β-Glucan administration to diabetic rats alleviates oxidative stress by lowering hyperglycaemia, decreasing non-enzymatic glycation and protein O-GlcNAcylation

This effect of commercially available β-glucan-enriched extract (BGEE) in streptozotocin-induced diabetic rats on protein glycation and enzymatic post-translational glycosylation with O-linked N-acetylglucosamine (O-GlcNAc) groups was examined. The BGEE-promoted improvement of diabetic hyperglycaemia was accompanied by significantly lower serum protein glycation. While this revealed an indirect effect of BGEE on protein glycation through its ability to improve hyperglycaemia, the observed BGEE capability to decrease the formation of advanced glycation end-products (AGE) in an in vitro glycation process pointed to its direct glycation-suppressive function in vivo. Compared to untreated diabetic rats, BGEE-treated diabetic rats displayed lower levels of O-GlcNAc-modified liver and kidney antioxidant enzymes, Mn- and CuZn superoxide dismutases and catalase, their improved specific enzymatic activities and increased transcription of genes encoding for them. These results show that BGEE exerts a normalizing effect on diabetes-linked protein modifications, adding to the list of beneficial effects it could provide in diabetes management.