Phenolic compounds of "blue food" Porphyra haitanensis: Chemical fingerprints, antioxidant activities, and in vitro antiproliferative activities against HepG2 cells.

China has implemented "Blue Granary" strategy to promote "blue foods" for ensuring sustainable food security due to the increased demand from the populations. In addition, the production of plant-based "blue foods" also promoted the reduction of greenhouse gas emissions compared to land-based agricultural products. Therefore, there is a growing interest to investigate plant-based "blue food" recently for better understanding their functional properties and health benefits. Porphyra haitanensis (P. haitanensis) belonged to red algae, is mainly cultivated in southern coast of China. P. haitanensis has been reported to contain health-promoting phenolic compounds which are beneficial for human health. However, little is known about the optimum extraction method of polyphenols and fingerprinting of true polyphenols from P. haitanensis. In addition, the physiological properties of polyphenols extract from P. haitanensis such as antioxidant activities and antiproliferative properties against cancer cells in vitro are not fully understood. Therefore, this study will focus on the polyphenols extract in P. haitanensis regarding to optimization of ultrasonic-assisted extraction, fingerprinting through UPLC-ESI-QTOF-MS, antioxidant activities, and antiproliferative properties against HepG2 cells in vitro for better understanding the health benefits of polyphenols in P. haitanensis.