In vitro assessment of Sargassum platycarpum extract as a novel antimicrobial agent and functional prebiotics

Abstract Sargassum platycarpum is a brown macroalgae species commonly found in coastal areas. This macroalgae is a source of important bioactive compounds that can be utilized as functional food ingredients and pharmaceutical agents. In the current study, S. platycarpum collected from the Red Sea was dried and extracted with methanol . S. platycarpum methanolic extract (SME) was evaluated as a potent antibacterial agent and as a prebiotic for marine probiotic consumption. SME demonstrated significant antimicrobial activity, with Bacillus subtilis ATCC 6633 being the most affected pathogen, exhibiting a clear zone diameter of 25 mm. Conversely, Staphylococcus aureus ATCC 25,923 displayed the least susceptibility, with a clear zone diameter of 14 mm. Moreover, SME (0.1%, 0.5%) exhibited a significant increase in the marine probiotic Enterococcus faecalis H2 growth, indicated by a high OD value of 1.3 at 620 nm after 6 h of incubation and viable bacterial count > 300*10 2 CFU mL −1 , which is equivalent to inulin. Furthermore, the chemical composition of SME was determined through GC–MS analysis, demonstrating that it consists of forty-five phytochemical compounds, primarily terpenoids, fatty acids/lipids, steroids, carotenoids, and polyphenolic/aromatic derivatives. These results offer new perspectives on integrating SME into future research paths related to functional food and pharmaceutics.