The increasing drug resistance of pathogenic microorganisms raises concern worldwide and necessitates the search for new natural compounds with antibacterial properties. Marine algae are considered a natural and attractive biotechnological source of novel antibiotics. The high antimicrobial activity of their polyphenolic compounds is a promising basis for designing innovative pharmaceuticals. They can become both a serious alternative to traditional antimicrobial agents and an effective supplement to antibiotic therapy. The present review summarizes the results of numerous studies on polyphenols from algae and the range of biological activities that determine their biomedical significance. The main focus is put on a group of the polyphenolic metabolites referred to as phlorotannins and, particularly, on their structural diversity and mechanisms of antimicrobial effects. Brown algae are an almost inexhaustible resource with a high biotechnological potential for obtaining these polyfunctional compounds. An opinion is expressed that the effectiveness of the antibacterial activity of phlorotannins depends on the methods of their extraction aimed at preserving the phenolic structure. The use of modern analytical tools opens up a broad range of opportunities for studying the metabolic pathways of phlorotannins and identifying their structural and functional relationships. The high antimicrobial activity of phlorotannins against both Gram-positive and Gram-negative bacteria provides a promising framework for creating novel drugs to be used in the treatment and prevention of infectious diseases.
Keywords: antibacterial properties; antibiofilm properties; drug resistance of microorganisms; marine algae; phlorotannins (PT); polyphenols (PP).