Phytochemical characterization and evaluation of the antioxidant, antimicrobial, and In Vivo protective effects of Ulva lactuca extracts from the Algerian coast

Marine macroalgae are increasingly recognized as valuable sources of bioactive compounds with potential applications in food, pharmaceutical, and biomedical fields. In this context, Ulva lactuca from the Algerian Mediterranean coast was investigated for its phytochemical profile and biological effects. The methanolic extract showed higher yields of phenolics (45.8 mg GAE/g), flavonoids (10.5 ± 1.1 mg QE/g), and tannins (15.7 ± 1.5 mg TAE/g) compared to the oil extract. Antioxidant assays confirmed superior activity of the methanolic extract with lower IC₅₀ values in DPPH (69.3 ± 1.8 %), ABTS (70.5 ± 1.6 %), and CUPRAC (213.7 mg TE/g) tests. Antimicrobial activity was notable against Staphylococcus aureus (14 mm), Candida albicans (10 mm), and Escherichia coli (9 mm), while the oil extract showed stronger inhibition against E. coli (13 mm). In vivo, both extracts significantly reduced ALT, AST, ALP, and bilirubin levels, lowered lipid peroxidation (MDA), and enhanced antioxidant defenses (SOD, CAT, GSH). Histological analysis confirmed hepatoprotective effects. These findings highlight U. lactuca, particularly its methanolic extract, as a promising natural source of antioxidants, antimicrobial agents, and liver-protective compounds.