Use of Weed Extracts as Antifouling Additives for Marine Paints: Two Case Studies

Abstract

The present work explores the use of weed extracts and purified compounds as environmentally friendly antifouling additives with a possible application in marine paints. Two species were selected as case studies: Verbena bonariensis L., Verbenaceae, and Tillandsia tenuifolia L., Bromeliaceae. The extracts of both species showed promising antifouling activity in laboratory experiments (byssal thread formation of the mussel Mytilus edulis) and also in field assays by incorporation to soluble-matrix paints, which were used to coat acrylic tiles that were submerged in the sea for a period of 45 days. In the case of the Verbena extract, it was not possible to identify a major bioactive component, and aralidioside, the main iridoid, did not show antifouling activity. However, in the case of the Tillandsia extract, the main component, which was isolated and identified as cycloartenone, displayed potent antifouling activity in laboratory and field assays. Since both species have high growth rates, these results may help overcome the sustainability issues of the use of natural products as antifoulants. At the same time, the technological use of these untapped biological resources may offer a new possibility for weed management.