Biofouling deterrent activity of the natural product from ascidian, Distaplia nathensis [Chordata]

Abstract

Growth of marine sedentary organisms causes notable damage to ship-hull, harbour structures and industrial cooling and filtration systems. TBT based antifouling paints are widely used worldwide and is to be phased out by the year 2008 because of its adverse effect on non-target organisms. Efforts are therefore being made to develop alternative eco-friendly antifoulant paints. The crude methanol: water extract of the ascidian, Distaplia nathensis showed antimicrobial activity against 12 out of 14 bacteria screened in the present study. At a concentration of 0.1 mg/ml, the crude extract completely inhibited the byssal production and attachment in the mussel Perna indica. The EC 50 and LC 50 were found to be 50±6.45 μg/ml and 150±19.2 μg/ml respectively. The gradient partition showed high polar nature of the active component. The indication of non-toxic nature of the extract in the toxicity assay and the broad spectral antimicrobial activity has revealed that it could be a potential source of the antifouling compound.