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Oligopeptide (AYAPE, AYP) has been isolated from Isochrysis Zhanjiangensis and it has been proven to have good biological activity potential, but its structural characteristics and structure-activity are not yet very clear. As an oligopeptide of five amino acids, the structural characteristics of AYP are the key factors of its activity. Therefore, through evaluating the antioxidant mechanism and stress degree of AYP in different cells, the active action sites were analyzed to explain the antioxidant structure activity relationship of AYP. The results indicate that under oxidative stress, 50 μM AYP can restore 78.53 % of cell viability. AYP through NF-κB and MAPK signaling pathways inhibit inflammation and cell apoptosis. And then, it activates Nrf2/Keap1 pathway, promotes Nrf2 nuclear transfer, and increases the expression of antioxidant enzymes, thus exerting antioxidant effects. In addition, in order to further explore the structure activity relationship of AYP, quantum mechanics and molecular docking were combined for analysis. The results showed that tyrosine, alanine, proline, and glutamic acid contained in AYP can all contribute to antioxidant activity, and the key amino acids that mainly play an antioxidant role are tyrosine and alanine. Therefore, this study provides a new idea for the rational design of marine oligopeptides based on the activity mechanism in the application of food and health products.

Hepatocellular carcinoma (HCC) is one of the deadliest forms of cancer, but the drugs currently used for its treatment are less than ideal. Tilapia oligopeptides have a wide range of biological activities and are potential sources of new drugs. In this study, the role and mechanism of TBP-1 (Ser-Val-Val-Ala-Ile), an oligopeptide from tilapia, on inflammation and endothelial-mesenchymal transition (EMT) in HCC was investigated using the LPS-induced RAW264.7 inflammation model and the transforming growth factor (TGF)-β1-induced HCC EMT model. The results showed that TBP-1 could effectively inhibit inflammatory response. Moreover, in TGF-β1-induced human hepatocellular carcinoma (HepG2) cells, 100 μM TBP-1 significantly reduced the secretion of N-cadherin (54.2 ± 10.6 %), Vimentin (47.0 ± 9.4 %) and Snail (76.0 ± 9.0 %), increased the secretion of E-cadherin (56.0 ± 16.3 %), inhibited cell metastasis, and participated in the regulatory mechanisms of TGF-β/Smad and non-TGF-β/Smad mediated EMT. TBP-1 may be a potentially valuable inhibitor of HCC.

Periodontitis is a common chronic inflammatory disease of the supporting tissues of the tooth that involves a complex interaction of microorganisms and various cell lines around the infected site. To prevent and treat this disease, several options are available, such as scaling, root planning, antibiotic treatment, and dental surgeries, depending on the stage of the disease. However, these treatments can have various side effects, including additional inflammatory responses, chronic wounds, and the need for secondary surgery. Consequently, numerous studies have focused on developing new therapeutic agents for more effective periodontitis treatment. This review explores the latest trends in bioactive substances with therapeutic effects for periodontitis using various search engines. Therefore, this study aimed to suggest effective directions for therapeutic approaches. Additionally, we provide a summary of the current applications and underlying mechanisms of bioactive substances, which can serve as a reference for the development of periodontitis treatments.

Parkinson’s disease (PD) is a progressive neurodegenerative disorder of the elderly for which there is no cure or disease-modifying therapy. Mitochondrial dysfunction and oxidative stress play a central role in dopaminergic neurodegeneration in PD. Therefore, antioxidants are considered a promising neuroprotective approach. In in vivo activity studies, 6-OHDA-induced oxidative stress in SH-SY5Y cells was established as a model of PD for cellular experiments. IIAVE (Ile–Ile–Ala–Val–Glu) was derived from Isochrysis zhanjiangensis octapeptide (IIAVEAGC), which has a small molecular weight. The structure and antioxidant activity of IIAVE were tested in a previous study and proved to have good antioxidant potential. In this study, the chemical properties of IIAVE were calculated using quantum chemical methods, including frontier molecular orbital (FMO), molecular electrostatic potential (MEP), natural population analysis (NPA), and global reactivity properties. The interaction of IIAVE with Bcl-2 and DJ-1 was investigated using the molecular docking method. The results showed that IIAVE promoted the activation of the Keap1/Nrf2 pathway and up-regulated the expression of the superoxide dismutase 1 (SOD-1) protein by inhibiting the level of reactive oxygen species (ROS) in cells. In addition, IIAVE inhibits ROS production and prevents 6-OHDA-induced oxidative damage by restoring mitochondrial membrane potential. Furthermore, IIAVE inhibited cell apoptosis by increasing the Bcl-2/Bax ratio and inhibiting the activation of Caspase-9 and Caspase-3. Thus, IIAVE may become a potential drug for the treatment and prevention of PD.

Microalgae are primary producers in marine ecosystems, and have been diffusely used in medicine and food. In this research, we evaluated the protective effects of polypeptides from microalgae, Isochrysis zhanjiangensis (EMFGTSSET, ETT) on endothelial injury in angiotensin II (Ang II)-induced human umbilical vein endothelial cells (HUVEC). The results showed that ETT inhibited the fluorescence intensity of intracellular reactive oxygen species (ROS), and reduces the expression of related cytokines, such as IL-1β, IL-8, TNF-α, iNOS, COX-2, ET-1, AT-1, and adhesion factor. It blocks inflammation and apoptosis through mitogen-activated protein kinases (MAPK), nuclear factor κB (NF-κB) and serine/threonine kinase (Akt) signal pathways, thereby alleviating endothelial damage. Meanwhile, ETT (IC50 = 15.08 μM) antagonizes Angiotensin-I Converting Enzyme (ACE) in a non-competitive binding mode, and has an antihypertensive effect in spontaneously hypertensive rats (SHR). Therefore, ETT has excellent effect in regulating hypertension, can become the main component of potential functional food for the prevention of cardiovascular diseases, and further improve the use value of Isochrysis Zhanjiangensis.

Epi-aszonalenin A (EAA) is an alkaloid that is isolated and purified from the secondary metabolites of coral symbiotic fungi and has been shown to have good atherosclerotic intervention activity and anti-angiogenic activity in our previous studies. In the present study, antiangiogenic activity was used as a basis of an intensive study of its mechanism of action against tumor metastasis and invasion. Invasive metastatic pairs are a hallmark of malignancy, and the dissemination of tumor cells is the most dangerous process in the development of tumors. The results of cell wound healing and the Transwell chamber assay showed that EAA interfered well with PMA-induced migration and invasion of HT1080 cells. Western blot and the ELISA assay showed that EAA decreased MMPs and vascular endothelial growth factor (VEGF) activity and inhibited the expression of N-cadherin and hypoxia-inducible factor-1α (HIF-1α) by regulating the phosphorylation of downstream mitogen-activated protein kinase (MAPK), PI3K/AKT, and NF-κB pathways. Simultaneous molecular docking results revealed that the mimic coupling between the EAA and MMP-2/-9 molecules formed a stable interaction. The results of this study provide a research basis for the inhibition of tumor metastasis by EAA, and together with previous studies, confirm the potential pharmacology and drug potential for this class of compound for application in angiogenesis-related diseases and further improve the availability of coral symbiotic fungi.

The coexistence of nanoplastics (NPs) and pollutants such as arsenic (As) has become an unignorable environmental problem. However, there is still a considerable knowledge gap about the impact of NPs and pollutants on human health risks. In this study, the human gastric adenocarcinoma (AGS) cells were used as a model to investigate the toxicity of NPs with different particle sizes and As by MTT assay, western blotting, immunofluorescence and so on. The results showed that 20 nm (8 μg/mL), 50 nm (128 μg/mL), 200 nm (128 μg/mL), 500 nm (128 μg/mL), 1000 nm (128 μg/mL) polystyrene (PS) did not affect cell viability, ROS, intracellular calcium and activate apoptosis pathway in AGS cells. However, noncytotoxic concentration of NPs enhanced the cytotoxicity and intracellular accumulation of As. NPs destroys the fluidity of cell membrane and cytoskeleton, inhibits the activity of ABC transporter, and leads to the accumulation of As in cells. This work highlights that the damage caused by NPs, especially at the level of noncytotoxicity, joint with As cannot be ignored and provides a specific toxicological mechanism of NPs accompanied by exposure to As.

Gelidium crinale, the red algae belonging to Geliaceae Gelidium, is a traditional edible and industrial alga in China. A sulfated polysaccharide (GNP) is successfully separated from Gelidium crinale by acid extraction and two-step column chromatography. Chemical analysis showed that the molecular weight of GNP was 25.8 kDa and the monosaccharide composition had the highest galactose content and confirmed the presence and content (16.5%) of sulfate by Fourier transform infrared spectroscopy (FT-IR) spectrometry as well as barium chloride-gelatin methods. In addition, the effect of GNP on lipopolysaccharide (LPS)-induced oxidative stress and inflammation in macrophages was also evaluated. The research results showed that GNP had fairly strong scavenging activities on 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical, hydroxyl radical, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and had Fe2+-chelating ability in a dose-dependent manner. At the same time, it significantly inhibits the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and the production of pro-inflammatory cytokines in RAW 264.7 cells induced by LPS through blocking the mitogen-activated protein kinase (MAPK)/nuclear factor kappa beta (NF-κB) signaling pathway. These results indicate that GNP may be a latent component anti-inflammation in pharmaceutical and functional food industries.

Introduction: A previous study has shown that Ala–Thr–Pro–Gly–Asp–Glu–Gly (ATPGDEG) peptide identified from boiled abalone by-products has high antioxidant activities and antihypertensive effect. Objective: In this study, we further investigated its antiphotoaging activities by ultraviolet B (UVB)-induced HaCaT cells. Result: UVB irradiation significantly increased the content of intercellular reactive oxygen species (ROS) and the production of matrix metalloproteinases (MMPs) in HaCaT cells and decreased its content of collagen. First, the generation of intercellular ROS was reduced by abalone peptide in UVB-induced HaCaT cells. And activities of MMP-1 and MMP-9 were reduced by abalone peptide in a dose-dependent manner. Furthermore, western blot analysis demonstrated that abalone peptide downregulated the expression of p38, c-Jun N-terminal kinases, and extracellular signal-regulated kinases via mitogen-activated protein kinases (MAPKs) and NF-κB signaling to protect type I pro collagen and DNA damage. Molecular docking simulation confirms that abalone peptide inhibited activities of MMP-1 and MMP-9 by docking their active site, among them N-terminal Ala, C-terminal Gly, and Pro at the third position of N-terminal made a great contribution. Conclusion and recommendation: Abalone peptide could protect type I procollagen synthesis in UVB-irradiated HaCaT cells, and it is a potential peptide for the treatment of skin photoaging in the future.

A new nanopore array/Au electrode was fabricated and applied to the detection of microRNA. The electrode was prepared via alternating current electrodeposition of Au nanowires in the nanopores of a porous anodic alumina membrane (without the need to remove aluminum or any barrier layer). The internal surface of the nanopores was then functionalized with an electrically neutral morpholino with a specially designed sequence. The resulting electrode shows excellent sensitivity and selectivity in detection of the target miRNA-155. The detection limit is 10 aM and the linear range 10 aM–1 nM in aqueous solution and the electrode can be reused in 6 M urea solution. In addition, it shows good linearity (100 aM–0.1 nM) in a serum sample. This new biosensor is expected to enhance miRNA detection in clinical diagnosis. Keywords: Nanopores, Label-free detection, microRNA, Porous anodic alumina

As one of the malignant tumors with high mortality, liver cancer has the characteristics of early invasion and metastasis, and lacks effective treatment methods. Therefore, it is urgent to find new safe, efficient and low-toxic anti-liver cancer drugs. In this study, the evaluated mechanism of Ecklonia cava polyphenols (7PE, 7-phloro-eckol) as a potential active substance for inhibiting liver cancer metastasis (HepG2 cell) and angiogenesis (HUVEC cell). The results have shown that 7PE can inhibit the expression of hypoxia-inducible factors (HIF-1α) protein by regulating the PI3K/AKT/mTOR and Ras/MEK/ERK/MNK signaling pathways under hypoxic conditions in HepG2 cells, thereby blocking the secretion of vascular growth factor (VEGF) protein. At the same time, 7PE can significantly inhibit the conduction of AKT and MAPK signaling pathways in HUVEC by suppressing the activation of VEGFR-2 protein, which verifies the prediction of molecular docking. Therefore, the results of this study provide a research basis for 7PE to inhibit metastasis and angiogenesis of liver cancer cells, and provide a theoretical basis for the high-value utilization of Ecklonia cava.

Sulfated polysaccharides from red algae have a variety of biological activities, especially antitumor activities. Matrix metalloproteinase-9 (MMP-9) is a proteolytic metalloenzyme that degrades the central part of the extracellular matrix (ECM) and promotes tumor metastasis. In this research, we have investigated the influence and mechanism of GNP (sulfated polysaccharide from Gelidium crinale) on tumor metastasis and MMP-9 expression of human fibrosarcoma (HT1080) cells. The results inflected that the concentration of GNP below 100 μg/mL has no toxicity to HT1080 cells, but showed excellent activity in inhibiting cells migration and invasion. In addition, GNP effectively inhibits the mRNA of MMP-9 and reduces its expression and activity by regulating nuclear factor-kappa B (NF-κB), mitogen-activated protein kinases (MAPK) and mTOR/PI3K/Akt signaling pathways. GNP has great potential as MMP-9 inhibitor and could be developed as a functional food or drug to prevent tumor metastasis.

Ultraviolet radiation B cause photoaging of the skin by enhancing the high expression of matrix metalloproteinases (MMPs) to degrade collagen and inhibit the synthesis of procollagen. Trehalose (TRE), a widely occurring natural disaccharide, has been shown to play a cytoprotective role in many pathological processes. However, few studies have evaluated whether it has anti-photoaging potential. In this study, we investigated the anti-photoaging and mechanism of action of TRE using Human immortalized keratinocytes (HaCaT) cells. The results indicated that TRE pretreatment effectively scavenges reactive oxygen species (ROS) accumulation induced by UVB and increases the content of certain endogenous antioxidant factors in HaCaT cells. TRE suppressed UVB-induced MMP expression by blocking mitogen-activated protein kinases (MAPKs), activator protein 1 (AP-1) and NF-κB signaling. TRE treatment increased procollagen I synthesis via activating transforming growth factor-β (TGF-β)/Smad pathway and demonstrated that TRE may be a potential natural disaccharide for photoaging therapy in the future.

Marine microalgae can be used as sustainable protein sources in many fields with positive effects on human and animal health. DAPTMGY is a heptapeptide isolated from Isochrysis zhanjiangensis which is a microalga. In this study, we evaluated its anti-photoaging properties and mechanism of action in human immortalized keratinocytes cells (HaCaT). The results showed that DAPTMGY scavenged reactive oxygen species (ROS) and increase the level of endogenous antioxidants. In addition, through the exploration of its mechanism, it was determined that DAPIMGY exerted anti-photoaging effects. Specifically, the heptapeptide inhibits UVB-induced apoptosis through down-regulation of p53, caspase-8, caspase-3 and Bax and up-regulation of Bcl-2. Thus, DAPTMGY, isolated from I. zhanjiangensis, exhibits protective effects against UVB-induced damage.

Abalone viscera (AV) is one of the byproducts of the seafood processing industry. The low molecular weight (Dermatophagoides farinae. The results demonstrated that the LMW-AV reduced a number of clinical symptoms, such as the severity of the dermatitis and serum immunoglobulin E levels. Moreover, LMW-AV could inhibit the expression of chemokines and cytokines. The histological analysis indicated that the LMW-AV has suppressed the eosinophil count and the mast cell infiltration into the upper dermis. The results suggest that LMW-AV can be considered as a promising candidate for AD treatment.

Seahorse is been used as a traditional Chinese medicine and invigorant for many years. Among, the seahorse is considered to have anti-fatigue effects. However, few researches have demonstrated such an effect. This study, the anti-fatigue effect of a novel peptide purified (SH200) from the seahorse (Hippocampus abdominalis) was investigated in C57BL/6 mice. The effect of SH200 on exercise performance was assessed using a Rotarod test and clinical biochemical parameters. In addition, the expression levels of muscular-associated proteins were examined by western blot and immunohistochemical analysis. The results revealed that SH200 prolonged the running time of mice, reduced the expression of creatine, CK, LDH, l-lactate, Citrate, and increased the production serum glucose and FFA, hepatic glycogen, ATP, and SDH. Addition, SH200 also improved mitochondrial function and protected muscle fibers via AMMPK/PGC-1α signal pathway. Thus, the SH200 is a potential candidate natural agent that could be used to reduce physical fatigue.

The liver is vulnerable to oxidative stress-induced damage, which leads to many diseases, including alcoholic liver disease (ALD). Liver disease endanger people’s health, and the incidence of ALD is increasing; therefore, prevention is very important. 7-phloro-eckol (7PE) is a seaweed polyphenol, which was isolated from Ecklonia cava in a previous study. In this study, the antioxidative stress effect of 7PE on HepG2/CYP2E1 cells was evaluated by alcohol-induced cytotoxicity, DNA damage, and expression of related inflammation and apoptosis proteins. The results showed that 7PE caused alcohol-induced cytotoxicity to abate, reduced the amount of reactive oxygen species (ROS) and nitric oxide (NO), and effectively inhibited DNA damage in HepG2/CYP2E1 cells. Additionally, the expression levels of glutathione (GSH), superoxide dismutase (SOD), B cell lymphoma 2 (Bcl-2), and Akt increased, while γ-glutamyltransferase (GGT), Bcl-2 related x (Bax), cleaved caspase-3, cleaved caspase-9, nuclear factor-κB (NF-κB), and JNK decreased. Finally, molecular docking proved that 7PE could bind to BCL-2 and GSH protein. These results indicate that 7PE can alleviate the alcohol-induced oxidative stress injury of HepG2 cells and that 7PE may have a potential application prospect in the future development of antioxidants.

Alcoholic liver disease (ALD) threatens human health, so it is imperative that we find ways to prevent or treat it. In recent years, the study of polysaccharides has shown that they have different kinds of bioactivities. Among them are many biological effects that have been attributed to polysaccharide precursors. D-Isofloridoside (DIF) is one of the polysaccharide precursors from the marine red alga Laurencia undulata. This study evaluated the effect of DIF on alcohol-induced oxidative stress in human hepatoma cells (HepG2). As a result, DIF attenuated alcohol-induced cytotoxicity, reduced the amount of intracellular reactive oxygen species (ROS), and effectively reduced alcohol-induced DNA damage in HepG2 cells. In addition, a western blot showed that, after DIF treatment, the expression levels of glutathione (GSH), superoxide dismutase (SOD), and B-cell lymphoma-2 (bcl-2) increased, while the expression levels of γ-glutamyl transferase (GGT), BCL2-associated X (bax), cleaved caspase-3, and mitogen-activated protein kinase (p38 and c-Jun N-terminal kinase) signal transduction proteins reduced. This showed that DIF may protect cells by reducing the amount of intracellular ROS and inhibiting intracellular oxidative stress and apoptotic processes. Finally, molecular docking demonstrated that DIF can bind to SOD, GGT, B-cell lymphoma-2, and bax proteins. These results indicated that DIF can protect HepG2 cells from alcohol-induced oxidative stress damage, making it an effective potential ingredient in functional foods.

Angiotensin II (Ang II) is closely involved in endothelial injury during the development of hypertension. In this study, the protective effects of the tilapia by-product oligopeptide Leu-Ser-Gly-Tyr-Gly-Pro (LSGYGP) on oxidative stress and endothelial injury in Angiotensin II (Ang II)-stimulated human umbilical vein endothelial cells (HUVEC) were evaluated. LSGYGP dose-dependently suppressed the fluorescence intensities of nitric oxide (NO) and reactive oxygen species (ROS), inhibited the nuclear factor-kappa B (NF-κB) pathway, and reduced inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and endothelin-1 (ET-1) expression, as shown by western blot. In addition, it attenuated the expression of gamma-glutamyltransferase (GGT) and heme oxygenase 1 (HO-1), as well as increasing superoxide dismutase (SOD) and glutathione (GSH) expression through the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Other experiments revealed that LSGYGP increased the apoptotic inhibition ratio between cleaved-caspase-3/procaspase-3, reduced expressions of pro-apoptotic ratio between Bcl-2/Bax, inhibited phosphorylation of mitogen-activated protein kinases (MAPK), and increased phosphorylation of the serine/threonine kinase (Akt) pathway. Furthermore, LSGYGP significantly decreased Ang II-induced DNA damage in a comet assay, and molecular docking results showed that the steady interaction between LSGYGP with NF-κB may be attributed to hydrogen bonds. These results suggest that this oligopeptide is effective in protecting against Ang II-induced HUVEC injury through the reduction of oxidative stress and alleviating endothelial damage. Thus, it has the potential for the therapeutic treatment of hypertension-associated diseases.

Vasculogenic mimicry (VM) formed by tumor cells plays a vital role in the progress of tumor, because it provides nutrition for tumor cells and takes away the metabolites. Therefore, the inhibition of VM is crucial to the clinical treatment of tumors. In this study, we investigated the anti-tumor effect of a novel peptide, KVEPQDPSEW (AATP), isolated from abalone (Haliotis discus hannai) on HT1080 cells by migration, invasion analysis and the mode of action. The results showed that AATP effectively inhibited MMPs by blocking MAPKs and NF-κB pathways, leading to the downregulation of metastasis of tumor cells. Moreover, AATP significantly inhibited VM and pro-angiogenic factors, including VEGF and MMPs by suppression of AKT/mTOR signaling. In addition, molecular docking was used to study the interaction of AATP and HIF-1α, and the results showed that AATP was combined with an active site of HIF-1α by a hydrogen bond. The effect of AATP on anti-metastatic and anti-vascular in HT1080 cells revealed that AATP may be a potential lead compound for treatment of tumors in the future.

Gliotoxin, a secondary metabolite produced by marine fungus Aspergillus sp., possesses various biological activities including anticancer activity. However, the mechanism underlying gliotoxin-induced cytotoxicity on human cervical cancer (Hela) and human chondrosarcoma (SW1353) cells remains unclear. In this study, we focused on the effect of gliotoxin induction on apoptosis, the activating expressions of caspase family enzymes in the cells. Apoptotic cell levels were measured through DAPI and Annexin V/Propidium Iodide (PI) double staining analysis. The apoptotic protein expression of Bcl-2 and caspase family was detected by Western blot in Hela and SW1353 cells. Our results showed that gliotoxin treatment inhibited cell proliferation and induced significant morphological changes. Gliotoxin induced apoptosis was further confirmed by DNA fragmentation, chromatin condensation and disrupted mitochondrial membrane potential. Gliotoxin-induced activation of caspase-3, caspase-8 and caspase-9, down-regulation of Bcl-2, up-regulation of Bax and cytochromec (cyt c) release showed evidence for the gliotoxin activity on apoptosis. These findings suggest that gliotoxin isolated from marine fungus Aspergillus sp. induced apoptosis in Hela and SW1353 cells via the mitochondrial pathway followed by downstream events leading to apoptotic mode of cell death.

Phosphorylated chitooligosaccharides (P-COS) were prepared using a H3PO4, P2O5, Et3PO4 and hexanol solvent system. The P-COS were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermo gravimetric-Differential Thermal Analyzer (TG-DTA), 13C NMR, 31P NMR, X-ray diffraction analysis, solubility studies, biocompatibility and Alkaline Phosphatase Activity (ALP). The results reveal that phosphorylation occurred at the C3 and C6 position of OH groups and the C2 position of NH2 group. FT-IR confirmed no decomposition in pyranose ring in P-COS even with heating and treatment in acidic conditions. The amorphous nature of P-COS was confirmed by X-ray diffraction analysis. Further, the biocompatibility and alkaline phosphatase activity of P-COS were checked against the osteosarcoma MG63 cell line at different concentrations and no cytotoxicity was observed. After 12 h and 24 h of incubation, the ALP activity of P-COS was higher compared with the control group. These results suggest that P-COS is a biocompatible material and in future P-COS could open up a number of promising pharmaceutical and clinical applications to mankind.

Butyrolactone-I (ZB5-1) from the coral-derived fungus Aspergillus terreus was investigated in this study to estimate its anti-neuroinflammatory effects on lipopolysaccharide (LPS)-induced BV-2 microglia cells. MTT assay indicated that ZB5-1 in tested concentrations had no cytotoxicity on BV-2 cells, and significantly reduced the production of nitric oxide (NO), measured using Griess reagent, and interleukin-1 beta (IL-1β), detected by enzyme-linked immunosorbent assay (ELISA). ZB5-1 also down-regulated the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose-dependent manner by Western blot analysis. Moreover, the effect of ZB5-1 on the nuclear factor-κB (NF-κB) signaling pathway was studied via the expression of phosphorylation of NF-κB p65 and inhibitor of NF-κB (IκB), and the nuclear translocation of NF-κB p65 respectively. The results showed that ZB5-1 could inhibit the phosphorylation of p65 and IκB. Furthermore, molecular docking study suggested that ZB5-1 bound at the active sites of NF-κB to prevent its translocation to the nucleus. Therefore, we suggest ZB5-1 has a potential to reduce the anti-inflammatory response in LPS-induced BV-2 cells.

In the present study, a peptide possessing antioxidant properties was isolated from Nile tilapia (Oreochromis niloticus) scale gelatin. Gelatin protein was hydrolyzed using alcalase, pronase E, trypsin and pepsin. Antioxidant efficacy of respective hydrolysates were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical and superoxide radical anion scavenging activities. Moreover, protective effect on DNA damage caused by hydroxyl radicals generated was determined. Further, the level of reactive oxygen species (ROS) was determined using a fluorescence probe, 2′,7′-dichlorofluorescin diacetate (DCFH-DA), which could be converted to highly fluorescent dichlorofluorescein (DCF) with the presence of intracellular ROS on mouse macrophages, RAW 264.7 cells. Among hydrolysates, alcalase-derived hydrolysate exhibited the highest antioxidant activity compared to other enzymatic hydrolysates. Therefore, it was further analyzed and the sequence of an active peptide present in it was identified as Asp-Pro-Ala-Leu-Ala-Thr-Glu-Pro-Asp-Pro-Met-Pro-Phe (1382.57 Da). This peptide showed no cytotoxic effect on mouse macrophages (RAW 264.7) and human lung fibroblasts (MRC-5). In addition, it scavenged hydroxyl, DPPH and superoxide radicals at the IC50 values of 7.56, 8.82 and 17.83 μM, respectively. These results suggest that the peptide derived from Nile tilapia (O. niloticus) scale gelatin acts as a candidate against oxidative stress and could be used as a potential functional food ingredient.