Molecular design of anti-biofouling materials from natural phenolic compounds

Many natural phenolic compounds found in plants are well known for their antibiotic and antioxidant activities. It has been hypothesized that these activities of natural phenols could be used for developing permanent anti-biofouling coatings. In this study, two phenolic components, anacardic acid and cardanol, were extracted from cashew nut shell liquid, and tested for their antibiotic and anti-biofouling activities against Pseudomonas fluorescens. Both compounds killed all the cells within 18 hours (anacardic acid) and 30 hours (cardanol) after the addition to the culture media at a concentration of 800 mu g/ml. To form a stable permanent coating of these compounds, first they were polymerized by enzymatic polymerization, and the polymers were cross-linked on a glass slide. P. fluorescens were cultured on the coated and uncoated glasses for two weeks, and the images of the cells grown on the surfaces were taken by SEM. The coated surfaces clearly demonstrated anti-biofouling activities, showing not only fewer numbers of cells but also less exopolymer than the uncoated surfaces. Based on these results, a phenolic compound with a similar structure of anacardic acid was synthesized by using propylene diamine and fluorocarboxylic acid with cardanol. The synthesized phenolic compound was polymerized and cross-linked on a glass slide to test the anti-biofouling activity. The SEM images of the cells on the coated surface showed considerable decreases in the number of adhered cells and the amount of exopolymers even more than the anacardic acid and cardanol coatings. It is thought that the natural phenolic compounds with active functional groups can be used for anti-biofouling agents.