Antialgal and Antilarval Activities of Bioactive Compounds Extracted from the Marine Dinoflagellate Amphidinium carterae

With the global ban on the application of organotin-based marine coatings by the International Maritime Organization, the development of environmentally friendly, low-toxic and nontoxic antifouling compounds for marine industries has become an urgent need. Marine microorganisms have been considered as a potential source of natural antifoulants. In this study, the antifouling potential of marine dinoflagellate Amphidinium carterae, the toxic and red-tide microalgae, was investigated. We performed a series of operations to extract the bioactive substances from Amphidinium carterae and tested their antialgal and antilarval activities. The crude extract of Amphidinium carterae showed significant antialgal activity and the EC50 value against Skeletonema costatum was 55.4 μg m L~(-1). After purification, the isolated bioactive substances(the organic extract C) exhibited much higher antialgal and antilarval activities with EC50 of 12.9 μg m L~(-1) against Skeletonema costatum and LC50 of 15.1 μg m L~(-1) against Amphibalanus amphitrite larvae. Subsequently, IR, Q-TOFMS, and GC-MS were utilized for the structural elucidation of the bioactive compounds, and a series of unsaturated and saturated 16- to 22-carbon fatty acids were detected. The data suggested the bioactive compounds isolated from Amphidinium carterae exhibited a significant inhibiting effect against the diatom Skeletonema costatum and Amphibalanus amphitrite larvae, and could be substitutes for persistent, toxic antifouling compounds.     

Antifouling potential of bacteria isolated from a marine biofilm

Marine microorganisms are a new source of natural antifouling compounds. In this study, two bacterial strains, Kytococcus sedentarius QDG-B506 and Bacillus cereus QDG-B509, were isolated from a marine biofilm and identified. The bacteria fermentation broth could exert inhibitory effects on the growth of Skeletonema costatum and barnacle larvae. A procedure was employed to extract and identify the antifouling compounds. Firstly, a toxicity test was conducted by graduated pH and liquid-liquid extraction to determine the optimal extraction conditions. The best extraction conditions were found to be pH 2 and 100% petroleum ether. The EC50 value of the crude extract of K. sedentarius against the test microalgae was 236.7 ± 14.08 μg mL-1, and that of B. cereus was 290.6 ± 27.11 μg mL-1. Secondly, HLB SPE columns were used to purify the two crude extracts. After purification, the antifouling activities of the two extracts significantly increased: the EC50 of the K. sedentarius extract against the test microalgae was 86.4 ± 3.71 μg mL-1, and that of B. cereus was 92.6 ± 1.47 μg mL-1. These results suggest that the metabolites produced by the two bacterial strains are with high antifouling activities and they should be fatty acid compounds. Lastly, GC-MS was used for the structural elucidation of the compounds. The results show that the antifouling compounds produced by the two bacterial strains are myristic, palmitic and octadecanoic acids.     

Isolation and pharmacological activities of bromophenols from Rhodomela confervoides

Four bromophenols were isolated from the extract of marine red alga, Rhodomela confervoides by column chromatography and HPLC methods. By means of spectroscopic methods including IR, MS, 1D, and 2D-NMR techniques, their structures were elucidated as (1) 3-bromo-4,5-dihydroxy benzoic acid methyl ester; (2) his (2,3-dibromo-4,5-dihydroxybenzyl) ether; (3) 3,4-dibromo-5-(methoxymethyl)-1,2-benzenediol and (4)3-bromo-4,5-dihydroxy-benzaldehyde. Compound 1 was first isolated from the algae in nature, and 1, 4 were found to have selective cytotoxic activities against KB, Bel 7402 and A549 cells, 2 showed powerful antibacterial activities against Staphylococcus aurens and Pseudomonas aeruginosa.     

Anti-proliferative activity of phlorotannin extracts from brown algae Laminaria japonica Aresch

In this study,we evaluated the anti-proliferative activity of phlorotannins derived from brown algae Laminaria japonica Aresch extracts on the human hepatocellular carcinoma cell (BEL-7402) and on murine leukemic cells (P388) by MTT assay.Cells were incubated with 100 μg/mL of the phlorotannin extract (PE) for 48 h.The inhibitory rate of PE on BEL-7402 and P388 cells was 30.20±1.16% and 43.44±1.86%,respectively,and the half-inhibitory concentration of PE (IC50) on P388 and BEL-7402 cells was 120 μg/mL and >...     

Isolation and characterization of fucoidans from five brown algae and evaluation of their antioxidant activity

In this study, we evaluated the chemical property and antioxidant activity of fucoidans isolated from brown algae, Laminaria japonica(LJF), Lessonia nigrescens(LNF), Lessonia trabeculata(LTF), Ascophyllum mackaii(AMF), and Ecklonia maxima(EMF). LJF was less in sulfate content(14.16%) and more in galactose and mannose content(1.08 and 0.68) than the documented early. EMF contained 20%–30% of sulfate and fucose, 0.97 in molar ratio which was lower than that of sulfate to other four fucoidans(1.21–1.41). AMF(162 kDa) and EMF(150 kDa) were the first two largest in molecular weight, which were followed by LJP(126 kDa), LNF(113 kDa) and LTF(105 kDa). The fucoidans isolated these algae showed a wide range of antioxidant activity in vitro. It was found that the reducing power of the isolated fucoidans was positively correlated with their sulfate content and molecular weight. In addition, LNF and LTF at low concentrations exhibited high superoxide and hydroxyl radical scavenging activity. This demonstrated that low molecular weight fucoidans may perform a high antioxidant activity.     

Properties of polysaccharides in several seaweeds from Atlantic Canada and their potential anti-influenza viral activities

To explore the polysaccharides from selected seaweeds of Atlantic Canada and to evaluate their potential anti-influenza virus activities, polysaccharides were isolated from several Atlantic Canadian seaweeds, including three red algae (Polysiphonia lanosa, Furcellaria lumbricalis, and Palmaria palmata), two brown algae (Ascophyllum nodosum and Fucus vesiculosus), and one green alga (Ulva lactuca) by sequential extraction with cold water, hot water, and alkali solutions. These polysaccharides were ana-lyzed for monosaccharide composition and other general chemical properties, and they were evaluated for anti-influenza virus activities. Total sugar contents in these polysaccharides ranged from 15.4% (in U. lactuca) to 91.4% (in F. lumbricalis); sulfation level was as high as 17.6% in a polysaccharide from U. lactuca, whereas it could not be detected in an alikali-extract from P. palmaria. For polysaccharides from red seaweeds, the main sugar units were sulfated galactans (agar or carrageenan) for P. lanosa, F. lumbricalis, and xylans for P. palmata. In brown seaweeds, the polysaccharides largely contained sulfated fucans, whereas the polysaccharides in green seaweed were mainly composed of heteroglycuronans. Screening for antiviral activity against influenza A/PR/8/34 (H1N1) virus revealed that brown algal polysaccharides were particularly effective. Seaweeds from Atlantic Canada are a good source of marine polysaccharides with potential antiviral properties.     

Main nutritional contents of 30 Dalian coastal microalgae species

This paper reports results of study on the contents of proteins, amino acids, polysaccharose and uronic acids in 30 species of macroalgae from Shicao, Heishijiao, Shimiao, and Xiaofujiazhuang in the vicinity of Dalian City, N.E.China. The results showed that the protein contents of the 30 algae from highest (112.55μg/ml) to the lowest (0.24 p.g/ml) was in the descending order of Dictyopteris ndalata, Gelidium vagum,Gymnogongrus japonican, Ectocarpus confervoides, Tinocladia crassa, Sargassum thunberii. In general, the protein content in red algae was higher than that in brown algae. The content of free ami no acids showed nosignificent differences from 7.44μg/ml-4.96μg/ml in all these algae, in the descending order of Gymnogongrusrus japonican, Sargassum confusum, Undoria pinnatifida, Laminaria japonica and Ectocarpus confervoides. The content of polysaccharose varied from 168.2 gg/ml-22.15 p.g/ml in the descending order of Symphyocladiaia tiuscula, Scytosiphon lomentarius, Desmarestia viridis., Tinocladia crassa, Gracilaria asiatica and Porphyra yezoensis. The content of uronic acids is from 196.24μg/ml-20.77μg/ml in the descending order of Ulva lactuca,Symphyoclaldia latiuscula, Scytosiphon lomentarius, Ceramimum kondoi, Gracilaria vemucosa and Porphyra yezoensis. The fatty acids in 30 species of algae belong to Rhodophyta, Chlorophyta and Phaeophyta. Most phaeophytes have many (4-12) types of fatty acids.     

Laminarin and Laminarin Oligosaccharides Originating from Brown Algae: Preparation,Biological Activities,and Potential Applications

Brown algae is one of the three major types of marine algae and includes approximately 2000 species. It is widely distributed in various seas around the world. Brown algae contain a plethora of active substances, such as polysaccharides, polyphenols, omega-3 fatty acids, and carotenoids. Laminarin, a type of storage carbohydrate found abundantly in brown algae, is mainly formed by glucose monomers linked by β-1, 3-glucosidic bonds and partial β-1, 6-glucosidic bonds. Laminarin and laminarin oligosaccharides, which contain 2–10 saccharide units, have extensive biological activities, such as antitumor, antioxidant, anti-inflammatory, and prebiotic properties. Moreover, both laminarin and laminarin oligosaccharides can be considered as ideal substrates for bioethanol production because they are composed of abundant glucose residues. Therefore, brown algae-derived laminarin and laminarin oligosaccharides have various potential applications in the food, medicine, cosmetics, and bioenergy fields. This paper reviews the preparation methods of laminarin and laminarin oligosaccharides, as well as their biological activities and potential applications.     

Antifouling effect of bioactive compounds from selected marine organisms in the Obhur Creek,Red Sea

Three species of sponges and a tunicate were collected from Obhur creek of Jeddah coast for this bioactivity study. In order to assess the antifouling efficacy of selected marine organisms, methanolic extracts of these organisms were tested against different fouling bacterial forms and II-instar stage of the barnacle, Balanus amphitrite. Antibiosis, bioactivity and followed by multivariate analyses were carried out to check the efficacy of antifouling effect of the selected marine organisms. Principal component analysis revealed the exemplary antifouling efficacy of the sponge extracts of Stylissa sp. observed followed by Hyrtios sp. against bacterial forms in the laboratory study. De-trended correspondence analysis confirmed that the contribution of antifouling efficacy of the selected sponge extracts was observed to be more towards Bacillus sp., Vibrio sp. and Alteromonas sp. Moreover, the efficacy of Hyrtios sp. extract(20.430 μg m L~(-1)) followed by Stylissa sp.(30.945 μg m L~(-1)) showed higher against barnacle instar compared with other extracts in the bioactivity assay. Bray-Curtis cluster analysis under paired linkage categorized all the sponge extracts into one major cluster with 75% similarity, and one outlier tunicate. More than 80% similarity observed between Hyrtios sp. and Stylissa sp. Fourier transform infrared spectroscopy(FTIR) showed that the contribution of major peaks found in the marine organisms were towards sulfones, sulfoxides, cyanates and ketones.     

Algicidal activities of secondary metabolites of marine macroalgal-derived endophytic fungi

Red tide occurrs frequently and causes signi?cant damage to the environment and human health. As a result, development of new effcient and environment friendly red-tide microalgae inhibitors has gained increasing attention in recent times. Algicolous endophytic fungi with unique habitats are promising sources for active agents owing to their abundant secondary metabolites and distinguished activities. In this study, the algicidal activities of 49 marine macroalgal-derived endophytic fungi against phytoplankton Alexandrium tamarense, Prorocentrum donghaiense, Heterosigma akashiwo, and Chattonella marina were examined using 96-well microplate. Four fungal strains, including Aspergillus wentii(pt-1), A. ustus(cf-42),and A. versicolor(dl-29, pt-20), exhibited potent algicidal activities. A total of 32 pure compounds isolated from these fungi were noted to possess dif ferent degrees of algicidal activities. Of those, 11 compounds comprising ?ve anthraquinones, two terpenoids, and four steroids showed high 24-h inhibition rates for the four red tide algae, with 24 h EC_(50) values ranging from 0.01 to 14.29 μg/mL. Among them, compound1(1,5-dihydroxy-3-methoxy-7-methylanthraquinone) presented the strongest activity against H. akashiwo,and could decrease its chlorophyll a(Chl a) and superoxide dismutase contents and increase the soluble protein, malondialdehyde, and peroxidase contents. These results suggested that the identi?ed anti-algal compound might inhibit the growth of red tide algae by weakening photosynthesis(reducing Chl a content),destroying cell membrane, and damaging the antioxidant system.     

A new acyclic peroxide from Aspergillus nidulans SD-531, a fungus obtained from deep-sea sediment of cold spring in the South China Sea

A new acyclic peroxide derivative asperoxide A(1),along with 13 known compounds,namely,microperfuranone(2),9-hydroxymicroperfuranone(3),gibellulin A(4),lecanoric acid(5),terrequinone A(6),sterigmatocystin(7),isosecosterigmatocystin(8),arugo sin C(9),curvularin(10),3,3 '-diindolylmethane(11),austinol(12),austin(13),and dehydroaustin(14),were isolated and identified from the culture extract of Aspergillus nidulans SD-531,a fungus obtained from the deep-sea sediment of cold spring in the South China Sea.Their structures were determined based on detailed interpretation of nuclear magnetic resonance(NMR) spectroscopic and mass spectrometry data analysis.All the isolated compounds were evaluated for antimicrobial activities against human and aquatic bacteria as well as plant pathogenic fungi.Compounds1-8,10,and 11 exhibited antimicrobial activities against some of the te sted strains with minimum inhibitory concentration(MIC) values ranging from 2 to 64 μg/mL.Compounds 4 and 6 displayed strongest activities among the tested samples and might be used as promising molecules for the development of natural antimicrobial agents.     

Mineral Components and Anti-oxidant Activities of Tropical Seaweeds

Seaweeds are known to hold substances of high nutritional value; they are the richest resources of minerals important to the biochemical reactions in the human body. Seaweeds also hold non-nutrient compounds like dietary fiber and polyphenols. However, there is not enough information on the mineral compounds of tropical seaweeds. Also we are interested in the antioxidant activities of seaweeds, especially those in the tropical area. In this study, Indonesian green, brown and red algae were used as experimental materials with their mineral components analyzed by using an atomic absorption spectrophotometer. The catechins and flavonoids of these seaweeds were extracted with methanol and analyzed by high performance liquid chromatography （HPLC） ; the anti-oxidant activities of these seaweeds were evaluated in a fish oil emulsion system. The mineral components of tropical seaweeds are dominated by calcium, potassium and sodium, as well as small amounts of copper, iron and zinc. A green alga usually contains epigallocatechin, gallocatechin, epigallocatechin gallate and catechin. However, catechin and its isomers are not found in some green and red algae. In the presence of a ferrous ion catalyst, all the methanol extracts from the seaweeds show significantly lower peroxide values of the emulsion than the control, and that of a green alga shows the strongest anti-oxidant extract of this alga, which is significantly different from activity. The highest chelation on ferrous ions is also found in the the other methanol extracts in both 3 and 24 h incubations.     

Antitumor and Antifungal Activities of Organic Extracts of SeacucumberHolothuria atra from the Southeast Coast of India

In phylum Echinodermata, the family Holothuridae is distinguished by its capacity of bioactive compounds. Sea cucumber Holothuria atra is commonly known as the lollyfish. The antifungal activity was detected using agar well diffusion method against the various fungal strains such as Trichoderma viride, Aspergillus niger, Aspergillus flavis, Candida albicans and Penicillium chrysogenum. Relatively high antifungal activity was seen against Candida albicans at 100 μL-1 concentration of extracts. Zone of inhibition was measured at 18 mm of diameter. The anti-tumor activities were detected against the Vero and Hep2 cell lines using MTT assay. The cells were treated with H. atra extract at concentrations 0.078-10 mg m L-1. The extract showed high proliferative activity against the Hep2 cells. The body wall extracts of sea cucumber(H. atra) showed effective antifungal and antitumor activities. All these findings suggest that the extracts could be used for the development of drugs.     

Antifungal Secondary Metabolites Isolated from Mangrove Rhizosphere Soil-Derived Penicillium Fungi

Fungi isolated from mangrove rhizosphere soil of the South China Sea were investigated for the production of potential antifungal metabolites. With 28 fungal isolates, the strains Penicillium javanicum HK1-23 and P. janthinellum HK1-6 showed significant antifungal activities. A bioassay-guided investigation of the two fungal strains led to the isolation of two secondary metabolites, brefeldin A and penicillic acid, with high yields of 143 and 423 mg L~(-1), respectively. Penicillic acid showed potent antifungal activities toward Rhizoctonia solani and R. cerealis, with 67.5% and 76% growth inhibition, respectively, at 50 μg m L~(-1). Brefeldin A showed strong activity toward R. cerealis, with 56.4% growth inhibition at 50 μg m L~(-1). The research highlights the importance of exploring microbes from mangrove rhizosphere soil for the identification of bioactive metabolites for future fungicide development.     

SCREENING FOR ANTIBACTERIAL AND ANTIFUNGAL ACTIVITIES IN SOME MARINE ALGAE FROM THE FUJIAN COAST OF CHINA WITH THREE DIFFERENT SOLVENTS

Three different solvents viz ethanol, acetone and methanol-toluene (3:1) were used to extract antibiotics from 23 species of marine algae belonging to the Chlomphyta, Phaeophyta and Rhodophyta. Their crude extracts were tested for antibacterial and antifungal activities. Among them, the ethanol extract showed the strongest activity against the bacteria and fungi tested. Four species of the Rhodophyta (Laurenc/a okamurai, Dasya scoparia, Grateloupia filicina and plocamium telfairiae ) showed a wide spectrum of antibacterial activity. Every solvent extract from the four species was active against all the bacteria tested. The test bacterium Pseudomonas solancearum and the fungus Penicilium citrinum were most sensitive to the extracts of marine algae. In general, the extracts of seaweeds inhibited bacteria more strongly than fungi and species of the Rhodophyta showed the greatest activity against the bacteria and fungi tested.     

Screening and isolation of the algicidal compounds from marine green alga Ulva intestinalis

Twenty species of seaweed were collected from the coast of Zhejiang, China, extracted with ethanol, and screened for algicidal activity against red tide microalgae H eterosigma akashiwo and Prorocentrum micans. Inhibitory eff ects of fresh and dried tissues of green alga U lva intestinalis were assessed and the main algicidal compounds were isolated, purifi ed, and identifi ed. Five seaweed species, U. intestinalis, U. fasciata, Grateloupia romosissima, Chondria crassicaulis, and Gracilariopsis lemaneiformis, were investigated for their algicidal activities. Fresh tissues of 8.0 and 16.0 mg/m L of U. intestinalis dissolved in media signifi cantly inhibited growth of H. akashiwo and P. micans, respectively. Dried tissue and ethyl acetate(Et OAc) extracts of U. intestinalis at greater than 1.2 and 0.04 mg/m L, respectively, were fatal to H. akashiwo, while its water and Et OAc extracts in excess of 0.96 and 0.32 mg/m L, respectively, were lethal to P. micans. Three algicidal compounds in the Et OAc extracts were identifi ed as 15-ethoxy-(6z,9z,12z)-hexadecatrienoic acid(I),(6E,9E,12E)-(2-acetoxy- β- D-glucose)-octadecatrienoic acid ester(II) and hexadecanoic acid(III). Of these, compound II displayed the most potent algicidal activity with IC_(50) values of 4.9 and 14.1 μg/m L for H. akashiwo and P. micans, respectively. Compound I showed moderate algicidal activity with IC_(50) values of 13.4 and 24.7 μg/m L for H. akashiwo and P. micans, respectively. These fi ndings suggested that certain macroalgae or products therefrom could be used as ef fective biological control agents against red tide algae.     

The cytotoxic constituents from marine-derived streptomyces 3320#

The present work studies the chemical constituents from marine-derived streptomyces 3320^# and their antitumor activities. The n-BuOH extract of the ferment broth of 3320^# was chromatographed on silica gel, Sephadex LH-20, ODS columns and HPLC to separate the compounds with antitoumor activities. Their structures were identified using IR, UV, NMR, MS spectroscopic techniques and compared with published data. The antitumor activities of the isolates were assayed using SRB method and flow cytometry assay, accompanied with the morphological observation of the cells under light micro- scope against mammalian tsFT210 cells. Ten compounds, cyclo-（Ala-Leu） 1, cyclo-（Ala-Ile） 2, cyclo-（Ala-Val） 3, cyclo- （Phe-Pro） 4, cyclo-（Phe-Gly）5, cyclo-（Leu-Pro）6, 1-methyl-1, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid 7, N-（4- hydroxyphenethyl） acetamide 8, 4-methyoxy-l-（2-hydroxy） ethylbenzene 9 and uridine 10, were isolated from the ferment broth of streptomyces 3320^# . Among them, compounds 6, 7, 8 and 10 showed potent cytotoxicity against the tsFT210 cell with the IC50 values of 3.6, 7.2, 5.2 and 1.6 mmol L-1, respectively. Compounds 8, 10 also exhibited apoptosis inducing activity under 2.0 mmol L-1. Compounds 6, 7, 8 and 10 are the principle bioactive constituents responsible for the antitumor activities of marine streptomyces 3320^#. Compound 7 was isolated from this species for the first time.     

Laboratory simulation of dissolved oxygen reduction and ammonia nitrogen generation in the decay stage of harmful algae bloom

To evaluate how the decay of bloom-forming algae affect the coastal dissolved oxygen,a laboratory simulation was conducted in terms of three typical harmful algae,Alexandrium catenella,Prorocentrum donghaiense,and Skeletonema costatum.Algae of same biomass(55 μg/mL) were conducted in lightproof columns,and the cell density,dissolved oxygen(DO),and ammonia nitrogen of different layers were monitored at certain time series.Results show that the decomposition of algae significantly decreased the DO,and increased the ammonia nitrogen in all layers;and significant deference between different species was observed.The A.catenella treatment showed the lowest DO(average concentration of 3.4 mg/L) and the highest ammonia nitrogen(average concentration of 0.98 mg/L) at the end of test,followed by P.donghaiense; and the S.costatum showed relatively high DO and low ammonia nitrogen due to slow decay rate.Results indicate that decomposition of harmful bloom algae,especially dinoflagellate,would cause significantly DO depletion and toxic ammonia nitrogen increase,which will detrimentally affect both pelagic and benthic ecosystem.     

STUDIES ON MARINE HUMIC SUBSTANCES I.ISOLATION OF HUMIC SUBSTANCES FROM SEAWATER WITH AN EFFECTIVE ADSORBENT,GDX-102 ADSORPTION RESIN

The adsorption efficiency of five home-made resins and Amberlite XAD-2 resin forhumic substances in seawater are compared.1.GDX-102 resin,a home-made adsorbent,could effectively adsorb the hydrophobicorganic matters,rather than the hydrophilic ones such as amino acids and sugar.Underthe same conditions,the amount of humic substances and ethenol-soluble matter adsorbedon GDX-102 resin were respectively 2.24 and 1.23 times more than that on Amberlite XAD-2 resin,and the water flow rate through GDX-102 resin column was 1.5 times faster thanthat through XAD-2 resin.Thus,GDX-102 resin is proved to be an effective adsorptionresin for isolating humic substances from seawater.2 The fulvic acids isolated with GDX-102 and Amberlite XAD-2 resins were chemi-cally characterized by determining their elementary composition,ultraviolet absorption spectra,E_4/E_6 ratio,infrared absorption spectra and gel electrophoresis pattern.The comparisonof FA of seawater with that of soil showed a close similarity between them.3.After elution of humic substances from GDX-102 resin with alkali,an ethanol-solublematter and an ether-soluble matter were isolated by elution with ethanol and ether suc-cessively.The former seemed to be organic compounds differing from FA both in elementary composition and in infrared absorption spectra and containing more hydrophobic portions,and the latter was identified by liquid chromatograph to be the polynuclear aromatic hydro-carbons(PAH).The GDX-102 resin,therefore,might as well be an effective adsorptionresin for isolating PAH from seawater.     

Antifouling activities of marine bacteria associated with sponge (Sigmadocia sp.)

The present study aimed at assessing the antifouling activity of bacteria associated with marine sponges. A total of eight bacterial strains were isolated from the surface of sponge Sigmadocia sp., of them, SS02, SS05 and SS06 showed inhibitory activity against biofilm-forming bacteria. The extracts of these 3 strains considerably affected the extracellular polymeric substance producing ability and adhesion of biofilm-forming bacterial strains. In addition to disc diffusion assay, microalgal settlement assay was carried out with the extracts mixed with polyurethane wood polish and coated onto stainless steel coupons. The extract of strain SS05 showed strong microalgal settlement inhibitory activity. Strain SS05 was identified as Bacillus cereus based on its 16S rRNA gene. Metabolites of the bacterial strains associated with marine invertebrates promise to be developed into environment-friendly antifouling agents.