Hydroxyl Radical-Scavenging Activity-Guided Extraction of Peptides from Oviductus ranae

Oviductus Ranae (OR) is a traditional Chinese medicinal material that is listed in Chinese Pharmacopeia with proteins the most abundant ingredients. In present work, pepsin/trypsin-based stepwise hydrolysis was applied to extract Antioxidant Peptides from OR (APOR) using hydroxyl radical-scavenging capacity as evaluation index. After single-factor experiment, response surface method coupled with Box-Behnken design were used for optimizing process parameters and achieved the optimal conditions: Pepsin amount of 2.0%, pepsin incubation time of 3.5 h, trypsin amount of 2.0% and trypsin incubation time of 3.0 h, under these conditions, the hydroxyl radical-scavenging rate of obtained APOR was 75.52±1.92%, which was extremely similar to the predicated value with relative deviation of ±1.42%. The half inhibitory concentration of APOR against hydroxyl radical was 3.71±0.71 mg.ml1, which was lower than that of proteins from OR (4.85±0.06 mg.mL1, disclosed in our previously published paper). The higher antioxidant capacity of APOR could be related to the presence of rich antioxidant amino acids and relatively lower molecular weights, which deserve to be explored in the next future.