Antibacterial actions of fatty acids isolated from marine algae: An in vitro evidence-based review

Fatty acids are well-known molecules from diverse sources that are toxic to microorganisms. As infectious diseases become a severe threat to human health and economy due to the dramatic emergence of antibiotic resistance, a quest for novel antibacterial agents from natural sources, including the marine ecosystem, has increased last few decades. Seaweeds, mainly marine algae, are being studied as a potential source of bioactive molecules to combat the new trend of acquired resistance in microbes. Algae contain plenty of different fatty acids including ω3 (i.e., 16:4 ω3 and 18:4 ω3), eicosapentaenoic (20:5 ω3), α-linolenic (18:3 ω-3), octadecatetraenoic (18:4 ω-3), and arachidonic (20:4 ω-6) acid. These fatty acids have a wide range of direct and indirect inhibitory effects majorly by destabilizing bacterial cell membranes. Therefore, the present study summarised and discussed the available pieces of evidence related to fatty acid activities in bacterial growth inhibition. Following the PRISMA guidelines, the literature mining was conducted using PubMed, Scopus, Web of Science, and Google Scholar databases published within the year 2011 to 2020. The search was limited to in vitro research regarding the antibacterial role of fatty acids isolated from marine algae. The literature search revealed 570 potentially relevant records, of which 28 were relevant in vitro studies that investigated the role of fatty acids for antibacterial effects, were included finally. Fatty acids were reported to be isolated following the bioassay-guided fractionation of algal extracts, followed by chromatographic techniques, and identified by nuclear magnetic resonance (NMR). The included studies showed various algal species as a potential source of fatty acids that were significant in inhibiting different bacterial strains, limited to gram-positive: Bacillus subtilis, Enterococcus faecalis, and Staphylococcus aureus, as well as gram-negative: Escherichia coli, Pseudomonas aeruginosa, for example. Present in vitro evidence-based review highlighted the cellular and molecular actions of fatty acids that positively affect bacterial growth inhibition. The evidence thus recommends that the algal fatty acids might act as potential antibacterial agents, thereby can be used as pharmaceutical products for infectious diseases.