Bioactive compounds of sea cucumber (Holothuria leucospilota) added to epoxy resin as environmental friendly antifouling coats

The use of natural antifouling agents is a new and suitable approach to solve the worldwide biofouling problem. In this study, anti-micro algal and antifouling activity of a series of n-hexane, ethyl acetate and methanol extracts from four sections of sea cucumber Holothuria leucospilota (body wall, gonad, digestive tract and respiratory tree) were investigated. Anti-microalgal assay against two microalgae species Chlorella vulgaris and Isochrysis galbana was conducted to determine the minimum inhibitory concentration (MIC) for each extract. The best extracts were added to resin epoxy and applied on fiberglass panels (10×10cm). All panels were immersed in the Persian Gulf (Bandar-e-Gorzeh) for three months. Results indicated that ethyl acetate extract of the body wall had the best inhibitory activity against I. galbana, with MIC of 0.062 mg/mL. Based on field results, the panel coated with 4% ethyl acetate extract from body wall added to resin epoxy had the lowest final weight (123.33±8.32g) and lowest fouling cover percentage (57.8%) among all panels after three months‏ (P<0.05). Regarding the high antifouling activity of ethyl acetate extract from the body wall of sea cucumber H. leucospilota, its use as a potential alternative to commercial biocides in antifouling coats is suggestable.