Optimization of polyphenols process and their hypoglycemic and antioxidant activities of Porphyra haitanensis

Objective: This study aimed to optimize the extraction process of Porphyra haitanensis polyphenols to develop natural hypoglycemic foods. Methods: The Box-Behnken response surface method was used to optimize the extraction process of P. haitanensis polyphenols. The a-glucosidase inhibition activity was applied to evaluate the hypoglycemic activity of P. haitanensis polyphenols at different harvest periods, and the antioxidant activities of them were evaluated based on DPPH, ABTS radical scavenging rate and ORAC value. Results: The optimal extraction process conditions were liquid-solid ratio (Vethanol: mp. haitanensis) 51 ! 1. ethanol concentration 56% and ultrasonication time 51 min. Under the control of these conditions* the extracted content of polyphenols was 5. 027 rag/g. The inhibition of a-glucosidase activity by P. haitanensis polyphenols was in a concentration-dependent manner, and the inhibition by the fourth-harvest-period polyphenols was significantly higher than other harvest periods polyphenols. P. haitanensis polyphenols at different harvest periods showed antioxidant activity, and the antioxidant activity of the fourth-harvest-period polyphenols was strongest. Conclusion; The high polyphenol contents, strong inhibition of a-glucosidase activity and strong antioxidant capacity of the fourth-harvest-period makes it an excellent food source for developing natural hypoglycemic foods and antioxidants.