Marine Drugs

21 pages, 2405 KiB

Open AccessReview

by Isabel Viera, Antonio Pérez-Gálvez and María Roca

Mar. Drugs 2018, 16(10), 397; https://doi.org/10.3390/md16100397 - 22 Oct 2018

Cited by 59 | Viewed by 6391

The benefit of carotenoids to human health is undeniable and consequently, their use for this purpose is growing rapidly. Additionally, the nutraceutical properties of carotenoids have attracted attention of the food industry, especially in a new market area, the ‘cosmeceuticals.’ Marine organisms (microalgae, [...] Read more.

The benefit of carotenoids to human health is undeniable and consequently, their use for this purpose is growing rapidly. Additionally, the nutraceutical properties of carotenoids have attracted attention of the food industry, especially in a new market area, the ‘cosmeceuticals.’ Marine organisms (microalgae, seaweeds, animals, etc.) are a rich source of carotenoids, with optimal properties for industrial production and biotechnological manipulation. Consequently, several papers have reviewed the analysis, characterization, extraction and determination methods, biological functions and industrial applications. But, now, the bioaccessibility and bioactivity of marine carotenoids has not been focused of any review, although important achievements have been published. The specific and diverse characteristic of the marine matrix determines the bioavailability of carotenoids, some of them unique in the nature. Considering the importance of the bioavailability not just from the health and nutritional point of view but also to the food and pharmaceutical industry, we consider that the present review responds to an actual demand. Full article

(This article belongs to the Special Issue Marine Health Compounds: From Extraction to Food and Pharmaceutical Application)

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10 pages, 288 KiB

Open AccessArticle

The Large Jellyfish Rhizostoma luteum as Sustainable a Resource for Antioxidant Properties, Nutraceutical Value and Biomedical Applications

by Laura Prieto, Angélica Enrique-Navarro, Rosalia Li Volsi and María J. Ortega

Mar. Drugs 2018, 16(10), 396; https://doi.org/10.3390/md16100396 - 21 Oct 2018

Cited by 22 | Viewed by 6713

Abstract

Jellyfish is a compartment in the marine food web that often achieves high increases of biomass and that it is starting to be explored for several human potential uses. In this paper, a recently rediscovered large jellyfish, Rhizostoma luteum, is studied for [...] Read more.

Jellyfish is a compartment in the marine food web that often achieves high increases of biomass and that it is starting to be explored for several human potential uses. In this paper, a recently rediscovered large jellyfish, Rhizostoma luteum, is studied for the first time to describe its organic compounds for the isolation and production of bioactive compounds in several fields of food, cosmetics, or biomedical industries. The biogeochemical composition (Carbon, Nitrogen and Sulfur content), protein and phenols content, together with their antioxidant activity, and the analysis of lipid content (identifying each of the fatty acids presented) was analyzed. The results presented here suggested this jellyfish has the highest antioxidant activity ever measured in a jellyfish, but also with high content in polyunsaturated fatty acids (PUFAs), including the essential fatty acid linoleic. The large natural biomass of Rhizostoma luteum in nature, the wide geographical spread, the fact that already its life cycle has been completed in captivity, establishes a promising positive association of this giant jellyfish species and the isolation of bioactive compounds for future use in marine biotechnology. Full article

(This article belongs to the Special Issue Jellyfish and Polyps: Cnidarians as Sustainable Resources for Biotechnological Applications and Bioprospecting)

18 pages, 3086 KiB

Open AccessArticle

A High-Content Screening Assay for the Discovery of Novel Proteasome Inhibitors from Formosan Soft Corals

by Xue-Hua Ling, Shang-Kwei Wang, Yun-Hsuan Huang, Min-Jay Huang and Chang-Yih Duh

Mar. Drugs 2018, 16(10), 395; https://doi.org/10.3390/md16100395 - 21 Oct 2018

Cited by 8 | Viewed by 3835

Abstract

The ubiquitin-proteasome system (UPS) is a major proteolytic pathway that safeguards protein homeostasis. The main 26S proteasome consists of a 20S catalytic core proteasome and a 19S substrate recognition proteasome. UPS dysfunction underlies many important clinical diseases involving inflammation, tumors, and neurodegeneration. Currently, [...] Read more.

The ubiquitin-proteasome system (UPS) is a major proteolytic pathway that safeguards protein homeostasis. The main 26S proteasome consists of a 20S catalytic core proteasome and a 19S substrate recognition proteasome. UPS dysfunction underlies many important clinical diseases involving inflammation, tumors, and neurodegeneration. Currently, three 20S proteasome inhibitors, bortezomib, carfilzomib, and ixazomib, have been approved for the treatment of multiple myeloma. We aim to screen UPS inhibitors for biomedical purposes. The protein interaction network of human cytomegalovirus UL76 targets UPS, resulting in aggregations of ubiquitinated proteins termed aggresomes. In this study, we demonstrated that cell-based high-content measurements of EGFP-UL76 aggresomes responded to bortezomib and MG132 treatment in a dose-dependent manner. Employing this high-content screening (HCS) assay, we screened natural compounds purified from Formosan soft corals. Four cembrane-based compounds, sarcophytonin A (1), sarcophytoxide (2), sarcophine (3), and laevigatol A (4), were found to enhance the high-content profiles of EGFP-UL76 aggresomes with relative ratios of 0.2. By comparison to the mechanistic action of proteasome inhibitors, compounds 1 and 3 modulated the accumulation of ubiquitinated proteins, with a unique pattern likely targeting 19S proteasome. We confirmed that the EGFP-UL76 aggresome-based HCS system greatly improves the efficacy and sensitivity of the identification of proteasome inhibitors. Full article

(This article belongs to the Special Issue Screening for Marine Natural Products with Potential as Chemotherapeutics)

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19 pages, 6241 KiB

Open AccessArticle

Physicochemical and Antioxidant Properties of Acid- and Pepsin-Soluble Collagens from the Scales of Miiuy Croaker (Miichthys Miiuy)

by Long-Yan Li, Yu-Qin Zhao, Yu He, Chang-Feng Chi and Bin Wang

Mar. Drugs 2018, 16(10), 394; https://doi.org/10.3390/md16100394 - 20 Oct 2018

Cited by 49 | Viewed by 4446

Abstract

In this report, acid-soluble collagen (ASC-MC) and pepsin-soluble collagen (PSC-MC) were extracted from the scales of miiuy croaker (Miichthys miiuy) with yields of 0.64 ± 0.07% and 3.87 ± 0.15% of dry weight basis, respectively. ASC-MC and PSC-MC had glycine as [...] Read more.

In this report, acid-soluble collagen (ASC-MC) and pepsin-soluble collagen (PSC-MC) were extracted from the scales of miiuy croaker (Miichthys miiuy) with yields of 0.64 ± 0.07% and 3.87 ± 0.15% of dry weight basis, respectively. ASC-MC and PSC-MC had glycine as the major amino acid with the contents of 341.8 ± 4.2 and 344.5 ± 3.2 residues/1000 residues, respectively. ASC-MC and PSC-MC had lower denaturation temperatures (32.2 °C and 29.0 °C for ASC-MC and PSC-MC, respectively) compared to mammalian collagen due to their low imino acid content (197.6 and 195.2 residues/1000 residues for ASC-MC and PSC-MC, respectively). ASC-MC and PSC-MC were mainly composed of type I collagen on the literatures and results of amino acid composition, SDS-PAGE pattern, ultraviolet (UV) and Fourier-transform infrared spectroscopy (FTIR) spectra. The maximum solubility of ASC-MC and PSC-MC was appeared at pH 1–3 and a sharp decrease in solubility was observed when the NaCl concentration was above 2%. Zeta potential studies indicated that ASC-MC and PSC-MC exhibited a net zero charge at pH 6.66 and 6.81, respectively. Furthermore, the scavenging capabilities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical, superoxide anion radical and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical of ASC-MC and PSC-MC were positively correlated with their tested concentration ranged from 0 to 5 mg/mL and PSC-MC showed significantly higher activity than that of ASC-MC at most tested concentrations (p < 0.05). In addition, the scavenging capability of PSC-MC on hydroxyl radical and superoxide anion radical was higher than those of DPPH radical and ABTS radical, which suggested that ASC-SC and PSC-SC might be served as hydroxyl radical and superoxide anion radical scavenger in cosmeceutical products for protecting skins from photoaging and ultraviolet damage. Full article

(This article belongs to the Special Issue Anti-Photoagaing and Photo-Protective Compounds from Marine Organisms)

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12 pages, 1642 KiB

Open AccessArticle

Increasing Metabolic Diversity in Marine Sponges Extracts by Controlling Extraction Parameters

by Lina M. Bayona, Melina Videnova and Young Hae Choi

Mar. Drugs 2018, 16(10), 393; https://doi.org/10.3390/md16100393 - 20 Oct 2018

Cited by 12 | Viewed by 4333

Abstract

Metabolomics has become an important tool in the search for bioactive compounds from natural sources, with the recent inclusion of marine organisms. Of the several steps performed in metabolomics studies, the extraction process is a crucial step—one which has been overlooked for a [...] Read more.

Metabolomics has become an important tool in the search for bioactive compounds from natural sources, with the recent inclusion of marine organisms. Of the several steps performed in metabolomics studies, the extraction process is a crucial step—one which has been overlooked for a long time. In the presented study, a pressurized liquid extraction system was used to investigate the effect of extraction parameters such as pressure, temperature, number of cycles, and solvent polarity on the chemical diversity of the extract obtained from the marine sponge, Xestospongia. For this, a full factorial design (2⁴) was performed using a chemical diversity index, which was found to be a suitable tool to determine the efficiency of the extraction process, as the response variable. This index was calculated using a logarithmic transformation of ¹H NMR signals. Three factors (number of cycles, temperature, and solvent polarity) and two interactions were found to affect the chemical diversity of the obtained extracts significantly. Two individual factors (temperature and solvent polarity) were selected for further study on their influence on sponge metabolites using orthogonal partial least square (OPLS) modeling. Based on the results, the groups of compounds that were most influenced by these parameters were determined, and it was concluded that ethanol as the extraction solvent together with low temperatures were the conditions that provided a higher chemical diversity in the extract. Full article

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14 pages, 8316 KiB

Open AccessArticle

Fucoidan Inhibits Radiation-Induced Pneumonitis and Lung Fibrosis by Reducing Inflammatory Cytokine Expression in Lung Tissues

by Hsin-Hsien Yu, Edward Chengchuan KO, Chia-Lun Chang, Kevin Sheng-Po Yuan, Alexander T. H. Wu, Yan-Shen Shan and Szu-Yuan Wu

Mar. Drugs 2018, 16(10), 392; https://doi.org/10.3390/md16100392 - 19 Oct 2018

Cited by 48 | Viewed by 7992

Abstract

Purpose: Radiotherapy is a crucial treatment approach for many types of cancer. Radiation pneumonitis (RP) is one of the major complications in chest irradiation. Fucoidan is a sulfated polysaccharide found mainly in various species of brown seaweed. Recent studies have demonstrated the [...] Read more.

Purpose: Radiotherapy is a crucial treatment approach for many types of cancer. Radiation pneumonitis (RP) is one of the major complications in chest irradiation. Fucoidan is a sulfated polysaccharide found mainly in various species of brown seaweed. Recent studies have demonstrated the anti-inflammatory effects of fucoidan. However, no study has reported a well-established prophylactic agent for RP. Therefore, we investigated the effects of fucoidan on RP and radiotherapy (RT)-induced lung fibrosis. Materials and Methods: We compared RP and RT-induced fibrosis in lung tissue specimens obtained from irradiated (10 Gy/shot) C57BL/6 mice with or without fucoidan administration (200 mg/kg/day, oral gavage for 14 days). The expression patterns of cytokines in the pleural fluid were determined using a cytokine array and confirmed through enzyme immunoassays. Results: Fucoidan administration attenuated RP and RT-induced fibrosis in lung tissues. Decreased neutrophil and macrophage accumulation was observed in irradiated lung tissues, and radiation-induced lung fibrosis, as demonstrated by Masson trichrome staining, was attenuated. We investigated the expression patterns of inflammatory cytokines in the irradiated lung pleural fluid through the protein array; results revealed that fucoidan administration changed the expression patterns of inflammatory cytokines in irradiated lung tissues. Furthermore, the expression levels of TIMP-1, CXCL1, MCP-1, MIP-2, and interleukin-1Ra were substantially enhanced in the pleural fluid, but fucoidan administration significantly reduced their expression. Conclusions: Fucoidan changes the expression patterns of inflammatory cytokines, which may consequently attenuate RP and RT-induced lung fibrosis. Full article

(This article belongs to the Special Issue Development and Application of Herbal Medicine from Marine Origin)

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13 pages, 2565 KiB

Open AccessArticle

Characterization of MK₈(H₂) from Rhodococcus sp. B7740 and Its Potential Antiglycation Capacity Measurements

by Yashu Chen, Qin Mu, Kai Hu, Mo Chen, Jifang Yang, Jigang Chen, Bijun Xie and Zhida Sun

Mar. Drugs 2018, 16(10), 391; https://doi.org/10.3390/md16100391 - 18 Oct 2018

Cited by 7 | Viewed by 3630

Abstract

Menaquinone (MK) has an important role in human metabolism as an essential vitamin (VK₂), which is mainly produced through the fermentation of microorganisms. MK₈(H₂) was identified to be the main menaquinone from Rhodococcus sp. B7740, a bacterium [...] Read more.

Menaquinone (MK) has an important role in human metabolism as an essential vitamin (VK₂), which is mainly produced through the fermentation of microorganisms. MK₈(H₂) was identified to be the main menaquinone from Rhodococcus sp. B7740, a bacterium isolated from the arctic ocean. In this work, MK₈(H₂) (purity: 99.75%) was collected through a convenient and economic extraction process followed by high-speed countercurrent chromatography (HSCCC) purification. Additionally, high-resolution mass spectrometry (HRMS) was performed for further identification and the hydrogenation position of MK₈(H₂) (terminal unit) was determined using nuclear magnetic resonance (NMR) for the first time. MK₈(H₂) showed a superior antioxidant effect and antiglycation capacity compared with ubiquinone Q10 and MK₄. High-performance liquid chromatography–mass spectrometer (HPLC-MS/MS) and molecular docking showed the fine interaction between MK₈(H₂) with methylglyoxal (MGO) and bull serum albumin (BSA), respectively. These properties make MK₈(H₂) a promising natural active ingredient with future food and medicine applications. Full article

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12 pages, 1211 KiB

Open AccessArticle

¹H NMR Spectroscopy and MVA to Evaluate the Effects of Caulerpin-Based Diet on Diplodus sargus Lipid Profiles

by Laura Del Coco, Serena Felline, Chiara Roberta Girelli, Federica Angilè, Laura Magliozzi, Frederico Almada, Biagio D’Aniello, Ernesto Mollo, Antonio Terlizzi and Francesco P. Fanizzi

Mar. Drugs 2018, 16(10), 390; https://doi.org/10.3390/md16100390 - 18 Oct 2018

Cited by 19 | Viewed by 5348

Abstract

The biological invasion of the green algae Caulerpa cylindracea represents a serious scientific and public issue in the Mediterranean Sea, essentially due to strong modifications both to habitat structure and native benthic communities. Although alterations in health status and changes in flesh quality [...] Read more.

The biological invasion of the green algae Caulerpa cylindracea represents a serious scientific and public issue in the Mediterranean Sea, essentially due to strong modifications both to habitat structure and native benthic communities. Although alterations in health status and changes in flesh quality of some marine species (dietary exposed to C. cylindracea) have been observed, no studies on cause-effect relationships have been carried out. Here, for the first time, through a controlled feeding experiment followed by ¹H NMR Spectroscopy and multivariate analysis (PCA, OPLS-DA), we showed that caulerpin taken with diet is directly responsible of changes observed in metabolic profile of fish flesh, including alteration of lipid metabolism, in particular with a reduction of ω3 PUFA content. The potential of caulerpin to directly modulate lipid metabolism opens up new questions about causal mechanism triggered by algal metabolite also in view of a possible exploitation in the nutraceutical/medical field. Full article

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12 pages, 1905 KiB

Open AccessArticle

Structure and Anti-Inflammatory Activity of a New Unusual Fucosylated Chondroitin Sulfate from Cucumaria djakonovi

by Nadezhda E. Ustyuzhanina, Maria I. Bilan, Elena G. Panina, Nadezhda P. Sanamyan, Andrey S. Dmitrenok, Eugenia A. Tsvetkova, Natalia A. Ushakova, Alexander S. Shashkov, Nikolay E. Nifantiev and Anatolii I. Usov

Mar. Drugs 2018, 16(10), 389; https://doi.org/10.3390/md16100389 - 17 Oct 2018

Cited by 47 | Viewed by 5043

Abstract

Fucosylated chondroitin sulfate CD was isolated from the sea cucumber Cucumaria djakonovi collected from the Avachinsky Gulf of the eastern coast of Kamchatka. Structural characterization of CD was performed using a series of non-destructive NMR spectroscopic procedures. The polysaccharide was shown to contain [...] Read more.

Fucosylated chondroitin sulfate CD was isolated from the sea cucumber Cucumaria djakonovi collected from the Avachinsky Gulf of the eastern coast of Kamchatka. Structural characterization of CD was performed using a series of non-destructive NMR spectroscopic procedures. The polysaccharide was shown to contain a chondroitin core [→3)-β-d-GalNAc-(1→4)-β-d-GlcA-(1→]_n where about 60% of GlcA residues were 3-O-fucosylated, while another part of GlcA units did not contain any substituents. The presence of unsubstituted both at O-2 and O-3 glucuronic acid residues in a structure of holothurian chondroitin sulfate is unusual and has not been reported previously. Three different fucosyl branches Fucp2S4S, Fucp3S4S and Fucp4S were found in the ratio of 2:1:1. The GalNAc units were mono- or disulfated at positions 4 and 6. Anti-inflammatory activity of CD was assessed on a model of acute peritoneal inflammation in rats. About 45% inhibition was found for CD, while a structurally related linear chondroitin sulfate SS from cartilage of the fish Salmo salar demonstrated only 31% inhibition, indicating that the presence of sulfated fucosyl branches is essential for anti-inflammatory effect of chondroitin sulfates of marine origin. Full article

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12 pages, 2915 KiB

Open AccessArticle

For a Correct Application of the CD Exciton Chirality Method: The Case of Laucysteinamide A

by Gennaro Pescitelli

Mar. Drugs 2018, 16(10), 388; https://doi.org/10.3390/md16100388 - 16 Oct 2018

Cited by 13 | Viewed by 3675

Abstract

The circular dichroism (CD) exciton chirality method (ECM) is a very popular approach for assigning the absolute configuration (AC) of natural products, thanks to its immediacy and ease of application. The sign of an exciton couplet (two electronic CD bands with opposite sign [...] Read more.

The circular dichroism (CD) exciton chirality method (ECM) is a very popular approach for assigning the absolute configuration (AC) of natural products, thanks to its immediacy and ease of application. The sign of an exciton couplet (two electronic CD bands with opposite sign and similar intensity) can be directly correlated with the molecular stereochemistry, including the AC. However, a correct application of the ECM necessitates several prerequisites: knowledge of the molecular conformation; knowledge of transition moment direction; and preeminence of the exciton coupling mechanism with respect to other sources of CD signals. In recent years, by using quantum-chemical CD calculations, we have demonstrated that some previous applications of ECM were wrong or based on incorrect assumptions. In a recent publication of this journal (Mar. Drugs, 2017, 15(4), 121), the ECM was employed to assign the AC of a marine metabolite, laucysteinamide A. This is a further case of incorrect application of the method, where none of the aforementioned prerequisites is fully met. Using this example, we will discuss the criteria required for a correct application of the ECM. Full article

(This article belongs to the Special Issue Advances in Marine Natural Product Characterisation and Separation Methodologies)

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15 pages, 5918 KiB

Open AccessArticle

Sandensolide Induces Oxidative Stress-Mediated Apoptosis in Oral Cancer Cells and in Zebrafish Xenograft Model

by Chung-I Yu, Chung-Yi Chen, Wangta Liu, Po-Chih Chang, Chiung-Wei Huang, Kuang-Fen Han, In-Pin Lin, Mei-Ying Lin and Chien-Hsing Lee

Mar. Drugs 2018, 16(10), 387; https://doi.org/10.3390/md16100387 - 16 Oct 2018

Cited by 30 | Viewed by 4232

Abstract

Presently, natural sources and herbs are being sought for the treatment of human oral squamous cell carcinoma (OSCC) in order to alleviate the side effects of chemotherapy. This study investigates the effect of sandensolide, a cembrane isolated from Sinularia flexibilis, to inhibit [...] Read more.

Presently, natural sources and herbs are being sought for the treatment of human oral squamous cell carcinoma (OSCC) in order to alleviate the side effects of chemotherapy. This study investigates the effect of sandensolide, a cembrane isolated from Sinularia flexibilis, to inhibit human OSCC cell growth with the aim of developing a new drug for the treatment of oral cancer. In vitro cultured human OSCC models (Ca9.22, SCC9 and HSC-3 cell lines) and oral normal cells (HGF-1), as well as a zebrafish xenograft model, were used to test the cytotoxicity of sandensolide (MTT assay), as well as to perform cell cycle analysis and Western blotting. Both the in vitro bioassay and the zebrafish xenograft model demonstrated the anti-oral cancer effect of sandensolide. Moreover, sandensolide was able to significantly suppress colony formation and induce apoptosis, as well as cell cycle arrest, in OSCC by regulating multiple key proteins. Induction of reactive oxygen species (ROS) was observed in sandensolide-treated oral cancer cells. However, these apoptotic changes were rescued by NAC pretreatment. These findings contribute to the knowledge of the model of action of sandensolide, which may induce oxidative stress-mediated cell death pathways as a potential agent in oral cancer therapeutics. Full article

(This article belongs to the Special Issue Antitumor Compounds from Marine Invertebrates)

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32 pages, 5604 KiB

Open AccessArticle

Kororamides, Convolutamines, and Indole Derivatives as Possible Tau and Dual-Specificity Kinase Inhibitors for Alzheimer’s Disease: A Computational Study

by Laura Llorach-Pares, Alfons Nonell-Canals, Conxita Avila and Melchor Sanchez-Martinez

Mar. Drugs 2018, 16(10), 386; https://doi.org/10.3390/md16100386 - 16 Oct 2018

Cited by 28 | Viewed by 4662

Abstract

Alzheimer’s disease (AD) is becoming one of the most disturbing health and socioeconomic problems nowadays, as it is a neurodegenerative pathology with no treatment, which is expected to grow further due to population ageing. Actual treatments for AD produce only a modest amelioration [...] Read more.

Alzheimer’s disease (AD) is becoming one of the most disturbing health and socioeconomic problems nowadays, as it is a neurodegenerative pathology with no treatment, which is expected to grow further due to population ageing. Actual treatments for AD produce only a modest amelioration of symptoms, although there is a constant ongoing research of new therapeutic strategies oriented to improve the amelioration of the symptoms, and even to completely cure the disease. A principal feature of AD is the presence of neurofibrillary tangles (NFT) induced by the aberrant phosphorylation of the microtubule-associated protein tau in the brains of affected individuals. Glycogen synthetase kinase-3 beta (GSK3β), casein kinase 1 delta (CK1δ), dual-specificity tyrosine phosphorylation regulated kinase 1A (DYRK1A) and dual-specificity kinase cdc2-like kinase 1 (CLK1) have been identified as the principal proteins involved in this process. Due to this, the inhibition of these kinases has been proposed as a plausible therapeutic strategy to fight AD. In this study, we tested in silico the inhibitory activity of different marine natural compounds, as well as newly-designed molecules from some of them, over the mentioned protein kinases, finding some new possible inhibitors with potential therapeutic application. Full article

(This article belongs to the Special Issue Screening for Marine Natural Products with Potential as Chemotherapeutics)

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24 pages, 9108 KiB

Open AccessArticle

New Mammalian Target of Rapamycin (mTOR) Modulators Derived from Natural Product Databases and Marine Extracts by Using Molecular Docking Techniques

by Verónica Ruiz-Torres, Maria Losada-Echeberría, Maria Herranz-López, Enrique Barrajón-Catalán, Vicente Galiano, Vicente Micol and José Antonio Encinar

Mar. Drugs 2018, 16(10), 385; https://doi.org/10.3390/md16100385 - 15 Oct 2018

Cited by 25 | Viewed by 7197

Abstract

Mammalian target of rapamycin (mTOR) is a PI3K-related serine/threonine protein kinase that functions as a master regulator of cellular growth and metabolism, in response to nutrient and hormonal stimuli. mTOR functions in two distinct complexes—mTORC1 is sensitive to rapamycin, while, mTORC2 is insensitive [...] Read more.

Mammalian target of rapamycin (mTOR) is a PI3K-related serine/threonine protein kinase that functions as a master regulator of cellular growth and metabolism, in response to nutrient and hormonal stimuli. mTOR functions in two distinct complexes—mTORC1 is sensitive to rapamycin, while, mTORC2 is insensitive to this drug. Deregulation of mTOR’s enzymatic activity has roles in cancer, obesity, and aging. Rapamycin and its chemical derivatives are the only drugs that inhibit the hyperactivity of mTOR, but numerous side effects have been described due to its therapeutic use. The purpose of this study was to identify new compounds of natural origin that can lead to drugs with fewer side effects. We have used computational techniques (molecular docking and calculated ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) parameters) that have enabled the selection of candidate compounds, derived from marine natural products, SuperNatural II, and ZINC natural products, for inhibitors targeting, both, the ATP and the rapamycin binding sites of mTOR. We have shown experimental evidence of the inhibitory activity of eleven selected compounds against mTOR. We have also discovered the inhibitory activity of a new marine extract against this enzyme. The results have been discussed concerning the necessity to identify new molecules for therapeutic use, especially against aging, and with fewer side effects. Full article

(This article belongs to the Special Issue Marine Small-Molecule Bioactive Agents and Therapeutic Targets)

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19 pages, 16325 KiB

Open AccessArticle

A Structure- and Ligand-Based Virtual Screening of a Database of “Small” Marine Natural Products for the Identification of “Blue” Sigma-2 Receptor Ligands

by Giuseppe Floresta, Emanuele Amata, Carla Barbaraci, Davide Gentile, Rita Turnaturi, Agostino Marrazzo and Antonio Rescifina

Mar. Drugs 2018, 16(10), 384; https://doi.org/10.3390/md16100384 - 14 Oct 2018

Cited by 29 | Viewed by 5377

Abstract

Sigma receptors are a fascinating receptor protein class whose ligands are actually under clinical evaluation for the modulation of opioid analgesia and their use as positron emission tomography radiotracers. In particular, peculiar biological and therapeutic functions are associated with the sigma-2 (σ₂ [...] Read more.

Sigma receptors are a fascinating receptor protein class whose ligands are actually under clinical evaluation for the modulation of opioid analgesia and their use as positron emission tomography radiotracers. In particular, peculiar biological and therapeutic functions are associated with the sigma-2 (σ₂) receptor. The σ₂ receptor ligands determine tumor cell death through apoptotic and non-apoptotic pathways, and the overexpression of σ₂ receptors in several tumor cell lines has been well documented, with significantly higher levels in proliferating tumor cells compared to quiescent ones. This acknowledged feature has found practical application in the development of cancer cell tracers and for ligand-targeting therapy. In this context, the development of new ligands that target the σ₂ receptors is beneficial for those diseases in which this protein is involved. In this paper, we conducted a search of new potential σ₂ receptor ligands among a database of 1517 “small” marine natural products constructed by the union of the Seaweed Metabolite and the Chemical Entities of Biological Interest (ChEBI) Databases. The structures were passed through two filters that were constituted by our developed two-dimensional (2D) and three-dimensional Quantitative Structure-Activity Relationship (3D-QSAR) statistical models, and successively docked upon a σ₂ receptor homology model that we built according to the FASTA sequence of the σ₂/TMEM97 (SGMR2_HUMAN) receptor. Full article

(This article belongs to the Special Issue Marine Small-Molecule Bioactive Agents and Therapeutic Targets)

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12 pages, 2794 KiB

Open AccessArticle

Anticancer Activity of Fascaplysin against Lung Cancer Cell and Small Cell Lung Cancer Circulating Tumor Cell Lines

by Barbara Rath, Maximilian Hochmair, Adelina Plangger and Gerhard Hamilton

Mar. Drugs 2018, 16(10), 383; https://doi.org/10.3390/md16100383 - 14 Oct 2018

Cited by 33 | Viewed by 5999

Abstract

Lung cancer is a leading cause of tumor-associated mortality. Fascaplysin, a bis-indole of a marine sponge, exhibit broad anticancer activity as specific CDK4 inhibitor among several other mechanisms, and is investigated as a drug to overcome chemoresistance after the failure of targeted agents [...] Read more.

Lung cancer is a leading cause of tumor-associated mortality. Fascaplysin, a bis-indole of a marine sponge, exhibit broad anticancer activity as specific CDK4 inhibitor among several other mechanisms, and is investigated as a drug to overcome chemoresistance after the failure of targeted agents or immunotherapy. The cytotoxic activity of fascaplysin was studied using lung cancer cell lines, primary Non-Small Cell Lung Cancer (NSCLC) and Small Cell Lung Cancer (SCLC) cells, as well as SCLC circulating tumor cell lines (CTCs). This compound exhibited high activity against SCLC cell lines (mean IC₅₀ 0.89 µM), as well as SCLC CTCs as single cells and in the form of tumorospheres (mean IC₅₀ 0.57 µM). NSCLC lines showed a mean IC₅₀ of 1.15 µM for fascaplysin. Analysis of signal transduction mediators point to an ATM-triggered signaling cascade provoked by drug-induced DNA damage. Fascaplysin reveals at least an additive cytotoxic effect with cisplatin, which is the mainstay of lung cancer chemotherapy. In conclusion, fascaplysin shows high activity against lung cancer cell lines and spheroids of SCLC CTCs which are linked to the dismal prognosis of this tumor type. Derivatives of fascaplysin may constitute valuable new agents for the treatment of lung cancer. Full article

(This article belongs to the Collection Marine Compounds and Cancer)

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14 pages, 952 KiB

Open AccessArticle

New Sulfur-Containing Polyarsenicals from the New Caledonian Sponge Echinochalina bargibanti

by Petri Tähtinen, Graziano Guella, Giacomo Saielli, Cécile Debitus, Edouard Hnawia and Ines Mancini

Mar. Drugs 2018, 16(10), 382; https://doi.org/10.3390/md16100382 - 11 Oct 2018

Cited by 6 | Viewed by 3826

Abstract

Arsenicin A (C₃H₆As₄O₃) was isolated from the New Caledonian poecilosclerid sponge Echinochalina bargibanti, and described as the first natural organic polyarsenic compound. Further bioguided fractionation of the extracts of this sponge led us to [...] Read more.

Arsenicin A (C₃H₆As₄O₃) was isolated from the New Caledonian poecilosclerid sponge Echinochalina bargibanti, and described as the first natural organic polyarsenic compound. Further bioguided fractionation of the extracts of this sponge led us to isolate the first sulfur-containing organic polyarsenicals ever found in Nature. These metabolites, called arsenicin B and arsenicin C, are built on a noradamantane-type framework that is characterized by an unusual As–As bonding. Extensive NMR measurements, in combination with mass spectra, enabled the assignment of the structure for arsenicin B (C₃H₆As₄S₂) as 2. The scarcity of arsenicin C and its intrinsic chemical instability only allowed the collection of partial spectral data, which prevented the full structural definition. After the extensive computational testing of several putative structures, structure 3 was inferred for arsenicin C (C₃H₆As₄OS) by comparing the experimental and density functional theory (DFT)-calculated ¹H and ¹³C NMR spectra. Finally, the absolute configurations of 2 and 3 were determined with a combined use of experimental and time-dependent (TD)-DFT calculated electronic circular dichroism (ECD) spectra and observed specific rotations. These findings pose great challenges for the investigation of the biosynthesis of these metabolites and the cycle of arsenic in Nature. Arsenicins B and C showed strong antimicrobial activities, especially against S. aureus, which is comparable to the reference compound gentamycin. Full article

(This article belongs to the Special Issue Bioactive Compounds from Marine Sponges)

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17 pages, 6270 KiB

Open AccessArticle

Massive Gene Expansion and Sequence Diversification Is Associated with Diverse Tissue Distribution, Regulation and Antimicrobial Properties of Anti-Lipopolysaccharide Factors in Shrimp

by Gabriel Machado Matos, Paulina Schmitt, Cairé Barreto, Natanael Dantas Farias, Guilherme Toledo-Silva, Fanny Guzmán, Delphine Destoumieux-Garzón, Luciane Maria Perazzolo and Rafael Diego Rosa

Mar. Drugs 2018, 16(10), 381; https://doi.org/10.3390/md16100381 - 11 Oct 2018

Cited by 30 | Viewed by 4704

Abstract

Anti-lipopolysaccharide factors (ALFs) are antimicrobial peptides with a central β-hairpin structure able to bind to microbial components. Mining sequence databases for ALFs allowed us to show the remarkable diversity of ALF sequences in shrimp. We found at least seven members of the ALF [...] Read more.

Anti-lipopolysaccharide factors (ALFs) are antimicrobial peptides with a central β-hairpin structure able to bind to microbial components. Mining sequence databases for ALFs allowed us to show the remarkable diversity of ALF sequences in shrimp. We found at least seven members of the ALF family (Groups A to G), including two novel Groups (F and G), all of which are encoded by different loci with conserved gene organization. Phylogenetic analyses revealed that gene expansion and subsequent diversification of the ALF family occurred in crustaceans before shrimp speciation occurred. The transcriptional profile of ALFs was compared in terms of tissue distribution, response to two pathogens and during shrimp development in Litopenaeus vannamei, the most cultivated species. ALFs were found to be constitutively expressed in hemocytes and to respond differently to tissue damage. While synthetic β-hairpins of Groups E and G displayed both antibacterial and antifungal activities, no activity was recorded for Group F β-hairpins. Altogether, our results showed that ALFs form a family of shrimp AMPs that has been the subject of intense diversification. The different genes differ in terms of tissue expression, regulation and function. These data strongly suggest that multiple selection pressures have led to functional diversification of ALFs in shrimp. Full article

(This article belongs to the Special Issue Marine Bioactive Peptides: Structure, Function, and Therapeutic Potential)

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11 pages, 2137 KiB

Open AccessArticle

Synthesis of Novel Chitin Derivatives Bearing Amino Groups and Evaluation of Their Antifungal Activity

by Jingjing Zhang, Fang Luan, Qing Li, Guodong Gu, Fang Dong and Zhanyong Guo

Mar. Drugs 2018, 16(10), 380; https://doi.org/10.3390/md16100380 - 11 Oct 2018

Cited by 6 | Viewed by 3136

Abstract

Chemical modification is one of the most effective methods to improve the biological activity of chitin. In the current study, we modified C3-OH and C6-OH of chitin (CT) and successfully synthesized 6-amino-chitin (NCT) and 3,6-diamino-chitin (DNCT) through a series of chemical reactions. The [...] Read more.

Chemical modification is one of the most effective methods to improve the biological activity of chitin. In the current study, we modified C3-OH and C6-OH of chitin (CT) and successfully synthesized 6-amino-chitin (NCT) and 3,6-diamino-chitin (DNCT) through a series of chemical reactions. The structure of NCT and DNCT were characterized by elemental analyses, FT-IR, ¹³C NMR, XRD, and SEM. The inhibitory effects of CT, NCT, and DNCT against six kinds of phytopathogen (F. oxysporum f. sp. cucumerium, B. cinerea, C. lagenarium, P. asparagi, F. oxysporum f. niveum, and G. zeae) were evaluated using disk diffusion method in vitro. Meanwhile, carbendazim and amphotericin B were used as positive controls. Results revealed that 6-amino-chitin (NCT) and 3,6-diamino-chitin (DNCT) showed improved antifungal properties compared with pristine chitin. Moreover, DNCT exhibited the better antifungal property than NCT. Especially, while the inhibition zone diameters of NCT are ranged from 11.2 to 16.3 mm, DNCT are about 11.4–20.4 mm. These data demonstrated that the introduction of amino group into chitin derivatives could be key to increasing the antifungal activity of such compounds, and the greater the number of amino groups in the chitin derivatives, the better their antifungal activity was. Full article

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22 pages, 550 KiB

Open AccessArticle

Fatty Acid Composition and Fatty Acid Associated Gene-Expression in Gilthead Sea Bream (Sparus aurata) are Affected by Low-Fish Oil Diets, Dietary Resveratrol, and Holding Temperature

by Claudia Torno, Stefanie Staats, Stéphanie Céline Michl, Sonia De Pascual-Teresa, Marisol Izquierdo, Gerald Rimbach and Carsten Schulz

Mar. Drugs 2018, 16(10), 379; https://doi.org/10.3390/md16100379 - 10 Oct 2018

Cited by 22 | Viewed by 4302

Abstract

To sustainably produce marine fish with a high lipid quality rich in omega-3 fatty acids, alternative sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are being identified. Moreover, the use of bioactive compounds that would stimulate the in vivo fatty acid synthesis, [...] Read more.

To sustainably produce marine fish with a high lipid quality rich in omega-3 fatty acids, alternative sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are being identified. Moreover, the use of bioactive compounds that would stimulate the in vivo fatty acid synthesis, such as resveratrol (RV), would reduce the dependence on fish oil in aquafeeds. Gilthead sea bream (Sparus aurata) were fed four experimental diets combining two fish oil levels (6% dry matter (DM); 2% DM) with or without 0.15% DM resveratrol supplementation (F6, F2, F6 + RV, F2 + RV) for two months. Additionally, the fish were challenged either at 19 °C or 23 °C. A higher water temperature promoted their feed intake and growth, resulting in an increased crude lipid content irrespective of dietary treatment. The fatty acid composition of different tissues was significantly affected by the holding temperature and dietary fish oil level. The dietary RV significantly affected the hepatic EPA and DHA content of fish held at 19 °C. The observed effect of RV may be partly explained by alterations of the mRNA steady-state levels of ∆6-desaturase and β-oxidation-related genes. Besides the relevant results concerning RV-mediated regulation of fatty acid synthesis in marine fish, further studies need to be conducted to clarify the potential value of RV to enhance fillet lipid quality. Full article

(This article belongs to the Special Issue The Sources and Production of Polyunsaturated Fatty Acids)

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22 pages, 3796 KiB

Open AccessArticle

Fucoxanthin-Containing Cream Prevents Epidermal Hyperplasia and UVB-Induced Skin Erythema in Mice

by Azahara Rodríguez-Luna, Javier Ávila-Román, María Luisa González-Rodríguez, María José Cózar, Antonio M Rabasco, Virginia Motilva and Elena Talero

Mar. Drugs 2018, 16(10), 378; https://doi.org/10.3390/md16100378 - 10 Oct 2018

Cited by 66 | Viewed by 6843

Abstract

Microalgae represent a source of bio-active compounds such as carotenoids with potent anti-inflammatory and antioxidant properties. We aimed to investigate the effects of fucoxanthin (FX) in both in vitro and in vivo skin models. Firstly, its anti-inflammatory activity was evaluated in LPS-stimulated THP-1 [...] Read more.

Microalgae represent a source of bio-active compounds such as carotenoids with potent anti-inflammatory and antioxidant properties. We aimed to investigate the effects of fucoxanthin (FX) in both in vitro and in vivo skin models. Firstly, its anti-inflammatory activity was evaluated in LPS-stimulated THP-1 macrophages and TNF-α-stimulated HaCaT keratinocytes, and its antioxidant activity in UVB-irradiated HaCaT cells. Next, in vitro and ex vivo permeation studies were developed to determine the most suitable formulation for in vivo FX topical application. Then, we evaluated the effects of a FX-containing cream on TPA-induced epidermal hyperplasia in mice, as well as on UVB-induced acute erythema in hairless mice. Our results confirmed the in vitro reduction of TNF-α, IL-6, ROS and LDH production. Since the permeation results showed that cream was the most favourable vehicle, FX-cream was elaborated. This formulation effectively ameliorated TPA-induced hyperplasia, by reducing skin edema, epidermal thickness, MPO activity and COX-2 expression. Moreover, FX-cream reduced UVB-induced erythema through down-regulation of COX-2 and iNOS as well as up-regulation of HO-1 protein via Nrf-2 pathway. In conclusion, FX, administered in a topical formulation, could be a novel natural adjuvant for preventing exacerbations associated with skin inflammatory pathologies as well as protecting skin against UV radiation. Full article

(This article belongs to the Special Issue Marine Anti-inflammatory Agents)

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14 pages, 3080 KiB

Open AccessArticle

A Novel Natural Influenza A H1N1 Virus Neuraminidase Inhibitory Peptide Derived from Cod Skin Hydrolysates and Its Antiviral Mechanism

by Jianpeng Li, Yiping Chen, Ning Yuan, Mingyong Zeng, Yuanhui Zhao, Rilei Yu, Zunying Liu, Haohao Wu and Shiyuan Dong

Mar. Drugs 2018, 16(10), 377; https://doi.org/10.3390/md16100377 - 10 Oct 2018

Cited by 9 | Viewed by 4105

Abstract

In this paper, a novel natural influenza A H1N1 virus neuraminidase (NA) inhibitory peptide derived from cod skin hydrolysates was purified and its antiviral mechanism was explored. From the hydrolysates, novel efficient NA-inhibitory peptides were purified by a sequential approach utilizing an ultrafiltration [...] Read more.

In this paper, a novel natural influenza A H1N1 virus neuraminidase (NA) inhibitory peptide derived from cod skin hydrolysates was purified and its antiviral mechanism was explored. From the hydrolysates, novel efficient NA-inhibitory peptides were purified by a sequential approach utilizing an ultrafiltration membrane (5000 Da), sephadex G-15 gel column and reverse-phase high-performance liquid chromatography (RP-HPLC). The amino acid sequence of the pure peptide was determined by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) was PGEKGPSGEAGTAGPPGTPGPQGL, with a molecular weight of 2163 Da. The analysis of the Lineweacer–Burk model indicated that the peptide was a competitive NA inhibitor with Ki of 0.29 mM and could directly bind free enzymes. In addition, docking studies suggested that hydrogen binding might be the driving force for the binding affinity of PGEKGPSGEAGTAGPPGTPGPQGL to NA. The cytopathic effect reduction assay showed that the peptide PGEKGPSGEAGTAGPPGTPGPQGL protected Madin–Darby canine kidney (MDCK) cells from viral infection and reduced the viral production in a dose-dependent manner. The EC₅₀ value was 471 ± 12 μg/mL against H1N1. Time-course analysis showed that PGEKGPSGEAGTAGPPGTPGPQGL inhibited influenza virus in the early stage of the infectious cycle. The virus titers assay indicated that the NA-inhibitory peptide PGEKGPSGEAGTAGPPGTPGPQGL could directly affect the virus toxicity and adsorption by host cells, further proving that the peptide had an anti-viral effect with multiple target sites. The activity of NA-inhibitory peptide was almost inactivated during the simulated in vitro gastrointestinal digestion, suggesting that oral administration is not recommended. The peptide PGEKGPSGEAGTAGPPGTPGPQGL acts as a neuraminidase blocker to inhibit influenza A virus in MDCK cells. Thus, the peptide PGEKGPSGEAGTAGPPGTPGPQGL has potential utility in the treatment of the influenza virus infection. Full article

(This article belongs to the Special Issue Marine Bioactive Peptides: Structure, Function, and Therapeutic Potential)

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11 pages, 2491 KiB

Open AccessArticle

Exploitation of Mangrove Endophytic Fungi for Infectious Disease Drug Discovery

by Danielle H. Demers, Matthew A. Knestrick, Renee Fleeman, Rahmy Tawfik, Ala Azhari, Ashley Souza, Brian Vesely, Mandy Netherton, Rashmi Gupta, Beatrice L. Colon, Christopher A. Rice, Mario A. Rodríguez-Pérez, Kyle H. Rohde, Dennis E. Kyle, Lindsey N. Shaw and Bill J. Baker

Mar. Drugs 2018, 16(10), 376; https://doi.org/10.3390/md16100376 - 10 Oct 2018

Cited by 22 | Viewed by 7410

Abstract

There is an acute need for new and effective agents to treat infectious diseases. We conducted a screening program to assess the potential of mangrove-derived endophytic fungi as a source of new antibiotics. Fungi cultured in the presence and absence of small molecule [...] Read more.

There is an acute need for new and effective agents to treat infectious diseases. We conducted a screening program to assess the potential of mangrove-derived endophytic fungi as a source of new antibiotics. Fungi cultured in the presence and absence of small molecule epigenetic modulators were screened against Mycobacterium tuberculosis and the ESKAPE panel of bacterial pathogens, as well as two eukaryotic infective agents, Leishmania donovani and Naegleria fowleri. By comparison of bioactivity data among treatments and targets, trends became evident, such as the result that more than 60% of active extracts were revealed to be selective to a single target. Validating the technique of using small molecules to dysregulate secondary metabolite production pathways, nearly half (44%) of those fungi producing active extracts only did so following histone deacetylase inhibitory (HDACi) or DNA methyltransferase inhibitory (DNMTi) treatment. Full article

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15 pages, 5215 KiB

Open AccessArticle

Diphlorethohydroxycarmalol Isolated from Ishige okamurae Represses High Glucose-Induced Angiogenesis In Vitro and In Vivo

by K. H. N. Fernando, Hye-Won Yang, Yunfei Jiang, You-Jin Jeon and BoMi Ryu

Mar. Drugs 2018, 16(10), 375; https://doi.org/10.3390/md16100375 - 10 Oct 2018

Cited by 32 | Viewed by 4510

Abstract

Diabetes mellitus causes abnormalities of angiogenesis leading to vascular dysfunction and serious pathologies. Diphlorethohydroxycarmalol (DPHC), which is isolated from Ishige okamurae, is well known for its bioactivities, including antihyperglycemic and protective functions against diabetes-related pathologies. In the present study, the inhibitory effect [...] Read more.

Diabetes mellitus causes abnormalities of angiogenesis leading to vascular dysfunction and serious pathologies. Diphlorethohydroxycarmalol (DPHC), which is isolated from Ishige okamurae, is well known for its bioactivities, including antihyperglycemic and protective functions against diabetes-related pathologies. In the present study, the inhibitory effect of DPHC on high glucose-induced angiogenesis was investigated on the human vascular endothelial cell line EA.hy926. DPHC inhibited the cell proliferation, cell migration, and tube formation in cells exposed to 30 mM of glucose to induce angiogenesis. Furthermore, the effect of DPHC against high glucose-induced angiogenesis was evaluated in zebrafish embryos. The treatment of embryos with DPHC suppressed high glucose-induced dilation in the retinal vessel diameter and vessel formation. Moreover, DPHC could inhibit high glucose-induced vascular endothelial growth factor receptor 2 (VEGFR-2) expression and its downstream signaling cascade. Overall, these findings suggest that DPHC is actively involved in the suppression of high glucose-induced angiogenesis. Hence, DPHC is a potential agent for the development of therapeutics against angiogenesis induced by diabetes. Full article

(This article belongs to the Special Issue Seaweeds and Their Biological Actions)

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13 pages, 2681 KiB

Open AccessArticle

Meroterpenoid-Rich Fraction of the Ethanolic Extract from Sargassum serratifolium Suppressed Oxidative Stress Induced by Tert-Butyl Hydroperoxide in HepG2 Cells

by Sujin Lim, Misung Kwon, Eun-Ji Joung, Taisun Shin, Chul-Woong Oh, Jae Sue Choi and Hyeung-Rak Kim

Mar. Drugs 2018, 16(10), 374; https://doi.org/10.3390/md16100374 - 9 Oct 2018

Cited by 18 | Viewed by 3718

Abstract

Sargassum species have been reported to be a source of phytochemicals, with a wide range of biological activities. In this study, we evaluated the hepatoprotective effect of a meroterpenoid-rich fraction of the ethanolic extract from Sargassum serratifolium (MES) against tert-butyl hydroperoxide ( [...] Read more.

Sargassum species have been reported to be a source of phytochemicals, with a wide range of biological activities. In this study, we evaluated the hepatoprotective effect of a meroterpenoid-rich fraction of the ethanolic extract from Sargassum serratifolium (MES) against tert-butyl hydroperoxide (t-BHP)-treated HepG2 cells. Treatment with MES recovered the cell viability from the t-BHP-induced oxidative damage in a dose-dependent manner. It suppressed the reactive oxygen species production, lipid peroxidation, and glutathione depletion in the t-BHP-treated HepG2 cells. The activity of the antioxidants induced by t-BHP, including superoxide dismutase (SOD) and catalase, was reduced by the MES treatment. Moreover, it increased the nuclear translocation of nuclear factor erythroid 2-related factor 2, leading to the enhanced activity of glutathione S transferase, and the increased production of heme oxygenase-1 and NAD(P)H:quinine oxidoreductase 1 in t-BHP-treated HepG2 cells. These results demonstrate that the antioxidant activity of MES substituted the activity of the SOD and catalase, and induced the production of detoxifying enzymes, indicating that MES might be used as a hepatoprotectant against t-BHP-induced oxidative stress. Full article

(This article belongs to the Special Issue Marine Antioxidant)

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23 pages, 2175 KiB

Open AccessReview

Chitosan-Based In Situ Gels for Ocular Delivery of Therapeutics: A State-of-the-Art Review

by Teodora Irimia, Cristina-Elena Dinu-Pîrvu, Mihaela Violeta Ghica, Dumitru Lupuleasa, Daniela-Lucia Muntean, Denisa Ioana Udeanu and Lăcrămioara Popa

Mar. Drugs 2018, 16(10), 373; https://doi.org/10.3390/md16100373 - 9 Oct 2018

Cited by 111 | Viewed by 8511

Abstract

Ocular in situ gels are a promising alternative to overcome drawbacks of conventional eye drops because they associate the advantages of solutions such as accuracy and reproducibility of dosing, or ease of administration with prolonged contact time of ointments. Chitosan is a natural [...] Read more.

Ocular in situ gels are a promising alternative to overcome drawbacks of conventional eye drops because they associate the advantages of solutions such as accuracy and reproducibility of dosing, or ease of administration with prolonged contact time of ointments. Chitosan is a natural polymer suitable for use in ophthalmic formulations due to its biocompatibility, biodegradability, mucoadhesive character, antibacterial and antifungal properties, permeation enhancement and corneal wound healing effects. The combination of chitosan, pH-sensitive polymer, with other stimuli-responsive polymers leads to increased mechanical strength of formulations and an improved therapeutic effect due to prolonged ocular contact time. This review describes in situ gelling systems resulting from the association of chitosan with various stimuli-responsive polymers with emphasis on the mechanism of gel formation and application in ophthalmology. It also comprises the main techniques for evaluation of chitosan in situ gels, along with requirements of safety and ocular tolerability. Full article

(This article belongs to the Special Issue Marine Biopolymers and Drug Delivery)

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12 pages, 2214 KiB

Open AccessFeature PaperArticle

Optimization of Growth and Carotenoid Production by Haloferax mediterranei Using Response Surface Methodology

by Zaida Montero-Lobato, Adrián Ramos-Merchante, Juan Luis Fuentes, Ana Sayago, Ángeles Fernández-Recamales, Rosa María Martínez-Espinosa, José María Vega, Carlos Vílchez and Inés Garbayo

Mar. Drugs 2018, 16(10), 372; https://doi.org/10.3390/md16100372 - 9 Oct 2018

Cited by 34 | Viewed by 5459

Abstract

Haloferax mediterranei produces C50 carotenoids that have strong antioxidant properties. The response surface methodology (RSM) tool helps to accurately analyze the most suitable conditions to maximize C50 carotenoids production by haloarchaea. The effects of temperature (15–50 °C), pH (4−10), and salinity (5–28% NaCl [...] Read more.

Haloferax mediterranei produces C50 carotenoids that have strong antioxidant properties. The response surface methodology (RSM) tool helps to accurately analyze the most suitable conditions to maximize C50 carotenoids production by haloarchaea. The effects of temperature (15–50 °C), pH (4−10), and salinity (5–28% NaCl (w/v)) on the growth and carotenoid content of H. mediterranei were analyzed using the RSM approach. Growth was determined by measuring the turbidity at 600 nm. To determine the carotenoid content, harvested cells were lysed by freeze/thawing, then re-suspended in acetone and the total carotenoid content determined by measuring the absorbance at 494 nm. The analysis of carotenoids was performed by an HPLC system coupled with mass spectrometry. The results indicated the theoretical optimal conditions of 36.51 or 36.81 °C, pH of 8.20 or 8.96, and 15.01% or 12.03% (w/v) salinity for the growth of haloarchaea (OD600 = 12.5 ± 0.64) and production of total carotenoids (3.34 ± 0.29 mg/L), respectively. These conditions were validated experimentally for growth (OD600 = 13.72 ± 0.98) and carotenoid production (3.74 ± 0.20 mg/L). The carotenoid profile showed four isomers of bacterioruberin (89.13%). Our findings suggest that the RSM approach is highly useful for determining optimal conditions for large-scale production of bacterioruberin by haloarchaea. Full article

(This article belongs to the Special Issue Marine Bacteria as Sources of Bioactive Compounds)

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11 pages, 1313 KiB

Open AccessArticle

New 3-Hydroxyquinaldic Acid Derivatives from Cultures of the Marine Derived Actinomycete Streptomyces cyaneofuscatus M-157

by Francisco Javier Ortiz-López, Elsa Alcalde, Aida Sarmiento-Vizcaíno, Caridad Díaz, Bastien Cautain, Luis A. García, Gloria Blanco and Fernando Reyes

Mar. Drugs 2018, 16(10), 371; https://doi.org/10.3390/md16100371 - 8 Oct 2018

Cited by 23 | Viewed by 5118

Abstract

Fractionation of the bioactive extract of a culture of the marine derived actinomycete Streptomyces cyaneofuscatus M-157 led to the isolation of the known 3-hydroxyquinaldic acid (4), its amide (5) and three new derivatives (1–3) containing [...] Read more.

Fractionation of the bioactive extract of a culture of the marine derived actinomycete Streptomyces cyaneofuscatus M-157 led to the isolation of the known 3-hydroxyquinaldic acid (4), its amide (5) and three new derivatives (1–3) containing different amino acid residues. The structures of the new molecules (1–3), including their absolute configuration, were determined by the analysis of their ESI-TOF MS and one-dimensional (1D) and two-dimensional (2D) NMR spectra and advanced Marfey’s analysis of their hydrolyzation products. Compound 3 spontaneously dimerized in solution to give the disulfide derivative 6. Unfortunately, none of the new compounds isolated confirmed the antimicrobial activity found in the bacterial extract, perhaps indicating that such antibacterial activity might be due to presence in the extract at the trace level of larger bioactive 3-hydroxyquinaldic acid derivatives from which compounds 1–3 are biosynthetic precursors. Cytotoxicity tests confirmed the moderate and weak IC₅₀ values of 15.6 and 51.5 µM for compounds 5 and 1, respectively. Full article

(This article belongs to the Special Issue Isolation and Structure Elucidation of Marine Secondary Metabolites)

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11 pages, 7049 KiB

Open AccessArticle

Characterization of a Novel N-Acylhomoserine Lactonase RmmL from Ruegeria mobilis YJ3

by Xiulei Cai, Min Yu, Hu Shan, Xiaorong Tian, Yanfen Zheng, Chunxu Xue and Xiao-Hua Zhang

Mar. Drugs 2018, 16(10), 370; https://doi.org/10.3390/md16100370 - 8 Oct 2018

Cited by 17 | Viewed by 4836

Abstract

Gram-negative bacteria utilize N-acylhomoserine lactones (AHLs) as quorum sensing (QS) signaling molecules for intercellular communication. Cell-to-cell communication depends on cell population density, and AHL-dependent QS is related to the production of multiple genes including virulence factors. Quorum quenching (QQ), signal inactivation by [...] Read more.

Gram-negative bacteria utilize N-acylhomoserine lactones (AHLs) as quorum sensing (QS) signaling molecules for intercellular communication. Cell-to-cell communication depends on cell population density, and AHL-dependent QS is related to the production of multiple genes including virulence factors. Quorum quenching (QQ), signal inactivation by enzymatic degradation, is a potential strategy for attenuating QS regulated bacterial infections. Both Gram-positive and -negative bacteria have QQ enzymes that can degrade AHLs. In our previous study, strain Ruegeria mobilis YJ3, isolated from healthy shrimp, showed strong AHLs degradative activity. In the current study, an AHL lactonase (designated RmmL) was cloned and characterized from Ruegeria mobilis YJ3. Amino acid sequence analysis showed that RmmL has a conserved “HXHXDH” motif and clusters together with lactonase AidC that belongs to the metallo-β-lactamase superfamily. Recombinant RmmL could degrade either short- or long-chain AHLs in vitro. High-performance liquid chromatography analysis indicated that RmmL works as an AHL lactonase catalyzing AHL ring-opening by hydrolyzing lactones. Furthermore, RmmL can reduce the production of pyocyanin by Pseudomonas aeruginosa PAO1, while for the violacein and the extracellular protease activities by Chromobacterium violaceum CV026 and Vibrio anguillarum VIB72, no significant reduction was observed. This study suggests that RmmL might be used as a therapeutic agent in aquaculture. Full article

(This article belongs to the Special Issue Quorum Quenching Agents: Exploring Quorum Sensing Interfering Strategies in Marine Bacteria for the Development of Novel Therapeutics)

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16 pages, 1747 KiB

Open AccessArticle

Cyclopropane-Containing Fatty Acids from the Marine Bacterium Labrenzia sp. 011 with Antimicrobial and GPR84 Activity

by Jamshid Amiri Moghaddam, Antonio Dávila-Céspedes, Stefan Kehraus, Max Crüsemann, Meryem Köse, Christa E. Müller and Gabriele Maria König

Mar. Drugs 2018, 16(10), 369; https://doi.org/10.3390/md16100369 - 8 Oct 2018

Cited by 28 | Viewed by 7287

Abstract

Bacteria of the family Rhodobacteraceae are widespread in marine environments and known to colonize surfaces, such as those of e.g., oysters and shells. The marine bacterium Labrenzia sp. 011 is here investigated and it was found to produce two cyclopropane-containing medium-chain fatty acids [...] Read more.

Bacteria of the family Rhodobacteraceae are widespread in marine environments and known to colonize surfaces, such as those of e.g., oysters and shells. The marine bacterium Labrenzia sp. 011 is here investigated and it was found to produce two cyclopropane-containing medium-chain fatty acids (1, 2), which inhibit the growth of a range of bacteria and fungi, most effectively that of a causative agent of Roseovarius oyster disease (ROD), Pseudoroseovarius crassostreae DSM 16950. Additionally, compound 2 acts as a potent partial, β-arrestin-biased agonist at the medium-chain fatty acid-activated orphan G-protein coupled receptor GPR84, which is highly expressed on immune cells. The genome of Labrenzia sp. 011 was sequenced and bioinformatically compared with those of other Labrenzia spp. This analysis revealed several cyclopropane fatty acid synthases (CFAS) conserved in all Labrenzia strains analyzed and a putative gene cluster encoding for two distinct CFASs is proposed as the biosynthetic origin of 1 and 2. Full article

(This article belongs to the Special Issue Marine-Derived Polyketides with Antibiotic Activity)

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15 pages, 2850 KiB

Open AccessArticle

Fucosterol from an Edible Brown Alga Ecklonia stolonifera Prevents Soluble Amyloid Beta-Induced Cognitive Dysfunction in Aging Rats

by Jeong Hwan Oh, Jae Sue Choi and Taek-Jeong Nam

Mar. Drugs 2018, 16(10), 368; https://doi.org/10.3390/md16100368 - 5 Oct 2018

Cited by 39 | Viewed by 4633

Abstract

Fucosterol from edible brown seaweeds has various biological activities, including anti-inflammatory, anti-adipogenic, antiphotoaging, anti-acetylcholinesterase, and anti-beta-secretase 1 activities. However, little is known about its effects on soluble amyloid beta peptide (sAβ)-induced endoplasmic reticulum (ER) stress and cognitive impairment. Fucosterol was isolated from the [...] Read more.

Fucosterol from edible brown seaweeds has various biological activities, including anti-inflammatory, anti-adipogenic, antiphotoaging, anti-acetylcholinesterase, and anti-beta-secretase 1 activities. However, little is known about its effects on soluble amyloid beta peptide (sAβ)-induced endoplasmic reticulum (ER) stress and cognitive impairment. Fucosterol was isolated from the edible brown seaweed Ecklonia stolonifera, and its neuroprotective effects were analyzed in primary hippocampal neurons and in aging rats. Fucosterol attenuated sAβ_1-42-induced decrease in the viability of hippocampal neurons and downregulated sAβ_1-42-induced increase in glucose-regulated protein 78 (GRP78) expression in hippocampal neurons via activation of tyrosine receptor kinase B-mediated ERK1/2 signaling. Fucosterol co-infusion attenuated sAβ_1-42-induced cognitive impairment in aging rats via downregulation of GRP78 expression and upregulation of mature brain-derived neurotrophic factor expression in the dentate gyrus. Fucosterol might be beneficial for the management of cognitive dysfunction via suppression of aging-induced ER stress. Full article

(This article belongs to the Special Issue Marine Compounds in Neurodegenerative Diseases)

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