Comparison of Antioxidant Properties of Evening Primrose Seeds by Different Processing Methods, and Physiological Properties of Evening Primrose Seed Powder

This study proposes the processing method that could maximize the functional properties of evening primrose seeds (EPS) and its various nutritional components. EPS can be prepared by different methods, such as being left raw, roasting, steaming, and powdering. Processing of EPS to create EPS powder (EPSP) resulted in higher levels of vitamin E, fatty acids, total phenolic contents, and antioxidant activity, compared with the other processing methods. Also, EPSP maintained lipid peroxidation inhibitory activity for 49 days. In particular, the EPSP ethyl acetate (EtOAc) fraction exhibited high antioxidant, antidiabetic, and angiotensin I-converting enzyme inhibitory activities. The EPSP ethyl acetate fraction showed a high cytoprotective effect against H₂O₂-induced cell damage in both RAW264.7 and EA.hy926 cells. In addition, the EtOAc fraction showed anti-inflammatory activity by the inhibitory activity of nitric oxide (NO) in RAW264.7 cells, and antihypertensive activity by the activity of NO in EA.hy926 cells. These results suggest that EPSP could be useful as a food ingredient that assists the prevention of various diseases caused by oxidative stress.