Protective Effects of Chungkookjang Extract on High Glucose Induced Oxidative Stress in LLC-PK1Cells

Abstract

This study was designed to investigate the protective effect of a methanol extract of Chungkookjang (CKJ) on high glucose induced oxidative stress in LLC-PK₁ cells (renal tubular epithelial cells), which are susceptible to oxidative stress. Freeze dried CKJ powder was extracted with methanol, and the extract solution was concentrated, and then used in this study. To determine the protective effect of CKJ extract, oxidative stress was induced by exposing of LLC-PK₁ cells to high glucose (30 mM) or normal glucose (5 mM) for 24 hr. Exposure of LLC-PK₁ cells to high glucose for 24 hr resulted in a significant (p＜0.05) decrease in cell viability, catalase, SOD and GSH-px activity and a significant (p＜0.05) increase in intracellular ROS level and thiobarbituric acid reactive substances (TBARS) formation in comparison to the cells treated with 5 mM glucose. CKJ extract treatment decreased intracellular ROS level and TBARS formation, and increased cell viability and activities of antioxidant enzymes including catalase, SOD and GSH-px in high glucose pretreated LLC-PK₁ cells. These results suggest that CKJ extract may be able to protect LLC-PK₁ cells from high glucose-induced oxidative stress, partially through the antioxidative defense systems.