Role of saturated and unsaturated fatty acids on dicarbonyl-albumin derived advanced glycation end products in vitro.

Glycation is a non-enzymatic reaction that occurs between the free amino group of proteins and reducing sugars and/or lipids, leading to the formation of advanced glycation end products (AGEs). The reaction also produces reactive oxygen species that have detrimental effects on cellular and extracellular proteins. Aminoguanidine is a known inhibitor of AGEs, and some fatty acids are known to have a beneficial role in vivo by reducing inflammation and oxidative stress. However, the role of fatty acids on AGE formation has not been thoroughly reported. We investigated the role of a range of fatty acids in the formation of AGEs and their reactive intermediates using an in vitro BSA-dicarbonyl model. The model assessed a time-dependent (0-72 h) and dicarbonyl concentration (0-2 mM) -dependent studies for the optimal formation of AGEs. A 72 h time point was found to be optimal for the reaction of BSA with either methylglyoxal (MGO) or glyoxal (GO) to generate AGE-BSA complexes. When arachidonic, eicosapentaenoic or docosahexaenoic acids were included in the reaction, a significant decrease in protein-bound fluorescent AGEs was seen compared to the respective controls. In contrast, saturated and 18 carbon polyunsaturated fatty acids showed no significant activity. Liquid chromatography-mass spectrometry (LC-MS/MS) analysis showed saturated fatty acids significantly decreased the production of Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL) from GO and MGO models, respectively, whilst increasing methylglyoxal-derived hydroimidazolone (MG-H1). In contrast, arachidonic, eicosapentaenoic and docosahexaenoic acids did not significantly change either CEL or MG-H1 compared to no treatment controls whilst significantly reducing CML levels.

Advanced glycation end-products accelerate telomere attrition and increase pro-inflammatory mediators in human WIL2-NS cells.

This study investigated the effect of dietary sugars and advanced glycation end-products (AGE) on telomere dynamics in WIL2-NS cells. Dietary sugars [glucose (Glu) and fructose (Fru); 0.1 M each] were incubated with bovine serum albumin (BSA) (10 mg/ml) at 60 ± 1°C for 6 weeks to generate AGE-BSA. Liquid chromatography-mass spectrometry (LC-MS/MS) analysis showed total AGE levels as 87.74 ± 4.46 nmol/mg and 84.94 ± 4.28 nmol/mg respectively in Glu-BSA and Fru-BSA model. Cell treatment studies using WIL2-NS cells were based on either glucose, fructose (each 2.5-40 mM) or AGE-BSA (200-600 µg/ml) in a dose-dependent manner for 9 days. Telomere length (TL) was measured using qPCR. Nitric oxide (NO) production and tumour necrosis factor-α (TNF-α) levels were measured in WIL2-NS culture medium. An increasing trend for TNF-α and NO production was observed with higher concentration of glucose (R2 = 0.358; P = 0.019; R2 = 0.307; P = 0.027) and fructose (R2 = 0.669; P = 0.001; R2 = 0.339; P = 0.006). A decreasing trend for TL (R2 = 0.828; P = 0.000), and an increasing trend for NO production (R2 = 0.352; P = 0.031) were observed with increasing Glu-BSA concentrations. Fru-BSA treatment did not show significant trend on TL (R2 = 0.135; P = 0.352) with increasing concentration, however, a significant reduction was observed at 600 µg/ml (P < 0.01) when compared to BSA treatment. No trends for TNF-α levels and a decreasing trend on NO production (R2 = 0.5201; P = 0.019) was observed with increasing Fru-BSA treatment. In conclusion, this study demonstrates a potential relationship between dietary sugars, AGEs and telomere attrition. AGEs may also exert telomere shortening through the production of pro-inflammatory metabolites, which ultimately increase the risk of diabetes complications and age-related disease throughout lifespan.

Non-nutritive sweeteners are in concomitant with the formation of endogenous and exogenous advanced glycation end-products.

This study investigated the role of non-nutritive sweeteners in the formation of advanced glycation end-products (AGEs) and their reactive intermediates using endogenous and exogenous models. In the endogenous model, xylitol and sorbitol formed similar levels of reactive intermediates compared to sucralose. Protein-bound fluorescent AGEs, Nε-carboxymethyllysine (CML), and Nε-carboxyethyllysine (CEL) levels in the xylitol and sorbitol treatment were significantly higher compared to the sucralose treatment. In the exogenous model, sucralose treatment showed significantly higher glyoxal and fructosamine levels compared to xylitol and sorbitol, respectively. However, protein-bound fluorescent AGEs, CML, and CEL were lower in the sucralose treatment compared to other sugar treatments. The data suggest that the structure of sugar alcohols which are similar to reducing sugars may contribute to the formation of AGEs and their reactive intermediates in the endogenous model. The long-term effects of non-nutritive sweeteners consumption on AGEs formation and health implications should be verified with population studies.