Abstract: The objective of this work was to investigate the protective effect and underlying mechanism of a bioactive peptide from coix seeds (Coix lacryma-jobi) on high glucose-injured human umbilical vein endothelial cells (HUVEC). HUVEC injured by 30 mmol/L glucose were treated with different concentrations of the peptide and were evaluated for the secretion of nitric oxide (NO) by the nitrate reductase method. The content of reactive oxygen species (ROS) was detected by flow cytometry. Cell apoptosis was detected by Annexin V-FITC/PI double staining. Quantitative real-time polymerase chain reaction (qPCR) was applied to detect the expression of inflammation-related genes. The results showed that NO secretion was decreased by 28.72% (P < 0.05), ROS secretion was increased by 96.19% (P < 0.05), and the expression of the ICAM-1, IL-6, MCP-1 and VCAM genes was significantly increased in HUVEC induced by high glucose compared with the normal control group. The prolongation of high glucose treatment time significantly increased the apoptosis rate of HUVECs, and after 14 days, the apoptosis rate of HUVECs was 1.61 times higher than that in the normal control group. Treatment with the peptide at all concentrations increased NO secretion, decreased ROS content and the expression of inflammatory genes and reduced cell apoptosis. In summary, the coix seed biopeptide possesses a protective effect on high glucose-injured HUVEC. 

Key words: coix seed bioactive petide; high glucose; human umbilical vein endothelial cells; oxidative stress; inflammation