Isolation of antifouling substances from the Palauan sponge Protophlitaspongia aga

ABSTRACT: Fouling organisms cause serious problems by settling on ships' hulls, and other marine infrastructures. Organotin compounds have been developed as effective antifoulants. However, environmental problems are associated with these compounds. It is necessary to find antifouling substances that exhibit a lower toxicity than those substances currently used. A new pyrimidine derivative, 3,4,5,6-tetrahydro-6-hydroxymethyl-3,6-dimethyl-4-pyrimidinecarboxylic acid, (compound 1) and zooanemonin (compound 2) were isolated from the marine sponge Protophlitaspongia aga as antifouling substances against the barnacle Balanus amphitrite . We also found that α-nicotinamide ribose (compound 3) inhibited germination and the attachment of Ulva spores.     

SAR of Sponge-Inspired Hemibastadin Congeners Inhibiting Blue Mussel PhenolOxidase

Hemibastadin derivatives, including the synthetically-derived 5,5′-dibromohemibastadin-1 (DBHB), are potent inhibitors of blue mussel phenoloxidase (PO), which is a key enzyme involved in the firm attachment of this invertebrate to substrates and, thus, a promising molecular target for anti-fouling research. For a systematic investigation of the enzyme inhibitory activity of hemibastadin derivatives, we have synthesized nine new congeners, which feature structural variations of the DBHB core structure. These structural modifications include, e.g., different halogen substituents present at the aromatic rings, different amine moieties linked to the (E)-2-(hydroxyimino)-3-(4-hydroxyphenyl)propionic acid, the presence of free vs. substituted aromatic hydroxyl groups and a free vs. methylated oxime group. All compounds were tested for their inhibitory activity towards the target enzyme in vitro, and IC₅₀ values were calculated. Derivatives, which structurally closely resemble sponge-derived hemibastadins, revealed superior enzyme inhibitory properties vs. congeners featuring structural moieties that are absent in the respective natural products. This study suggests that natural selection has yielded structurally-optimized antifouling compounds.     

Antifouling Activity of Halogenated Compounds Derived from the Red Alga Sphaerococcus coronopifolius: Potential for the Development of Environmentally Friendly Solutions

Nowadays, biofouling is responsible for enormous economic losses in the maritime sector, and its treatment with conventional antifouling paints is causing significant problems to the environment. Biomimetism and green chemistry approaches are very promising research strategies for the discovery of new antifouling compounds. This study focused on the red alga Sphaerococcus coronopifolius, which is known as a producer of bioactive secondary metabolites. Fifteen compounds, including bromosphaerol (1), were tested against key marine biofoulers (five marine bacteria and three microalgae) and two enzymes associated with the adhesion process in macroalgae and invertebrates. Each metabolite presented antifouling activity against at least one organism/enzyme. This investigation also revealed that two compounds, sphaerococcinol A (4) and 14R-hydroxy-13,14-dihydro-sphaerococcinol A (5), were the most potent compounds without toxicity towards oyster larvae used as non-target organisms. These compounds are of high potential as they are active towards key biofoulers and could be produced by a cultivable alga, a fact that is important from the green chemistry point of view.     

海水网箱网衣防污技术的研究进展

海水网箱养殖中,网衣污损附着物会影响网箱设施安全及其养殖鱼类的健康生长,因此,网衣防污是网箱养殖业备受关注的问题.本文在简述海水网箱网衣分类与特点的基础上,重点介绍了人工清除法、防污涂料法、机械清除法、金属合金网衣防污法、箱体转动防污法、生物防污法、网衣本征防污法等网衣防污技术最新研究进展;结合本课题组在网衣防污方面的...     

Predicting Antifouling Activity and Acetylcholinesterase Inhibition of Marine-Derived Compounds Using a Computer-Aided Drug Design Approach

Biofouling is the undesirable growth of micro- and macro-organisms on artificial water-immersed surfaces, which results in high costs for the prevention and maintenance of this process (billion €/year) for aquaculture, shipping and other industries that rely on coastal and off-shore infrastructure. To date, there are still no sustainable, economical and environmentally safe solutions to overcome this challenging phenomenon. A computer-aided drug design (CADD) approach comprising ligand- and structure-based methods was explored for predicting the antifouling activities of marine natural products (MNPs). In the CADD ligand-based method, 141 organic molecules extracted from the ChEMBL database and literature with antifouling screening data were used to build the quantitative structure–activity relationship (QSAR) classification model. An overall predictive accuracy score of up to 71% was achieved with the best QSAR model for external and internal validation using test and training sets. A virtual screening campaign of 14,492 MNPs from Encinar’s website and 14 MNPs that are currently in the clinical pipeline was also carried out using the best QSAR model developed. In the CADD structure-based approach, the 125 MNPs that were selected by the QSAR approach were used in molecular docking experiments against the acetylcholinesterase enzyme. Overall, 16 MNPs were proposed as the most promising marine drug-like leads as antifouling agents, e.g., macrocyclic lactam, macrocyclic alkaloids, indole and pyridine derivatives.     

大型抗风浪网箱网衣防污涂料选优试验报告

2004年3月～2005年2月,在福建省围头海域对进口的13种配方和国产的14种配方的防污涂料开展防污效果选优试验.结果表明,进口的防污涂料中,以日本油脂公司提供、编号为X2、X3和x4的涂料,防污效果最好,缦海时间六个月时,其污损生物的面积覆盖率均≤3%;国产的防污涂料中,以厦门某研究所提供、编号为X11、X20和X27的效果最好,浸海时间六个月时,其污损生物的面积覆盖率均≤25%,且其价格远低于进口涂料,可作为春季、夏季和秋季进行网片防污处理的推荐涂料,供生产者选择.     

Synthetic Analogue of Butenolide as an Antifouling Agent

Butenolide derivatives have the potential to be effective and environmentally friendly antifouling agents. In the present study, a butenolide derivative was structurally modified into Boc-butenolide to increase its melting point and remove its foul smell. The structurally modified Boc-butenolide demonstrated similar antifouling capabilities to butenolide in larval settlement bioassays but with significantly lower toxicity at high concentrations. Release-rate measurements demonstrated that the antifouling compound Boc-butenolide could be released from polycaprolactone-polyurethane (PCL-PU)-based coatings to inhibit the attachment of foulers. The coating matrix was easily degraded in the marine environment. The performance of the Boc-butenolide antifouling coatings was further examined through a marine field test. The coverage of biofouler on the Boc-butenolide coatings was low after 2 months, indicating the antifouling potential of Boc-butenolide.     

The antifouling activity of some juvenoids on three species of acorn barnacle, Balanus

Analogues of insect juvenile hormones (juvenoids) have been tested for settling inhibition of cyprids from three species of barnacle, Balanus balanoides (L.), Balanus improvisus Darwin and Balanus amphitrite Darwin. Some 3-alkoxypyridine derivatives exhibited strong activity at mg litre(-1) concentrations; 3,7-dimethyloctyl 2-methyl-5-pyridyl ether (8) gave an EC(50) of 0.006 mg litre(-1) when tested on B. balanoides. When compound 8 and similar juvenoids were incorporated into paints, test panels kept in seawater for 8 months were free of barnacles.