Marine bacterial inhibitors from the sponge-derived fungus Aspergillus sp

Chromatographic separation of a crude extract obtained from the fungus Aspergillus sp., isolated from the Mediterranean sponge Tethya aurantium, yielded a new tryptophan derived alkaloid, 34(1-hydroxy-3-(2methylbut-3-en-2-y1)-2-oxoindolin-3-yl)methyl)-1-methyl-3,4-dihydrobenzo[e][1,41diazepine-2, 5-dione (1), and a new meroterpenoid, austalide R (2), together with three known compounds (3-5). The structures of the new compounds were unambiguously elucidated on the basis of extensive one and twodimensional NMR (1H, 13C, COSY, HMBC, and ROESY) and mass spectral analysis. Interestingly, the compounds exhibited antibacterial activity when tested against a panel of marine bacteria, with 1 selectively inhibiting Vibrio species and 2 showing a broad spectrum of activity. In contrast, no significant activity was observed against terrestrial bacterial strains and the murine cancer cell line L5178Y. (C) 2014 Elsevier Ltd. All rights reserved.Chemistry, OrganicSCI(E)[email protected]

The bromotyrosine derivative Ianthelline isolated from the Arctic marine sponge Stryphnus fortis inhibits marine micro- and macrobiofouling

International audienceThe 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 mu g/mL) and barnacle larval settlement (IC50= 3.0 mu g/mL). Moderate effects are recorded on M. edulis (IC50= 45.2 mu g/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 mu g/mL. In summary, the effect of ianthelline on 20 different representative marine antifouling organisms and seven human pathogenic bacterial strains is presented

Design and Biological Evaluation of Antifouling Dihydrostilbene Oxime Hybrids

Source at https://doi.org/10.1007/s10126-018-9802-z. By combining the recently reported repelling natural dihydrostilbene scaffold with an oxime moiety found in many marine antifoulants, a library of nine antifouling hybrid compounds was developed and biologically evaluated. The prepared compounds were shown to display a low antifouling effect against marine bacteria but a high potency against the attachment and growth of microalgae down to MIC values of 0.01 μg/mL for the most potent hybrid. The mode of action can be characterized as repelling via a reversible non-toxic biostatic mechanism. Barnacle cyprid larval settlement was also inhibited at low μg/mL concentrations with low levels or no toxicity observed. Several of the prepared compounds performed better than many reported antifouling marine natural products. While several of the prepared compounds are highly active as antifoulants, no apparent synergy is observed by incorporating the oxime functionality into the dihydrostilbene scaffold. This observation is discussed in light of recently reported literature data on related marine natural antifoulants and antifouling hybrids as a potentially general strategy for generation of improved antifoulants

Protocol for assessing antifouling activities of macroalgal extracts.

International audienceThe development of novel environmentally friendly antifouling (AF) solutions is a very active field in fundamental and applied research. An attractive option in producing such material resides in biomimetic studies: living organisms have evolved well-adapted structures and materials over geological times through natural selection. In this chapter, we explain the experimental procedure to be followed for the preparation of macroalgal extracts and to assess their AF efficiency towards key species. All bioassays described here have the advantage of being fast, reliable, and standardized

Evaluation of cationic micropeptides derived from the innate immune system as inhibitors of marine biofouling

WOS:000356074000007A series of 13 short synthetic amphiphilic cationic micropeptides, derived from the antimicrobial iron-binding innate defence protein lactoferrin, have been evaluated for their capacity to inhibit the marine fouling process. The whole biofouling process was studied and microfouling organisms such as marine bacteria and microalgae were included as well as the macrofouling barnacle Balanus improvisus. In total 19 different marine fouling organisms (18 microfoulers and one macrofouler) were included and both the adhesion and growth of the microfoulers were investigated. It was shown that the majority of the peptides inhibited barnacle cyprid settlement via a reversible nontoxic mechanism, with IC50 values as low as 0.5 mu g ml(-1). Six peptides inhibited adhesion and growth of microorganisms. Two of these were particularly active against the microfoulers with MIC-values ranging between 0.01 and 1 mu g ml(-1), which is comparable with the commercial reference antifoulant SeaNine

Development of alginate hydrogels active against adhesion of microalgae

Microorganisms have the ability to settle on nearly all man-made surfaces in contact with seawater and subsequently to form biofilm. Biofilms control and removal is necessary in the sectors of maritime transport, energy... In this work, we present the development of new pure calcium, zinc or copper alginate, but also mixed Ca/Cu and Ca/Zn alginate hydrogels. These materials have been evaluated for their potential inhibition of adhesion of two key biofilm-forming microalgae Halamphora coffeaeformis and Cylindrotheca closterium). All the tested materials have presented high adhesion inhibition about 80%). Copper-base materials present a high toxicity against H. coffeaeformis. Pure zinc alginate is also toxic for this strain. However, the addition of calcium in zinc alginate leads to the toxicity reduction. The toxicity of these materials differs according to the strains. Consequently, mixed zinc/calcium alginate are efficient at inhibiting microalgal adhesion with a low level of cells toxicity. These alginate hydrogels are promising materials because they are efficient, cheap, easy to develop and eco-friendly

From Ecology to Biotechnology, Study of the Defense Strategies of Algae and Halophytes (from Trapani Saltworks, NW Sicily) with a Focus on Antioxidants and Antimicrobial Properties

This study aimed at the characterization of the antioxidant power of polyphenol extracts (PE) obtained from the algae Cystoseira foeniculacea (CYS) (Phaeophyta) and from the halophyte Halocnemum strobilaceum (HAL), growing in the solar saltworks of western Sicily (Italy), and at the evaluation of their anti-microfouling properties, in order to correlate these activities to defense strategies in extreme environmental conditions. The antioxidant properties were assessed in the PE based on the total antioxidant activity test and the reducing power test; the anti-microfouling properties of the two PE were evaluated by measuring the growth inhibition of marine fish and shellfish pathogen bacteria as well as marine surface fouling bacteria and microalgae exposed to the fractions. Similar polyphenol content (CYS 5.88 ± 0.75 and HAL 6.03 ± 0.25 mg gallic acid equivalents (GAE) g−1 dried weight, DW) and similar reducing power percentage (93.91 ± 4.34 and 90.03 ± 6.19) were recorded for both species, even if they exhibited a different total antioxidant power (measured by the percentage of inhibition of the radical 2,2 diphenyl-1-picrylhydrazyl DPPH), with CYS (79.30) more active than HAL (59.90). Both PE showed anti-microfouling properties, being inhibitors of adhesion and growth of marine fish and shellfish pathogen bacteria (V. aestuarianus, V. carchariae, V. harveyi, P. elyakovii, H. aquamarina) and fouling bacteria (V. natriegens, V. proteolyticus, P. iirgensii, R. litoralis) with minimum inhibitory concentrations comparable to the commercial antifouling products used as a positive control (SEA-NINE™ 211N). Only CYS was a significant inhibitor of the microalgae strains tested, being able to reduce E. gayraliae and C. closterium growth (MIC 10 µg·mL−1) and the adhesion of all three strains tested (E. gayraliae, C. closterium and P. purpureum), suggesting its promise for use as an antifouling (AF) product