Antifouling Lipids from Marine Fungi of the Beibu Gulf

<b>Background</b>: The search for environmentally friendly antifouling agents has led to an increased focus on marine natural products. <b>Methods</b>: This study investigated the antifouling potential of lipid fractions extracted from ten marine fungal strains isolated from the Beibu Gulf, China. The lipids were evaluated through a multi-level bioassay approach, including the inhibition of microfouling (against four fouling bacteria: <i>Marinobacterium jannaschii</i>, <i>Vibrio pelagius</i>, <i>Vibrio rotiferianus</i>, and <i>Alteromonas macleodii</i>), the prevention of macrofouling (inhibition of barnacle <i>Amphibalanus reticulatus</i> cyprid settlement), and long-term (90-day) marine field trials. <b>Results</b>: Eight lipid fractions demonstrated inhibitory effects against at least one bacterial strain. Five lipids significantly inhibited barnacle cyprid settlement, with half-maximal effective concentration (EC₅₀) values ranging from 0.21 to 1.81 µg/mL and exhibited low toxicity (half-maximal lethal concentration (LC₅₀) > 50 µg/mL). Notably, four lipid fractions maintained potent antifouling efficacy (>70% inhibition) throughout the 90-day field exposure. Chemical characterization via gas chromatography-mass spectrometry (GC-MS) revealed that the bioactive fractions were predominantly composed of fatty acids and their derivatives. Major identified compounds included palmitic acid, methyl palmitate, linoleic acid, dodecyl-9-ynyl chloroacetate, <i>cis</i>-13-octadecenoic acid, oleic acid, methyl 11,14-octadecadienoate, and (<i>E</i>)-9-octadecenoic acid methyl ester. <b>Conclusions</b>: This work represents the first comprehensive investigation of marine fungal lipids from the Beibu Gulf with multi-target antifouling properties, providing a theoretical foundation and practical candidate compounds for developing eco-friendly antifouling coatings.