Determination of the molecular weight distribution of non-enzymatic browning products formed by roasting of glucose and glycine and studies on their effects on NADPH-cytochrome c-reductase and glutathione-S-transferase in Caco-2 cells

Abstract

After thermal treatment of a mixture of glucose and glycine for 2 h at 125 degrees C, about 60% of the starting material was converted into non-soluble, black pigments, whereas 40% of the mixture was still water-soluble. Dialysis of the latter fraction revealed 30.4% of low molecular weight compounds (LMWs; MW < 10,000 Da) and 10.0% high-molecular weight products (HMWs; MW > or = 10,000 Da). The water-soluble Maillard reaction products (MRPs) were separated by gel permeation chromatography and ultrafiltration, revealing that 60% of the water-soluble products of the total carbohydrate/amino acid mixture had MWs < 1,000 Da and consisted mainly of non-coloured reaction products. MRPs with MWs between 1,000 and 30,000 Da were found in comparatively low yields (about 1.3%). In contrast, about 31.1% of the MRPs exhibited MWs > 30,000 Da, amongst which 14.5% showed MWs > 100,000 Da, thus indicating an oligomerisation of LMWs to melanoidins under roasting conditions. To investigate the physiological effects of these MRPs, xenobiotic enzyme activities were analysed in intestinal Caco-2 cells. For Phase-I NADPH-cytochrome c-reductase, the activity in the presence of the LMW and HMW fraction was decreased by 13% and 22%, respectively. Phase-II glutathione-S-transferase activity decreased by 15% and 18%, respectively, after incubation with the LMW and the HMW fractions. Considering the different yields, 30% and 10%, respectively, of the LMW and the HMW fractions, the total amount of the LMW fraction present in the glucose-glycine mixture is more active in modulating these enzyme activities than that of the HMW fraction.

Potential bioactive effects of casein hydrolysates on human cultured cells

“…In addition, samples c, d, and e increased GSH content when compared with untreated cells. Our data support previous suggestions that the modulation of different detoxification enzymes can be selective (Hofmann et al, 2001;Kitts et al, 1993). Because hydrolysates d and e had similar protein levels of 10.37 and 10.49 mg 100 mL À1 , respectively, this would suggest that antioxidant activity may be related to the protein content of the samples.…”

Production and Use of Maillard Products as Oxidative Stress Modulators

“…The Glc-glycine MRPs also decreased both Phase-I NADPH-cytochrome c reductase and Phase-II glutathione-S-transferase activity of CaCo-2 cells, which could be attributed to the presence of the shortchain dicarbonyls, such as 2-oxopropanal and methylglyoxal. 35 The dicarbonyl compounds were reported to be very reactive at cross-linking proteins. 36,37 Heated Glc-and Fru-Lys mixtures were shown to inhibit the growth of mouse C6 glioma cells at concentrations ranging from 0.25 to 2.5 mg/mL after a 24-hour exposure.…”

Comparison of anti-browning ability and characteristics of the fractionated Maillard reaction products with different polarities

“…Chen and Kitts (2008) indicated that HMW MRPs had no higher antioxidant activity compared to LMW MRPs (Chen and Kitts 2008). Intermediate and LMW MRPs were reported to account for the antioxidant capacity (Morales and Babbel 2002;Hofmann et al 2001). Extraction was also an important method to enrich MRPs of certain property.…”