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Sang Geon Kim - One of the best experts on this subject based on the ideXlab platform.
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Antioxidant and mitochondrial protective effects of oxidized metabolites of oltipraz
Expert opinion on drug metabolism & toxicology, 2010Co-Authors: Songhwa Choi, Young Mi Kim, Jungmin Lee, Sang Geon KimAbstract:Importance of the field: Comprehensive studies indicate that oltipraz exerts cancer chemopreventive effects. Oltipraz has other therapeutic potentials, which include anti-fibrotic effect, inhibition of insulin resistance, mitochondrial protection and cytoprotective effect against oxidative stress. Although antioxidant mechanisms may account for its cancer chemopreventive effect, details on the molecular mechanism still remain to be clarified.Areas covered in this review: Two major metabolic pathways of oltipraz include oxidative desulfuration of the thione to yield 4-methyl-5-(pyrazin-2-yl)-3H-1,2-dithiol-3-one and molecular rearrangement to 7-methyl-6,8-bis(methylthio)H-pyrrolo[1,2-a]Pyrazine. In addition to the diverse pharmacological effects of oltipraz, the oxidized metabolites may have distinct biological effects on cell survival. The AMP-activated protein kinase pathway has been recognized as a key cascade for mitochondrial protection and cell survival events, which can be activated by the oxidized ...
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oxidized metabolites of oltipraz exert cytoprotective effects against arachidonic acid through amp activated protein kinase dependent cellular antioxidant effect and mitochondrial protection
Drug Metabolism and Disposition, 2009Co-Authors: Young Nam Kwon, Sang Mi Shin, Il Je Cho, Sang Geon KimAbstract:Oltipraz protects cells from chemical-induced carcinogenesis partly because of phase 2 enzyme induction. Certain oltipraz metabolites also induce phase 2 enzymes. This study investigated the cytoprotective effects of the oxidized metabolites of oltipraz against arachidonic acid (AA), a proinflammatory fatty acid that causes cellular reactive oxygen species (ROS) production and mitochondrial impairment, and the mechanistic basis of their action in HepG2 cells. Treatment with 4-methyl-5-(pyrazin-2-yl)-3H-1,2-dithiol-3-one (M1) or 7-methyl-6,8-bis(methylthio)H-pyrrolo[1,2-a]-Pyrazine (M2), but not 7-methyl-8-(methylsulfinyl)-6-(methylthio)H-pyrrolo[1,2-a]Pyrazine (M3) or 7-methyl-6,8-bis(methylsulfinyl)H-pyrrolo[1,2-a]Pyrazine (M4), enabled cells to protect against AA-induced apoptosis. M1 and M2 treatment protected cells from ROS produced by AA and inhibited AA-induced glutathione depletion. Moreover, both M1 and M2 effectively inhibited mitochondrial dysfunction induced by AA, although M2 alone slightly elicited it at a relatively high concentration. M1 and M2 activated AMP-activated protein kinase (AMPK), but M3 and M4 failed to do so. AMPK activation by M1 and M2 contributed to cell survival against AA through a decrease in cellular ROS production and prevention of mitochondrial dysfunction, as shown by the reversal of the metabolites9 restoration of mitochondrial membrane potential by compound C treatment or overexpression of a dominant-negative mutant AMPK. Consistently, 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside, an AMPK activator, also had a cytoprotective and antioxidant effect against AA. Our results demonstrate that, of the major metabolites of oltipraz, M1 and M2 are capable of protecting cells from AA-induced ROS production and mitochondrial dysfunction, which may be associated with AMPK activation.
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differential effects of the oxidized metabolites of oltipraz on the activation of ccaat enhancer binding protein β and nf e2 related factor 2 for gsta2 gene induction
Drug Metabolism and Disposition, 2006Co-Authors: Seungjin Lee, Jee Woong Lim, Sang Geon KimAbstract:Comprehensive mechanistic studies suggest that oltipraz exerts cancer chemopreventive effects through the induction of glutathione S-transferase (GST). Previously, we have shown that the activation of CCAAT/enhancer binding protein-beta (C/EBPbeta), promoted by oltipraz, contributes to the transcriptional induction of the GSTA2 gene. Studies also indicated that exposure of animals to oltipraz triggers nuclear accumulation of NF-E2-related factor-2 (Nrf2) with an increase in Nrf2's antioxidant response element (ARE) binding activity. Given the previous reports that C/EBPbeta activation contributes to oltipraz's induction of the GSTA2 gene and that Nrf2 activation by oltipraz was variable depending on the concentrations, this study investigated whether the major oxidized metabolites of oltipraz induce GSTA2 through the activation of C/EBPbeta and/or Nrf2. Immunoblot analysis revealed that M1 [4-methyl-5-(pyrazin-2-yl)-3H-1,2-dithiol-3-one] and M2 (7-methyl-6,8-bis(methylthio)H-pyrrolo[1,2-a]Pyrazine), but not M3 (7-methyl-8-(methylsulfinyl)-6-(methylthio)H-pyrrolo[1,2-a]Pyrazine) and M4 (7-methyl-6,8-bis(methylsulfinyl)H-pyrrolo[1,2-a]Pyrazine), induced GSTA2 in H4IIE cells. M1 and M2 also increased the luciferase activity from pGL-1651, which contained the luciferase structural gene downstream of the -1.65-kilobase GSTA2 promoter region. Nuclear C/EBPbeta levels were enhanced by the metabolites but not by M3 or M4. Among the oxidized metabolites examined, only M2, which elicited cell death at a relatively high concentration, activated Nrf2, as indicated by nuclear accumulation of Nrf2 and its ARE binding activity. The present study provides evidence that M1 and M2, but not M3 and M4, induce GSTA2 and that M1 induces GSTA2 only via C/EBPbeta activation, whereas M2 does so by activating Nrf2 as well as C/EBPbeta. These results substantiate the differential effects of oltipraz's metabolites on C/EBPbeta- and/or Nrf2-mediated GSTA2 induction.
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differential effects of the oxidized metabolites of oltipraz on the activation of ccaat enhancer binding protein beta and nf e2 related factor 2 for gsta2 gene induction
Drug Metabolism and Disposition, 2006Co-Authors: Seungjin Lee, Jee Woong Lim, Sang Geon KimAbstract:Comprehensive mechanistic studies suggest that oltipraz exerts cancer chemopreventive effects through the induction of glutathione S-transferase (GST). Previously, we have shown that the activation of CCAAT/enhancer binding protein-beta (C/EBPbeta), promoted by oltipraz, contributes to the transcriptional induction of the GSTA2 gene. Studies also indicated that exposure of animals to oltipraz triggers nuclear accumulation of NF-E2-related factor-2 (Nrf2) with an increase in Nrf2's antioxidant response element (ARE) binding activity. Given the previous reports that C/EBPbeta activation contributes to oltipraz's induction of the GSTA2 gene and that Nrf2 activation by oltipraz was variable depending on the concentrations, this study investigated whether the major oxidized metabolites of oltipraz induce GSTA2 through the activation of C/EBPbeta and/or Nrf2. Immunoblot analysis revealed that M1 [4-methyl-5-(pyrazin-2-yl)-3H-1,2-dithiol-3-one] and M2 (7-methyl-6,8-bis(methylthio)H-pyrrolo[1,2-a]Pyrazine), but not M3 (7-methyl-8-(methylsulfinyl)-6-(methylthio)H-pyrrolo[1,2-a]Pyrazine) and M4 (7-methyl-6,8-bis(methylsulfinyl)H-pyrrolo[1,2-a]Pyrazine), induced GSTA2 in H4IIE cells. M1 and M2 also increased the luciferase activity from pGL-1651, which contained the luciferase structural gene downstream of the -1.65-kilobase GSTA2 promoter region. Nuclear C/EBPbeta levels were enhanced by the metabolites but not by M3 or M4. Among the oxidized metabolites examined, only M2, which elicited cell death at a relatively high concentration, activated Nrf2, as indicated by nuclear accumulation of Nrf2 and its ARE binding activity. The present study provides evidence that M1 and M2, but not M3 and M4, induce GSTA2 and that M1 induces GSTA2 only via C/EBPbeta activation, whereas M2 does so by activating Nrf2 as well as C/EBPbeta. These results substantiate the differential effects of oltipraz's metabolites on C/EBPbeta- and/or Nrf2-mediated GSTA2 induction.
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Differential effects of the oxidized metabolites of oltipraz on the activation of CCAAT/enhancer binding protein-beta and NF-E2related factor-2 for GSTA2 gene induction. Drug Metab
2006Co-Authors: Seungjin Lee, Jee Woong Lim, Sang Geon KimAbstract:Comprehensive mechanistic studies suggest that oltipraz exerts cancer chemopreventive effects through the induction of glutathi-one S-transferase (GST). Previously, we have shown that the acti-vation of CCAAT/enhancer binding protein- (C/EBP), promoted by oltipraz, contributes to the transcriptional induction of the GSTA2 gene. Studies also indicated that exposure of animals to oltipraz triggers nuclear accumulation of NF-E2-related factor-2 (Nrf2) with an increase in Nrf2’s antioxidant response element (ARE) binding activity. Given the previous reports that C/EBP activation contributes to oltipraz’s induction of the GSTA2 gene and that Nrf2 activation by oltipraz was variable depending on the concentrations, this study investigated whether the major oxidized metabolites of oltipraz induce GSTA2 through the activation of C/EBP and/or Nrf2. Immunoblot analysis revealed that M1 [4-methyl-5-(pyrazin-2-yl)-3H-1,2-dithiol-3-one] and M2 (7-methyl-6,8-bis(methylthio)H-pyrrolo[1,2-a]Pyrazine), but not M3 (7-methyl
Norbert De Kimpe - One of the best experts on this subject based on the ideXlab platform.
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influence of free amino acids oligopeptides and polypeptides on the formation of Pyrazines in maillard model systems
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Gustavo Luis Leonardo Scalone, Norbert De Kimpe, Tatiana Cucu, Bruno De MeulenaerAbstract:Pyrazines are specific Maillard reaction compounds known to contribute to the unique aroma of many products. Most studies concerning the generation of Pyrazines in the Maillard reaction have focused on amino acids, while little information is available on the impact of peptides and proteins. The present study investigated the generation of Pyrazines in model systems containing whey protein, hydrolyzed whey protein, amino acids, and glucose. The impact of thermal conditions, ratio of reagents, and water activity (a(w)) on Pyrazine formation was measured by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME-GC/MS. The presence of oligopeptides from hydrolyzed whey protein contributed significantly to an increased amount of Pyrazines, while in contrast free amino acids generated during protein hydrolysis contributed to a lesser extent. The generation of Pyrazines was enhanced at low a(w) (0.33) and high temperatures (>120 °C). This study showed that the role of peptides in the generation of Pyrazines in Maillard reaction systems has been dramatically underestimated.
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influence of free amino acids oligopeptides and polypeptides on the formation of Pyrazines in maillard model systems
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Gustavo Luis Leonardo Scalone, Norbert De Kimpe, Tatiana Cucu, Bruno De MeulenaerAbstract:Pyrazines are specific Maillard reaction compounds known to contribute to the unique aroma of many products. Most studies concerning the generation of Pyrazines in the Maillard reaction have focused on amino acids, while little information is available on the impact of peptides and proteins. The present study investigated the generation of Pyrazines in model systems containing whey protein, hydrolyzed whey protein, amino acids, and glucose. The impact of thermal conditions, ratio of reagents, and water activity (aw) on Pyrazine formation was measured by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME–GC/MS. The presence of oligopeptides from hydrolyzed whey protein contributed significantly to an increased amount of Pyrazines, while in contrast free amino acids generated during protein hydrolysis contributed to a lesser extent. The generation of Pyrazines was enhanced at low aw (0.33) and high temperatures (>120 °C). This study showed that the role of peptides in t...
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formation of Pyrazines in maillard model systems of lysine containing dipeptides
Journal of Agricultural and Food Chemistry, 2010Co-Authors: Fien Van Lancker, An Adams, Norbert De KimpeAbstract:Whereas most studies concerning the Maillard reaction have focused on free amino acids, little information is available on the impact of peptides and proteins on this important reaction in food chemistry. Therefore, the formation of flavor compounds from the model reactions of glucose, methylglyoxal, or glyoxal with eight dipeptides with lysine at the N-terminus was studied in comparison with the corresponding free amino acids by means of stir bar sorptive extraction (SBSE) followed by GC-MS analysis. The reaction mixtures of the dipeptides containing glucose, methylglyoxal, and glyoxal produced 27, 18, and 2 different Pyrazines, respectively. Generally, the Pyrazines were produced more in the case of dipeptides as compared to free amino acids. For reactions with glucose and methylglyoxal, this difference was mainly caused by the large amounts of 2,5(6)-dimethylPyrazine and trimethylPyrazine produced from the reactions with dipeptides. For reactions with glyoxal, the difference in Pyrazine production was rather small and mostly unsubstituted Pyrazine was formed. A reaction mechanism for Pyrazine formation from dipeptides was proposed and evaluated. This study clearly illustrates the capability of peptides to produce flavor compounds that can differ from those obtained from the corresponding reactions with free amino acids.
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formation of Pyrazines from ascorbic acid and amino acids under dry roasting conditions
Food Chemistry, 2009Co-Authors: An Adams, Norbert De KimpeAbstract:Although the participation of ascorbic acid in Maillard-type reactions has been described, the formation of flavour compounds resulting from the interaction of ascorbic acid with different amino acids has not been reported before. Therefore, the formation of flavour compounds from the model reactions of 20 amino acids with ascorbic acid was studied under dry-roasting conditions. Thirty-six different Pyrazines were identified, mostly ethyl and methyl substituted Pyrazines. The amounts of Pyrazines detected were comparable to those formed from pentose sugars. Lysine was the most reactive amino acid and yielded the highest amounts of alkylPyrazines. The reducing activity of ascorbic acid influenced the reaction mechanism of Pyrazine formation and thus the type of Pyrazines produced. Addition of a base, such as potassium carbonate, significantly enhanced Pyrazine formation from ascorbic acid for most amino acids. The formation of Pyrazines from serine and threonine without a carbonyl compound was greatly enhanced by the addition of potassium carbonate as well. Furan was detected in all model systems in relatively low amounts and its formation was not enhanced by the addition of potassium carbonate.
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formation of Pyrazines and a novel pyrrole in maillard model systems of 1 3 dihydroxyacetone and 2 oxopropanal
Journal of Agricultural and Food Chemistry, 2008Co-Authors: An Adams, Viviana Polizzi, Martinus A J S Van Boekel, Norbert De KimpeAbstract:AlkylPyrazines are a very important class of Maillard flavor compounds, but their mechanism of formation is complex and consists of different pathways. The model reaction of 20 different amino acids with 1,3-dihydroxyacetone, as a precursor of 2-oxopropanal, was studied by means of SPME-GC-MS to investigate the involvement of the amino acid side chain in the substitution pattern of the resulting Pyrazines. 2,5-DimethylPyrazine was quantitatively the most important Pyrazine formed from all of the amino acids. The amino acid side chain is not involved in its formation. The substituents of other less abundant Pyrazines resulted mainly from the incorporation of the Strecker aldehyde or aldol condensation products in the intermediate dihydroPyrazine. The importance of different reaction mechanisms was evaluated, taking into account the pattern of Pyrazines identified. In the solvent extracts of aqueous model reactions of 2-oxopropanal with amino acids, the main reaction product was not a Pyrazine but a novel p...
Sanjay Batra - One of the best experts on this subject based on the ideXlab platform.
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expeditious synthesis of chiral 1 2 3 4 tetrahydropyrrolo 1 2 a Pyrazines
Tetrahedron Letters, 2013Co-Authors: Subhendu Bhowmik, Anil Kumar, Sanjay BatraAbstract:Abstract An expeditious one-pot two-step synthesis of chiral 4-substituted-6-methyl-1,2-dihydropyrrolo[1,2- a ]pyrazin-3(4 H )-ones via reaction between 5-methyl furfurylamine and N -Boc amino acids is described. LiAlH 4 -mediated reduction of 4-substituted-6-methyl-1,2-dihydropyrrolo[1,2- a ]pyrazin-3(4 H )-ones affords respective chiral 1,2,3,4-tetrahydropyrrolo[1,2- a ]Pyrazines in excellent yields.
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synthesis of pyrrolo 1 2 a Pyrazines and pyrazino 1 2 a indoles by curtius reaction in morita baylis hillman derivatives
Tetrahedron, 2011Co-Authors: Maloy Nayak, Garima Pandey, Sanjay BatraAbstract:Abstract Synthesis of substituted pyrrolo[1,2-a]Pyrazines and pyrazino[1,2-a]indoles from the Morita–Baylis–Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.
Seungjin Lee - One of the best experts on this subject based on the ideXlab platform.
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differential effects of the oxidized metabolites of oltipraz on the activation of ccaat enhancer binding protein beta and nf e2 related factor 2 for gsta2 gene induction
Drug Metabolism and Disposition, 2006Co-Authors: Seungjin Lee, Jee Woong Lim, Sang Geon KimAbstract:Comprehensive mechanistic studies suggest that oltipraz exerts cancer chemopreventive effects through the induction of glutathione S-transferase (GST). Previously, we have shown that the activation of CCAAT/enhancer binding protein-beta (C/EBPbeta), promoted by oltipraz, contributes to the transcriptional induction of the GSTA2 gene. Studies also indicated that exposure of animals to oltipraz triggers nuclear accumulation of NF-E2-related factor-2 (Nrf2) with an increase in Nrf2's antioxidant response element (ARE) binding activity. Given the previous reports that C/EBPbeta activation contributes to oltipraz's induction of the GSTA2 gene and that Nrf2 activation by oltipraz was variable depending on the concentrations, this study investigated whether the major oxidized metabolites of oltipraz induce GSTA2 through the activation of C/EBPbeta and/or Nrf2. Immunoblot analysis revealed that M1 [4-methyl-5-(pyrazin-2-yl)-3H-1,2-dithiol-3-one] and M2 (7-methyl-6,8-bis(methylthio)H-pyrrolo[1,2-a]Pyrazine), but not M3 (7-methyl-8-(methylsulfinyl)-6-(methylthio)H-pyrrolo[1,2-a]Pyrazine) and M4 (7-methyl-6,8-bis(methylsulfinyl)H-pyrrolo[1,2-a]Pyrazine), induced GSTA2 in H4IIE cells. M1 and M2 also increased the luciferase activity from pGL-1651, which contained the luciferase structural gene downstream of the -1.65-kilobase GSTA2 promoter region. Nuclear C/EBPbeta levels were enhanced by the metabolites but not by M3 or M4. Among the oxidized metabolites examined, only M2, which elicited cell death at a relatively high concentration, activated Nrf2, as indicated by nuclear accumulation of Nrf2 and its ARE binding activity. The present study provides evidence that M1 and M2, but not M3 and M4, induce GSTA2 and that M1 induces GSTA2 only via C/EBPbeta activation, whereas M2 does so by activating Nrf2 as well as C/EBPbeta. These results substantiate the differential effects of oltipraz's metabolites on C/EBPbeta- and/or Nrf2-mediated GSTA2 induction.
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differential effects of the oxidized metabolites of oltipraz on the activation of ccaat enhancer binding protein β and nf e2 related factor 2 for gsta2 gene induction
Drug Metabolism and Disposition, 2006Co-Authors: Seungjin Lee, Jee Woong Lim, Sang Geon KimAbstract:Comprehensive mechanistic studies suggest that oltipraz exerts cancer chemopreventive effects through the induction of glutathione S-transferase (GST). Previously, we have shown that the activation of CCAAT/enhancer binding protein-beta (C/EBPbeta), promoted by oltipraz, contributes to the transcriptional induction of the GSTA2 gene. Studies also indicated that exposure of animals to oltipraz triggers nuclear accumulation of NF-E2-related factor-2 (Nrf2) with an increase in Nrf2's antioxidant response element (ARE) binding activity. Given the previous reports that C/EBPbeta activation contributes to oltipraz's induction of the GSTA2 gene and that Nrf2 activation by oltipraz was variable depending on the concentrations, this study investigated whether the major oxidized metabolites of oltipraz induce GSTA2 through the activation of C/EBPbeta and/or Nrf2. Immunoblot analysis revealed that M1 [4-methyl-5-(pyrazin-2-yl)-3H-1,2-dithiol-3-one] and M2 (7-methyl-6,8-bis(methylthio)H-pyrrolo[1,2-a]Pyrazine), but not M3 (7-methyl-8-(methylsulfinyl)-6-(methylthio)H-pyrrolo[1,2-a]Pyrazine) and M4 (7-methyl-6,8-bis(methylsulfinyl)H-pyrrolo[1,2-a]Pyrazine), induced GSTA2 in H4IIE cells. M1 and M2 also increased the luciferase activity from pGL-1651, which contained the luciferase structural gene downstream of the -1.65-kilobase GSTA2 promoter region. Nuclear C/EBPbeta levels were enhanced by the metabolites but not by M3 or M4. Among the oxidized metabolites examined, only M2, which elicited cell death at a relatively high concentration, activated Nrf2, as indicated by nuclear accumulation of Nrf2 and its ARE binding activity. The present study provides evidence that M1 and M2, but not M3 and M4, induce GSTA2 and that M1 induces GSTA2 only via C/EBPbeta activation, whereas M2 does so by activating Nrf2 as well as C/EBPbeta. These results substantiate the differential effects of oltipraz's metabolites on C/EBPbeta- and/or Nrf2-mediated GSTA2 induction.
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Differential effects of the oxidized metabolites of oltipraz on the activation of CCAAT/enhancer binding protein-beta and NF-E2related factor-2 for GSTA2 gene induction. Drug Metab
2006Co-Authors: Seungjin Lee, Jee Woong Lim, Sang Geon KimAbstract:Comprehensive mechanistic studies suggest that oltipraz exerts cancer chemopreventive effects through the induction of glutathi-one S-transferase (GST). Previously, we have shown that the acti-vation of CCAAT/enhancer binding protein- (C/EBP), promoted by oltipraz, contributes to the transcriptional induction of the GSTA2 gene. Studies also indicated that exposure of animals to oltipraz triggers nuclear accumulation of NF-E2-related factor-2 (Nrf2) with an increase in Nrf2’s antioxidant response element (ARE) binding activity. Given the previous reports that C/EBP activation contributes to oltipraz’s induction of the GSTA2 gene and that Nrf2 activation by oltipraz was variable depending on the concentrations, this study investigated whether the major oxidized metabolites of oltipraz induce GSTA2 through the activation of C/EBP and/or Nrf2. Immunoblot analysis revealed that M1 [4-methyl-5-(pyrazin-2-yl)-3H-1,2-dithiol-3-one] and M2 (7-methyl-6,8-bis(methylthio)H-pyrrolo[1,2-a]Pyrazine), but not M3 (7-methyl
Bruno De Meulenaer - One of the best experts on this subject based on the ideXlab platform.
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influence of free amino acids oligopeptides and polypeptides on the formation of Pyrazines in maillard model systems
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Gustavo Luis Leonardo Scalone, Norbert De Kimpe, Tatiana Cucu, Bruno De MeulenaerAbstract:Pyrazines are specific Maillard reaction compounds known to contribute to the unique aroma of many products. Most studies concerning the generation of Pyrazines in the Maillard reaction have focused on amino acids, while little information is available on the impact of peptides and proteins. The present study investigated the generation of Pyrazines in model systems containing whey protein, hydrolyzed whey protein, amino acids, and glucose. The impact of thermal conditions, ratio of reagents, and water activity (a(w)) on Pyrazine formation was measured by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME-GC/MS. The presence of oligopeptides from hydrolyzed whey protein contributed significantly to an increased amount of Pyrazines, while in contrast free amino acids generated during protein hydrolysis contributed to a lesser extent. The generation of Pyrazines was enhanced at low a(w) (0.33) and high temperatures (>120 °C). This study showed that the role of peptides in the generation of Pyrazines in Maillard reaction systems has been dramatically underestimated.
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influence of free amino acids oligopeptides and polypeptides on the formation of Pyrazines in maillard model systems
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Gustavo Luis Leonardo Scalone, Norbert De Kimpe, Tatiana Cucu, Bruno De MeulenaerAbstract:Pyrazines are specific Maillard reaction compounds known to contribute to the unique aroma of many products. Most studies concerning the generation of Pyrazines in the Maillard reaction have focused on amino acids, while little information is available on the impact of peptides and proteins. The present study investigated the generation of Pyrazines in model systems containing whey protein, hydrolyzed whey protein, amino acids, and glucose. The impact of thermal conditions, ratio of reagents, and water activity (aw) on Pyrazine formation was measured by headspace solid-phase microextraction with gas chromatography/mass spectrometry (HS-SPME–GC/MS. The presence of oligopeptides from hydrolyzed whey protein contributed significantly to an increased amount of Pyrazines, while in contrast free amino acids generated during protein hydrolysis contributed to a lesser extent. The generation of Pyrazines was enhanced at low aw (0.33) and high temperatures (>120 °C). This study showed that the role of peptides in t...
