion filtering was established to systematically screen and characterize dipeptides in C. sinensis. Offline 2D LC integrating hydrophilic interaction LC and reverse phase separations was established to eliminate interference and identify the target dipeptides. A library containing the potential 400 dipeptides was created, and a precursor ion list with all theoretical precursor ions was adopted to trigger the MS/MS scan with high sensitivity. To identify dipeptides, the type and connection sequence of amino acids were determined according to the product ions. Ile and Leu residues were differentiated for the first time according to the characteristic ion at m/z 69.07. Ultimately, 170 dipeptides were identified or tentatively characterized from C. sinensis, and most are reported for the first time in this species herein. In addition, the identified dipeptides were also applied for discrimination among the three Cordyceps species, and 11 markers were identified. The obtained results provide a deeper understanding of the chemical basis of C. sinensis.

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An enhanced targeted identification strategy is presented.

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It involves offline 2D-LC/MS, in-house library searching and diagnostic product ion filtering.

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170 dipeptides were reported from Cordyceps sinensis.

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Characteristic ion was proposed for differentiation between Ile and Leu.

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Three Cordyceps species were differentiated.

Dipeptide YA is Responsible for the Positive Effect of Oyster Hydrolysates on Alcohol Metabolism in Single Ethanol Binge Rodent Models

Accumulative alcohol hangovers cause liver damage through oxidative and inflammatory stress. Numerous antioxidant and anti-inflammatory reagents have been developed to reduce alcohol hangovers, but these reagents are still insignificant and have limitations in that they can cause liver toxicity. Oyster hydrolysate (OH), another reagent that has antioxidant and anti-inflammatory activity, is a product extracted through an enzymatic hydrolysis process from oysters (Crassostrea gigas), which can be easily eaten in meals. This study was aimed at determining the effects of OH on alcohol metabolism, using a single high dose of ethanol (EtOH) administered to rodents, by monitoring alcohol metabolic enzymes, oxidative stress signals, and inflammatory mediators. The effect of tyrosine-alanine (YA) peptide, a main component of OH, on EtOH metabolism was also identified. In vitro experiments showed that OH pretreatment inhibited EtOH-induced cell death, oxidative stress, and inflammation in liver cells and macrophages. In vivo experiments showed that OH and YA pre-administration increased alcohol dehydrogenase, aldehyde dehydrogenase, and catalase activity in EtOH binge treatment. In addition, OH pre-administration alleviated CYP2E1 activity, ROS production, apoptotic signals, and inflammatory mediators in liver tissues. These results showed that OH and YA enhanced EtOH metabolism and had a protective effect against acute alcohol liver damage. Our findings offer new insights into a single high dose of EtOH drinking and suggest that OH and YA could be used as potential marine functional foods to prevent acute alcohol-induced liver damage.

Antioxidant Effects and Cytoprotective Potentials of Herbal Tea against H2O2-Induced Oxidative Damage by Activating Heme Oxygenase1 Pathway

Herbal tea with antioxidant ingredients has gained increasing attention in the field of functional foods due to their amelioration potential in aging-related diseases. Wanglaoji herbal tea (WHT) is a kind of traditional beverage made from herbal materials. This study was performed to investigate its antioxidant activity and identify its protective effect on a H₂O₂-induced cell damage model. In this study, we identified six kinds of phenolic acids with antioxidant activity in WHT, among which rosmarinic acid had the highest content and the highest contribution ratio to the antioxidant activity of WHT. Moreover, compared with the H₂O₂-induced damage group, the WHT treatment group can significantly increase the viability of cells and decrease the ratio of senescence-associated β-galactosidase-positive cells, intracellular malondialdehyde levels, and the percentage of G1 phase. Furthermore, enrichment analysis of differentially expressed genes revealed that heme oxygenase1 (HMOX1) was a key gene for protective effect of WHT on oxidative stress-induced cell damage. Thus, WHT exerted protective effects not only by scavenging reactive oxygen species but also by inducing the expression of cytoprotective genes by activating the HMOX1 pathway, which showed that WHT had a potential of promoting health by reducing oxidative stress-induced cell damage.