Butenolide is a promising antifouling natural product.

Rosin-based antifouling paint with the incorporation of butenolide, a promising antifoulant, possesses the potential to deter the settlement of marine organisms on submerged surfaces.

Butenolide with a purity >99% was synthesized by Medicilon.

Reference:

Lianguo Chen, et al. Optimization of antifouling coatings incorporating butenolide, a potent antifouling agent via field and laboratory tests. Progress in Organic Coatings. 2017 Aug; 109: 22-29.