The Role of Natural and Synthetic Flavonoids in the Prevention of Marine Biofouling

Abstract

Marine biofouling is a major concern for the maritime industry, environment, and human health. Biocides which are currently used in marine coatings to prevent this phenomenon are toxic to the marine environment, and therefore a search for antifoulants with environmentally safe properties is needed. A large number of scientific papers have been published showing natural and synthetic compounds with potential to prevent the attachment of macro- and microfouling marine organisms on submerged surfaces. Flavonoids are a class of compounds which are highly present in nature, including in marine organisms, and have been found in a wide range of biological activities. Some natural and synthetic flavonoids have been evaluated over the last few years for their potential to prevent the settlement and/or the growth of marine organisms on submerged structures, thereby preventing marine biofouling. This review compiles, for the first-time, natural flavonoids as well as their synthetic analogues with attributed antifouling activity against macrofouling and microfouling marine organisms.

Keywords: antifouling activity; biofouling; flavonoids; natural; synthesis.

Figure 1

Examples of subclasses of flavonoids.

Figure 2

(A) Classes of flavonoids with antifouling activity reported in this review. (B) Bioactivity evaluated for antifouling flavonoids against macrofouler, microfouler, or both types of fouling organisms. (C) Basis of flavonoids studied for antifouling activity. (D) Source of natural flavonoids.

Figure 3

Structures of chalcones 1–61 with antifouling activity and SAR considerations.

Figure 4

Structures of flavonols 62–82 with antifouling activity and some SAR considerations. Compounds 63, 64, and 77–79 were isolated from marine sources.

Figure 5

Structures of flavones 83–95 with antifouling activity and some SAR considerations. Compounds 84–86, 89, and 90 were isolated from marine sources.

Figure 6

Structures of flavanones 96–99 with antifouling activity.

Figure 7

Structures of isoflavones 100–102 with antifouling activity. Isoflavone 101 was isolated from marine sources.

Figure 8

Structures of other classes of flavonoids with antifouling activity, including flavans 103–104, flavanol 105, and flavanonol 106. Flavonoids 105 and 106 were isolated from marine sources.