322 Comparative Analysis of Antioxidant and Antibacterial Activities of Corallina officinalis

Abstract Introduction/Objective Marine red algae are increasingly recognized as potent sources of natural bioactive compounds with pharmaceutical relevance. Among these, Corallina officinalis is a calcified red alga rich in polyphenols and secondary metabolites, making it a promising candidate for therapeutic exploration. The rising resistance to synthetic antibiotics and prevalence of oxidative stress-related conditions drive the need for natural antioxidant and antimicrobial agents. This study aims to investigate the antioxidant and antibacterial activities of C. officinalis extracts prepared using different organic solvents. Objectives To evaluate the phytochemical content and bioactivities of C. officinalis extracts obtained via ethyl acetate, methanol, chloroform, and acetone extraction, focusing on antioxidant potential Methods/Case Report The algae were collected in fresh form 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 using the specified organic solvents. The 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 C. officinalis demonstrated the highest total phenolic content (5.8 mg/g) and moderate flavonoid content. The ethyl acetate extract exhibited strong reducing power (9.22 mg/ml) and moderate hydrogen peroxide scavenging activity (51.3%). In antibacterial assays, the ethyl acetate extract showed significant inhibition against Staphylococcus aureus (inhibition zones of up to 17.0 mm) and Klebsiella pneumoniae (inhibition zones of up to 10.0 mm). Conclusion Ethyl acetate proved to be the most effective solvent for extracting bioactive compounds from C. officinalis, demonstrating promising antioxidant and antibacterial properties. These findings support its potential use in developing natural therapeutic agents targeting oxidative stress and bacterial infections.