Unravelling the potential of seaweeds from the Black Sea coast of Romania as bioactive compounds sources. Part I: Cystoseira barbata (Stackhouse) C. Agardh.

The Romanian coastlines of the Black Sea have abundant seaweed resources, but little effort has been done to investigate their biological potential. The aim of the present study was to assess the in vitro antioxidant and anti-proliferative effects of Cystoseira barbata (Stackhouse) C. Agardh (Sargassaceae), a brown alga inhabiting the Black Sea coast of Romania. The 70% acetone, methanol and water extracts of C. barbata were evaluated for their total phenolic content, antioxidant activity and anti-proliferative potential against human tumor cell lines (pulmonary A549, colon HT-29, mammary MCF-7) and the non-tumor mammary epithelial MCF-10A cell line. C. barbata 70% acetone extract (CBAE) displayed the highest antioxidant and cytotoxic activities. The mechanism of CBAE anti-proliferative activity involved initially increased intracellular ROS accumulation, followed by increased DNA content in the subG1 phase and DNA fragmentation leading to excessive apoptosis. Thus, our study provides a theoretical basis for the use of CBAE as a tumor preventive agent. Furthermore, UHPLC-DAD-QTOF-MS analysis of CBAE tentatively identified 18 phlorotannins as fucophlorethol and eckol derivatives, containing three up to seven phloroglucinol units. In conclusion, C. barbata represents a valuable source for the development of macroalgal-based products with putative use as nutraceuticals and pharmaceuticals.