Isolation and Structure-Activity Relationship of Subergorgic Acid and Synthesis of Its Derivatives as Antifouling Agent

Abstract

In this study, as part of our continuous search for environmentally-friendly antifoulants from natural resources, subergorgic acid (SA) was identified from the gorgonian coral Subergorgia suberosa, demonstrating non-toxic, significant inhibitory effects (EC50 1.25 μg/mL, LC50 > 25 μg/mL) against the settlement of Balanus amphitrite. To further explore the bioactive functional groups of SA and synthesize more potent antifouling compounds based on the lead SA, the structure-activity relationships of SA were studied, followed by rational design and synthesis of two series of SA derivatives (one being benzyl esters of SA and another being SA derivatives containing methylene chains of various lengths). Our results indicated that (1) both the double bond and ketone carbonyl are essential elements responsible for the antifouling effect of SA, while the acid group is not absolutely necessary for maintaining the antifouling effect; (2) all benzyl esters of SA displayed good antifouling effects (EC50 ranged from 0.30 to 2.50 μg/mL) with the most potent compound being 5 (EC50 0.30 μg/mL, LC50 > 25 μg/mL), which was over four-fold more potent than SA; and (3) the introduction of a methylene chain into SA reduces the antifouling potency while the length of the methylene chain may differently influence the antifouling effect, depending on the functional group at the opposite site of the methylene chain. Not only has this study successfully revealed the bioactive functional groups of SA, contributing to the mechanism of SA against the settlement of B. amphitrite, but it has also resulted in the identification of a more potent compound 5, which might represent a non-toxic, high-efficiency antifoulant.

The Effect of Complex Emulsifier on the Structure of Tung Oil and Phenolic Amides Containing Microcapsules and Its Anti-Fouling and Anti-Corrosion Performances

“…Based on the analysis of microcapsules and coating characterization of the anti-corrosive and anti-fouling performance, the following conclusions can be drawn: In the process of biological fouling, first, a lipids and protein molecules thin film is formed on the material surface, micro-organisms such as bacteria and diatoms adhere to the thin film to form a biofilm, and then large fouling organisms begin to adhere [20]. Zhang et al [21] discovered that the double bond groups and ketone carbonyl were necessary elements for the anti-fouling effect, which can achieve the purpose of anti-fouling by inhibiting fouling biological activity. The phenolic amides anti-fouling agent used in the test is an anti-fouling active compound with a special molecular structure that is screened out using biological extraction and technology combined with chemical synthesis technology.…”

Research Strategies to Develop Environmentally Friendly Marine Antifouling Coatings

“…For example, Zhang et al [ 27 ] discovered subergorgic acid (SA) from Subergorgia suberosa , which proves that it is non-toxic and has a strong inhibitory effect on attachments. In addition, Zhang et al [ 28 ] conducted an in-depth study on the structure-activity relationship of SA and found that both ketone carbonyl and the double bond are necessary elements with antifouling activity. The experimental scheme is shown in Figure 3 .…”

“…( b ) Synthesis of benzyl esters of SA. ( c ) Synthesis of SA derivatives containing methylene chain of various lengths [ 28 ].…”

Modular Approaches to Cyclopentanoids and their Heteroanalogs

“…4 Subergorgic acid (Figure 2, N71) is an angularly fused triquinane with cardiotoxic activity, isolated from the Pacific gorgonian coral Subergorgia subeross 5 and its derivatives act as a promising antifouling agents. 6 Likewise, retigeranic acid ( Figure 2, N83 and N84) is an angularly fused sesterterpenoid that exhibits a wide range of pharmacological properties. 7 Presilphiperfolanol belongs to cyclohexane fused diquinane sesquiterpenes with modest biological activity.…”