Bioactive potential of mediterranean macroalgae: comparative insights from the extracts of native (Ericaria brachycarpa and Ericaria crinita) and invasive (Asparagopsis taxiformis) species

Marine species are a rich source of bioactive molecules. Among them, marine algae are known to produce various secondary metabolites with a wide range of biological activities, such as immunomodulatory, antioxidant, and antimicrobial. This study aimed to characterize the extracts of three Mediterranean macroalgae species: two native, Ericaria brachycarpa and Ericaria crinita, and one invasive, Asparagopsis taxiformis, to subsequently evaluate their haemolytic and antimicrobial activities. The characterization of secondary metabolites was performed using untargeted HPLC/ESI/MS and confirmed the presence of meroterpenoids for E. crinita, oxidized fatty acids (oxylipins) in E. brachycarpa, and brominated compounds as constituents of A. taxiformis. The extracts were tested for their antagonistic activities against some representative strains of the human bacterial pathogens Listeria monocytogenes and Staphylococcus aureus, isolated from food matrices and human stools. The extracts from E. brachycarpa and A. taxiformis inhibited all tested strains, while E. crinita barely inhibited two L. monocytogenes strains. These extracts also showed low haemolytic activity towards mammalian erythrocytes. These preliminary results encourage future investigation on the biological efficacy of the metabolites from E. brachycarpa and A. taxiformis.