Polyphenols of brown (Brassica juncea) and white (Sinapis alba) mustard seeds: Extraction optimization, compositional analysis, antioxidant, and immunomodulatory activities

Mustard seeds is a traditional Chinese natural product of pharmaceutical and dietary origin, rich in polyphenols, flavonoids, and other active ingredients, exhibiting multiple bioactivities. In order to improve the yield, polyphenols from brown and white mustard seeds were extracted under better circumstances using Response Surface Methodology (RSM). Subsequently, components were assessed using LC-MS/MS. A total of 8 phenolic compounds and 3 flavonoid compounds were identified in brown mustard seeds extracts (BMSE), and 14 phenolic compounds and 4 flavonoid compounds were identified in white mustard seeds extracts (WMSE). Meanwhile, the biological activities of BMSE and WMSE were compared via in vitro free radical scavenging, hepatocyte oxidative injury protection, and macrophage immunoregulation models. The results showed that both BMSE and WMSE exhibited antioxidant activity and oxidative damage protection activity on HL-7702 cells, and BMSE was more effective. The viability of HL-7702 cells induced oxidative damage by hydrogen peroxide treated with BMSE and WMSE was increased by 36.7% and 32.8%, respectively. WMSE exhibited better in vitro immunomodulatory activities than BMSE, including proliferation promoting, phagocytosis, and NO release abilities on RAW264.7 cells. This study can contribute to the application of mustard seeds polyphenols in the field of functional foods, as well as provide a direction for the high-value utilization of mustard seeds.