Optimization of Deproteinization Process of Polysaccharides Extracted from Abandoned Porphyra haitanensis and Their Antioxidant Activity

XIE Fei;CAO Chunjie;CHEN Meizhen;YE Tianwen;College of Science, Shantou University;

polysaccharides extracted from abandoned Porphyra haitanensis;;deproteinization;;antioxidant activity;;HeLa;;reactive oxygen species

Objective: This study aimed to investigate the deproteinization process of polysaccharides extracted from abandoned Porphyra haitanensis and to evaluate their cellular antioxidant activity. Methods: Response surface methodology was used to optimize the process conditions for the enzymatic deproteinization of P. haitanensis polysaccharides with papain. An oxidative stress model was built by stimulating He La cells with H_2O_2 and the methyl thiazolyl tetrazolium(MTT) method was used to determine the cell survival rate. The level of cellular reactive oxygen species(ROS) was also measured by 2',7'-dichlorodihydrofluorescin diacetate(DCFH-DA). Results: The optimized deproteinization conditions were determined as follows: hydrolysis time, 55 min; temperature, 50 ℃; and papain concentration, 0.7 mg/m L; giving a percentage of deproteinization of 61.28%. After further deproteinization with 4% trichloroacetic acid(TCA), the deproteinization rate increased up to 80.73%, and the retention rate of polysaccharide was 79.7%. Compared with the model group, the survival rate of cells treated with the purified polysaccharides from P. haitanensis was significantly increased(P < 0.01), and the level of ROS was significantly decreased(P < 0.01). Conclusions: The combination of papain hydrolysis and TCA treatment was an effective method for the removal of protein from Porphyra haitanensis polysaccharides. Porphyra haitanensis polysaccharides had significant antioxidant activity and could relieve the H_2O_2-induced injury in He La cells by eliminating redundant ROS.