Abstract: In this study, the protective effect of quercetin on high glucose-induced damage was investigated in Saccharomyces cerevisiae. Compared with the control group, the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) were all significantly decreased under high glucose-induced stress (P < 0.05), but intracellular ROS was no obviously changed. After being treated with quercetin, the ROS levels and SOD and CAT activities were dramatically inhibited (P < 0.05), but the POD activity was significantly enhanced in comparison to the control and high glucose groups (P < 0.01). The results showed that POD activity was more sensitive than other indicators in reflecting the resistance to high glucose-induced stress, and quercetin could effectively enhance the antioxidant capacity by regulating POD activity in S. cerevisiae S288c. In addition, high glucose-induced stress resulted in an significant decrease in the expression levels of glycerol-3-phosphate dehydrogenase 2 (GPD2) and sucrose transport protein-encoding genes (SUC2) (P < 0.05), but a significant increase in the expression level of hexose transport-1-encoding gene (HXT1) (P < 0.01), compared with the control. After being treated with quercetin, the expression profiles of GPD2, SUC2, and HXT1 were significantly increased in S. cerevisiae S288c (P < 0.05). However, the expression level of glycerol kinase gene (GUT1) was not changed significantly. These results suggested that quercetin could reduce high glucose-induced damage by regulating the high osmolarity glycerol (HOG) signaling pathway, inulin catabolism pathway and hexose transport pathway to accelerate glucose decomposition. Therefore, we conclude that quercetin plays an important role in protecting S. cerevisiae from damage caused by high glucose-induced stress, and the underlying mechanism may be associated with its antioxidant effect and being involved in the HOG signaling pathway and the glucose decomposition and transport pathways in S. cerevisiae.

Key words: Saccharomyces cerevisiae, high glucose-induced stress, quercetin, enzyme activitity, expression levels