321 Evaluation of Bioactive Properties of Enteromorpha intestinalis Extracts

Abstract Introduction/Objective Marine algae represent a valuable but underexplored source of bioactive compounds with potential applications in pharmaceuticals, nutraceuticals, and food preservation. Among these, Enteromorpha intestinalis, a green alga commonly found along coastal regions, is known to produce secondary metabolites with promising antioxidant and antimicrobial properties. As resistance to synthetic antibiotics continues to rise, there is growing interest in identifying natural compounds with comparable or complementary therapeutic effects. However, the biochemical potential of E. intestinalis remains largely untapped, particularly in regions like the Mediterranean. This study investigates the phytochemical composition and evaluates the antioxidant and antibacterial activities of various solvent extracts of E. intestinalis to determine its potential as a natural source of bioactive agents. Methods/Case Report Fresh samples of E. intestinalis were collected from several locations along the coasts of Alexandria, Egypt. Powdered samples (10 g) were extracted with 50 ml of 70% solvents (chloroform, acetone, ethyl acetate, and methanol). The filtrates were collected as crude extracts and analyzed phytochemically to screen for bioactive compounds such as alkaloids, anthraquinones, anthocyanins, carbohydrates, coumarins, emodin, flavonoids, and tannins. Quantitative phytochemical analysis was then performed. Antibacterial activity was assessed against two Gram-positive bacteria: Staphylococcus aureus ATCC6538 and Listeria monocytogenes FLB6, as well as two Gram-negative bacteria: E. coli ATCC11229 and Klebsiella pneumoniae ATCC13883. The antimicrobial properties of the various extracts were investigated. Extracts were dissolved in 4% dimethyl sulfoxide (DMSO) and tested at concentrations of 100 and 300 μl/ml against the bacterial pathogens. Data were expressed as mean ± SD, with p < 0.05 considered significant. Results Ethyl acetate and methanol extracts of E. intestinalis demonstrated moderate antioxidant activity, with phenolic content of 3.7 mg/g and flavonoid content of 0.95 mg/g. Hydrogen peroxide scavenging activity reached 55.62%, while reducing power peaked at 7.86 mg/ml. Antibacterial results indicated weak activity overall, with the highest inhibition against Klebsiella pneumoniae (11 mm) observed only in the ethyl acetate extract. Conclusion Enteromorpha intestinalis demonstrates potential as a moderate natural antioxidant source, with limited antibacterial effects. Further optimization and isolation of individual compounds are recommended to enhance its therapeutic potential.