Papers by Helmut Erbersdobler
Molecular Nutrition & Food Research, Apr 1, 2007
The Maillard reaction products (MRPs) most widely used as markers of the nutritional quality of f... more The Maillard reaction products (MRPs) most widely used as markers of the nutritional quality of foods are furosine, N(epsilon)-carboxymethyllysine (CML), hydroxymethylfurfural, pyrraline, pentosidine and pronyl-lysine. One of the MRPs identified first was furosine, which was quantified in foods 40 years ago as a chemical indicator of the Amadori compound N(epsilon)-fructoselysine. Since then, furosine has gained broad attention by food chemists and biomedical researchers, as its formation upon heat treatment is well characterised. Moreover, it represents the Amadori products from early Maillard reactions in which amino acids react with reducing carbohydrates, resulting in a loss of their availability. This is of importance for the essential amino acid lysine, which is also the limiting amino acid in many proteins. In order to evaluate the nutritional quality of a protein, the concomitant analysis of free - and nutritionally available - lysine and the amount of lysine reacted to form the respective MRP is essential, even for mildly processed foods. The other chemical markers of heat treatment such as CML, pyrraline, pentosidine or pronyl-lysine seem to be useful markers of the advanced stages of Maillard reactions. Compared to the conditions in which furosine is formed, these compounds are generated under more severe conditions of heat treatment. However, the concentrations analysed are significantly lower than those of furosine. Therefore, the nutritional evaluation of a food protein should include not only furosine, but also other chemical markers of heat treatment such as, for example, CML, pyrraline and pentosidine.
Molecular Nutrition & Food Research, 2011
Scope: trans-Resveratrol has been shown to improve insulin sensitivity and to enhance cellular gl... more Scope: trans-Resveratrol has been shown to improve insulin sensitivity and to enhance cellular glucose uptake. Evidence from recent studies indicates that these effects depend on SIRT1-pathways. Methods and results: Since ingestion of resveratrol leads to the presence of resveratrol and resveratrol metabolites in the body, we aimed at investigating (i) whether a daily dose of 300 mg resveratrol/kg body weight in healthy male Wistar rats for a period of 8 wk affects the selected parameters of glucose and lipid metabolism and (ii) whether the resulting plasma concentrations of resveratrol metabolites were effective in modulating SIRT1 expression. The dietary dose was based on the results from preceding toxicity studies. The results from the feeding experiment revealed plasma concentrations of resveratrol and its metabolites below 1 mmol/L and showed that fasting glucose and insulin levels were decreased by 35 and 41%, respectively, in the resveratrol group compared with controls. Insulin sensitivity was enhanced by 70%, whereas liver SIRT1 protein expression was not affected. Treatment of HepG2 cells with 10 mM resveratrol (1.49-fold) or its diglucuronides (1.21-fold) increased SIRT1 expression. Conclusion: These results suggest that the improved insulin sensitivity after dietary administration of 300 mg resveratrol/kg body weight does not involve increased protein expression of SIRT1.
Molecular Nutrition & Food Research, 2006
During the heat treatment of protein-containing foods, the amino acid lysine is most prone to und... more During the heat treatment of protein-containing foods, the amino acid lysine is most prone to undergo chemical reactions in the course of amino acid cross-linking or Maillard reactions. Among the reaction products formed, lysinoalanine (LAL), N(epsilon)-fructoselysine (FL) and N(epsilon)-carboxymethyllysine (CML) are those which serve as sensitive markers for the heat treatment applied. From a nutritional perspective, these compounds are ingested with the diet in considerable amounts but information about their metabolic transit and putative in vivo effects is scarce. In the present study, casein-linked LAL, FL and CML were administered to rats in two different doses for 10 days. Quantitation of LAL, FL and CML in plasma, tissue and faeces samples revealed that the kidneys are the predominant sites of accumulation and excretion. The maximum percent of dietary LAL, FL and CML excreted in the urine was 5.6, 5.2 and 29%, whereas the respective recoveries in the kidneys were 0.02, 26 and 1.4%. The plasma and tissue analyses revealed that the endogenous load of either compound is increased by its dietary intake. But the dose-dependent utilisation of dietary protein-linked LAL, FL and CML in rats has been demonstrated for the first time to vary substantially from each other.
Journal of Agricultural and Food Chemistry, 2003
The aim of the present study was to apply an activity-guided screening procedure to coffee brew t... more The aim of the present study was to apply an activity-guided screening procedure to coffee brew to identify a key chemopreventive compound by means of in vitro antioxidant tests as well as cell culture experiments and to prove the in vivo activity of that compound by an animal feeding experiment. Solvent fractionation, followed by multiple-step ultrafiltration, revealed that the polar coffee compounds with molecular weights below 1 kDa show the major inhibitory effect on the in vitro peroxidation of linoleic acid as well as the predominant chemopreventive enzyme modulating activity on the NADPHcytochrome c reductase (CCR) and glutathione S-transferase (GST) in human intestinal Caco-2 cells. To identify the chemical structure of the most active antioxidants and chemopreventive compounds, the polar compounds were further separated by HPLC techniques, followed by the activity-guided screening of the individual HPLC fraction. These experiments demonstrated 5-chlorogenic acid to be the most powerful antioxidant in vitro, whereas, in contrast, chemopreventive effects on the GST activity were found for the N-methylpyridinium ion, the structure of which was elucidated by LC-MS and NMR experiments and confirmed by synthesis. The in vivo activities of coffee beverage and N-methylpyridinium ions were tested in a 15-day feeding experiment on rats. In the liver, feeding of 4.5% coffee beverage resulted in increases of GST and UDP-GT activities by 24 and 40% compared to animals fed the control diet (p > 0.05), respectively. Plasma total antioxidant capacity and plasma tocopherol were elevated in animals fed the coffee beverage and the N-methylpyridinium-containing diet. In summary, the results demonstrating a strong in vitro antioxidant activity for coffee were confirmed by the feeding study. Surprisingly, feeding of N-methylpyridinium also resulted in an increased total antioxidant capacity in the plasma. The data indicate that the mode of action demonstrated for N-methylpyridinium in biological systems is different from that in foods.
Ann Nutr …, 2008
... of Glucose Metabolism in Healthy Volunteers Sarah Egert a, d Manfred Fobker b Gaby Andersen c... more ... of Glucose Metabolism in Healthy Volunteers Sarah Egert a, d Manfred Fobker b Gaby Andersen c Veronika Somoza c ... Am J Clin Nutr 2002; 76: 1007 1015. 31 Friedberg CE, Janssen MJ, Heine RJ, Grob-bee DE: Fish oil and glycemic control in dia-betes. A meta-analysis. ...
Annals of the New York Academy of Sciences, 2005
Annals of Nutrition and Metabolism, 2008
Aim: To investigate the effects of α-linolenic acid (ALA) and purified eicosapentaenoic acid (EPA... more Aim: To investigate the effects of α-linolenic acid (ALA) and purified eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) on fasting concentrations of glucose, insulin, fructosamine, on glycosylated haemoglobin (HbA1c) and on insulin sensitivity. Methods: A randomized strictly controlled dietary study in 48 healthy volunteers (13 males, 35 females) of normal body weight (mean age 25.9 years) with three dietary groups (ALA, EPA and DHA) and a parallel design, consisting of two consecutive periods. Subjects received a 2-week wash-in diet rich in monounsaturated fatty acids followed by experimental diets enriched with equal amounts of ALA, EPA, or DHA for 3 weeks. Mean dietary intake of ALA in the ALA group was 6.0 g/day (2.5% of energy intake), mean intake of EPA in the EPA group was 2.8 g/day (1.1% of energy intake) and mean intake of DHA in the DHA group was 2.9 g/day (1.1% of energy intake). Results: Fasting serum concentrations of insulin and fructosamine and of HbA1c did n...
Molecular Nutrition & Food Research, 2007
The Maillard reaction products (MRPs) most widely used as markers of the nutritional quality of f... more The Maillard reaction products (MRPs) most widely used as markers of the nutritional quality of foods are furosine, N(epsilon)-carboxymethyllysine (CML), hydroxymethylfurfural, pyrraline, pentosidine and pronyl-lysine. One of the MRPs identified first was furosine, which was quantified in foods 40 years ago as a chemical indicator of the Amadori compound N(epsilon)-fructoselysine. Since then, furosine has gained broad attention by food chemists and biomedical researchers, as its formation upon heat treatment is well characterised. Moreover, it represents the Amadori products from early Maillard reactions in which amino acids react with reducing carbohydrates, resulting in a loss of their availability. This is of importance for the essential amino acid lysine, which is also the limiting amino acid in many proteins. In order to evaluate the nutritional quality of a protein, the concomitant analysis of free - and nutritionally available - lysine and the amount of lysine reacted to form the respective MRP is essential, even for mildly processed foods. The other chemical markers of heat treatment such as CML, pyrraline, pentosidine or pronyl-lysine seem to be useful markers of the advanced stages of Maillard reactions. Compared to the conditions in which furosine is formed, these compounds are generated under more severe conditions of heat treatment. However, the concentrations analysed are significantly lower than those of furosine. Therefore, the nutritional evaluation of a food protein should include not only furosine, but also other chemical markers of heat treatment such as, for example, CML, pyrraline and pentosidine.
Zeitschrift für Ernährungswissenschaft, 1993
Am 22.9. 1993 ist der Herausgeber unserer Zeitschrift Prof. Dr. med vet. Helmut Haenel nach tapfe... more Am 22.9. 1993 ist der Herausgeber unserer Zeitschrift Prof. Dr. med vet. Helmut Haenel nach tapfer ertragenem Leiden gestorben. Helmut Haenel gehfrte zur Generation derjenigen, die noch direkt yon den Kriegsereignissen betroffen erst 1946 ihr Studium aufnehmen konnten. 1952 wurde er von Scheunert nach Rehbrficke geholt, um eine mikrobiologischeAbteilung aufzubauen. Daraus entwickelte er das Gebiet der Mikrofkologie, das dieWechselwirkungen von intestinaler Mikroflora mit dem Gesamtorganismus studiert. Von 1964-1981 war Haenel dann Direktor des Zentralinstituts ftir Ernfihrung der Akademie derWissenschaften. Sein Blick weitete sich fiber das Gebiet der gastrointestinalen Mikrofkologie hinaus und erfagte schlieglich alle Disziplinen der Ernfihrungswissenschaft. Er wurde in das Komitee ,,Recommended Dietary Allowances" der IUNS berufen, war Mitglied der Group of European Nutritionists und wurde Mitglied der Deutschen Akademie der Naturforscher Leopoldina. Weitere H6hepunkte seiner Laufbahn wurden durch die Verleihung der Federation of European Nutrition Sciences Award im Jahre 1991 und die Ehrenmitgliedschaft der Deutschen Gesellschaft ffir Ernfihrung 1992 markiert. lJber sein wissenschaftlich umfangreiches Werk hinaus erwarb er sich unvergegliche Verdiel)ste dadurch, dab er im Jahre 1990 zum zweiten Mal die schwere Btirde des Direktors des Instituts tibernahm, um dieses-getragen von tier Zustimmung seiner Mitarbeiter-in die neue F6rderungsform einer Blauen-Liste-Einrichtung zu fiberffihren. Damit hat er sich um die Ernfihrungsforschung und die deutsche Forschungstandschaft verdient gemacht. Helmut Haenel war ein Herausgeber, der das Prinzip der Begutachtung jedes Manuskriptes durch 2 Fachwissenschaftler aus innerster Uberzeugung mittrug und mit ihm eigenem Fingerspitzengeftihl anwandte, weil er davon fiberzeugt war, dab nur so ein bestimmter wissenschaftlicher Standard eingehalten werden kann. Zudem war er ein unersetzlicher Ratgeber bei der Einbeziehung yon Wissenschaftlern der Neuen Bundeslfinder und Mittel-und Osteuropas. Sein weitblickender Rat, seine Klugheit und seine Anregungen werden der Zeitschrift und den Herausgebern fehlen.
The Journal of Nutrition, 1999
The lipid-lowering effect of psyllium (PSY) is well established. Enhanced fecal bile acid excreti... more The lipid-lowering effect of psyllium (PSY) is well established. Enhanced fecal bile acid excretion and a stimulation of hepatic bile acid synthesis are discussed as primary mechanisms of this action. To further examine the effect of bile acid excretion and specifically of compositional alterations in the bile acid pool on the cholesterollowering and gallstone-preventing action of PSY, male golden Syrian hamsters were fed lithogenic diets containing 5 g/100 g fat, 0.4 g/100 g cholesterol and 0 (control), 4 or 6% PSY or 1% cholestyramine (CHY). PSY significantly lowered plasma total cholesterol and triacylglycerol at a magnitude comparable to that induced by CHY. Although hepatic cholesteryl ester accumulation was completely inhibited by CHY, PSY did not prevent the hepatic storage of esterified cholesterol. PSY and CHY caused distinct alterations in the bile acid profile. PSY caused a selective reduction of taurine-conjugated bile acids, especially of taurochenodeoxycholate. As a result, the glycine:taurine conjugation and the cholate:chenodeoxycholate ratios were significantly higher in PSY-fed hamsters. PSY and CHY normalized the lithogenic index and prevented cholesterol gallstone formation compared with controls. Daily fecal bile acid excretion was ϳ400% greater in hamsters fed 6% PSY, whereas CHY caused an 11-fold increase. Daily neutral sterol excretion did not differ in PSY-fed hamsters but was Ͼ100% greater in those fed CHY than in controls. These data emphasize the potent lipid-lowering effect of PSY. Increased fecal bile acid excretion and alterations of the circulating bile acid pool by removal of dihydroxy bile acids (e.g., taurochenodeoxycholate) appear to be main modulators of the hypocholesterolemic action of PSY by leading to an up-regulation of hepatic bile acid synthesis. J. Nutr. 129: 896-902, 1999. KEY WORDS: • psyllium • cholestyramine • cholesterol-lowering • bile acids • hamsters 1 Supported in part by a grant from FEI (Forschungskreis der Ernä hrungsindustrie e.V., Bonn, Germany, the AIF and the Ministry of Economics (Project No. 9670).
The Journal of Nutrition, 1998
The mechanisms by which inulin may elicit its lipid-lowering effect are not well elucidated. To e... more The mechanisms by which inulin may elicit its lipid-lowering effect are not well elucidated. To examine the lipid-lowering potential of inulin and especially its effect on bile acid metabolism, male golden Syrian hamsters were fed semipurified diets containing 20 g/100 g fat, 0.12 g/100 g cholesterol and 0 (control), 8, 12 or 16% inulin for 5 wk. Plasma total cholesterol concentrations were significantly lowered by 18, 15 and 29% in hamsters fed 8, 12 and 16% inulin, respectively. Dietary inulin specifically decreased VLDL cholesterol, which was significantly lower in hamsters fed 16% inulin compared with controls (1.1 Ϯ 0.3 vs. 2.9 Ϯ 0.6 mmol/L). LDL and HDL cholesterol were not significantly affected by dietary inulin. Plasma triacylglycerol was significantly reduced by 40 and 63% in hamsters fed 12 and 16% inulin, respectively. Hepatic total cholesterol and particularly esterified cholesterol accumulation were significantly lower in hamsters fed 8% inulin compared with controls. All three levels of dietary inulin caused distinct alterations in the bile acid profile of gallbladder bile. Taurochenodeoxycholic acid was significantly lower, whereas glycocholic and glycodeoxycholic acid were greater in hamsters fed inulin. Daily fecal bile acid excretion (mol/d) tended to be greater (P ϭ 0.056) in inulin-fed hamsters compared with controls, whereas daily neutral sterol excretion was not affected. These data demonstrate that the lipid-lowering action of inulin is possibly due to several mechanisms, including altered hepatic triacylglycerol synthesis and VLDL secretion and impaired reabsorption of circulating bile acids.
The Journal of Nutrition, 2012
We aimed to investigate the effects of increased intake of a-linolenic acid (ALA), EPA, or DHA in... more We aimed to investigate the effects of increased intake of a-linolenic acid (ALA), EPA, or DHA incorporated into a food matrix on the fatty acid composition of erythrocytes and on biomarkers of oxidant/antioxidant status. To this end, a controlled dietary study was conducted in 74 healthy men and women. The participants were randomly assigned to 1 of 3 interventions in which margarines fortified with either 10 weight percent ALA, EPA, or DHA ethyl esters replaced their normal spread for 6 wk. The total intakes of ALA, EPA, and DHA were 4.4, 2.2, and 2.3 g/d, respectively. Consuming EPA increased the erythrocyte proportion of EPA (394%) and the omega-3 index (sum of EPA and DHA, 38%). Consumption of DHA increased erythrocyte DHA (91%), the omega-3 index (98%), and EPA (137%). The omega-3 index increased to a significantly greater extent in the DHA group than in the EPA group. ALA did not increase erythrocyte EPA or the omega-3 index. We found no change in plasma uric acid or antioxidant capacity in any of the groups. Plasma malondialdehyde (MDA) increased with the EPA and DHA interventions. All 3 interventions decreased erythrocyte linoleic acid hydroperoxides but did not affect their MDA concentrations. In conclusion, the intake of both isolated EPA and DHA incorporated into margarine resulted in an enhanced incorporation of EPA and DHA into erythrocytes. Our findings indicate that DHA is quantitatively superior to EPA in view of the EPA+DHA tissue incorporation and also that 4 g/d ALA is not sufficient to increase the omega-3 index over a 6-wk period.
The Journal of Nutrition, 2009
Our aim was to study the effects of increased dietary intake of a-linolenic acid (ALA), eicosapen... more Our aim was to study the effects of increased dietary intake of a-linolenic acid (ALA), eicosapentaenoic acid (EPA), or docosahexaenoic acid (DHA) on serum lipids and LDL fatty acid compositions. To this end, a controlled parallel study was conducted in 74 healthy normolipidemic men and women aged 19-43 y. Participants were randomly assigned to 1 of 3 interventions and consumed a total intake of 4.4 g/d ALA (ALA group), 2.2 g/d EPA (EPA group), and 2.3 g/d DHA (DHA group) for 6 wk. Fatty acid ethyl esters were incorporated into margarines, which replaced the participant's normal spread. The ALA, EPA, or DHA intake led to a significant enrichment of the LDL with the respective (n-3) fatty acid. In addition, LDL EPA contents in the ALA group increased by 36% (P , 0.05) with no changes in LDL DHA. The EPA intervention led to an additional enrichment with DHA (24%; P , 0.001), whereas the DHA intervention further increased the amount of EPA (249%; P , 0.001). ALA, EPA, or DHA intake did not affect fasting serum concentrations of total and LDL cholesterol, but fasting serum triacylglycerol concentrations significantly decreased in the EPA (20.14 mmol/L) and DHA (20.30 mmol/L) interventions and also in the ALA intervention (20.17 mmol/L). DHA intake significantly increased serum HDL cholesterol, whereas no changes were found with ALA or EPA intake. In conclusion, the present data support the hypothesis that isolated dietary ALA, EPA, and DHA intakes lead to differential enrichment in LDL due to interconversion. Moderate amounts of ALA, EPA, and DHA are effective in improving lipid profiles of normolipidemic humans.
British Journal of Nutrition, 1998
The effect of high- (hePE) and low- (lePE) esterification pectin and high- (hvGG) and low-(lvGG) ... more The effect of high- (hePE) and low- (lePE) esterification pectin and high- (hvGG) and low-(lvGG) viscosity guar gum on plasma, hepatic and biliary lipids and on prevention of cholesterol gallstones was investigated in male golden Syrian hamsters (Mesocricetus auratus). Hamsters were fed on cholesterol-rich (4g/kg), gallstone-inducing diets for 6 weeks. The diets were supplemented with 80g hePE, lePE, hvGG or lvGG/kg or 80g additional cellulose/kg. No significant differences in plasma total cholesterol and triacylglycerol concentrations between hvGG and lvGG and the gallstone-inducing or cellulose-enriched diets were observed. The hePE diet produced a 16% (non-significant) reduction in total plasma cholesterol but significantly decreased the plasma triacylglycerol level by 45%. The lePE diet caused only minor changes in plasma lipids. Hepatic cholesterol concentrations were significantly higher in hamsters fed on hvGG, lvGG, hePE or lePE primarily due to the accumulation of esterifie...
British Journal of Nutrition, 2002
4-Desmethylsterols and -stanols reduce plasma total cholesterol (TC) and LDL cholesterol by inhib... more 4-Desmethylsterols and -stanols reduce plasma total cholesterol (TC) and LDL cholesterol by inhibition of intestinal cholesterol absorption, while the cholesterol-lowering potential of 4,4′-dimethylsterols is less well defined. The present study aimed to compare the effects of 4-desmethylsterols, -stanols, and 4,4′-dimethylsterols on plasma and hepatic cholesterol, sterol excretion and bile acid metabolism. Male golden Syrian hamsters were fed diets containing 13 g/100 g fat, 0·08 g/100 g cholesterol and 0 (control), 0·24 or 0·48 % (w/w) esterified 4-desmethylsterols (sterols) and esterified hydrogenated 4-desmethylsterols (stanols) from common vegetable oils or esterified 4,4′-dimethylsterols from rice bran oil for 5 weeks. Sterol and stanol esters at the dose of 0·24 % were equally effective and significantly (P<0·05) lowered TC by 15 %, while 0·24 % 4,4-dimethylsterols reduced TC by 10 %. Liver total and esterified cholesterol concentrations were significantly (P<0·05) lowe...
British Journal of Nutrition, 1997
Effects of different dietary fats on plasma, hepatic and biliary lipids were determined in male g... more Effects of different dietary fats on plasma, hepatic and biliary lipids were determined in male golden Syrian hamsters (Mesocricetus auratus) fed on purified diets for 7 weeks. Diets were made by blending different fats containing characteristic fatty acids: butter (14:0 + 16:0), palm stearin (16:0), coconut oil (12:0 + 14:0), rapeseed oil (18:1), olive oil (18:l) and sunflowerseed oil (18:2). In all diets except the sunflowerseed oil diet dietary 18:2 was held constant at 2% energy. Total fat supplied 12% of energy and cholesterol was added at 4 g/kg diet. Plasma cholesterol and triacyglycerol concentrations were increased by dietary cholesterol. After 7 weeks, plasma cholesterol concentrations were highest with the palm Stearin, coconut oil and olive oil diets (8·9, 8·9 and 9·2 mmol/l) and lowest with the rapeseed oil and sdowerseed oil diets (6·7 and 5·5 mmol/l) while the butter diet was intermediate (8·5 mmol/l). Hepatic cholesterol concentration was highest in hamsters fed on t...
Molecular Nutrition & Food Research, 2005
The purpose of this study was to investigate the implications of selected chemopreventive paramet... more The purpose of this study was to investigate the implications of selected chemopreventive parameters and metabolic conversion of resveratrol in vivo. In two 8-week long feeding experiments with rats, a low-resveratrol diet containing 50 mg resveratrol per kg body weight (bw) and day and a high-resveratrol diet with 300 mg per kg bw and day were administered. For chemopreventive evaluation selected phase I and phase II enzymes of the biotransformation system, the total antioxidant activity, and the vitamin E status of the animals were determined. The level of resveratrol and its metabolites in the feces, urine, plasma, liver, and kidneys was identified and quantitated by high-performance liquid chromatography-diode array detection (HPLC-DAD) using synthesized resveratrol conjugate standards. Feeding of different dosages of resveratrol revealed no effect on the different chemopreventive parameters, except for the total antioxidant activity, which was elevated in plasma by 19% after feeding 50 mg resveratrol per kg bw and day. The formation of trans-resveratrol-3-sulfate, trans-resveratrol-4&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-sulfate, trans-resveratrol-3,5-disulfate, trans-resveratrol-3,4&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-disulfate, trans-resveratrol-3,4&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;,5-trisulfate, trans-resveratrol-3-O-beta-D-glucuronide, and resveratrol aglycone was detected by HPLC analysis, depending on the biological material. Total resveratrol recovery in urine and feces of rats fed on 50 mg resveratrol per kg bw and day was 15% and 13%, respectively. For rats fed the higher dosage of 300 mg resveratrol per kg bw and day recovery was 54% and 17%, respectively. This is the first study performed with synthesized standards of relevant resveratrol conjugates. The lack of effect on the chemopreventive parameters is probably due to the formation of various resveratrol conjugates reducing its bioavailability in the rat.
Journal of Agricultural and Food Chemistry, 2002
In the present study, water-soluble nonenzymatic browning products (melanoidins) formed in roaste... more In the present study, water-soluble nonenzymatic browning products (melanoidins) formed in roasted malt were separated, quantified, and investigated for their effects on detoxifying mechanisms in intestinal Caco-2 cells. The melanoidins were prepared from roasted malt by hot water extraction, and the water-soluble compounds were separated into different molecular weight (MW) fractions by gel filtration chromatography. By monitoring the effluent at 300 nm, seven molecular fractions I-VII were consecutively collected, revealing that ∼2.3% of the water-soluble compounds had mean MWs between 10000 and 30000 Da. Thus, the bulk of water-soluble malt melanoidins consisted of MW > 30000 Da, among which ∼58% showed mean MWs between 60000 Da and 100000 Da, whereas ∼32% exhibited mean MWs of 200000 Da. Biotransformation enzyme activities of NADPHcytochrome c-reductase (CCR) and glutathione-S-transferase (GST) were analyzed in Caco-2 Cells after 48 h of exposure to the different MW fractions. The low MW fraction of 10000 Da was most effective in activating the CCR and the GST activities (+122 and +33% vs control, respectively). The majority of the mid molecular weight compounds tested showed an activating effect on CCR activity and an inhibitory effect on GST activity. These effects were most pronounced for compounds of up to 70000 Da and >200000 Da but less distinct for fractions of an average molecular weight of 100000 Da.
Journal of Agricultural and Food Chemistry, 2005
The aim of the present study was to investigate whether feeding of malt, bread crust, and a prony... more The aim of the present study was to investigate whether feeding of malt, bread crust, and a pronylated albumin modulates chemoprevention enzymes, such as glutathione-S-transferase (GST) and UDPglucuronyl-transferase (UDP-GT), and antioxidative defense parameters in vivo and whether the intake of these foods rich in Maillard reaction compounds results in an accumulation of compounds formed in in vivo glycation reactions. After quantitation of pronylated lysine in malt and bread crust, male Wistar rats were fed a standard chow supplemented with 28% of protein containing different amounts of casein, bread crust, caraffa malt, or pronyl bovine serum albumin (BSA) for 15 days. GST activity in the kidneys was increased by 18% (p > 0.05) in animals of the bread crust group, while UDP-GT activity was elevated by 27% in the liver of animals administered pronyl-BSA. Contents of tocopherol in plasma were increased by 33, 14, and 14% in the bread crust, malt, and pronyl-BSA group compared to the control group, while the levels of thiobarbituric acid reactive substances were decreased and the total antioxidant capacity was increased. Parameters of endogenous glycation indicated a 32 and 46% higher load of advanced glycation end products in the kidneys after administration of the malt and the pronyl-BSA containing diet. However, the main systemic effects of dietary malt, bread crust, and pronyl-BSA were, for the first time, demonstrated to be the enhanced antioxidant capacity and the particulate increase in chemopreventive enzymes.
International Dairy Journal, 2000
A modi"ed RP-HPLC method for the determination of lysinoalanine (LAL) with dansyl chloride deriva... more A modi"ed RP-HPLC method for the determination of lysinoalanine (LAL) with dansyl chloride derivatisation without solidphase extraction is presented. The method was applied to market samples of liquid milk (n"54) and cheese (n"32) as well as to human milk from healthy volunteers (n"12). Additional liquid milk samples were obtained from model experiments on falling stream heating (FSH) high-pasteurisation (n"40). In raw milk, pasteurised and FSH high-pasteurised milk products LAL was quanti"ed for the "rst time. The LAL contents analysed in raw and pasteurised milk ranged from 4 to 24 and 17 to 69 mg kg\ crude protein, respectively. Compared to that, UHT-treated milk and sterilised milk showed higher LAL levels up to 186 and 653 mg kg\ crude protein, respectively. Among all of the dairy samples, LAL was proven to be a suitable and sensitive indicator to assess the heat treatment intensity given to milk which was heated without and with the addition of dairy-based substitutes, like caseinates. 2000 Elsevier Science Ltd. All rights reserved.
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Papers by Helmut Erbersdobler