Screening for antibacterial and antifungal activities in marine benthic invertebrates from northern Norway

The Role of Oxidative Stress in the Antifungal Activity of Two Mollusk Fractions on Resistant Fungal Strains

Fungal infections are a significant global public health challenge because of their widespread occurrence, morbidity, and profound social and economic consequences. Antifungal resistance is also an increasing concern, posing a substantial risk to public health. There is a growing interest in searching for new antifungal drugs isolated from natural sources. This study aimed to evaluate the antifungal activity of novel mollusk fractions against fungal strains resistant to nystatin and amphotericin B. In addition, the role of oxidative stress in the mechanism of damage was determined. The mucus from the garden snail Cornu aspersum (MCa/1-20) and the hemolymph fraction from the marine snail Rapana venosa (HLRv/3-100) were obtained and characterized via 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and mass spectrometric -analyses. The results demonstrate that the spores and biomass of both mollusk fractions have a significant fungicidal effect against Penicillium griseofulvum, and Aspergillus niger. Compared to the control group, the release of intracellular proteins and reducing sugars was significantly increased in the treated groups. The data showed increased levels of oxidative stress biomarkers (lipid peroxidation and oxidatively damaged proteins) and a downregulated antioxidant enzyme defense, corresponding to increased antifungal activity. To our knowledge, this is the first study evaluating oxidative stress as a factor in mollusk fractions' antifungal activity.

Antibacterial Action of Protein Fraction Isolated from Rapana venosa Hemolymph against Escherichia coli NBIMCC 8785

Natural products and especially those from marine organisms are being intensively explored as an alternative to synthetic antibiotics. However, the exact mechanisms of their action are not yet well understood. The molecular masses of components in the hemolymph fraction with MW 50-100 kDa from Rapana venosa were determined using ImageQuant™ TL v8.2.0 software based on electrophoretic analysis. Mainly, three types of compounds with antibacterial potential were identified, namely proteins with MW at 50.230 kDa, 62.100 kDa and 93.088 kDa that were homologous to peroxidase-like protein, aplicyanin A and L-amino acid oxidase and functional units with MW 50 kDa from R. venous hemocyanin. Data for their antibacterial effect on Escherichia coli NBIMCC 8785 were obtained by CTC/DAPI-based fluorescent analysis (analysis based on the use of a functional fluorescence probe). The fluorescent analyses demonstrated that a 50% concentration of the fraction with MW 50-100 kDa was able to eliminate 99% of the live bacteria. The antimicrobial effect was detectable even at a 1% concentration of the active compounds. The bacteria in this case had reduced metabolic activity and a 24% decreased size. The fraction had superior action compared with another mollusc product-snail slime-which killed 60% of the E. coli NBIMCC 8785 cells at a 50% concentration and had no effect at a 1% concentration. The obtained results demonstrate the high potential of the fraction with MW 50-100 kDa from R. venosa to eliminate and suppress the development of Escherichia coli NBIMCC 8785 bacteria and could be applied as an appropriate component of therapeutics with the potential to replace antibiotics to avoid the development of antibiotic resistance.

35 Years of Marine Natural Product Research in Sweden: Cool Molecules and Models from Cold Waters

Currents efforts in marine biodiscovery have essentially focused on temperate to tropical shallow water organisms. With more than 6000 species of marine plants and animals, the Kosterfjord area has the richest marine biodiversity in Swedish waters, but it remains understudied. The overall objective of our marine pharmacognosy research is to explore and reveal the pharmacological potential of organisms from this poorly explored region. More generally, we wish to understand aspects of structure-activity relationships of chemical interactions in cold-water marine environment (shallow and deep). Our strategy is based on ecologically guided search for compounds through studies of physiology and organism interactions coupled to identification of bioactive molecules guided by especially in vivo assays. The research programme originated in the beginning of the 1980s with a broad screening of Swedish marine organisms using both in vitro and in vivo assays, resulting in isolation and identification of several different bioactive molecules. Two congenerous cyclopeptides, i.e. barettin and 8,9-dihydrobarettin, were isolated from the deep-sea sponge Geodia barretti, and structurally elucidated, guided by their antifouling activity and their affinity to a selection of human serotonin receptors. To optimize the activity a number of analogues of barettin were synthezised and tested for antifouling activity. Within the EU project BlueGenics, two larger homologous peptides, barrettides A and B, were isolated from G. baretti. Also, metabolic fingerprinting combined with sponge systematics was used to further study deep-sea natural product diversity in the genus Geodia. Finally, the chemical property space model 'ChemGPS-NP' has been developed and used in our research group, enabling a more efficient use of obtained compounds and exploration of possible biological activities and targets. Another approach is the broad application of phylogenetic frameworks, which can be used in prediction of where-in which organisms-to search for novel molecules or better sources of known molecules in marine organisms. In a further perspective, the deeper understanding of evolution and development of life on Earth can also provide answers to why marine organisms produce specific molecules.

Immunity in Protochordates: The Tunicate Perspective

Tunicates are the closest relatives of vertebrates, and their peculiar phylogenetic position explains the increasing interest toward tunicate immunobiology. They are filter-feeding organisms, and this greatly influences their defense strategies. The majority of the studies on tunicate immunity were carried out in ascidians. The tunic acts as a first barrier against pathogens and parasites. In addition, the oral siphon and the pharynx represent two major, highly vascularized, immune organs, where circulating hemocytes can sense non-self material and trigger immune responses that, usually, lead to inflammation and phagocytosis. Inflammation involves the recruitment of circulating cytotoxic, phenoloxidase (PO)-containing cells in the infected area, where they degranulate as a consequence of non-self recognition and release cytokines, complement factors, and the enzyme PO. The latter, acting on polyphenol substrata, produces cytotoxic quinones, which polymerize to melanin, and reactive oxygen species, which induce oxidative stress. Both the alternative and the lectin pathways of complement activation converge to activate C3: C3a and C3b are involved in the recruitment of hemocytes and in the opsonization of foreign materials, respectively. The interaction of circulating professional phagocytes with potentially pathogenic foreign material can be direct or mediated by opsonins, either complement dependent or complement independent. Together with cytotoxic cells, phagocytes are active in the encapsulation of large materials. Cells involved in immune responses, collectively called immunocytes, represent a large fraction of hemocytes, and the presence of a cross talk between cytotoxic cells and phagocytes, mediated by secreted humoral factors, was reported. Lectins play a pivotal role as pattern-recognition receptors and opsonizing agents. In addition, variable region-containing chitin-binding proteins, identified in the solitary ascidian Ciona intestinalis, control the settlement and colonization of bacteria in the gut.

3,7-Isoquinoline quinones from the ascidian tunicate Ascidia virginea

A new isoquinoline quinone system and its iodinated derivatives were isolated from the ascidian tunicate Ascidia virginea Müller 1776 (Phlebobranchia: Ascidiidae). Structures were elucidated by spectroscopic methods and derivatization reactions. Ascidine A (3,7-dihydro-1,8-dihydroxy-4-(4′-hydroxyphenyl)isoquinoline-3,7-dione (1), ascidine B (3,7-dihydro-1,8-dihydroxy-4-(4′-hydroxy-3′-iodophenyl)isoquinoline-3,7-dione (2), and ascidine C (3,7-dihydro-1,8-dihydroxy-4-(4′-hydroxy-3′,5′-diiodophenyl)isoquinoline-3,7-dione (3) represent a novel type of tyrosine-derived alkaloids.

Antimicrobials from Cnidarians. A New Perspective for Anti-Infective Therapy?

The ability of microbes to counter the scientific and therapeutic advancements achieved during the second half of the twentieth century to provide effective disease treatments is currently a significant challenge for researchers in biology and medicine. The discovery of antibiotics, and the subsequent development of synthetic antimicrobial compounds, altered our therapeutic approach towards infectious diseases, and improved the quality and length of life for humans and other organisms. The current alarming rise in cases of antibiotic-resistance has forced biomedical researchers to explore new ways to recognize and/or produce new antimicrobials or to find other approaches for existing therapeutics. Aquatic organisms are known to be a source of compounds having the potential to play a role in fighting the battle against pathogenic microbes. In this connection, cnidarians occupy a pre-eminent role. Over the past few decades several studies have explored the antimicrobial/antibiotic properties of cnidarian extracts with the aim of isolating compounds possessing useful therapeutic features. This paper aims to review the existing data on this subject, taking into account the possible utilization of identified compounds.

The bromotyrosine derivative ianthelline isolated from the arctic marine sponge Stryphnus fortis inhibits marine micro- and macrobiofouling

The inhibition of marine biofouling by the bromotyrosine derivative ianthelline, isolated from the Arctic marine sponge Stryphnus fortis, is described. All major stages of the fouling process are investigated. The effect of ianthelline on adhesion and growth of marine bacteria and microalgae is tested to investigate its influence on the initial microfouling process comparing with the known marine antifoulant barettin as a reference. Macrofouling is studied via barnacle (Balanus improvisus) settlement assays and blue mussel (Mytilus edulis) phenoloxidase inhibition. Ianthelline is shown to inhibit both marine micro- and macrofoulers with a pronounced effect on marine bacteria (minimum inhibitory concentration (MIC) values 0.1-10 μg/mL) and barnacle larval settlement (IC50 = 3.0 μg/mL). Moderate effects are recorded on M. edulis (IC50 = 45.2 μg/mL) and microalgae, where growth is more affected than surface adhesion. The effect of ianthelline is also investigated against human pathogenic bacteria. Ianthelline displayed low micromolar MIC values against several bacterial strains, both Gram positive and Gram negative, down to 2.5 μg/mL. In summary, the effect of ianthelline on 20 different representative marine antifouling organisms and seven human pathogenic bacterial strains is presented.

Antifouling compounds from the sub-arctic ascidian Synoicum pulmonaria: synoxazolidinones A and C, pulmonarins A and B, and synthetic analogues

The current study describes the antifouling properties of four members belonging to the recently discovered synoxazolidinone and pulmonarin families, isolated from the sub-Arctic sessile ascidian Synoicum pulmonaria collected off the Norwegian coast. Four simplified synthetic analogues were also prepared and included in the study. Several of the studied compounds displayed MIC values in the micro-nanomolar range against 16 relevant marine species involved in both the micro- and macrofouling process. Settlement studies on Balanus improvisus cyprids indicated a deterrent effect and a low toxicity for selected compounds. The two synoxazolidinones displayed broad activity and are shown to be among the most active natural antifouling bromotyrosine derivatives described. Synoxazolidinone C displayed selected antifouling properties comparable to the commercial antifouling product Sea-Nine-211. The pulmonarins prevented the growth of several bacterial strains at nanomolar concentrations but displayed a lower activity toward microalgae and no effect on barnacles. The linear and cyclic synthetic peptidic mimics also displayed potent antifouling activities mainly directed against bacterial adhesion and growth.

Isolation and synthesis of pulmonarins A and B, acetylcholinesterase inhibitors from the colonial ascidian Synoicum pulmonaria

Pulmonarins A and B are two new dibrominated marine acetylcholinesterase inhibitors that were isolated and characterized from the sub-Arctic ascidian Synoicum pulmonaria collected off the Norwegian coast. The structures of natural pulmonarins A and B were tentatively elucidated by spectroscopic methods and later verified by comparison with synthetically prepared material. Both pulmonarins A and B displayed reversible, noncompetitive acetylcholinesterase inhibition comparable to several known natural acetylcholinesterase inhibitiors. Pulmonarin B was the strongest inhibitor, with an inhibition constant (Ki) of 20 μM. In addition to reversible, noncompetitive acetylcholinesterase inhibition, the compounds displayed weak antibacterial activity but no cytotoxicity or other investigated bioactivities.

Studies on bioprospecting potential of a gastropod mollusc Cantharus tranquebaricus (Gmelin, 1791)

OBJECTIVE

To study the biological activities of the tissue extract of Cantharus tranquebaricus (C. tranquebaricus).

METHODS

Crude extract of gastropod was tested for inhibition of bacterial growth. Antibacterial assay was carried out by disc diffusion method and the activity was measured accordingly based on the inhibition zone around the disc impregnated with gastropod extract. Molecular weight of the extract was determined by using SDS-PAGE. Plasma coagulation, Fibrin plate assay and substrate SDS-PAGE were used to determine the effect of sample on plasma coagulation, fibrin (ogen) olytic and proteolytic activity.

RESULTS

The maximum inhibition zone (10 mm) was observed against Vibrio cholera (V. cholera) and minimum inhibition zone (2 mm) was noticed against Proteus mirablis (P. mirablis). The molecular weight was determined as 47-106 kDa. The tissue extract shows proteolytic activity above 48 kDa. SDS-PAGE analysis of fibrinogen after incubation with the tissue extract showed fibrinogenolytic activity. In plasma coagulation assay C. tranquebaricus tissue extract showed procoagulant property and it coagulated chicken plasma within 150 s, while control took 5 min to clot. The 9 HU hemolytic units were found against chicken blood and also exhibit high level of brine shrimp lethality.

CONCLUSIONS

This study suggests that C. tranquebaricus could be used as potential source for isolating bioactive compounds, since it is explored first time and found with promising results.

Medicinal benefits of marine invertebrates: sources for discovering natural drug candidates

Marine invertebrates are one of the major groups of organisms, which could be diversified under the major taxonomic groups of Porifera, Cnidaria, Mollusca, Arthropoda, Echinodermata, and many other minor phyla. To date, range of medicinal benefits and a significant number of marine natural products (MNPs) have been discovered from marine invertebrates. Seafood diet from edible marine invertebrates such as mollusks and crustaceans has been linked with various medicinal benefits to improve human health. Among marine invertebrates, spongers from phylum Porifera is the most dominant group responsible for discovering large number of MNPs, which have been used as template to develop therapeutic drugs. MNPs isolated from invertebrates have shown wide range of therapeutic properties including antimicrobial, antioxidant, antihypertensive, anticoagulant, anticancer, anti-inflammatory, wound healing and immune modulator, and other medicinal effects. Therefore, marine invertebrates are rich sources of chemical diversity and health benefits for developing drug candidates, cosmetics, nutritional supplements, and molecular probes that can be supported to increase the healthy life span of human.

Cytotoxic activity of extracts of marine sponges from NW Spain on a neuroblastoma cell line

Six species of marine sponges collected at intertidal and sublittoral sites of the coast of Galicia (NW Spain) were screened for potential cytotoxic properties on Neuroblastoma BE(2)-M17 cell line. Exposure to Halichondria panicea, Pachymatisma johnstonia, Ophlitaspongia seriata and Haliclona sp. aqueous extracts strongly affected cell appearance, inducing loss of neuron-like morphology and the formation of clumps. Extracts from these species also caused significant rates of cell detachment and decrease of mitochondrial membrane potential. Incubation with P. johnstonia, O. seriata and Suberites massa extracts also decreased the rate of cell proliferation. The increase of incubation time enhanced propidium iodide uptake by neuroblastoma cells. Toxic responses triggered by sponge extracts are compatible with apoptotic phenomena in neuroblastoma cells, even though increasing propidium uptake at long periods of exposure might indicate the induction of secondary necrosis. The cytotoxic properties of the tested extracts suggest the presence of compounds with potential pharmacological or biotechnological applications in the screened sponge species.

Antimicrobial peptides from marine invertebrates: challenges and perspectives in marine antimicrobial peptide discovery

The emergence of pathogenic bacteria resistance to conventional antibiotics calls for an increased focus on the purification and characterization of antimicrobials with new mechanisms of actions. Antimicrobial peptides are promising candidates, because their initial interaction with microbes is through binding to lipids. The interference with such a fundamental cell structure is assumed to hamper resistance development. In the present review we discuss antimicrobial peptides isolated from marine invertebrates, emphasizing the isolation and activity of these natural antibiotics. The marine environment is relatively poorly explored in terms of potential pharmaceuticals, and it contains a tremendous species diversity which evolved in close proximity to microorganisms. As invertebrates rely purely on innate immunity, including antimicrobial peptides, to combat infectious agents, it is believed that immune effectors from these animals are efficient and rapid inhibitors of microbial growth.

Marine pharmacology in 2007-8: Marine compounds with antibacterial, anticoagulant, antifungal, anti-inflammatory, antimalarial, antiprotozoal, antituberculosis, and antiviral activities; affecting the immune and nervous system, and other miscellaneous mechanisms of action

The peer-reviewed marine pharmacology literature in 2007-8 is covered in this review, which follows a similar format to the previous 1998-2006 reviews of this series. The preclinical pharmacology of structurally characterized marine compounds isolated from marine animals, algae, fungi and bacteria is discussed in a comprehensive manner. Antibacterial, anticoagulant, antifungal, antimalarial, antiprotozoal, antituberculosis and antiviral activities were reported for 74 marine natural products. Additionally, 59 marine compounds were reported to affect the cardiovascular, immune and nervous systems as well as to possess anti-inflammatory effects. Finally, 65 marine metabolites were shown to bind to a variety of receptors and miscellaneous molecular targets, and thus upon further completion of mechanism of action studies, will contribute to several pharmacological classes. Marine pharmacology research during 2007-8 remained a global enterprise, with researchers from 26 countries, and the United States, contributing to the preclinical pharmacology of 197 marine compounds which are part of the preclinical marine pharmaceuticals pipeline. Sustained preclinical research with marine natural products demonstrating novel pharmacological activities, will probably result in the expansion of the current marine pharmaceutical clinical pipeline, which currently consists of 13 marine natural products, analogs or derivatives targeting a limited number of disease categories.

[Seasonal and geographical variation range of antifungal activity of sponge extracts from the Moroccan Atlantic coasts]

Currently, marine organisms have a very important source of new molecules in pharmacology and thus in the development of new bioactive products. The organic and aqueous extracts of two marine sponges, Cinachyrella tarentine collected during two different seasons, winter and summer, and Cliona viridis collected in two different zones on the coast of El Jadida (Morocco) were tested for their antifungal activity using the diffusion method. The C. tarentine sponge collected in January (winter) has a very important activity compared to that collected in August (summer). While the sponge C. viridis collected from Jorf Lasfar port (shallower and polluted area) has a very important activity compared to that collected from the coast of El Jadida (depth and unpolluted area).