In-Vitro and In-Silico Antibiofilm Activity and Phytochemical Profiling of Extracts of Marine Macroalgae Collected From the Red Sea

Introduction: Biofilms cause human health-related issues like chronic infections and affect the performance of materials in the aquatic environment. Natural products are considered a potential agent for controlling biofilm growth on surfaces. Marine macroalgae are a good source of novel bioactive metabolites. In this study, the antibiofilm activity of extracts from Dictyota dichotoma (brown alga), Ulva reticulata (green alga), and Acanthophora spicifera (red alga) was analyzed against biofilm-forming bacteria isolated from marine waters. This study aimed to analyze the phytochemical composition and antibiofilm activity of three macroalgal extracts. Methods: Antibiofilm activity was assessed against two biofilm-forming strains. The phytochemical components, such as chlorophyll a, carotenoids, carbohydrates, proteins, lipids, and total polyphenols, were analyzed to understand their contribution to biofilm inhibition. The secondary metabolite composition of the extracts was identified using GC-MS, and the detected compounds were used for molecular docking against the Biofilm-associated protein (Bap) of Staphylococcus aureus. Results: The results revealed strong antibiofilm activity (more than 50% inhibition) in all three algal species, with higher activity recorded for the brown alga. Macroalgal extracts altered cell surface hydrophobicity and reduced the extracellular polymeric substance production in biofilm bacteria. Results indicated that A. spicifera (red alga) had high carbohydrate content, while U. reticulata (green alga) had high protein content. The carotenoids and chlorophyll a contents were higher in the green alga. GC-MS analysis showed a greater number of compounds for the brown alga, followed by the red and green algae. Discussion: Most of the identified compounds were predicted to be potential antibiofilm agents (with biofilm inhibition efficiency > 60%) based on aBiofilm database. Strong binding affinities were observed between some of the metabolites and the biofilm-associated protein of S. aureus in molecular docking analysis. result: The results revealed strong antibiofilm activity (above 50% of inhibition) in all three algal species with higher activity recorded in brown alga. Treatment macroalgal extracts resulted a change in cell surface hydrophobicity and reduction in extracellular polymeric substance production in biofilm bacteria. Results indicated a high carbohydrate content in red alga A. spicifera and protein content in green alga U. reticulata. The carotenoids and chlorophyll-a contents were high in the green algal samples. GC-MS analysis showed a greater number of compounds in brown alga followed by red and green algae. Most of compounds identified in the extracts are predicted as potential antibiofilm agents (biofilm inhibition efficiency of >60%) using abiofilm database. Strong binding affinities between some of the metabolites and biofilm-associated protein of S. aureus was observed in molecular docking analysis. Conclusion: The results suggest that the Red Sea macroalgae are good sources of antibiofilm compounds that could be used for both pharmacological and environmental applications.