Advancing Marine Biotechnology: Bioactive Compounds Extraction and Therapeutic Potential of the Brown Seaweed Dictyopteris woodwardia

Marine macroalgae are rich but underutilized as sources of bioactive compounds with significant pharmaceutical and nutraceutical potential. Dictyopteris woodwardia, a brown seaweed species, remains largely unexplored for its chemical composition and therapeutic applications. This study evaluated the extraction efficiency, bioactive content, antioxidant activity, antimicrobial properties, and chemical characterization of D. woodwardia extracts. Soxhlet extraction, maceration, and freeze-drying were performed using methanol, ethanol, ethyl acetate, and water as solvents. Freeze-dried methanol extracts yielded the highest recovery (9.3% w/w) and showed the highest total phenolic (76.5 ± 3.2 mg GAE/g) and flavonoid content (49.2 ± 2.7 mg QE/g). Antimicrobial assays demonstrated notable inhibition against Staphylococcus aureus (18.4 ± 0.7 mm), Enterococcus faecalis (13.6 ± 0.6 mm), and Klebsiella pneumoniae (15.8 ± 0.6 mm), while Pseudomonas aeruginosa exhibited resistance. Antioxidant potential, evaluated by DPPH and FRAP assays, revealed strong activity with Half Maximal Inhibitory Concentration (IC₅₀) values of 32.39 and 50.79 µg/mL, respectively. FTIR analysis confirmed the presence of hydroxyl (-OH) and carbonyl (C=O) groups associated with phenolics, flavonoids, and polysaccharides. These findings position D. woodwardia as a promising source of natural antimicrobial and antioxidant agents, emphasizing the critical role of solvent and extraction strategies in maximizing bioactive compound recovery.