Inhibitory activities of the edible brown alga <Emphasis Type="Italic">Laminaria japonica</Emphasis> on glucose-mediated protein damage and rat lens aldose reductase

Increased aldose reductase (AR)-related polyol pathway activity and the subsequent formation of advanced glycation end-products (AGEs) have been implicated in the onset of diabetic complications. We have evaluated the inhibitory effects of the methanolic extract and its fractions of Laminaria japonica on rat lens AR (RLAR) and AGE formation. The CH₂Cl₂ fraction was separated by high-performance liquid chromatography to yield active porphyrin derivatives, including pheophorbide a (1) and pheophytin a (2), which were assayed for their anti-diabetic complications and yield. Compound 1 exhibited potent inhibitory activities against both AGE formation and RLAR, with respective half-maximal inhibitory concentration (IC₅₀) values of 49.4 and 12.3 μM. Conversely, compound 2 was found to be active against AGE formation, with an IC₅₀ of 228.7 μM. For further elucidation of the structure–inhibitory activity relationship of the porphyrin derivatives, the inhibitory activities of four commercially available porphyrin derivatives on AGE formation and RLAR were measured. The presence of a carboxyl group and the absence of a phytyl group at the C-17² position of the porphyrin were found to contribute to the inhibitory effects towards both AGE formation and RLAR. These results suggest that the L. japonica and its porphyrin derivatives may represent a potential functional food resource for further prevention of diabetic complications.     

In vitro monoamine oxidase A and B inhibitory activity and molecular docking simulations of fucoxanthin

Fucoxanthin is the primary carotenoid found in edible seaweeds, such as Eisenia bicyclis, Undaria pinnatifida, and others. The aim of this study was to determine the effectiveness of fucoxanthin against Parkinson’s disease (PD) by inhibiting monoamine oxidase (MAO) A and B because MAO inhibitors are used in early management of PD. A sensitive enzyme-based chemiluminescent assay and kinetics methods were used to investigate the enzyme inhibitory activities and mode of inhibition. A molecular docking simulation was performed to clarify the binding characteristics of fucoxanthin to hMAO-A (2z5x) and hMAO-B (2v5z). Our results suggest that fucoxanthin shows significant inhibitory activity against hMAO-A and hMAO-B with IC₅₀ values of 197.41 ± 2.20 and 211.12 ± 1.17 μM, respectively. Selegiline was used as the positive control (IC₅₀: 10.54 ± 1.25 and 0.128 ± 0.01 μM for hMAO-A and hMAO-B, respectively). The enzyme-based kinetics results demonstrated that fucoxanthin inhibited both hMAOs in a reversible competitive manner. The molecular docking simulation predicted that fucoxanthin exhibits higher binding affinity towards hMAO-A and hMAO-B through hydrogen bonding and hydrophobic interactions. These findings suggest that fucoxanthin is a reversible competitive hMAO inhibitor that could be used to manage PD.     

两种芽孢杆菌体外体内拮抗气单胞菌的试验

将蜡样芽孢杆菌Y1和巨大芽孢杆菌BM1259混合培养,结合平板活菌计数、抑菌活性测定及体内拮抗试验,研究其对水产动物气单胞菌的抑菌效果。体外拮抗试验结果表明,这两种芽孢杆菌均能明显抑制嗜水气单胞菌NQ的增殖,抑制率分别为53.74%和56.12%。不同温度下的抑菌活性试验显示,2种芽孢杆菌的抑菌活性温度分别为32℃和29℃。体内拮抗试验结果表明,巨大芽孢杆菌能显著降低异育银鲫肠道气单胞菌的数量。提示巨大芽孢杆菌可作为潜在的水产专用微生态制剂。     

Structural characterization and antitumor and mitogenic activity of a lectin from the gill of bighead carp (Aristichthys nobilis)

In this study, we investigated the gross structure, secondary structure, and antitumor and mitogenic activity of GANL, a lectin from the gill of bighead carp (Aristichthys nobilis). We used infrared spectroscopy, β-elimination, and circular dichroism spectroscopy to determine the structure of GANL. We measured antiproliferation activity against six human tumor cell lines and mitogenic activity against murine splenocytes using the MTT assay. Based on infrared spectroscopy and β-elimination, we conclude that GANL is a glycoprotein. The protein and carbohydrate moieties are joined by O-glycosidic linkage. A circular dichroism spectroscopic analysis revealed that the secondary structure of GANL consists of α-helices (34.8 %), β-sheets (12.1 %), β-turns (24.5 %), and unordered structures (33.0 %). GANL exerted potent antitumor activity against the HeLa cell line (IC₅₀ = 11.86 μg/mL) and a mitogenic effect on murine splenocytes in the MTT assay. GANL, a lectin that is isolated from the gills of bighead carp, is a glycoprotein with potent antitumor and mitogenic activity.     

Antibacterial activity of immobilized silver nanoparticles on TEPA‐Den‐SiO2 against shrimp pathogen,Vibrio sp. Persian1

In this study, we prepared silver nanoparticles immobilized onto silica sand beads as an antibacterial material against pathogenic luminous Vibrio sp. Persian1. Silica beads were modified with 3‐aminopropyltriethoxysilane (APTES), cyanuric chlorid and tetraethylene pentamine, and silver nanoparticles were generated in various concentrations (0.5, 1, and 2 mM g^?1 of silica beads) of AgNO₃ on the surface using chemical reduction. Ag/TEPA‐Den‐SiO₂ samples were characterized by TEM, FE‐SEM/EDS, FT‐IR and ICP OES and their antibacterial activity assayed by zone of inhibition and test tube tests against pathogenic Vibrio sp. The results of the zone inhibitory test revealed that all the Ag/TEPA‐Den‐SiO₂ samples had an antibacterial effect against luminous Vibrio sp. Persian1. In addition, the tube test results showed 100% killing of bacteria in 2 h contact period. Ag/TEPA‐Den‐SiO₂ samples maintained their antibacterial activity after 14‐day immersion in seawater by slow release of silver ions. These results suggest that Ag/TEPA‐Den‐SiO₂ substrates could be effective antibacterial materials for disinfection of seawater used to culture Penaeid shrimp larvae.     

Comparative activity and stability under salinity conditions of different antimicrobial peptides isolated from aquatic animals

This study reports the in vitro activity of six antimicrobial peptides (AMPs) produced by aquatic animals (most marine invertebrates): tachyplesin (Tach), magainin (Mag), clavanin (Clav), penaeidin (Pen), mytilin (Myt) and antilipopolysaccharide factor (ALF) against marine vibrios, filamentous fungi and yeast. Their stability under salinity conditions and seawater was also examined. The results showed that Mag, Myt and especially Tach and ALF (minimum inhibitory concentration<1.5 μM) had a potent activity against all tested vibrio species, whereas Clav and Pen were ineffective (up to 50 μM). With respect to the antifungal activity, each AMP had a different potency according to the fungal species. In general terms, Tach was the most potent peptide, followed by Mag. Interestingly, Tach, Myt and ALF had a significant effect on the filamentous fungus Fusarium solani that could be pathogenic to marine organisms. All AMPs had a tendency to decrease or lose their activity at high salinity (>225 mM NaCl). Tach and Myt were the most stable peptides, maintaining significant activity under seawater salinity (450 mM). Curiously, all peptides lost their effect under seawater conditions. The results suggest that Tach, ALF and Myt are the most promising candidates for potential therapeutic use in farmed-marine species, because all have a significant and broad antimicrobial activity maintained at high salinity.     

Angiotensin-converting enzyme I inhibitory activity of phlorotannins from Ecklonia stolonifera

ABSTRACT:   As part of our study of the isolation of antihypertensive agents derived from natural marine products, the bioactivity of 10 edible Korean seaweeds were screened by angiotensin converting enzyme (ACE) inhibitory and peroxynitrite assays. Among the crude extracts of selected seaweeds, including five Phaeophyta ( Ecklonia stolonifera , E. cava , Pelvetia siliquosa , Hizikia fusiforme , and Undaria pinnatifida ), four Rhodophyta ( Gigartina tenella , Gelidium amansii , Chondria crassicaulis , and Porphyra tenera ) and one Chlorophyta ( Capsosiphon fulvescens ), the ethanol extracts of E. stolonifera , E. cava , P. siliquosa , U. pinnatifida , and G. tenella exhibited significant inhibitory properties against ACE at more than 50% inhibition at a concentration of 163.93 µg/mL. Phloroglucinol 1 , eckstolonol 2 , eckol 3 , phlorofucofuroeckol A 4 , and dieckol 5 had been isolated previously, and triphlorethol-A 6 and fucosterol 7 were isolated for the first time from E. stolonifera. Also, the ACE inhibitory and peroxynitrite scavenging properties of phlorotannins 1–6 were evaluated, along with fucosterol 7 obtained from E. stolonifera . Among profound peroxynitrite scavenging compounds 1–6 , phlorotannins 3 , 4 and 5 were also determined to manifest marked inhibitory activity against ACE, with 50% inhibition concentration (IC₅₀) values of 70.82 ± 0.25, 12.74 ± 0.15, and 34.25 ± 3.56 µM, respectively.     

The in vitro inhibition of proteases from Cryptobia salmositica Katz by a monoclonal antibody (MAb-001) against a glycoprotein on the pathogenic haemoflagellate

The monoclonal antibody (MAb-001), which was produced against a surface membrane glycoprotein on C. salmositica , significantly inhibited the activities of the intracellular proteases of the parasite. The total activity in the partially purified metallo-protease, and about 80% of activity in the partially purified cysteine protease, were inhibited by the antibody (at 10 μg protein ml^–1). The inhibitory effects of the antibody on the proteases were also demonstrated using haemoglobin (substrate)-SDS-PAGE. The activities of the metallo-protease band (200 kDa) and the three cysteine protease bands (66, 70 and 97 kDa) were inhibited by MAb-001, but the activity of the fourth cysteine protease band (49 kDa) was not affected. Similar inhibitory effects of the antibody were also found in the crude protease extract (parasite lysate), except that more antibody was required to obtain the same level of inhibition. The metallo-protease band was more sensitive than the cysteine protease bands to the antibody.     

Functional Properties of the Marine Gastropod Molluscs Chicoreus ramosus and Babylonia spirata Collected from the Southern Coast of India

ABSTRACT

This study characterized the functional properties of ethyl acetate-methanol (EA-MeOH) and chloroform extracts of the muricid gastropod Chicoreus ramosus and buccinid Babylonia spirata. The EA-MeOH extract of B. spirata was a potent quencher of radical cation (IC₉₀ < 1 mg/mL), whereas that of C. ramosus held greater anti–inflammatory potential (IC₉₀ 5-lipoxygenase inhibition 1.74 mg/mL) than the buccinid gastropod. The EA-MeOH extract of C. ramosus displayed potent antidiabetic activities as deduced by its attenuation properties against carbolytic enzymes α-amylase and α-glycosidase (IC₉₀ 1.06 and 2.25 mg/mL, respectively) than those exhibited by B. spirata (IC₉₀ 2.32 and 4.50 mg/mL, respectively). The spectroscopic dereplication studies to determine probable chemical groups in the solvent extracts of the studied gastropods revealed the presence of functionalities, which might augment the electronic properties of the bioactive principles present within the extract, thereby enhancing their activity. Thus, the present study recognized that marine gastropods C. ramosus and B. spirata have potential functional implications against oxidative stress-induced diseases, such as diabetes and inflammation. This research supports further investigation of these previously uncharacterized marine gastropod species to isolate potential bioactive leads for use against various biological targets and to develop functional food formulations.     

Glycoproteins isolated from scallop shells inhibit differentiation of 3T3-L1 preadipocyte cells

We previously demonstrated that the organic components isolated from scallop shells (scallop shell extract) inhibit the differentiation of 3T3-L1 preadipocyte cells. In this study, we show that a pronase-treated scallop shell extract inhibited differentiation, but degradation of sugar chains in the scallop shell extract with trifluoromethane sulfonic acid resulted in the loss of the differentiation-inhibiting activity, suggesting that the sugar chain modifications were responsible for the inhibitory activity. To identify the bioactive substance in the scallop shell extract, we isolated glycoproteins from the scallop shell extract via affinity chromatography using concanavalin A (Con A), wheat germ agglutinin, lens culinaris agglutinin (LCA), and ricinus communis agglutinin. LCA and Con A binding fractions inhibited the differentiation of 3T3-L1 preadipocyte cells. In addition, a glycoprotein with a molecular weight of 16 kDa that was purified from the LCA binding fraction reduced lipid accumulation in 3T3-L1 cells during differentiation. The glycoprotein inhibited differentiation-associated mitotic clonal expansion and suppressed the expression of an adipocyte-specific protein, fatty acid binding protein. These results suggest that the sugar chains of glycoproteins in the scallop shell extract inhibit the differentiation of 3T3-L1 preadipocyte cells.     

Application of Two-Level Full Factorial Design for the Extraction of Fucoxanthin and Antioxidant Activities from Sargassum siliquosum and Sargassum polycystum

Two-level full factorial design was employed to identify the extraction parameters that can improve the derivation of fucoxanthin content (FC), total carotenoid content (TCC), and antioxidant from two brown seaweeds, Sargassum siliquosum (SS) and Sargassum polycystum (SP). These parameters included temperature (A: 4–45°C), time (B: 30–1,440 min), and solvent-to-solid ratio (C: 10–50 ml/g). Antioxidant activities were determined as trolox equivalent antioxidant capacity (TEAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity, and ferric-reducing antioxidant power (FRAP). Results showed that all three factors were significant (p < 0.05) in providing higher FC in both species. These factors were also significant in obtaining higher TCC in SS; whereas in SP, TCC was only affected by solvent-to-solid ratio. Only temperature was found to contribute significantly to a higher TEAC in both species. However, none of the factors improved DPPH for SS, except temperature and time for SP. For SS, only time was significant in obtaining higher FRAP; whereas temperature and time were significant for SP. Hence, results indicate that a simple modification in the extraction temperature, time, and solvent-to-solid ratio will be able to improve the derivation of fucoxanthin, carotenoids, and antioxidant activities.     

Inhibitory activity of Ecklonia stolonifera and its isolated phlorotannins against Cu2+-induced low-density lipoprotein oxidation

Since the oxidation of low-density lipoprotein (LDL) is one of the main causes of atherosclerosis, Cu²⁺-induced LDL oxidation and conjugated diene formation is currently being explored for the development of pharmaceutical drugs or functional foods for the treatment of atherosclerosis. The present work investigated the inhibitory effects on in vitro Cu²⁺-induced human LDL oxidation and conjugated diene formation of the methanol (MeOH) extract of the edible brown alga (Ecklonia stolonifera) and its different solvent-soluble fractions, as well as the phlorotannins isolated from them. The most active ethyl acetate fraction was selected for chromatographic separation to isolate six phlorotannins: phloroglucinol (1), dioxinodehydroeckol (2), eckol (3), phlorofucofuroeckol A (4), dieckol (5), and 7-phloroeckol (6). Compounds 3?C6 showed potent inhibitory activity against Cu²⁺-induced LDL oxidation as compared with probucol, a well-known clinical therapeutic agent for hypercholesterolemia. Moreover, when compound 5 (at levels of 9 and 4.5???M) was used in combination with probucol (4.5???M), they additively inhibited Cu²⁺-induced LDL oxidation. In addition, 3?C5 significantly prolonged the lag time of conjugated diene formation at 10???M. These results suggest that the potent antiatherosclerotic effects of E. stolonifera and its isolated phlorotannins may be partly attributed to the inhibition of Cu²⁺-induced LDL oxidation and conjugated diene formation.     

The effect of piscidin antimicrobial peptides on the formation of Gram-negative bacterial biofilms

Fish-derived antimicrobial peptides are an important part of the innate immune system due to their potent antimicrobial properties. Piscidins are a class of antimicrobial peptides first described in hybrid striped bass (Morone chrysops x Morone saxatilis) but have also been identified in many other fish species. Previous work demonstrated the broad antimicrobial activity of piscidins against Gram-negative and Gram-positive bacterial species. This study sought to determine the extent to which class I (striped bass piscidin 1, white bass piscidin 1 and striped bass/white bass piscidin 3) and class II (striped bass piscidin 4 and white bass piscidin 5) piscidins inhibit biofilm formation of different Gram-negative bacteria. In general, the class I and II piscidins demonstrate potent activity against Escherichia coli and Flavobacterium columnare biofilms. The class II piscidins showed more activity against E. coli and F. columnare isolates than did the class I piscidins. The piscidins in general were much less effective against inhibiting Aeromonas hydrophila and A. veronii biofilm growth. Only the class I piscidins showed significant growth inhibition among the Aeromonas spp. examined.     

GnRH gene products downregulate their neighboring genes encoding protein tyrosine phosphatases

The decapeptide gonadotropin-releasing hormone (GnRH) has multiple functions, including the regulation of gonadotropin secretion, reproductive behavior, and cell proliferation. In this paper, we have found that in the medaka (Oryzias latipes) genome, gonadotropin-releasing hormone (GnRH) genes are adjacent to type IV protein tyrosine phosphatase (PTP) genes encoding PTPα and PTPε, which are known to regulate cellular activity via interacting with voltage-gated potassium channel. We have subsequently demonstrated using an in vitro medaka whole-brain culture system that GnRH downregulates the PTPα and PTPε gene expression. Inhibition of intracellular type IV PTP signaling, which probably results in the modulation of cellular activity, may account for multiplicity of GnRH function.     

Antibacterial benzaldehydes produced by seaweed-derived Streptomyces atrovirens PK288-21

Marine-derived actinomycetes (87 strains isolated from seaweed and 98 strains isolated from marine sediment) were screened for antimicrobial activity against bacterial fish pathogens. The most potent active strain (PK288-21) isolated from the rhizosphere of the marine seaweed Undaria pinnatifida was identified as Streptomyces atrovirens by 16S rDNA sequence analysis. Two active compounds were isolated from a culture extract of strain PK288-21 by silica-gel flash chromatography and high-performance liquid chromatography. The structures of the two compounds were identified as 2-hydroxy-5-(3-methylbut-2-enyl)benzaldehyde (B1) and 2-hepta-1,5-dienyl-3,6-dihydroxy-5-(3-methylbut-2-enyl) benzaldehyde (B2) by nuclear magnetic resonance and high-resolution fast atomic bombardment mass spectroscopy. The antimicrobial activities of the two compounds were tested against bacterial fish pathogens and expressed in terms of the minimum inhibitory concentration (MIC). Metabolite production was found to be optimized in A1BFe medium following the screening of eight different media. The two compounds killed Edwardsiella tarda after 12?h and Streptococcus iniae after 16?h at the MIC. Compound B1, 2-hydroxy-5-(3-methylbut-2-enyl)benzaldehyde, is a new benzaldehyde derivative, and this is the first time that either of these compounds have been reported in the genus Streptomyces.     

Identification of oyster-derived hypotensive peptide acting as angiotensin-I-converting enzyme inhibitor

Angiotensin-I-converting enzyme (ACE) plays a crucial role in the crisis of hypertension. Some peptides that originate from protease hydrolysates are known to suppress ACE activity in vitro and in vivo. Here, we investigated whether trypsin hydrolysate of oyster Crassostrea gigas showed hypotensive activity and ACE inhibition. The hydrolysate significantly suppressed systolic blood pressure and ACE activity in spontaneously hypertensive rats following a one-shot oral administration and a long-term feeding experiment lasting 9 weeks. Each hydrolysate from oyster tissue showed ACE inhibitory activity, indicating the hypotensive effect was due to synergism. One potent ACE inhibitory peptide, Asp-Leu-Thr-Asp-Tyr, was identified from the hydrolysate of the striate muscle, and the peptide exhibited hypotensive activity in vivo. Protease digestion analysis suggested that Asp-Tyr could be the real effector of this penta-peptide in vivo.     

Recovery of Aliphatic Fatty Acids from Red Seaweed Champia parvula (C. Agardh) and Its Antifungal Action

The aim of the present study was to evaluate the antifungal activity of seaweed Champia parvula and identification of active compounds for this action. In this regard, C. parvula crude extracts were obtained from n-hexane, ethyl acetate, chloroform, methanol, and water used to study the antifungal action. Results showed that methanolic extract had potent action against C. albicans, C. tropicalis, T. mentagrophytes, and A.flavus, with the highest inhibition of 16.7 mm found against C. tropicalis. Minimum inhibition concentration at 12.5 and minimum fungal concentration at 25 μg/mL were found in the methanolic extract. Therefore, to identify the bioactive compound for this antifungal action in the methanolic extract, thin-layer chromatography (TLC) and reverse-phase high-performance liquid chromatography (RP-HPLC) were used. The RP-HPLC had three peaks with retention times at 3.30, 3.86, and 4.73 min, showing the presence of ester fatty acid compound. Further, these compounds were characterized by nuclear magnetic resonance (NMR), gas chromatography (GC), and liquid chromatography-mass spectrometry (LC-MS), which showed the presence of long-chain aliphatic fatty acid like eicosanoic acid with formation of oct-1-en-3-ol compounds attached.     

Effects of cecropin peptides on bacteria pathogenic to fish

The antibacterial effects of synthetic cecropin B and cecropin P1 were tested against the fish-pathogenic bacteria Vibrio anguillarum, Vibrio salmonicida, Aeromonas salmonicida , Edwardsiella ictaluri and Yersinia ruckeri. Both cecropins were active against all bacteria tested, but the effect was strongly influenced by the growth media used. In brain heart infusion medium, the minimum inhibitory concentrations of cecropin B ranged from 0.3 to 1.3 μ m and from 0.3 to 1.0 μ m for cecropin P1, except for E. ictaluri , which was noticeably less sensitive to cecropin P1 (61 μ m ). The present authors have compared the bactericidal activity of these two peptides, showing that the killing rate for the selected bacteria was higher for cecropin B than for cecropin P1 . V. anguillarum was the most sensitive to the cecropins, and in the present study, no colony forming units were detected after 4 and 8 min of treatment with cecropin B and P1, respectively. Electron microscopy was performed to document the effect of cecropin on the bacterial surface.     

Inhibition of Saprolegnia pathogenic for fish by Pseudomonas fluorescens

Bacteria capable of inhibiting the growth of Saprolegnia were isolated from commercial channel catfish pond water during January and November 1991. The isolates were typed as Pseudomonas fluorescens with 96% confidence and fluoresced under ultraviolet light. Only three out of the seven otherwise identical subcultures have retained the ability to inhibit Saprolegnia hyphal growth and were positive in gelatin liquefaction assays. Saprolegnia cyst germination inhibition assays indicated that each of the P. fluorescens subcultures inhibited cyst germination at ratios as low as 0.5:1 to 10:1, while Escherichia coli (used as a control) was only inhibitory at a ratio of 500:1. The inhibitory activity against Saprolegnia did not appear to reside in bacterial culture supernatants.     

Effect of plant protease inhibitors on digestive proteases in two fish species, Lutjanus argentiventris and L. novemfasciatus

This work provides a comparative study of the inhibitory effect of several plant protein sources on digestive proteases of two snappers: yellow snapper (Lutjanus argentiventris) and dog snapper (Lutjanus novemfasciatus). Seed extracts did not affect gastric proteases whereas they significantly inhibit intestinal proteases. Inhibition of alkaline proteases showed that pancreatic proteases of L. argentiventris were more sensitive to seed protease inhibitors than those of L. novemfasciatus. Legume seeds showed the highest inhibitory capacity on alkaline proteases causing inhibition higher than 50% in total proteolytic activity. Protease inhibition on digestive extracts was assessed using different relative concentration of seed extracts and represented by constructing dose response curves. In order to reduce the inhibitory effect, seed extracts were acid-treated before the inhibition assay. Results showed that acid treatment did not affect the inhibitory capacity of seeds on alkaline proteases in both species. However, when the action of gastric enzymes was simulated on seed extracts, the inhibitory capacity was reduced significantly, mainly in the case of L. novemfasciatus. The responses of fish enzymes to heat-treated seed extracts were also tested. Only higher temperatures were capable of reducing the inhibitory capacity of seed, with the specific response to the snapper species. The use of biochemical assays allows us to quantify the action of inhibitors on total proteolytic activity. In addition, zymograms obtained by substrate-SDS-PAGE provided qualitative information about the number and type of proteases affected by each inhibitor. Each seed extract produces a characteristic profile of inhibition on alkaline protease. The results obtained are important for future formulation of feeds for these snapper species.