Rates of advanced glycosylation end products(AGEPs) formation stimulated by different sugars in vitro

Reducing sugars can react nonenzymatically with free amino groups on proteins, and form a variety of fluorescence-producing advanced glycosylation end products (AGEPs). These irreversible compounds have been previously identified as accumulating on long-lived extracellular matrix proteins, and probably also on DNA in tissues that are prone to diabetic complications such as retinopathies, cataract and atherosclerosis. In this study, we examined the AGEP-stimulating rates of various carbohydrates including glucose, galactose, mannose, fructose, arabinose and xylose by incubating these sugars with bovine serum albumin in vitro. The accumulations of AGEPs were monitored by fluorescence detection at 410 nm and Enzyme Linked Immunosorbent Assay (ELISA). We found that after 1 week incubation, arabinose and xylose stimulated 10 fold more AGEPs formation than other sugars. Further incubation resulted in protein cross-linking characterized by shifting of electrophoretic and TLC motilities. These results suggest that the rates of AGEPs formation by pentoses are faster than hexoses. In conventional glycemic control, pentoses have been preferentially employed due to their low absorption rate and greater clearance rate than those of glucose. However, long term usage of arabinose and xylose as diet sugar constituents may have adverse effects because of increased stimulation of AGEPs accumulation.