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1401 KiB

Open AccessArticle

Hydrolysates of Fish Skin Collagen: An Opportunity for Valorizing Fish Industry Byproducts

by María Blanco, José Antonio Vázquez, Ricardo I. Pérez-Martín and Carmen G. Sotelo

Mar. Drugs 2017, 15(5), 131; https://doi.org/10.3390/md15050131 - 5 May 2017

Cited by 119 | Viewed by 11748

Abstract

During fish processing operations, such as skinning and filleting, the removal of collagen-containing materials can account for up to 30% of the total fish byproducts. Collagen is the main structural protein in skin, representing up to 70% of dry weight depending on the [...] Read more.

During fish processing operations, such as skinning and filleting, the removal of collagen-containing materials can account for up to 30% of the total fish byproducts. Collagen is the main structural protein in skin, representing up to 70% of dry weight depending on the species, age and season. It has a wide range of applications including cosmetic, pharmaceutical, food industry, and medical. In the present work, collagen was obtained by pepsin extraction from the skin of two species of teleost and two species of chondrychtyes with yields varying between 14.16% and 61.17%. The storage conditions of the skins appear to influence these collagen extractions yields. Pepsin soluble collagen (PSC) was enzymatically hydrolyzed and the resultant hydrolysates were ultrafiltrated and characterized. Electrophoretic patterns showed the typical composition of type I collagen, with denaturation temperatures ranged between 23 °C and 33 °C. In terms of antioxidant capacity, results revealed significant intraspecific differences between hydrolysates, retentate, and permeate fractions when using β-Carotene and DPPH methods and also showed interspecies differences between those fractions when using DPPH and ABTS methods. Under controlled conditions, PSC hydrolysates from Prionace glauca, Scyliorhinus canicula, Xiphias gladius, and Thunnus albacares provide a valuable source of peptides with antioxidant capacities constituting a feasible way to efficiently upgrade fish skin biomass. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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1529 KiB

Open AccessArticle

In Vitro Antioxidant Activities of Enzymatic Hydrolysate from Schizochytrium sp. and Its Hepatoprotective Effects on Acute Alcohol-Induced Liver Injury In Vivo

by Xixi Cai, Ana Yan, Nanyan Fu and Shaoyun Wang

Mar. Drugs 2017, 15(4), 115; https://doi.org/10.3390/md15040115 - 10 Apr 2017

Cited by 37 | Viewed by 5406

Abstract

Schizochytrium protein hydrolysate (SPH) was prepared through stepwise enzymatic hydrolysis by alcalase and flavourzyme sequentially. The proportion of hydrophobic amino acids of SPH was 34.71%. The molecular weight (MW) of SPH was principally concentrated at 180–3000 Da (52.29%). SPH was divided into two [...] Read more.

Schizochytrium protein hydrolysate (SPH) was prepared through stepwise enzymatic hydrolysis by alcalase and flavourzyme sequentially. The proportion of hydrophobic amino acids of SPH was 34.71%. The molecular weight (MW) of SPH was principally concentrated at 180–3000 Da (52.29%). SPH was divided into two fractions by ultrafiltration: SPH-I (MW < 3 kDa) and SPH-II (MW > 3 kDa). Besides showing lipid peroxidation inhibitory activity in vitro, SPH-I exhibited high DPPH and ABTS radicals scavenging activities with IC₅₀ of 350 μg/mL and 17.5 μg/mL, respectively. In addition, the antioxidant activity of SPH-I was estimated in vivo using the model of acute alcohol-induced liver injury in mice. For the hepatoprotective effects, oral administration of SPH-I at different concentrations (100, 300 mg/kg BW) to the mice subjected to alcohol significantly decreased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and hepatic malondialdehyde (MDA) level compared to the untreated mice. Besides, SPH-I could effectively restore the hepatic superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities and glutathione (GSH) level. Results suggested that SPH was rich in biopeptides that could be exploited as antioxidant molecules against oxidative stress in human body. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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2034 KiB

Open AccessArticle

Purification and Identification of Antioxidant Peptides from Protein Hydrolysate of Scalloped Hammerhead (Sphyrna lewini) Cartilage

by Xue-Rong Li, Chang-Feng Chi, Li Li and Bin Wang

Mar. Drugs 2017, 15(3), 61; https://doi.org/10.3390/md15030061 - 1 Mar 2017

Cited by 58 | Viewed by 6524

Abstract

The aim of this study was to purify and identify peptides with antioxidant properties from protein hydrolysate of scalloped hammerhead (Sphyrna lewini) cartilage. Cartilaginous proteins of the scalloped hammerhead were extracted by guanidine hydrochloride, and three antioxidant peptides, named enzymolysis peptide [...] Read more.

The aim of this study was to purify and identify peptides with antioxidant properties from protein hydrolysate of scalloped hammerhead (Sphyrna lewini) cartilage. Cartilaginous proteins of the scalloped hammerhead were extracted by guanidine hydrochloride, and three antioxidant peptides, named enzymolysis peptide of scalloped hammerhead cartilage A (SCPE-A), SCPE-B and SCPE-C, were subsequently isolated from the hydrolysate of the cartilaginous proteins using ultrafiltration and chromatography. The amino acid sequences of SCPE-A, SCPE-B and SCPE-C were identified as Gly-Pro-Glu (GPE), Gly-Ala-Arg-Gly-Pro-Gln (GARGPQ), and Gly-Phe-Thr-Gly-Pro-Pro-Gly-Phe-Asn-Gly (GFTGPPGFNG), with molecular weights of 301.30 Da, 584.64 Da and 950.03 Da, respectively. As per in vitro activity testing, SCPE-A, SCPE-B and SCPE-C exhibited strong scavenging activities on 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH•) (half elimination ratio (EC₅₀) 2.43, 2.66 and 1.99 mg/mL), hydroxyl radicals (HO•) (EC₅₀ 0.28, 0.21 and 0.15 mg/mL), 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radicals (ABTS⁺•) (EC₅₀ 0.24, 0.18 and 0.29 mg/mL), and superoxide anion radicals (

O_{2}^{-}

•) (EC₅₀ 0.10, 0.14 and 0.11 mg/mL). In addition, SCPE-A showed inhibition activity similar to butylated hydroxytoluene (BHT) in lipid peroxidation in a linoleic acid model system. The amino acid residues of Gly, Pro and Phe could positively influence the antioxidant activities of GPE, GARGPQ and GFTGPPGFNG. These results suggested that GPE, GARGPQ and GFTGPPGFNG might serve as potential antioxidants and be used as food additives and functional foods. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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4807 KiB

Open AccessArticle

Preparation of Antioxidant Peptides from Salmon Byproducts with Bacterial Extracellular Proteases

by Ribang Wu, Leilei Chen, Dan Liu, Jiafeng Huang, Jiang Zhang, Xiao Xiao, Ming Lei, Yuelin Chen and Hailun He

Mar. Drugs 2017, 15(1), 4; https://doi.org/10.3390/md15010004 - 11 Jan 2017

Cited by 42 | Viewed by 7099

Abstract

Bacterial extracellular proteases from six strains of marine bacteria and seven strains of terrestrial bacteria were prepared through fermentation. Proteases were analyzed through substrate immersing zymography and used to hydrolyze the collagen and muscle proteins from a salmon skin byproduct, respectively. Collagen could [...] Read more.

Bacterial extracellular proteases from six strains of marine bacteria and seven strains of terrestrial bacteria were prepared through fermentation. Proteases were analyzed through substrate immersing zymography and used to hydrolyze the collagen and muscle proteins from a salmon skin byproduct, respectively. Collagen could be degraded much more easily than muscle protein, but it commonly showed weaker antioxidant capability. The hydrolysate of muscle proteins was prepared with crude enzymes from Pseudoalteromonas sp. SQN1 displayed the strongest activity of antioxidant in DPPH and hydroxyl radical scavenging assays (74.06% ± 1.14% and 69.71% ± 1.97%), but did not perform well in Fe²⁺ chelating assay. The antioxidant fractions were purified through ultrafiltration, cation exchange chromatography, and size exclusion chromatography gradually, and the final purified fraction U2-S2-I displayed strong activity of antioxidant in DPPH, hydroxyl radical scavenging assays (IC₅₀ = 0.263 ± 0.018 mg/mL and 0.512 ± 0.055 mg/mL), and oxygen radical absorption capability assay (1.960 ± 0.381 mmol·TE/g). The final purified fraction U2-S2-I possessed the capability to protect plasmid DNA against the damage of hydroxyl radical and its effect was similar to that of the original hydrolysis product. It indicated that U2-S2-I might be the major active fraction of the hydrolysate. This study proved that bacterial extracellular proteases could be utilized in hydrolysis of a salmon byproduct. Compared with collagen, muscle proteins was an ideal material used as an enzymatic substrate to prepare antioxidant peptides. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessArticle

Biochemical and Structural Insights into a Novel Thermostable β-1,3-Galactosidase from Marinomonas sp. BSi20414

by Haitao Ding, Qian Zeng, Lili Zhou, Yong Yu and Bo Chen

Mar. Drugs 2017, 15(1), 13; https://doi.org/10.3390/md15010013 - 8 Jan 2017

Cited by 21 | Viewed by 5744

Abstract

A novel β-1,3-galactosidase, designated as MaBGA (β-galactosidase from Marinomonas sp. BSi20414), was successfully purified to homogeneity from Marinomonas sp. BSi20414 isolated from Arctic sea ice by ammonium sulfate precipitation and anion exchange chromatography, resulting in an 8.12-fold increase in specific activity and 9.9% [...] Read more.

A novel β-1,3-galactosidase, designated as MaBGA (β-galactosidase from Marinomonas sp. BSi20414), was successfully purified to homogeneity from Marinomonas sp. BSi20414 isolated from Arctic sea ice by ammonium sulfate precipitation and anion exchange chromatography, resulting in an 8.12-fold increase in specific activity and 9.9% recovery in total activity. MaBGA displayed its maximum activity at pH 6.0 and 60 °C, and maintained at least 90% of its initial activity over the pH range of 5.0–8.0 after incubating for 1 h. It also exhibited considerable thermal stability, which retained 76% of its initial activity after incubating at 50 °C for 6 h. In contrast to other β-galactosidases, MaBGA displayed strict substrate specificity, not only for the glycosyl group, but also for the linkage type. To better understand the structure–function relationship, the encoding gene of MaBGA was obtained and subject to bioinformatics analysis. Multiple alignments and phylogenetic analysis revealed that MaBGA belonged to the glycoside hydrolase family 42 and had closer genetic relationships with thermophilic β-galactosidases of extremophiles. With the aid of homology modeling and molecular docking, we proposed a reasonable explanation for the linkage selectivity of MaBGA from a structural perspective. On account of the robust stability and 1,3-linkage selectivity, MaBGA would be a promising candidate in the biosynthesis of galacto-oligosaccharide with β1–3 linkage. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessArticle

In vitro Anti-Thrombotic Activity of Extracts from Blacklip Abalone (Haliotis rubra) Processing Waste

by Hafiz Ansar Rasul Suleria, Barney M. Hines, Rama Addepalli, Wei Chen, Paul Masci, Glenda Gobe and Simone A. Osborne

Mar. Drugs 2017, 15(1), 8; https://doi.org/10.3390/md15010008 - 31 Dec 2016

Cited by 10 | Viewed by 7147

Abstract

Waste generated from the processing of marine organisms for food represents an underutilized resource that has the potential to provide bioactive molecules with pharmaceutical applications. Some of these molecules have known anti-thrombotic and anti-coagulant activities and are being investigated as alternatives to common [...] Read more.

Waste generated from the processing of marine organisms for food represents an underutilized resource that has the potential to provide bioactive molecules with pharmaceutical applications. Some of these molecules have known anti-thrombotic and anti-coagulant activities and are being investigated as alternatives to common anti-thrombotic drugs, like heparin and warfarin that have serious side effects. In the current study, extracts prepared from blacklip abalone (Haliotis rubra) processing waste, using food grade enzymes papain and bromelain, were found to contain sulphated polysaccharide with anti-thrombotic activity. Extracts were found to be enriched with sulphated polysaccharides and assessed for anti-thrombotic activity in vitro through heparin cofactor-II (HCII)-mediated inhibition of thrombin. More than 60% thrombin inhibition was observed in response to 100 μg/mL sulphated polysaccharides. Anti-thrombotic potential was further assessed as anti-coagulant activity in plasma and blood, using prothrombin time (PT), activated partial thromboplastin time (aPTT), and thromboelastography (TEG). All abalone extracts had significant activity compared with saline control. Anion exchange chromatography was used to separate extracts into fractions with enhanced anti-thrombotic activity, improving HCII-mediated thrombin inhibition, PT and aPTT almost 2-fold. Overall this study identifies an alternative source of anti-thrombotic molecules that can be easily processed offering alternatives to current anti-thrombotic agents like heparin. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessArticle

Novel Peptide with Specific Calcium-Binding Capacity from Schizochytrium sp. Protein Hydrolysates and Calcium Bioavailability in Caco-2 Cells

by Xixi Cai, Jiaping Lin and Shaoyun Wang

Mar. Drugs 2017, 15(1), 3; https://doi.org/10.3390/md15010003 - 27 Dec 2016

Cited by 59 | Viewed by 7844

Abstract

Peptide-calcium can probably be a suitable supplement to improve calcium absorption in the human body. In this study, a specific peptide Phe-Tyr (FY) with calcium-binding capacity was purified from Schizochytrium sp. protein hydrolysates through gel filtration chromatography and reversed phase HPLC. The calcium-binding [...] Read more.

Peptide-calcium can probably be a suitable supplement to improve calcium absorption in the human body. In this study, a specific peptide Phe-Tyr (FY) with calcium-binding capacity was purified from Schizochytrium sp. protein hydrolysates through gel filtration chromatography and reversed phase HPLC. The calcium-binding capacity of FY reached 128.77 ± 2.57 μg/mg. Results of ultraviolet spectroscopy, fluorescence spectroscopy, and infrared spectroscopy showed that carboxyl groups, amino groups, and amido groups were the major chelating sites. FY-Ca exhibited excellent thermal stability and solubility, which were beneficial to be absorbed and transported in the basic intestinal tract of the human body. Moreover, the calcium bioavailability in Caco-2 cells showed that FY-Ca could enhance calcium uptake efficiency by more than three times when compared with CaCl₂, and protect calcium ions against dietary inhibitors, such as tannic acid, oxalate, phytate, and Zn²⁺. Our findings further the progress of algae-based peptide-calcium, suggesting that FY-Ca has the potential to be developed as functionally nutraceutical additives. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessArticle

Protective Effects of Hydrolyzed Nucleoproteins from Salmon Milt against Ethanol-Induced Liver Injury in Rats

by Akiko Kojima-Yuasa, Mayu Goto, Eri Yoshikawa, Yuri Morita, Hirotaka Sekiguchi, Keita Sutoh, Koji Usumi and Isao Matsui-Yuasa

Mar. Drugs 2016, 14(12), 232; https://doi.org/10.3390/md14120232 - 19 Dec 2016

Cited by 24 | Viewed by 7234

Abstract

Dietary nucleotides play a role in maintaining the immune responses of both animals and humans. Oral administration of nucleic acids from salmon milt have physiological functions in the cellular metabolism, proliferation, differentiation, and apoptosis of human small intestinal epithelial cells. In this study, [...] Read more.

Dietary nucleotides play a role in maintaining the immune responses of both animals and humans. Oral administration of nucleic acids from salmon milt have physiological functions in the cellular metabolism, proliferation, differentiation, and apoptosis of human small intestinal epithelial cells. In this study, we examined the effects of DNA-rich nucleic acids prepared from salmon milt (DNSM) on the development of liver fibrosis in an in vivo ethanol-carbon tetrachloride cirrhosis model. Plasma aspartate transaminase and alanine transaminase were significantly less active in the DNSM-treated group than in the ethanol plus carbon tetrachloride (CCl₄)-treated group. Collagen accumulation in the liver and hepatic necrosis were observed histologically in ethanol plus CCl₄-treated rats; however, DNSM-treatment fully protected rats against ethanol plus CCl₄-induced liver fibrosis and necrosis. Furthermore, we examined whether DNSM had a preventive effect against alcohol-induced liver injury by regulating the cytochrome p450 2E1 (CYP2E1)-mediated oxidative stress pathway in an in vivo model. In this model, CYP2E1 activity in ethanol plus CCl₄-treated rats increased significantly, but DNSM-treatment suppressed the enzyme’s activity and reduced intracellular thiobarbituric acid reactive substances (TBARS) levels. Furthermore, the hepatocytes treated with 100 mM ethanol induced an increase in cell death and were not restored to the control levels when treated with DNSM, suggesting that digestive products of DNSM are effective for the prevention of alcohol-induced liver injury. Deoxyadenosine suppressed the ethanol-induced increase in cell death and increased the activity of alcohol dehydrogenase. These results suggest that DNSM treatment represents a novel tool for the prevention of alcohol-induced liver injury. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessArticle

Antimicrobial and Antitumor Activities of Novel Peptides Derived from the Lipopolysaccharide- and β-1,3-Glucan Binding Protein of the Pacific Abalone Haliotis discus hannai

by Bo-Hye Nam, Ji Young Moon, Eun Hee Park, Hee Jeong Kong, Young-Ok Kim, Dong-Gyun Kim, Woo-Jin Kim, Chul Min An and Jung-Kil Seo

Mar. Drugs 2016, 14(12), 227; https://doi.org/10.3390/md14120227 - 14 Dec 2016

Cited by 12 | Viewed by 6479

Abstract

Antimicrobial peptides are a pivotal component of the invertebrate innate immune system. In this study, we identified a lipopolysaccharide- and β-1,3-glucan-binding protein (LGBP) gene from the pacific abalone Haliotis discus hannai (HDH), which is involved in the pattern recognition mechanism and plays avital [...] Read more.

Antimicrobial peptides are a pivotal component of the invertebrate innate immune system. In this study, we identified a lipopolysaccharide- and β-1,3-glucan-binding protein (LGBP) gene from the pacific abalone Haliotis discus hannai (HDH), which is involved in the pattern recognition mechanism and plays avital role in the defense mechanism of invertebrates immune system. The HDH-LGBP cDNA consisted of a 1263-bp open reading frame (ORF) encoding a polypeptide of 420 amino acids, with a 20-amino-acid signal sequence. The molecular mass of the protein portion was 45.5 kDa, and the predicted isoelectric point of the mature protein was 4.93. Characteristic potential polysaccharide binding motif, glucanase motif, and β-glucan recognition motif were identified in the LGBP of HDH. We used its polysaccharide-binding motif sequence to design two novel antimicrobial peptide analogs (HDH-LGBP-A1 and HDH-LGBP-A2). By substituting a positively charged amino acid and amidation at the C-terminus, the pI and net charge of the HDH-LGBP increased, and the proteins formed an α-helical structure. The HDH-LGBP analogs exhibited antibacterial and antifungal activity, with minimal effective concentrations ranging from 0.008 to 2.2 μg/mL. Additionally, both were toxic against human cervix (HeLa), lung (A549), and colon (HCT 116) carcinoma cell lines but not much on human umbilical vein cell (HUVEC). Fluorescence-activated cell sorter (FACS) analysis showed that HDH-LGBP analogs disturb the cancer cell membrane and cause apoptotic cell death. These results suggest the use of HDH-LGBP analogs as multifunctional drugs. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessArticle

Anti-Fatigue Effect by Peptide Fraction from Protein Hydrolysate of Croceine Croaker (Pseudosciaena crocea) Swim Bladder through Inhibiting the Oxidative Reactions including DNA Damage

by Yu-Qin Zhao, Li Zeng, Zui-Su Yang, Fang-Fang Huang, Guo-Fang Ding and Bin Wang

Mar. Drugs 2016, 14(12), 221; https://doi.org/10.3390/md14120221 - 13 Dec 2016

Cited by 73 | Viewed by 7907

Abstract

The swim bladder of the croceine croaker (Pseudosciaena crocea) was believed to have good curative effects in various diseases, including amnesia, insomnia, dizziness, anepithymia, and weakness after giving birth, in traditional Chinese medicine. However, there is no research focusing on the [...] Read more.

The swim bladder of the croceine croaker (Pseudosciaena crocea) was believed to have good curative effects in various diseases, including amnesia, insomnia, dizziness, anepithymia, and weakness after giving birth, in traditional Chinese medicine. However, there is no research focusing on the antioxidant and anti-fatigue peptides from croceine croaker swim bladders at present. Therefore, the purpose of this study was to investigate the bioactivities of peptide fractions from the protein hydrolysate of croceine croaker related to antioxidant and anti-fatigue effects. In the study, swim bladder peptide fraction (SBP-III-3) was isolated from the protein hydrolysate of the croceine croaker, and its antioxidant and anti-fatigue activities were measured using in vitro and in vivo methods. The results indicated that SBP-III-3 exhibited good scavenging activities on hydroxyl radicals (HO•) (EC₅₀ (the concentration where a sample caused a 50% decrease of the initial concentration of HO•) = 0.867 mg/mL), 2,2-diphenyl-1-picrylhydrazyl radicals (DPPH•) (EC₅₀ = 0.895 mg/mL), superoxide anion radical (

O_{2}^{-}

•) (EC₅₀ = 0.871 mg/mL), and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical (ABTS⁺•) (EC₅₀ = 0.346 mg/mL). SBP-III-3 also showed protective effects on DNA damage in a concentration-effect manner and prolonged the swimming time to exhaustion of Institute of Cancer Research (ICR) mice by 57.9%–107.5% greater than that of the control. SBP-III-3 could increase the levels of muscle glucose (9.4%–115.2% increase) and liver glycogen (35.7%–157.3%), and decrease the levels of blood urea nitrogen (BUN), lactic acid (LA), and malondialdehyde (MDA) by 16.4%–22.4%, 13.9%–20.1%, and 28.0%–53.6%, respectively. SBP-III-3 also enhanced the activity of lactic dehydrogenase to scavenge excessive LA for slowing the development of fatigue. In addition, SBP-III-3 increased the activities superoxide dismutase, catalase, and glutathione peroxidase to reduce the reactive oxygen species (ROS) damage in mice. In conclusion, SBP-III-3 possessed good anti-fatigue capacities on mice by inhibiting the oxidative reactions and provided an important basis for developing the swim bladder peptide functional food. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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868 KiB

Open AccessArticle

Enzymatic Pre-Treatment Increases the Protein Bioaccessibility and Extractability in Dulse (Palmaria palmata)

by Hanne K. Mæhre, Ida-Johanne Jensen and Karl-Erik Eilertsen

Mar. Drugs 2016, 14(11), 196; https://doi.org/10.3390/md14110196 - 26 Oct 2016

Cited by 69 | Viewed by 7813

Abstract

Several common protein extraction protocols have been applied on seaweeds, but extraction yields have been limited. The aims of this study were to further develop and optimize existing extraction protocols and to examine the effect of enzymatic pre-treatment on bioaccessibility and extractability of [...] Read more.

Several common protein extraction protocols have been applied on seaweeds, but extraction yields have been limited. The aims of this study were to further develop and optimize existing extraction protocols and to examine the effect of enzymatic pre-treatment on bioaccessibility and extractability of seaweed proteins. Enzymatic pre-treatment of seaweed samples resulted in a three-fold increase in amino acids available for extraction. Combining enzymatic pre-treatment with alkaline extraction resulted in a 1.6-fold increase in the protein extraction yield compared to a standard alkaline extraction protocol. A simulated in vitro gastrointestinal digestion model showed that enzymatic pre-treatment of seaweed increased the amount of amino acids available for intestinal absorption 3.2-fold. In conclusion, enzymatic pre-treatment of seaweeds is effective for increasing the amount of amino acids available for utilization and may thus be an effective means for increasing the utilization potential of seaweed proteins. However, both the enzymatic pre-treatment protocol and the protein extraction protocol need further optimization in order to obtain optimal cost-benefit and results from the in vitro gastrointestinal digestion model need to be confirmed in clinical models. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessArticle

Purification of Antioxidant Peptides by High Resolution Mass Spectrometry from Simulated Gastrointestinal Digestion Hydrolysates of Alaska Pollock (Theragra chalcogramma) Skin Collagen

by Liping Sun, Weidan Chang, Qingyu Ma and Yongliang Zhuang

Mar. Drugs 2016, 14(10), 186; https://doi.org/10.3390/md14100186 - 17 Oct 2016

Cited by 43 | Viewed by 7834

Abstract

In this study, the stable collagen hydrolysate was prepared by alcalase hydrolysis and twice simulated gastrointestinal digestion from Alaska pollock skin. The characteristics of hydrolysates and antioxidant activities in vitro, including 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS^•+) scavenging activity, ferric-reducing antioxidant power [...] Read more.

In this study, the stable collagen hydrolysate was prepared by alcalase hydrolysis and twice simulated gastrointestinal digestion from Alaska pollock skin. The characteristics of hydrolysates and antioxidant activities in vitro, including 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS^•+) scavenging activity, ferric-reducing antioxidant power (FRAP) and hydroxyl radical (OH·) scavenging activity, were determined. After twice simulated gastrointestinal digestion of skin collagen (SGI-2), the degree of hydrolysis (DH) reached 26.17%. The main molecular weight fractions of SGI-2 were 1026.26 and 640.53 Da, accounting for 59.49% and 18.34%, respectively. Amino acid composition analysis showed that SGI-2 had high content of total hydrophobic amino acid (307.98/1000). With the simulated gastrointestinal digestion progressing, the antioxidant activities increased significantly (p < 0.05). SGI-2 was further purified by gel filtration chromatography, ion exchange chromatography and high performance liquid chromatography, and the A_1a3c–p fraction with high hydroxyl radical scavenging activity (IC50 = 7.63 μg/mL) was obtained. The molecular weights and amino acid sequences of key peptides of A_1a3c–p were analyzed using high resolution mass spectrometry (LC-ESI-LTQ-Orbitrap-MS) combined with de novo software and UniProt of MaxQuant software. Four peptides were identified from A_1a3c–p, including YGCC (444.1137 Da) and DSSCSG (554.1642 Da) identified by de novo software and NNAEYYK (900.3978 Da) and PAGNVR (612.3344 Da) identified by UniProt of MaxQuant software. The molecular weights and amino acid sequences of four peptides were in accordance with the features of antioxidant peptides. The results indicated that different peptides were identified by different data analysis software according to spectrometry mass data. Considering the complexity of LC-ESI-LTQ-Orbitrap-MS, it was necessary to use the different methods to identify the key peptides from protein hydrolysates. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessArticle

Anticancer Activity of a Hexapeptide from Skate (Raja porosa) Cartilage Protein Hydrolysate in HeLa Cells

by Xin Pan, Yu-Qin Zhao, Fa-Yuan Hu, Chang-Feng Chi and Bin Wang

Mar. Drugs 2016, 14(8), 153; https://doi.org/10.3390/md14080153 - 16 Aug 2016

Cited by 73 | Viewed by 7638

Abstract

In this study, the hexapeptide Phe-Ile-Met-Gly-Pro-Tyr (FIMGPY), which has a molecular weight of 726.9 Da, was separated from skate (Raja porosa) cartilage protein hydrolysate using ultrafiltration and chromatographic methods, and its anticancer activity was evaluated in HeLa cells. Methylthiazolyldiphenyl-tetrazolium bromide (MTT) [...] Read more.

In this study, the hexapeptide Phe-Ile-Met-Gly-Pro-Tyr (FIMGPY), which has a molecular weight of 726.9 Da, was separated from skate (Raja porosa) cartilage protein hydrolysate using ultrafiltration and chromatographic methods, and its anticancer activity was evaluated in HeLa cells. Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay indicated that FIMGPY exhibited high, dose-dependent anti-proliferation activities in HeLa cells with an IC₅₀ of 4.81 mg/mL. Acridine orange/ethidium bromide (AO/EB) fluorescence staining and flow cytometry methods confirmed that FIMGPY could inhibit HeLa cell proliferation by inducing apoptosis. Western blot assay revealed that the Bax/Bcl-2 ratio and relative intensity of caspase-3 in HeLa cells treated with 7-mg/mL FIMGPY were 2.63 and 1.83, respectively, significantly higher than those of the blank control (p < 0.01). Thus, FIMGPY could induce apoptosis by upregulating the Bax/Bcl-2 ratio and caspase-3 activation. Using a DNA ladder method further confirmed that the anti-proliferation activity of FIMGPY was attributable to its role in inducing apoptosis. These results suggest that FIMGPY from skate cartilage protein hydrolysate may have applications as functional foods and nutraceuticals for the treatment and prevention of cancer. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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10169 KiB

Open AccessArticle

Recombinant Expression of a Modified Shrimp Anti-Lipopolysaccharide Factor Gene in Pichia pastoris GS115 and Its Characteristic Analysis

by Hui Yang, Shihao Li, Fuhua Li, Kuijie Yu, Fusheng Yang and Jianhai Xiang

Mar. Drugs 2016, 14(8), 152; https://doi.org/10.3390/md14080152 - 9 Aug 2016

Cited by 27 | Viewed by 8025

Abstract

Anti-lipopolysaccharide factors (ALFs) with a LPS-binding domain (LBD) are considered to have broad spectrum antimicrobial activities and certain antiviral properties in crustaceans. FcALF2 was one isoform of ALFs isolated from the Chinese shrimp Fenneropenaeus chinensis. Our previous study showed that a modified [...] Read more.

Anti-lipopolysaccharide factors (ALFs) with a LPS-binding domain (LBD) are considered to have broad spectrum antimicrobial activities and certain antiviral properties in crustaceans. FcALF2 was one isoform of ALFs isolated from the Chinese shrimp Fenneropenaeus chinensis. Our previous study showed that a modified LBD domain (named LBDv) of FcALF2 exhibited a highly enhanced antimicrobial activity. In the present study, a modified FcALF2 gene (mFcALF2), in which the LBD was substituted by LBDv, was designed and synthesized. This gene was successfully expressed in yeast Pichia pastoris GS115 eukaryotic expression system, and the characteristics of the recombinant protein mFcALF2 were analyzed. mFcALF2 exhibited apparent antibacterial activities against Gram-negative bacteria, including Escherichia coli, Vibrio alginolyticus, Vibrio harveyi, and Vibrio parahaemolyticus, and Gram-positive bacteria, including Bacillus licheniformis and Staphylococcus epidermidis. In addition, mFcALF2 could reduce the propagation of white spot syndrome virus (WSSV) in vivo by pre-incubation with virus. The present study paves the way for developing antimicrobial drugs in aquaculture. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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2255 KiB

Open AccessArticle

Identification of Angiotensin I-Converting Enzyme Inhibitory Peptides Derived from Enzymatic Hydrolysates of Razor Clam Sinonovacula constricta

by Yun Li, Faizan A. Sadiq, Li Fu, Hui Zhu, Minghua Zhong and Muhammad Sohail

Mar. Drugs 2016, 14(6), 110; https://doi.org/10.3390/md14060110 - 3 Jun 2016

Cited by 28 | Viewed by 7332

Abstract

Angiotensin I-converting enzyme (ACE) inhibitory activity of razor clam hydrolysates produced using five proteases, namely, pepsin, trypsin, alcalase, flavourzyme and proteases from Actinomucor elegans T3 was investigated. Flavourzyme hydrolysate showed the highest level of degree of hydrolysis (DH) (45.87%) followed by A. elegans [...] Read more.

Angiotensin I-converting enzyme (ACE) inhibitory activity of razor clam hydrolysates produced using five proteases, namely, pepsin, trypsin, alcalase, flavourzyme and proteases from Actinomucor elegans T3 was investigated. Flavourzyme hydrolysate showed the highest level of degree of hydrolysis (DH) (45.87%) followed by A. elegans T3 proteases hydrolysate (37.84%) and alcalase (30.55%). The A. elegans T3 proteases was observed to be more effective in generating small peptides with ACE-inhibitory activity. The 3 kDa membrane permeate of A. elegans T3 proteases hydrolysate showed the highest ACE-inhibitory activity with an IC₅₀ of 0.79 mg/mL. After chromatographic separation by Sephadex G-15 gel filtration and reverse phase-high performance liquid chromatography, the potent fraction was subjected to MALDI/TOF-TOF MS/MS for identification. A novel ACE-inhibitory peptide (VQY) was identified exhibiting an IC₅₀ of 9.8 μM. The inhibitory kinetics investigation by Lineweaver-Burk plots demonstrated that the peptide acts as a competitive ACE inhibitor. The razor clam hydrolysate obtained by A. elegans T3 proteases could serve as a source of functional peptides with ACE-inhibitory activity for physiological benefits. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessArticle

Coral Carbonic Anhydrases: Regulation by Ocean Acidification

by Didier Zoccola, Alessio Innocenti, Anthony Bertucci, Eric Tambutté, Claudiu T. Supuran and Sylvie Tambutté

Mar. Drugs 2016, 14(6), 109; https://doi.org/10.3390/md14060109 - 3 Jun 2016

Cited by 37 | Viewed by 10090

Abstract

Global change is a major threat to the oceans, as it implies temperature increase and acidification. Ocean acidification (OA) involving decreasing pH and changes in seawater carbonate chemistry challenges the capacity of corals to form their skeletons. Despite the large number of studies [...] Read more.

Global change is a major threat to the oceans, as it implies temperature increase and acidification. Ocean acidification (OA) involving decreasing pH and changes in seawater carbonate chemistry challenges the capacity of corals to form their skeletons. Despite the large number of studies that have investigated how rates of calcification respond to ocean acidification scenarios, comparatively few studies tackle how ocean acidification impacts the physiological mechanisms that drive calcification itself. The aim of our paper was to determine how the carbonic anhydrases, which play a major role in calcification, are potentially regulated by ocean acidification. For this we measured the effect of pH on enzyme activity of two carbonic anhydrase isoforms that have been previously characterized in the scleractinian coral Stylophora pistillata. In addition we looked at gene expression of these enzymes in vivo. For both isoforms, our results show (1) a change in gene expression under OA (2) an effect of OA and temperature on carbonic anhydrase activity. We suggest that temperature increase could counterbalance the effect of OA on enzyme activity. Finally we point out that caution must, thus, be taken when interpreting transcriptomic data on carbonic anhydrases in ocean acidification and temperature stress experiments, as the effect of these stressors on the physiological function of CA will depend both on gene expression and enzyme activity. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Review

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Open AccessReview

Microbial Diseases of Bivalve Mollusks: Infections, Immunology and Antimicrobial Defense

by Carla Zannella, Francesco Mosca, Francesca Mariani, Gianluigi Franci, Veronica Folliero, Marilena Galdiero, Pietro Giorgio Tiscar and Massimiliano Galdiero

Mar. Drugs 2017, 15(6), 182; https://doi.org/10.3390/md15060182 - 17 Jun 2017

Cited by 139 | Viewed by 13995

Abstract

A variety of bivalve mollusks (phylum Mollusca, class Bivalvia) constitute a prominent commodity in fisheries and aquacultures, but are also crucial in order to preserve our ecosystem’s complexity and function. Bivalve mollusks, such as clams, mussels, oysters and scallops, are relevant bred species, [...] Read more.

A variety of bivalve mollusks (phylum Mollusca, class Bivalvia) constitute a prominent commodity in fisheries and aquacultures, but are also crucial in order to preserve our ecosystem’s complexity and function. Bivalve mollusks, such as clams, mussels, oysters and scallops, are relevant bred species, and their global farming maintains a high incremental annual growth rate, representing a considerable proportion of the overall fishery activities. Bivalve mollusks are filter feeders; therefore by filtering a great quantity of water, they may bioaccumulate in their tissues a high number of microorganisms that can be considered infectious for humans and higher vertebrates. Moreover, since some pathogens are also able to infect bivalve mollusks, they are a threat for the entire mollusk farming industry. In consideration of the leading role in aquaculture and the growing financial importance of bivalve farming, much interest has been recently devoted to investigate the pathogenesis of infectious diseases of these mollusks in order to be prepared for public health emergencies and to avoid dreadful income losses. Several bacterial and viral pathogens will be described herein. Despite the minor complexity of the organization of the immune system of bivalves, compared to mammalian immune systems, a precise description of the different mechanisms that induce its activation and functioning is still missing. In the present review, a substantial consideration will be devoted in outlining the immune responses of bivalves and their repertoire of immune cells. Finally, we will focus on the description of antimicrobial peptides that have been identified and characterized in bivalve mollusks. Their structural and antimicrobial features are also of great interest for the biotechnology sector as antimicrobial templates to combat the increasing antibiotic-resistance of different pathogenic bacteria that plague the human population all over the world. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessFeature PaperReview

Marine Fish Proteins and Peptides for Cosmeceuticals: A Review

by Jayachandran Venkatesan, Sukumaran Anil, Se-Kwon Kim and Min Suk Shim

Mar. Drugs 2017, 15(5), 143; https://doi.org/10.3390/md15050143 - 18 May 2017

Cited by 202 | Viewed by 18274

Abstract

Marine fish provide a rich source of bioactive compounds such as proteins and peptides. The bioactive proteins and peptides derived from marine fish have gained enormous interest in nutraceutical, pharmaceutical, and cosmeceutical industries due to their broad spectrum of bioactivities, including antioxidant, antimicrobial, [...] Read more.

Marine fish provide a rich source of bioactive compounds such as proteins and peptides. The bioactive proteins and peptides derived from marine fish have gained enormous interest in nutraceutical, pharmaceutical, and cosmeceutical industries due to their broad spectrum of bioactivities, including antioxidant, antimicrobial, and anti-aging activities. Recently, the development of cosmeceuticals using marine fish-derived proteins and peptides obtained from chemical or enzymatical hydrolysis of fish processing by-products has increased rapidly owing to their activities in antioxidation and tissue regeneration. Marine fish-derived collagen has been utilized for the development of cosmeceutical products due to its abilities in skin repair and tissue regeneration. Marine fish-derived peptides have also been utilized for various cosmeceutical applications due to their antioxidant, antimicrobial, and matrix metalloproteinase inhibitory activities. In addition, marine fish-derived proteins and hydrolysates demonstrated efficient anti-photoaging activity. The present review highlights and presents an overview of the current status of the isolation and applications of marine fish-derived proteins and peptides. This review also demonstrates that marine fish-derived proteins and peptides have high potential for biocompatible and effective cosmeceuticals. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessReview

Marine Peptides as Potential Agents for the Management of Type 2 Diabetes Mellitus—A Prospect

by En-Qin Xia, Shan-Shan Zhu, Min-Jing He, Fei Luo, Cheng-Zhan Fu and Tang-Bin Zou

Mar. Drugs 2017, 15(4), 88; https://doi.org/10.3390/md15040088 - 23 Mar 2017

Cited by 55 | Viewed by 6984

Abstract

An increasing prevalence of diabetes is known as a main risk for human health in the last future worldwide. There is limited evidence on the potential management of type 2 diabetes mellitus using bioactive peptides from marine organisms, besides from milk and beans. [...] Read more.

An increasing prevalence of diabetes is known as a main risk for human health in the last future worldwide. There is limited evidence on the potential management of type 2 diabetes mellitus using bioactive peptides from marine organisms, besides from milk and beans. We summarized here recent advances in our understanding of the regulation of glucose metabolism using bioactive peptides from natural proteins, including regulation of insulin-regulated glucose metabolism, such as protection and reparation of pancreatic β-cells, enhancing glucose-stimulated insulin secretion and influencing the sensitivity of insulin and the signaling pathways, and inhibition of bioactive peptides to dipeptidyl peptidase IV, α-amylase and α-glucosidase activities. The present paper tried to understand the underlying mechanism involved and the structure characteristics of bioactive peptides responsible for its antidiabetic activities to prospect the utilization of rich marine organism proteins. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessFeature PaperReview

Bioactive Peptide of Marine Origin for the Prevention and Treatment of Non-Communicable Diseases

by Ratih Pangestuti and Se-Kwon Kim

Mar. Drugs 2017, 15(3), 67; https://doi.org/10.3390/md15030067 - 9 Mar 2017

Cited by 80 | Viewed by 9693

Abstract

Non-communicable diseases (NCD) are the leading cause of death and disability worldwide. The four main leading causes of NCD are cardiovascular diseases, cancers, respiratory diseases and diabetes. Recognizing the devastating impact of NCD, novel prevention and treatment strategies are extensively sought. Marine organisms [...] Read more.

Non-communicable diseases (NCD) are the leading cause of death and disability worldwide. The four main leading causes of NCD are cardiovascular diseases, cancers, respiratory diseases and diabetes. Recognizing the devastating impact of NCD, novel prevention and treatment strategies are extensively sought. Marine organisms are considered as an important source of bioactive peptides that can exert biological functions to prevent and treatment of NCD. Recent pharmacological investigations reported cardio protective, anticancer, antioxidative, anti-diabetic, and anti-obesity effects of marine-derived bioactive peptides. Moreover, there is available evidence supporting the utilization of marine organisms and its bioactive peptides to alleviate NCD. Marine-derived bioactive peptides are alternative sources for synthetic ingredients that can contribute to a consumer’s well-being, as a part of nutraceuticals and functional foods. This contribution focus on the bioactive peptides derived from marine organisms and elaborates its possible prevention and therapeutic roles in NCD. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessFeature PaperReview

Enzyme-Assisted Discovery of Antioxidant Peptides from Edible Marine Invertebrates: A Review

by Tsun-Thai Chai, Yew-Chye Law, Fai-Chu Wong and Se-Kwon Kim

Mar. Drugs 2017, 15(2), 42; https://doi.org/10.3390/md15020042 - 16 Feb 2017

Cited by 99 | Viewed by 11338

Abstract

Marine invertebrates, such as oysters, mussels, clams, scallop, jellyfishes, squids, prawns, sea cucumbers and sea squirts, are consumed as foods. These edible marine invertebrates are sources of potent bioactive peptides. The last two decades have seen a surge of interest in the discovery [...] Read more.

Marine invertebrates, such as oysters, mussels, clams, scallop, jellyfishes, squids, prawns, sea cucumbers and sea squirts, are consumed as foods. These edible marine invertebrates are sources of potent bioactive peptides. The last two decades have seen a surge of interest in the discovery of antioxidant peptides from edible marine invertebrates. Enzymatic hydrolysis is an efficient strategy commonly used for releasing antioxidant peptides from food proteins. A growing number of antioxidant peptide sequences have been identified from the enzymatic hydrolysates of edible marine invertebrates. Antioxidant peptides have potential applications in food, pharmaceuticals and cosmetics. In this review, we first give a brief overview of the current state of progress of antioxidant peptide research, with special attention to marine antioxidant peptides. We then focus on 22 investigations which identified 32 antioxidant peptides from enzymatic hydrolysates of edible marine invertebrates. Strategies adopted by various research groups in the purification and identification of the antioxidant peptides will be summarized. Structural characteristic of the peptide sequences in relation to their antioxidant activities will be reviewed. Potential applications of the peptide sequences and future research prospects will also be discussed. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessReview

Marine Antifreeze Proteins: Structure, Function, and Application to Cryopreservation as a Potential Cryoprotectant

by Hak Jun Kim, Jun Hyuck Lee, Young Baek Hur, Chang Woo Lee, Sun-Ha Park and Bon-Won Koo

Mar. Drugs 2017, 15(2), 27; https://doi.org/10.3390/md15020027 - 27 Jan 2017

Cited by 140 | Viewed by 17354

Abstract

Antifreeze proteins (AFPs) are biological antifreezes with unique properties, including thermal hysteresis(TH),ice recrystallization inhibition(IRI),and interaction with membranes and/or membrane proteins. These properties have been utilized in the preservation of biological samples at low temperatures. Here, we review the structure and function of marine-derived [...] Read more.

Antifreeze proteins (AFPs) are biological antifreezes with unique properties, including thermal hysteresis(TH),ice recrystallization inhibition(IRI),and interaction with membranes and/or membrane proteins. These properties have been utilized in the preservation of biological samples at low temperatures. Here, we review the structure and function of marine-derived AFPs, including moderately active ﬁsh AFPs and hyperactive polar AFPs. We also survey previous and current reports of cryopreservation using AFPs. Cryopreserved biological samples are relatively diverse ranging from diatoms and reproductive cells to embryos and organs. Cryopreserved biological samples mainly originate from mammals. Most cryopreservation trials using marine-derived AFPs have demonstrated that addition of AFPs can improve post-thaw viability regardless of freezing method (slow-freezing or vitriﬁcation), storage temperature, and types of biological sample type. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessReview

Alkynyl-Containing Peptides of Marine Origin: A Review

by Qiu-Ye Chai, Zhen Yang, Hou-Wen Lin and Bing-Nan Han

Mar. Drugs 2016, 14(11), 216; https://doi.org/10.3390/md14110216 - 23 Nov 2016

Cited by 44 | Viewed by 8576

Abstract

Since the 1990s, a number of terminal alkynyl residue-containing cyclic/acyclic peptides have been identified from marine organisms, especially cyanobacteria and marine mollusks. This review has presented 66 peptides, which covers over 90% marine peptides with terminal alkynyl fatty acyl units. In fact, more [...] Read more.

Since the 1990s, a number of terminal alkynyl residue-containing cyclic/acyclic peptides have been identified from marine organisms, especially cyanobacteria and marine mollusks. This review has presented 66 peptides, which covers over 90% marine peptides with terminal alkynyl fatty acyl units. In fact, more than 90% of these peptides described in the literature are of cyanobacterial origin. Interestingly, all the linear peptides featured with terminal alkyne were solely discovered from marine cyanobacteria. The objective of this article is to provide an overview on the types, structural characterization of these unusual terminal alkynyl fatty acyl units, as well as the sources and biological functions of their composed peptides. Many of these peptides have a variety of biological activities, including antitumor, antibacterial, antimalarial, etc. Further, we have also discussed the evident biosynthetic origin responsible for formation of terminal alkynes of natural PKS (polyketide synthase)/NRPS (nonribosome peptide synthetase) hybrids. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessReview

Preclinical and Clinical Studies on Antioxidative, Antihypertensive and Cardioprotective Effect of Marine Proteins and Peptides—A Review

by Ida-Johanne Jensen and Hanne K. Mæhre

Mar. Drugs 2016, 14(11), 211; https://doi.org/10.3390/md14110211 - 18 Nov 2016

Cited by 34 | Viewed by 7613

Abstract

High seafood consumption has traditionally been linked to a reduced risk of cardiovascular diseases, mainly due to the lipid lowering effects of the long chained omega 3 fatty acids. However, fish and seafood are also excellent sources of good quality proteins and emerging [...] Read more.

High seafood consumption has traditionally been linked to a reduced risk of cardiovascular diseases, mainly due to the lipid lowering effects of the long chained omega 3 fatty acids. However, fish and seafood are also excellent sources of good quality proteins and emerging documentation show that, upon digestion, these proteins are sources for bioactive peptides with documented favorable physiological effects such as antioxidative, antihypertensive and other cardioprotective effects. This documentation is mainly from in vitro studies, but also animal studies are arising. Evidence from human studies evaluating the positive health effects of marine proteins and peptides are scarce. In one study, a reduction in oxidative stress after intake of cod has been documented and a few human clinical trials have been performed evaluating the effect on blood pressure. The results are, however, inconclusive. The majority of the human clinical trials performed to investigate positive health effects of marine protein and lean fish intake, has focused on blood lipids. While some studies have documented a reduction in triglycerides after intake of lean fish, others have documented no effects. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessReview

Natural Proline-Rich Cyclopolypeptides from Marine Organisms: Chemistry, Synthetic Methodologies and Biological Status

by Wan-Yin Fang, Rajiv Dahiya, Hua-Li Qin, Rita Mourya and Sandeep Maharaj

Mar. Drugs 2016, 14(11), 194; https://doi.org/10.3390/md14110194 - 26 Oct 2016

Cited by 66 | Viewed by 11762

Abstract

Peptides have gained increased interest as therapeutics during recent years. More than 60 peptide drugs have reached the market for the benefit of patients and several hundreds of novel therapeutic peptides are in preclinical and clinical development. The key contributor to this success [...] Read more.

Peptides have gained increased interest as therapeutics during recent years. More than 60 peptide drugs have reached the market for the benefit of patients and several hundreds of novel therapeutic peptides are in preclinical and clinical development. The key contributor to this success is the potent and specific, yet safe, mode of action of peptides. Among the wide range of biologically-active peptides, naturally-occurring marine-derived cyclopolypeptides exhibit a broad range of unusual and potent pharmacological activities. Because of their size and complexity, proline-rich cyclic peptides (PRCPs) occupy a crucial chemical space in drug discovery that may provide useful scaffolds for modulating more challenging biological targets, such as protein-protein interactions and allosteric binding sites. Diverse pharmacological activities of natural cyclic peptides from marine sponges, tunicates and cyanobacteria have encouraged efforts to develop cyclic peptides with well-known synthetic methods, including solid-phase and solution-phase techniques of peptide synthesis. The present review highlights the natural resources, unique structural features and the most relevant biological properties of proline-rich peptides of marine-origin, focusing on the potential therapeutic role that the PRCPs may play as a promising source of new peptide-based novel drugs. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessReview

Marine Microbiological Enzymes: Studies with Multiple Strategies and Prospects

by Yan Wang, Qinghao Song and Xiao-Hua Zhang

Mar. Drugs 2016, 14(10), 171; https://doi.org/10.3390/md14100171 - 22 Sep 2016

Cited by 23 | Viewed by 7491

Abstract

Marine microorganisms produce a series of promising enzymes that have been widely used or are potentially valuable for our daily life. Both classic and newly developed biochemistry technologies have been broadly used to study marine and terrestrial microbiological enzymes. In this brief review, [...] Read more.

Marine microorganisms produce a series of promising enzymes that have been widely used or are potentially valuable for our daily life. Both classic and newly developed biochemistry technologies have been broadly used to study marine and terrestrial microbiological enzymes. In this brief review, we provide a research update and prospects regarding regulatory mechanisms and related strategies of acyl-homoserine lactones (AHL) lactonase, which is an important but largely unexplored enzyme. We also detail the status and catalytic mechanism of the main types of polysaccharide-degrading enzymes that broadly exist among marine microorganisms but have been poorly explored. In order to facilitate understanding, the regulatory and synthetic biology strategies of terrestrial microorganisms are also mentioned in comparison. We anticipate that this review will provide an outline of multiple strategies for promising marine microbial enzymes and open new avenues for the exploration, engineering and application of various enzymes. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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Open AccessReview

An Overview of the Medical Applications of Marine Skeletal Matrix Proteins

by M. Azizur Rahman

Mar. Drugs 2016, 14(9), 167; https://doi.org/10.3390/md14090167 - 12 Sep 2016

Cited by 13 | Viewed by 7492

Abstract

In recent years, the medicinal potential of marine organisms has attracted increasing attention. This is due to their immense diversity and adaptation to unique ecological niches that has led to vast physiological and biochemical diversification. Among these organisms, marine calcifiers are an abundant [...] Read more.

In recent years, the medicinal potential of marine organisms has attracted increasing attention. This is due to their immense diversity and adaptation to unique ecological niches that has led to vast physiological and biochemical diversification. Among these organisms, marine calcifiers are an abundant source of novel proteins and chemical entities that can be used for drug discovery. Studies of the skeletal organic matrix proteins of marine calcifiers have focused on biomedical applications such as the identification of growth inducing proteins that can be used for bone regeneration, for example, 2/4 bone morphogenic proteins (BMP). Although a few reports on the functions of proteins derived from marine calcifiers can be found in the literature, marine calcifiers themselves remain an untapped source of proteins for the development of innovative pharmaceuticals. Following an overview of the current knowledge of skeletal organic matrix proteins from marine calcifiers, this review will focus on various aspects of marine skeletal protein research including sources, biosynthesis, structures, and possible strategies for chemical or physical modification. Special attention will be given to potential medical applications and recent discoveries of skeletal proteins and polysaccharides with biologically appealing characteristics. In addition, I will introduce an effective protocol for sample preparation and protein purification that includes isolation technology for biopolymers (of both soluble and insoluble organic matrices) from coralline algae. These algae are a widespread but poorly studied group of shallow marine calcifiers that have great potential for marine drug discovery. Full article

(This article belongs to the Special Issue Marine Proteins and Peptides)

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