Alleviation effect of heat-treated and in vitro gastrointestinal digested soymilks on AAPH-induced oxidative stress in human erythrocytes: Digested soymilks alleviate oxidative stress

- Digested soymilks alleviated AAPH-induced hemolysis in human erythrocytes.
- Heat treatment prior to gastrointestinal enhanced the protection effect of soymilk.
- Digested soymilks enhanced the enzymatic defense system of erythrocytes.
- Digested soymilks enhanced the non-enzymatic defense system of erythrocytes.

To investigate the potential protective effect of raw and heat-treated soymilks after gastrointestinal digestion against chemical oxidative stress induced by 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) on human erythrocytes, soymilk was subjected to heat treatment and in vitro gastrointestinal digestion. The inhibition rate of hemolysis, generation of reactive oxygen species (ROS), concentration of malondialdehyde (MDA), reduced glutathione (GSH) and oxidized glutathione (GSSH) and the enzyme activity of total superoxide dismutase (SOD) and cellular glutathione peroxidase (GPx) were evaluated as the biomarkers of oxidative status. Hemolysis of erythrocytes induced by AAPH was significantly inhibited by pretreatment with the digested raw soymilk (DRS) and digested heat-treated soymilk (DHS). Moreover, heat treatment prior to gastrointestinal digestion improved the inhibition effect of soymilk on erythrocytes hemolysis. The soymilk treated at 95 °C showed the highest inhibition rate, followed by 121 °C and 143 °C, revealed that the increase of temperature caused the decrease of hemolysis inhibition rate of DHS. Preincubation with the digested soymilks reduced the accumulation of MDA in erythrocytes, indicating the inhibition effect of the digested soymilks on lipid peroxidation. Results revealed that DRS and DHS alleviated the hemolysis of erythrocytes and lipid peroxidation resulted from oxidative stress by suppressing the accumulation of ROS, reducing the increase of SOD activity and decrease of non-enzymatic antioxidant GSH and enzymatic antioxidant GPx activity. Compared with raw soymilk, heat treatment improved the protective effect of the digested soymilk on erythrocytes against oxidative stress via enhancing the free radicals scavenging activity instead of improving the inhibition effect on the generation of free radicals.