Bacterial biofilms are highly organized surface-associated communities of bacteria encased within an
extracellular matrix produced by themselves, capable of growing in connection with different biological or inert
surfaces such as artificial joints or catheters. Biofilms are commonly associated with many health problems, such as
endocarditis, otitis media, periodontitis, prostatitis, and urinary tract infections. Several bacteria, such as Escherichia coli,
Staphylococcus aureus, Streptococcus mutans, and Pseudomonas aeruginosa, or fungal pathogen as Candida albicans,
can form biofilms in the body tissues, leading to different infections. The inherently defensive character of the biofilm is
demonstrated by enhanced persistence of bacteria grown in the sessile mode respect to bacteria grown planktonically.
This makes most biofilm- associated infections difficult to eradicate, thus contributing to disease chronicity. Since natural
products provide a diverse array of chemical structures and possess a wide variety of biological properties, natural
resources are worldwide exploited in the search of new pharmaceuticals. In this context bioactive secondary metabolites
from natural sources, useful for the new antimicrobial and anti-biofilm drugs, are of interest. In this review, the role of
small molecules from plants and marine organisms in inhibiting and/or dispersing bacterial biofilms is discussed, as
well as the approaches that have been applied to the discovery of lead small molecules that mediate biofilm
development. Molecules inhibiting the formation of biofilm may have therapeutic potential. Several candidates, as
halogenated furanones, 2-amminoimidazole alkaloids and flavonoids have been already isolated and characterized
from many plants and from marine organisms.