Marine organisms are a rich and still unexplored source of compounds with novel molecular structures and activities. In recent years many secondary metabolites from macrophytes were shown to possess different bioactivities such as antimicrobial, antiviral and antifungal [1] and thus they are promising agents for drug discovery and development. Some of the marine-derived compounds are either in preclinical or clinical trials [2].
Currently, emergence of microbial resistance to antibiotics has become a global problem and macrophytes might be a potential source of new therapeutics. Some promising results have already been obtained for organisms collected in tropical and subtropical ecosystems. However, there is still no information about the antibacterial activity of the macrophytes form the Baltic Sea. The aim of our work was to screen crude extracts from the Baltic macrophytes against antibiotic-resistant strains of Gram-positive and Gram-negative bacteria. Individuals from Chara, Cladophora, Myriophyllum and Ulva genera were collected in the Puck Bay (Gulf of Gdańsk). In order to extract a wide range of metabolites different solvents were used: 90% ethanol, water and isopropanol/hexane (1:1). Agar disc diffusion method was applied in search for antibacterial activity of the obtained crude extracts.