Mining Xanthine Oxidase Inhibitors from an Edible Seaweed Pterocladiella capillacea by Using In Vitro Bioassays, Affinity Ultrafiltration LC-MS/MS, Metabolomics Tools, and In Silico Prediction.

The prevalence of gout and the adverse effects of current synthetic anti-gout drugs call for new natural and effective xanthine oxidase (XOD) inhibitors to target this disease. Based on our previous finding that an edible seaweed Pterocladiella capillacea extract inhibits XOD, XOD-inhibitory and anti-inflammatory activities were used to evaluate the anti-gout potential of different P. capillacea extract fractions. Through affinity ultrafiltration coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS), feature-based molecular networking (FBMN), and database mining of multiple natural products, the extract's bioactive components were traced and annotated. Through molecular docking and ADMET analysis, the possibility and drug-likeness of the annotated XOD inhibitors were predicted. The results showed that fractions F4, F6, F4-2, and F4-3 exhibited strong XOD inhibition activity, among which F4-3 reached an inhibition ratio of 77.96% ± 4.91% to XOD at a concentration of 0.14 mg/mL. In addition, the P. capillacea extract and fractions also displayed anti-inflammatory activity. Affinity ultrafiltration LC-MS/MS analysis and molecular networking showed that out of the 20 annotated compounds, 8 compounds have been previously directly or indirectly reported from seaweeds, and 4 compounds have been reported to exhibit anti-gout activity. Molecular docking and ADMET showed that six seaweed-derived compounds can dock with the XOD activity pocket and follow the Lipinski drug-like rule. These results support the value of further investigating P. capillacea as part of the development of anti-gout drugs or related functional foods.

Mechanism Analysis of Antiangiogenic d-Isofloridoside from Marine Edible Red algae Laurencia undulata in HUVEC and HT1080 cell.

Laurencia undulata, as one of the most biologically active species in the genus Laurencia, is an edible folk herb red algae. Among them, d-isofloridoside (DIF, 940.68 Da) is isolated from Laurencia undulata, which has antioxidant and matrix metalloproteinases (MMP) inhibitory activities. However, its mechanism of action on tumor angiogenesis has not yet been reported. In this study, we have studied the mechanism of DIF on tumor metastasis and angiogenesis in HT1080 cell and human vascular endothelial cell (HUVEC). The results show that DIF can reduce the activity of MMP-2/9, and can inhibit the expression of hypoxia-inducible factor-1α (HIF-1α) by regulating the downstream PI3K/AKT and mitogen-activated protein kinases (MAPK) pathways, thereby down-regulating the production of vascular endothelial growth factor (VEGF) in CoCl2-induced HT1080 cell. In addition, DIF can inhibit the activation of VEGF receptor (VEGFR-2), regulate downstream PI3K/AKT, MAPK, nuclear factor-kappa B (NF-κB) signal pathways, activate apoptosis, and thus down-regulate the production of platelet-derived growth factor (PDGF) in VEGF-induced HUVEC. In conclusion, our research shows that DIF has the potential to develop into a tumor-preventing functional food and tumor angiogenesis inhibitor, and it can provide theoretical guidance for the high-value comprehensive utilization of edible red algae Laurencia undulata.

Heterophyllin B, a cyclopeptide from Pseudostellaria heterophylla, enhances cognitive function via neurite outgrowth and synaptic plasticity.

Neurite outgrowth-induced construction of neural circuits and networks is responsible for memory generalization, consolidation, and retrieval. In this study, we found that the traditional Chinese medicine Pseudostellaria heterophylla promoted neurite regrowth and enhanced cognitive function in normal mice. Further, we orally administered Pseudostellaria heterophylla water extracts (PHE) to ICR mice, and detected heterophyllin B (HET-B), an important cyclopeptide, in the plasma and cerebral cortex. We demonstrated that neurites were significantly elongated after coculturing with HET-B for 4 days. Next, the intraperitoneal injection of HET-B on seven consecutive days in 3-month-old ICR mice significantly enhanced the object recognition memory and object location memory than that in control. Immunohistochemical analysis indicated significantly increased ß3-tubulin-positive neurite density, synaptophysin, and postsynaptic density 95 in the perirhinal cortex and hippocampus after administering HET-B. Furthermore, the concentration of neurotransmitters was measured using HPLC analysis; HET-B significantly increased five-levels of HT in the hippocampus, and decreased metabolites of dopamine, dihydroxyphenylacetic acid, and homovanillic acid, in the prefrontal cortex and hippocampus. Taken together, HET-B induces neurite elongation and neurotransmitter regulation and possibly enhances cognitive memory.

Chemical Composition and Anti-Alzheimer's Disease-Related Activities of a Functional Oil from the Edible Seaweed Hizikia fusiforme.

Cholinergic disorder, oxidative stress, and neuroinflammation play important roles in the pathology of Alzheimer's disease. To explore the healthy potential of the edible seaweed Hizikia fusiforme on this aspect, a functional oil (HFFO) was extracted from this alga and investigated on its constituents by gas chromatography-mass spectrometry (GC/MS) in this study. Its anti-Alzheimer's related bioactivities including acetylcholinesterase (AChE) inhibition, antioxidation, and anti-neuroinflammation were evaluated, traced, and simulated by in vitro and in silico methods. GC/MS analysis indicated that HFFO mainly contained arachidonic acid (ARA), 11,14,17-eicosatrienoic acid (ETrA), palmitic acid, phytol, etc. HFFO showed moderate AChE inhibition and antioxidant activity. Bioactivity tracing using commercial standards verified that AChE inhibition of HFFO mainly originated from ARA and ETrA, whereas antioxidant activity mainly from ARA. Lineweaver-Burk plots showed that both ARA and ETrA are noncompetitive AChE inhibitors. A molecular docking study demonstrated low CDOCKER interaction energy of -26.33 kcal/mol for ARA and -43.70 kcal/mol for ETrA when interacting with AChE and multiple interactions in the ARA (or ETrA)-AChE complex. In the anti-neuroinflammatory evaluation, HFFO showed no toxicity toward BV-2 cells at 20 µg/mL and effectively inhibited the production of nitroxide and reduced the level of reactive oxygen species in lipopolysaccharide-induced BV-2 cells. The results indicated that HFFO could be used in functional foods for its anti-Alzheimer's disease-related activities.

Mechanism Analysis of a Novel Angiotensin-I-Converting Enzyme Inhibitory Peptide from Isochrysis zhanjiangensis Microalgae for Suppressing Vascular Injury in Human Umbilical Vein Endothelial Cells.

Microalgae are primary producers with multiple nutrients in aquatic environments and mostly have applications in biological feed and fuel industry. There are few studies assessing the angiotensin-I-converting enzyme (ACE) inhibition potential of Isochrysis zhanjiangensis, other than its antioxidant potential. In this study, we evaluated a peptide from I. zhanjiangensis (PIZ, FEIHCC) and its vascular endothelial factors and mechanism in human umbilical vein endothelial cells (HUVEC). The results reveal that PIZ (IC50 = 61.38 µM) acts against ACE in a non-competitive binding mode. In addition, PIZ inhibits angiotensin II (Ang II)-induced vascular factor secretion and expression by blocking inflammation and apoptosis through nuclear factor κB (NF-κB), nuclear erythroid 2-related factor 2 (Nrf2), mitogen-activated protein kinases (MAPKs), and the serine/threonine kinase (Akt) signal pathways. This study reveals that PIZ has potential to be developed as a therapeutic agent for hypertension and provides a new method of high-value utilization of I. zhanjiangensis.

2'-Hydroxy-5'-methoxyacetophenone attenuates the inflammatory response in LPS-induced BV-2 and RAW264.7 cells via NF-κB signaling pathway.

Seahorse has been used as a traditional medicine in Southeast Asian countries for a long time. A compound, 2'-Hydroxy-5'-Methoxyacetophenone (2H5M) isolated from seahorse, Hippocampus kuda, was tested for its anti-inflammatory effect in lipopolysaccharides (LPS)-stimulated BV-2 cells and RAW264.7 cells. MTT assay indicated that 2H5M has no cytotoxicity on two kinds of cells. The concentration of nitric oxide (NO) measured by Griess Reaction System showed that 2H5M could significantly inhibit the NO concentration. The ELISA results showed that 2H5M could suppress the secretion of TNF-α in a dose-dependent manner. Moreover, western blot analysis was utilized to measure the protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways. Electrophoretic mobility shift assay (EMSA) demonstrated that 2H5M reduced NF-κB DNA binding activity. Furthermore, the molecular docking study showed that 2H5M can form active sites with NF-κB. Collectively, these results indicated that 2H5M possesses anti-inflammatory effects and may have a potential application in inflammatory disorders in the future.

1-(5-Bromo-2-hydroxy-4-methoxyphenyl)ethanone [SE1] Inhibits MMP-9 Expression by Regulating NF-κB and MAPKs Signaling Pathways in HT1080 Human Fibrosarcoma Cells.

Hippocampus is a traditional medicine in China, which can be used for treating tumors, aging, fatigue, thrombosis, inflammation, hypertension, prostatic hyperplasia, and other diseases. 1-(5-Bromo-2-hydroxy-4-methoxyphenyl)ethanone [SE1] from seahorse (Hippocampus kuda Bleeler) has been shown to suppress proinflammatory responses. In the present study, SE1 potently inhibited gelatin digestion by MMP-9 induced by phorbol 12-myristate 13-acetate (PMA) and migration of human fibrosarcoma HT1080 cells in dose-dependent manner. Moreover, western blot analysis and immunofluorescence analysis have been studied on MAPKs (ERK1/2, p38 kinase and JNK) and NF-κB (p65 and IκB), which refer to the clear molecular mechanism. The results indicated that SE1 significantly suppressed the phosphorylation of mitogen-activated protein kinases (MAPK: p38 kinase and JNK) and NF-κB. Finally, molecular docking result showed SE1 interacts with TYR245 and HIS226 of MMP-9 by hydrogen bond and Pi-Pi bond to suppress MMP-9 activity. This data suggested that the SE1 may possess therapeutic and preventive potential for the treatment of MMP-9 related disorders.

Cellular properties of the fermented microalgae Pavlova lutheri and its isolated active peptide in osteoblastic differentiation of MG­63 cells.

Fermented microalgae Pavlova lutheri (P. lutheri), the product of Hansenula polymorpha fermentation, exhibited an increase in alkaline phosphatase (ALP) activity in MG­63 osteoblastic cells when compared to that of non­fermented P. lutheri. Fractionation of the fermented P. lutheri resulted in identification of the active peptide [peptide of P. lutheri fermentation (PPLF)] with the sequence of EPQWFL. PPLF significantly increased ALP release from MG­63 cells and mineralization in a dose­dependent manner. In addition, the intracellular levels of ALP and osteocalcin (OCN) proteins were augmented by PPLF treatment. To identify the molecular mechanism underlying the effect of PPLF on osteoblastic differentiation, the phosphorylation levels of the mitogen­activated protein kinases, p38, extracellular signal­regulated kinases 1/2 and Jun, and nuclear factor (NF)­κB were determined following PPLF treatment and the differences in expression were analyzed using p38 and NF­κB selective inhibitors. These results concluded that PPLF from fermented P. lutheri induced osteoblastic differentiation by increasing ALP and OCN release in MG­63 cells via the p38/p65 signaling pathway, indicating that PPLF supplement may be effective for therapeutic application in the field of bone health.

Photo-oxidative stress by ultraviolet-B radiation and antioxidative defense of eckstolonol in human keratinocytes.

Ultraviolet-B (UV-B) irradiation has been known to generate oxidative stress by increasing reactive oxygen species (ROS) in skin cells. Several naturally occurring antioxidant compounds isolated from marine algae are believed to protect against ROS. In this study, we assessed the antioxidative effect of eckstolonol isolated from Ecklonia cava against UV-B-induced ROS in human keratinocytes (HaCaTs). We investigated the effects of photo-oxidative stress by UV-B (50 mJ/cm(2)) and the antioxidative effects of eckstolonol using fluorometry, flow cytometry, microscopy, and cell viability and comet assays. UV-B irradiation decreased cell viability, which was restored in a dose-dependent manner with eckstolonol treatment (0, 5, 50, 100, and 200 µM). Moreover, eckstolonol reduced UV-B-induced ROS, lipid peroxidation, damaged DNA levels, and cell death. These antioxidative effects seem to be due to the enzymatic activities of catalase (CAT) and superoxide dismutase (SOD). Collectively, these results indicate that eckstolonol is capable of protecting keratinocytes from photo-oxidative stress.

Antioxidant peptides from protein hydrolysate of microalgae Navicula incerta and their protective effects in HepG2/CYP2E1 cells induced by ethanol.

Marine microalgae have been reported as valuable new sources of pharmacologically active compounds and there are now numerous commercial applications of microalgae. Hence, in this study we evaluated the protective effects of peptides purified from marine microalgae, Navicula incerta, against alcohol-induced damage in HepG2/CYP2E1 cells. To obtain bioactive peptides from microalgae, N. incerta was hydrolysed using various enzymes (alcalase, α-chymotrypsin, neutrase, papain, pepsin, pronase-E and trypsin), and the hydrolysates were evaluated for cytoprotective activity. Among them, papain-derived hydrolysate exhibited higher antioxidant activities than those of other enzymes. Therefore, papain hydrolysate was purified in order to obtain potent antihepatotoxic and antioxidative peptides. The amino acid sequences of the purified peptides were analysed as; NIPP-1 (Pro-Gly-Trp-Asn-Gln-Trp-Phe-Leu) with molecular mass 1 171 Da, and NIPP-2 (Val-Glu-Val-Leu-Pro-Pro-Ala-Glu-Leu) with molecular mass 1108 Da. Furthermore, this study demonstrated that NIPP-1 and NIPP-2 peptides inhibited ethanol-induced cytotoxicity in HepG2/CYP2E1 cells.

Protective Effects of Emodin and Chrysophanol Isolated from Marine Fungus Aspergillus sp. on Ethanol-Induced Toxicity in HepG2/CYP2E1 Cells.

Alcohol-induced liver injury progresses from fatty infiltration followed by a harmful cause of inflammation leading to an irreversible damage. In this study, two compounds (emodin and chrysophanol) isolated from marine fungus Aspergillus sp. were examined for their protective effects against ethanol-induced toxicity in vitro. Ethanol-induced HepG2/CYP2E1 cells were treated with the compounds at various concentrations, and the results showed that there was a dose-dependent decrease of gamma-glutamyl transpeptidase (GGT) activity and increase of glutathione (GSH) in the culture media with an increase in cell viability. Furthermore, the protective effects of the compounds were evaluated by protein expression levels of GGT, GSH, and CYP2E1 using Western blot. Among the compounds, emodin addressed to the ethanol-induced cytotoxicity more effectively compared to the chrysophanol. It could be suggested that emodin isolated from this genus would be a potential candidate for attenuating ethanol induced liver damage for further industrial applications such as functional food and pharmaceutical developments.

Dieckol from Ecklonia cava Regulates Invasion of Human Fibrosarcoma Cells and Modulates MMP-2 and MMP-9 Expression via NF-κB Pathway.

The matrix metalloproteinase (MMP) family is involved in the breakdown of extracellular matrix in normal physiological processes, as well as in the disease processes such as arthritis and cancer metastasis. In the present study, dieckol was obtained with high yield from marine brown alga Ecklonia cava (EC), and its effect was assessed on the expression of MMP-2 and -9 and morphological changes in human fibrosarcoma cell line (HT1080). Dieckol inhibited the expression of MMP-2 and -9 in a dose-dependent manner and also suppressed the cell invasion and the cytomorphology in 3D culture system on HT1080 cells. Moreover, dieckol may influence nuclear factor kappa B (NF-κB) pathway without obvious influence on activator protein-1 (AP-1) pathway and tissue inhibitor of metalloproteinases (TIMPs). In conclusion, dieckol could significantly suppress MMP-2 and -9 expression and alter cytomorphology of HT1080 cell line via NF-κB pathway.

Sea cucumber, Stichopus japonicus ethyl acetate fraction modulates the lipopolysaccharide induced iNOS and COX-2 via MAPK signaling pathway in murine macrophages.

The sea cucumber Stichopus japonicus is an important food and traditional medicine in Asian countries. However, ethyl acetate solvent fraction of S. japonicus (SCEA-F) is largely unknown for its anti-inflammatory activity and related molecular mechanisms. In this study, effect of SCEA-F on inflammation was investigated in LPS stimulated RAW264.7 cells. SCEA-F significantly inhibited the productions of NO and PGE(2) by inhibiting iNOS and COX-2 at their protein and gene levels. The production and the gene transcription of pro-inflammatory cytokines are also inhibited. The responsible molecular signaling for these inhibitory actions was found to be through suppression of the phosphorylation of MAPK molecules; ERK and p38 MAPK. These results indicate that SCEA-F inhibits LPS-induced inflammatory response via blocking of MAPK signaling pathway in murine macrophages, thus demonstrated its in vitro anti-inflammatory potential. Therefore it could be suggested that SCEA-F could be effectively used in functional food preparations.

Inhibitors of oxidation and matrix metalloproteinases, floridoside, and D-isofloridoside from marine red alga Laurencia undulata.

In the exploration of abundant marine biological resources, edible red alga Laurencia undulata led to two bioactive isolates: floridoside (1) and D-isofloridoside (2). For the first time, the antioxidant properties of both derivatives (1 and 2) were characterized via free radical scavenging using the ESR technique, reactive oxygen species (ROS) inhibition, membrane protein oxidation, myeloperoxidase (MPO) inhibition, gene expression levels of glutathione (GSH) and superoxide dismutase (SOD), and protein expression of MMP-2 and MMP-9. The results demonstrate that floridoside and D-isofloridoside possess significant antioxidant capacity and are potential inhibitors of MMP-2 and MMP-9. These results clarified that these components may be responsible for the relative activities of crude extract from this genus, which is used as folk medicine. Furthermore, the structure-activity relationships were also suggested. Both isomers could be effective candidates for applications in food and pharmaceutical fields as natural marine antioxidants.

Differentiation of human osteosarcoma cells by isolated phlorotannins is subtly linked to COX-2, iNOS, MMPs, and MAPK signaling: implication for chronic articular disease.

Arthritis is one of the most prevalent chronic inflammatory diseases, and it is characterized by structural and biochemical changes in major tissues of the joint, including degradation of the cartilage matrix, insufficient synthesis of extracellular matrix (ECM). Ecklonia cava (EC) is a member of the family of Laminariaceae, which is an edible marine brown alga with various bioactivities. In this study of the methanol extract of brown alga EC, the dieckol (1) and 1-(3',5'-dihydroxyphenoxy)-7-(2'',4'',6''-trihydroxyphenoxy) 2,4,9-trihydroxydibenzo-1,4,-dioxin (2) were isolated and characterized by NMR techniques with high yield. Phlorotannin derivatives (1, 2) promoted osteosarcoma differentiation by increasing alkaline phosphatase (ALP) activity, mineralization, total protein and collagen synthesis in human osteosarcoma cell (MG-63 cells), respectively. Furthermore, these phlorotannin derivatives (1, 2) inhibited mRNA gene and protein levels of matrix metalloproteinase (MMP-1, MMP-3, and MMP-13), iNOS and COX-2 in casein zymography, Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) assays. In addition, it was observed that the phlorotannins inhibited phosphorylation of JNK and p38 MAPK in human osteosarcoma cell. These results suggested the phlorotannin derivatives (1, 2) could promote cell differentiation, attenuate MMP-1, MMP-3, MMP-13 expressions, and inflammatory response via MAPK pathway in chronic articular diseases.

Chemical components and its antioxidant properties in vitro: an edible marine brown alga, Ecklonia cava.

Seven phlorotannins were isolated and characterized from an edible marine brown alga Ecklonia cava (EC), along with three common sterol derivatives (fucosterol, ergosterol, and cholesterol) according to the comprehensive spectral analysis of MS and NMR data. Compounds 5 (7-phloro eckol) and 7 (6,6'-bieckoll) of phlorotannin derivatives were obtained for the first time with the high yields. No reports of compound 3 (Fucodiphloroethol G) was published up to date. The antioxidant properties of all phlorotannins were assessed by total antioxidant activity in a linoleic acid model, free radicals scavenging assay using electron spin resonance spectrometry (ESR) technique, cellular reactive oxygen species (ROS) assay by DCFH-DA, membrane protein oxidation assay; measurement of cellular glutathione (GSH) level in RAW264.7 cell line, and myeloperoxidase (MPO) assay in HL-60 cell line. The results revealed that all phlorotannins had antioxidant properties in vitro, especially, compounds 7 (6,6'-bieckol), 6, and 3 showed the significant activities compared to the other phlorotannins. Furthermore, the structure-activity relationship (SAR) was discussed based on the structural differences of the tested phlorotannins which have polymeriged phloroglucinal units with diverse skeletons and linkages. It could be suggested that phlorotaninns from this genus would be more potential candidates for the development of unique natural antioxidants for further industrial applications as functional foods, cosmetics and pharmaceuticals. As well as our results makes it clear to understand the reason behind the use of EC as traditional folk herb for a long history.

Purification and antioxidant properties of bigeye tuna (Thunnus obesus) dark muscle peptide on free radical-mediated oxidative systems.

To produce bioactive peptides from by-products of fish processing, bigeye tuna dark muscle was hydrolyzed using various enzymes (alcalase, alpha-chymotrypsin, neutrase, papain, pepsin, and trypsin), and the hydrolysates were evaluated for antioxidant activity. Considering the results of degree of hydrolysis and antioxidant activities, peptic hydrolysate was used for further studies to identify a potent antioxidant peptide. Antioxidant peptide was purified using consecutive chromatographic methods and was identified as being H-Leu-Asn-Leu-Pro-Thr-Ala-Val-Tyr-Met-Val-Thr-OH (MW 1,222 Da) by quantitative time-of-flight electrospray ionization mass spectrometry. Purified antioxidant peptide from bigeye tuna dark muscle (APTDM) was investigated for its antioxidant activities using both free radical scavenging effects and polyunsaturated fatty acid (PUFA) peroxidation inhibitory activity. The results showed that APTDM effectively quenched with low 50% inhibitory concentration values compared to vitamin C as a positive control against four different free radicals: 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, superoxide, and alkyl radical. APTDM also inhibited PUFA peroxidation in a linoleic acid emulsion system, and the activity was similar to that of alpha-tocopherol. We further investigated its antioxidant activities on cellular systems, and the results showed that APTDM significantly scavenged cellular radicals and enhanced the viability of tert-butyl hydroperoxide-induced cytotoxicity. These results indicate that APTDM or a peptide fraction containing APTDM would be a beneficial ingredient for functional food and/or pharmaceuticals.

Antioxidant peptide isolated from muscle protein of bullfrog, Rana catesbeiana Shaw.

Bullfrog (Rana catesbeiana Shaw) muscle protein was enzymatically hydrolyzed for extraction of an antioxidant peptide. Antioxidant peptide from bullfrog muscle protein hydrolysate (APBMH) was purified using consecutive chromatographic methods, and the amino acid sequence was identified as being Leu-Glu-Gln-Gln-Val-Asp-Asp-Leu-Glu-Gly-Ser-Leu-Glu-Gln-Glu-Lys-Lys (molecular mass of 1,988 Da) by quantitative time-of-flight electrospray ionization mass spectroscopy. To assess antioxidant activities of APBMH, two different in vitro systems were employed: free radical scavenging activity by electron spin resonance (ESR) spectroscopy and polyunsaturated fatty acid (PUFA) peroxidation inhibition assay. ESR revealed that APBMH is an effective free radial scavenger with activity similar to that of vitamin C against 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, and superoxide radicals, and its 50% inhibitory concentration values were 179.4 microM, 162.7 microM, and 176.1 microM, respectively. APBMH also significantly retarded PUFA oxidation, and more potently than did alpha-tocopherol, which was used as a positive control. In addition, the ability of APBMH to inhibit the oxidative damage of DNA was assessed, in vitro, by measuring the conversion of supercoiled pBR322 plasmid DNA to the open circular form. It was found that APBMH significantly protected hydroxyl radical-induced DNA damage dose-dependently.

Free radical scavenging activity of a novel antioxidative peptide isolated from in vitro gastrointestinal digests of Mytilus coruscus.

A low-molecular-weight peptide with potent antioxidative activity was obtained from Mytilus coruscus muscle protein using an in vitro gastrointestinal digestion system. The potent antioxidant peptide, which was identified as Leu-Val-Gly-Asp-Glu-Gln-Ala-Val-Pro-Ala-Val-Cys-Val-Pro (1.59 kDa), exhibited higher protective activity against polyunsaturated fatty acid (PUFA) peroxidation than the native antioxidants, ascorbic acid and alpha-tocopherol. In a free radical scavenging assay using electron spin resonance spectroscopy, hydroxyl radical formation was quenched by 75.04% in the presence of M. coruscus peptide (50 microg/mL), which was similar to ascorbic acid. In addition, the purified peptide could also quench super-oxide and carbon-centered radicals, but those activities were weaker than for ascorbic acid. This study showed that the low-molecular-weight peptide released from in vitro gastrointestinal digestion of mussel exhibited potent antioxidant potential by inhibiting the formation of reactive oxygen species formed by the peroxidation of PUFAs.