Exploring the biomedicinal properties of Padina boergesenii ethanolic extract against human pathogens: An in vitro approach.

Seaweeds are recognized for their productivity and extensive nutritional, biomedicinal, and pharmaceutical properties. This study investigates the phytochemical composition and biological activities of the brown seaweed Padina boergesenii, collected from the Gulf of Mannar, Tamil Nadu, India. The phytochemical screening confirmed the presence of diverse metabolites, including alkaloids, glycosides, steroids, terpenoids, flavonoids, phenols, and proteins. Quantitative assays revealed total flavonoid and phenolic contents of 19.83 mg QE/g and 44.93 mg GAE/g, respectively. The ethanolic extract exhibited excellent antibacterial activity against Escherichia coli, Streptococcus mutans, and Enterococcus faecalis, with inhibition zone from 15 ± 0.88 to 21 ± 0.84 mm, MIC values of 6.25 to 25 μg/mL, and MBC values of 12.5 to 50 μg/mL. Biofilm inhibition (12 to 97%) and an augmentation of extracellular protein leakage (10 to 82%) at different time intervals against pathogenic bacteria support its antimicrobial activity. The antioxidant activity demonstrated dose-dependent radical scavenging activity, while α-amylase inhibition with an IC50 value of 16.12 μg/mL indicated strong antidiabetic potential. Cytotoxic assay revealed anticancer activity against MCF-7 and HepG-2 cell lines with IC50values of 73.32 and 31.63 μg/mL, respectively. The biocompatibility evaluation showed moderate hemolytic - (IC50: 5.95 μg/mL) and cytotoxicity to Artemia nauplii (LC50: 61.23 μg/mL). LC-MS profiling combined with molecular docking suggested milbemycin and artemisinin as key contributors to the observed pharmacological effects. Collectively, these results underscore P. boergesenii as a valuable candidate for future pharmaceutical exploration.