Bifurcaria bifurcata is a marine brown seaweed mainly found on the Atlantic coast. Herein, we report the antioxidant and neuroprotective activities of seven fractions (F1–F7) obtained by normal phase chromatography from the B. bifurcata dichloromethane extract, as well as of its two major isolated diterpenes. Total phenolic content of fractions was determined by the Folin–Ciocalteu method, while antioxidant activity was evaluated by the DPPH, ORAC, and FRAP assays. Neuroprotective effects were evaluated in a neurotoxic model induced by 6-hydroxydopamine (6-OHDA) in a human neuroblastoma cell line (SH-SY5Y), while the mechanisms associated to neuroprotection were investigated by the determination of mitochondrial membrane potential, H2O2 production, Caspase-3 activity, and by observation of DNA fragmentation. Fractions F4 and F5 exhibited the best neuroprotective and antioxidant activities, respectively. F4 fraction prevented changes in mitochondrial potential, and induced a reduction of H2O2 levels production and an increase in cell viability, suggesting that it may contain multi-target compounds acting on different pathways. Hence, this fraction was subjected to purification steps, affording the known diterpenes eleganolone and eleganonal. Both compounds exhibited antioxidant potential, being interesting candidates for further neuroprotective studies.
Macroalgae‐associated bacteria have already proved to be an interesting source of compounds with therapeutic potential. Accordingly, the main aim of this study was to characterize Asparagopsis armata‐associated bacteria community and evaluate their capacity to produce substances with antitumor and antimicrobial potential. Bacteria were selected according to their phenotype and isolated by the streak plate technique. The identification was carried out by the RNA ribosomal 16s gene amplification through PCR techniques. The antimicrobial activities were evaluated against seven microorganisms (Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, Salmonella enteritidis, Staphylococcus aureus, Saccharomyces cerevisiae, Candida albicans) by following their growth through spectrophotometric readings. Antitumor activities were evaluated in vitro on human cell lines derived from hepatocellular (HepG‐2) and breast carcinoma (MCF‐7) using the MTT method. The present work identified a total of 21 bacteria belonging to the genus Vibrio, Staphylococcus, Shewanella, Alteromonadaceae, Bacillus, Cobetia, and Photobacterium, with Vibrio being the most abundant (42.86%). The extract of Shewanella sp. ASP 26 bacterial strain induced the highest antimicrobial activity, namely against Bacillus subtilis and Staphylococcus aureus with an IC
50 of 151.1 and 346.8 μg/mL, respectively. These bacteria (Shewanella sp.) were also the ones with highest antitumor potential, demonstrating antiproliferative activity on HepG‐2 cells. Asparagopsis armata‐associated bacteria revealed to be a potential source of compounds with antitumor and antibacterial activity.
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