Effects of ultra-high pressure assisted extraction on the structure, antioxidant and hypolipidemic activities of Porphyra haitanensis polysaccharides

Porphyra haitanensis polysaccharides (PHPs) have potential antioxidant and hypolipidemic activities, but still need improvement. Therefore, ultra-high pressure (UHP) assisted extraction was applied to modify the structure, antioxidant, and hypolipidemic activities of PHPs. UHP assisted extraction increased the total sugar, uronic acid, and 3,6-anhydro-ʟ-galactose contents of PHP, which increased by 15.85 %-16.12 %, 18.95 %-24.32 %, 20.54 %-23.66 % with 500-600 MPa UHP, respectively. Meanwhile, UHP modified PHP became more rough and porous than native PHP. Besides, UHP assisted extracted PHP showed better in vitro antioxidant and hypolipidemic abilities. Especially, 500-600 MPa UHP increased 72.43 %-86.42 % 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacities, 12.32 %-12.82 % pancreatic lipase inhibitory ability, and 14.93 %-15.23 % glycocholate binding abilities of PHP (p < 0.05). Moreover, UHP assisted extracted PHP greatly decreased the lipid droplet and triglyceride contents of 3T3-L1 adipocytes (p < 0.05). Our findings can provide the theoretical basis for the high value utilization of Porphyra haitanensis and its polysaccharides with UHP modification.