Journal of Agricultural and Food Chemistry, Apr 1, 1995
Cholesterol oxidation products (COPs) may produce adverse biological effects, and there is increa... more Cholesterol oxidation products (COPs) may produce adverse biological effects, and there is increasing concern regarding the potential health implications of these products in the diet. We have developed a GC/MS method allowing the quantification of COPs in commercially available milk powders and infant formulas. Since oxidation artifacts from cholesterol are essentially impossible to avoid, we have used a deuteriated cholesterol probe to precisely monitor the formation of cholesterol oxidative artifacts during all stages of sample analysis. This strategy allowed the determination of the artifactfree cholesterol oxide content of the samples. We found that freshly opened full cream powders which had been packed under inert gas contained only traces of COPs (<250 nglg total). Infant formulas were also found to contain very low levels of COPs. Our values were considerably lower than those previously reported, especially for 7-ketocholesterol. This difference is at least in part explained by the correction of the oxidation artifacts applied to our samples. We conclude that the exposure to COPs from commercial milk powders and infant formulas, and consequently their potential health hazard, may have been previously overestimated.
Journal of the American Oil Chemists' Society, Aug 1, 1998
The fatty acid composition, tocopherol and tocotrienol content, and oxidative stability of petrol... more The fatty acid composition, tocopherol and tocotrienol content, and oxidative stability of petroleum benzene‐extracted Gevuina avellana Mol (Proteaceae) seed oil were determined. Positional isomers of monounsaturated fatty acids were elucidated by gas chromatography‐electron impact mass spectrometry after 2‐alkenyl‐4,4‐dimethyloxazoline derivatization. This stable oil (Rancimat induction period at 110°C: 20 h) is composed of more than 85% monounsaturated fatty acids and about equal amounts (6%) of saturated and polyunsaturated (principally linoleic) fatty acids. Unusual positional isomers of monounsaturated fatty acids, i.e., C16:1 Δ11, C18:1 Δ12, C20:1 Δ11, C20:1 Δ15, C22:1 Δ17, and presumably C22:1 Δ19 were identified. The C18:1 Δ12 and C22:1 Δ19 fatty acids are described for the first time in G. avellana seed oil. While only minute quantities of α‐, γ‐tocopherols and β‐, γ‐ and δ‐tocotrienols were found, the oil contained a substantial amount of α‐tocotrienol (130 mg/kg). The potential nutritional value of G. avellana seed oil is discussed on the basis of its composition.
2-Amino-3,8-dimethylimadazo[4,5-f]quinoxaline (MeIQx) and other heterocyclic aromatic amines (HAA... more 2-Amino-3,8-dimethylimadazo[4,5-f]quinoxaline (MeIQx) and other heterocyclic aromatic amines (HAAs) are rodent carcinogens and potential human carcinogens formed in cooked meats and fish. Metabolic activation of MeIQx to a genotoxin occurs through cytochrome P450 mediated N-oxidation to form N-hydroxy-MeIQx which may undergo further activation by esterification to product species which bind to DNA. Pathways of MeIQx metabolism have been elucidated in rodents and nonhuman primates to develop strategies of human biomonitoring. In addition to N-oxidation, predominant routes of detoxification include direct conjugation at the exoyclic amino group with sulfate or glucuronic acid and cytochrome P450 mediated ring oxidation. Analysis of urine from five human subjects exposed to MeIQx reveals that phase II conjugation reactions to the exocyclic amine group are prominent detoxifaction pathways while heterocyclic ring oxidation is a minor pathway. Notably, the N{sup 2-} glucuronide conjugate of N-hydroxy-MeIQx is an important metabolite in human urine. Several other metabolites have been detected in human urine which have not been previously identified in rats or nonhuman primates. Similarities and differences exist in the metabolic processing of MeIQx by humans and other species and may be a critical determinant in assessing the human health risk of HAAs.
Sw i tze r la n d 'Deutsche Forsch u ngsanstalt fü r Lebensmittelc hem ie, Lichten bergstrasse 4,... more Sw i tze r la n d 'Deutsche Forsch u ngsanstalt fü r Lebensmittelc hem ie, Lichten bergstrasse 4, D-85748 Garching, Germany '
ABSTRACT Quantification of o-tyrosine, o-nitrotyrosine, and o,o&#39;dityrosine from cat urine... more ABSTRACT Quantification of o-tyrosine, o-nitrotyrosine, and o,o&#39;dityrosine from cat urine samples was achieved by LC/ electrospray ionization-MS/MS (LC/ESI-MS/MS) using an isotope dilution technique in multiple reaction monitoring mode before butylation of o,o&#39;-dityrosine and after butylation of o-tyrosine and o-nitrotyrosine. This novel approach of amino acids butylation enhanced the MS response by a factor of 7-fold for o-tyrosine and 6-fold for o-nitrotyrosine and decreased the overall chemical background noise. Butylation of o,o&#39;-dityrosine resulted in a lower MS response as a result of the formation of both mono- and doubly butylated species. The mean recovery for the oxidized amino acids was estimated at 73 +/- 2%. The limits of quantitation of NO2-Tyr butyl ester, o-Tyr butyl ester, and di-Tyr in cat urine samples were calculated at 14.5, 28.2 and 140.9 nM, respectively. The oxidized amino acids levels in cat urine extracts ranged from 157 to 250 ng/day for o-Tyr and from 3,289 to 11,803 ng/day for di-Tyr. NO2-Tyr was found in only two urine extracts at levels below 58 ng/day. A certain trend of correlation was observed between o,o&#39;-dityrosine and o-tyrosine when comparing these values against their respective creatinine amounts. A comparison of the data gathered from the ThermoFinnigan TSQ 7000 and Micromass Q-TOF instruments revealed several advantages of using the Q-TOF regarding the exact mass measurement, a lower ion suppression effect and the possibility to perform analyses in full scan product ion mode. These results demonstrate that a Q-TOF instrument can be a good alternative to classical triple quadrupole for quantitative purposes on a relatively small linear dynamic range (4 orders of magnitude for the Q-TOF, as compared to 6 for the triple quadrupole).
Arsenic species in arsenic-accumulating mushrooms (Sarcosphaera coronaria, Laccaria amethystina, ... more Arsenic species in arsenic-accumulating mushrooms (Sarcosphaera coronaria, Laccaria amethystina, Sarcodon imbricatum, Entoloma lividum, Agaricus haemorrhoidarius, Agaricus placomyces, Lycoperdon perlaturn) were determined. HPLC/ICP MS and ion-exchange chromatography-instrumental neutron activation analysis (NAA) combinations were used. The remarkable accumulator Sarcosphaera coronaria (up to 2000 mg As kg-' dry wt) contained only methylarsonic acid, Entoloma lividum only arsenite and arsenate. In Laccaria amethystina dimethylarsinic acid was the major arsenic compound. Sarcodon imbricatum and the two Agaricus sp. were found to contain arsenobetaine as the major arsenic species, a form which had previously been found only in marine biota. Its identification was confirmed by electron impact MS.
Plant sterols reduce cholesterol absorption, which leads to a decrease in plasma and LDL-choleste... more Plant sterols reduce cholesterol absorption, which leads to a decrease in plasma and LDL-cholesterol concentrations. Plant sterols also lower plasma concentrations of carotenoids and alpha-tocopherol, but the mechanism of action is not yet understood. The aims of this clinical study were to determine whether plant sterols affect the bioavailability of beta-carotene and alpha-tocopherol in normocholesterolemic men and to compare the effects of plant sterol esters and plant free sterols on cholesterol absorption. Twenty-six normocholesterolemic men completed the double-blind, randomized, crossover study. Subjects consumed daily, for 1 wk, each of the following 3 supplements: a low-fat milk-based beverage alone (control) or the same beverage supplemented with 2.2 g plant sterol equivalents provided as either free sterols or sterol esters. During this 1-wk supplementation period, subjects consumed a standardized diet. Both of the milks enriched with plant sterols induced a similar (60%)...
Isotopes in Environmental and Health Studies, 2003
Hypercholesterolemia is a major health risk. Dietary cholesterol absorption is one important fact... more Hypercholesterolemia is a major health risk. Dietary cholesterol absorption is one important factor affecting levels of plasma and tissue cholesterol. Considerable effort has thus been devoted to develop reliable in vivo clinical methodologies to determine dietary cholesterol absorption in humans. The present paper summarises radiolabelled experiments and major advances in stable isotope technologies to determine cholesterol absorption. Initially, direct methods employing gastro-intestinal intubation were developed. Later, indirect methods using oral-faecal cholesterol balance permitted calculation of cholesterol mass absorption. Once the use of radiolabelled [3H, 14C]cholesterol balance was developed in healthy humans, it was finally possible to distinguish exogenous and endogenous cholesterol. Non-invasive and safer stable isotope (2H, 13C, 18O) labelled cholesterol tracers then replaced radioisotopes for use in infants and adults. Stable isotopes and radioisotopes showed identical cholesterol kinetics. The most promising contemporary stable isotope assessment of cholesterol absorption is a dual stable isotope dual tracer approach based on simultaneous administration of oral and intravenous differentially labelled cholesterol tracers, followed by plasma sampling for 3-4 d. Online GC/Combustion/IRMS and GC/Pyrolysis/IRMS allow minimal amounts of dual stable isotope cholesterol tracers to be detected. Using the dual stable isotope dual tracer approach, the percent cholesterol absorption in adult volunteers has been determined to be 50-70%.
The mass spectrometric behaviour of four new macrocyclic compounds, all containing the 13,Striazi... more The mass spectrometric behaviour of four new macrocyclic compounds, all containing the 13,Striazine moiety, was studied with the aid of different ionization methods and mass-analysed ion kinetic energy spectrometry. Extensive fragmentation of the oligoethylene glycol side-chains is observed, with the usual loss of C2H,0 units. The favoured cleavage of the ethereal bond nearest to the etherocyclic ring gives rise-to both complementary ions.
Journal of Agricultural and Food Chemistry, Nov 1, 1995
... Miriam Amrani-Hemaimi,+ Christoph Cerny,*Bt and Laurent B. Fay ... pyrazine this result was i... more ... Miriam Amrani-Hemaimi,+ Christoph Cerny,*Bt and Laurent B. Fay ... pyrazine this result was in accordance with a proposed mechanism in which acet-aldehyde is added to an intermediate dimethyldihydro-pyrazine (Shibamoto et al., 1979; Milic and Piletic, 1984), the origin of the ...
The heterocyclic aromatic amines (HAAs) 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2... more The heterocyclic aromatic amines (HAAs) 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) and 2-amino alpha carboline (A alpha C) were quantitated in grilled bacon and beef. The levels of PhIP in bacon ranged from &amp;amp;lt; 0.1 to 52 p.p.b., MeIQx was detected at levels ranging from 0.9 to 18 p.p.b. Both 4,8-DiMeIQx and A alpha C were found at &amp;amp;lt; 1 p.p.b. In grilled meat patties, MeIQx and PhIP were detected at levels ranging from 0.8 to 3.2 p.p.b., while 4,8-DiMeIQx and A alpha C were below the limit of detection (approximately 0.5 p.p.b.). HAAs were below the limit of detection in grilled fish. The bacon fat drippings and the pan scrapings obtained from grilled meat and fish also contained significant amounts of HAAs and indicated that either these carcinogens are released with the fat during grilling or that HAAs are formed directly in the released fat and juices. Several of these carcinogens were detected in the pan scrapings at concentrations 10- to 100-fold higher than in cooked meats. PhIP was detected at 144 p.p.b. in combined grilled meat and fish scrapings, followed by A alpha C at 77 p.p.b., MeIQx at 29 p.p.b. and 4,8-DiMeIQx at 4 p.p.b. The co-mutagens harman and norharman were also detected in cooked meats and fish at amounts ranging from 5 to 30 p.p.b. Fat drippings and grill residue scrapings are often used as a base for gravies and sauces. Thus, cooking practices and dietary habits have a strong impact on HAA exposure.
www.molecularsystemsbiology.com Probiotic modulation of symbiotic gut microbial–host metabolic in... more www.molecularsystemsbiology.com Probiotic modulation of symbiotic gut microbial–host metabolic interactions in a humanized microbiome mouse model
The metabolism of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo[4,... more The metabolism of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), two carcinogenic heterocyclic aromatic amines (HCAs) formed in cooked meats and fish, was studied in animal models and in vitro with human tissues to develop strategies for human biomonitoring. Both IQ and MeIQx are rapidly absorbed from the gastrointestinal tract of rodents and transformed into a number of products which are excreted in urine and feces. Detoxification occurs via cytochrome P450 mediated ring hydroxylation at the C-5 position followed by conjugation to sulfuric or beta-glucuronic acid. Other routes of detoxification include N2-glucuronidation and the uncommon pathway of sulfamate formation; N2-acetylation, however, appears to be a minor pathway. Metabolic activation by N-oxidation was demonstrated through formation of the metastable N2-glucuronide conjugate of the mutagenic N-hydroxy metabolites. These conjugates are excreted preferentially in ur...
www.molecularsystemsbiology.com Top-down systems biology integration of conditional prebiotic mod... more www.molecularsystemsbiology.com Top-down systems biology integration of conditional prebiotic modulated transgenomic interactions in a humanized microbiome mouse model
Thiols are important constituents of the flavour of many foods and beverages. They were produced ... more Thiols are important constituents of the flavour of many foods and beverages. They were produced efficiently by enzymatic hydrolysis of thioacetates, which are commercially available or easily accessible, by reaction of thioacetic acid with alkenes. Enzymatic ...
Abstract: The present invention is directed to procedures for the controlled natural bioprocessin... more Abstract: The present invention is directed to procedures for the controlled natural bioprocessing of naturally occurring biological molecules by processing activities present in select organisms, extracts of such organisms or other natural processing agents. The invention also covers the methods for developing these procedures and compositions prepared by the procedures.
Journal of Agricultural and Food Chemistry, Apr 1, 1995
Cholesterol oxidation products (COPs) may produce adverse biological effects, and there is increa... more Cholesterol oxidation products (COPs) may produce adverse biological effects, and there is increasing concern regarding the potential health implications of these products in the diet. We have developed a GC/MS method allowing the quantification of COPs in commercially available milk powders and infant formulas. Since oxidation artifacts from cholesterol are essentially impossible to avoid, we have used a deuteriated cholesterol probe to precisely monitor the formation of cholesterol oxidative artifacts during all stages of sample analysis. This strategy allowed the determination of the artifactfree cholesterol oxide content of the samples. We found that freshly opened full cream powders which had been packed under inert gas contained only traces of COPs (<250 nglg total). Infant formulas were also found to contain very low levels of COPs. Our values were considerably lower than those previously reported, especially for 7-ketocholesterol. This difference is at least in part explained by the correction of the oxidation artifacts applied to our samples. We conclude that the exposure to COPs from commercial milk powders and infant formulas, and consequently their potential health hazard, may have been previously overestimated.
Journal of the American Oil Chemists' Society, Aug 1, 1998
The fatty acid composition, tocopherol and tocotrienol content, and oxidative stability of petrol... more The fatty acid composition, tocopherol and tocotrienol content, and oxidative stability of petroleum benzene‐extracted Gevuina avellana Mol (Proteaceae) seed oil were determined. Positional isomers of monounsaturated fatty acids were elucidated by gas chromatography‐electron impact mass spectrometry after 2‐alkenyl‐4,4‐dimethyloxazoline derivatization. This stable oil (Rancimat induction period at 110°C: 20 h) is composed of more than 85% monounsaturated fatty acids and about equal amounts (6%) of saturated and polyunsaturated (principally linoleic) fatty acids. Unusual positional isomers of monounsaturated fatty acids, i.e., C16:1 Δ11, C18:1 Δ12, C20:1 Δ11, C20:1 Δ15, C22:1 Δ17, and presumably C22:1 Δ19 were identified. The C18:1 Δ12 and C22:1 Δ19 fatty acids are described for the first time in G. avellana seed oil. While only minute quantities of α‐, γ‐tocopherols and β‐, γ‐ and δ‐tocotrienols were found, the oil contained a substantial amount of α‐tocotrienol (130 mg/kg). The potential nutritional value of G. avellana seed oil is discussed on the basis of its composition.
2-Amino-3,8-dimethylimadazo[4,5-f]quinoxaline (MeIQx) and other heterocyclic aromatic amines (HAA... more 2-Amino-3,8-dimethylimadazo[4,5-f]quinoxaline (MeIQx) and other heterocyclic aromatic amines (HAAs) are rodent carcinogens and potential human carcinogens formed in cooked meats and fish. Metabolic activation of MeIQx to a genotoxin occurs through cytochrome P450 mediated N-oxidation to form N-hydroxy-MeIQx which may undergo further activation by esterification to product species which bind to DNA. Pathways of MeIQx metabolism have been elucidated in rodents and nonhuman primates to develop strategies of human biomonitoring. In addition to N-oxidation, predominant routes of detoxification include direct conjugation at the exoyclic amino group with sulfate or glucuronic acid and cytochrome P450 mediated ring oxidation. Analysis of urine from five human subjects exposed to MeIQx reveals that phase II conjugation reactions to the exocyclic amine group are prominent detoxifaction pathways while heterocyclic ring oxidation is a minor pathway. Notably, the N{sup 2-} glucuronide conjugate of N-hydroxy-MeIQx is an important metabolite in human urine. Several other metabolites have been detected in human urine which have not been previously identified in rats or nonhuman primates. Similarities and differences exist in the metabolic processing of MeIQx by humans and other species and may be a critical determinant in assessing the human health risk of HAAs.
Sw i tze r la n d 'Deutsche Forsch u ngsanstalt fü r Lebensmittelc hem ie, Lichten bergstrasse 4,... more Sw i tze r la n d 'Deutsche Forsch u ngsanstalt fü r Lebensmittelc hem ie, Lichten bergstrasse 4, D-85748 Garching, Germany '
ABSTRACT Quantification of o-tyrosine, o-nitrotyrosine, and o,o&#39;dityrosine from cat urine... more ABSTRACT Quantification of o-tyrosine, o-nitrotyrosine, and o,o&#39;dityrosine from cat urine samples was achieved by LC/ electrospray ionization-MS/MS (LC/ESI-MS/MS) using an isotope dilution technique in multiple reaction monitoring mode before butylation of o,o&#39;-dityrosine and after butylation of o-tyrosine and o-nitrotyrosine. This novel approach of amino acids butylation enhanced the MS response by a factor of 7-fold for o-tyrosine and 6-fold for o-nitrotyrosine and decreased the overall chemical background noise. Butylation of o,o&#39;-dityrosine resulted in a lower MS response as a result of the formation of both mono- and doubly butylated species. The mean recovery for the oxidized amino acids was estimated at 73 +/- 2%. The limits of quantitation of NO2-Tyr butyl ester, o-Tyr butyl ester, and di-Tyr in cat urine samples were calculated at 14.5, 28.2 and 140.9 nM, respectively. The oxidized amino acids levels in cat urine extracts ranged from 157 to 250 ng/day for o-Tyr and from 3,289 to 11,803 ng/day for di-Tyr. NO2-Tyr was found in only two urine extracts at levels below 58 ng/day. A certain trend of correlation was observed between o,o&#39;-dityrosine and o-tyrosine when comparing these values against their respective creatinine amounts. A comparison of the data gathered from the ThermoFinnigan TSQ 7000 and Micromass Q-TOF instruments revealed several advantages of using the Q-TOF regarding the exact mass measurement, a lower ion suppression effect and the possibility to perform analyses in full scan product ion mode. These results demonstrate that a Q-TOF instrument can be a good alternative to classical triple quadrupole for quantitative purposes on a relatively small linear dynamic range (4 orders of magnitude for the Q-TOF, as compared to 6 for the triple quadrupole).
Arsenic species in arsenic-accumulating mushrooms (Sarcosphaera coronaria, Laccaria amethystina, ... more Arsenic species in arsenic-accumulating mushrooms (Sarcosphaera coronaria, Laccaria amethystina, Sarcodon imbricatum, Entoloma lividum, Agaricus haemorrhoidarius, Agaricus placomyces, Lycoperdon perlaturn) were determined. HPLC/ICP MS and ion-exchange chromatography-instrumental neutron activation analysis (NAA) combinations were used. The remarkable accumulator Sarcosphaera coronaria (up to 2000 mg As kg-' dry wt) contained only methylarsonic acid, Entoloma lividum only arsenite and arsenate. In Laccaria amethystina dimethylarsinic acid was the major arsenic compound. Sarcodon imbricatum and the two Agaricus sp. were found to contain arsenobetaine as the major arsenic species, a form which had previously been found only in marine biota. Its identification was confirmed by electron impact MS.
Plant sterols reduce cholesterol absorption, which leads to a decrease in plasma and LDL-choleste... more Plant sterols reduce cholesterol absorption, which leads to a decrease in plasma and LDL-cholesterol concentrations. Plant sterols also lower plasma concentrations of carotenoids and alpha-tocopherol, but the mechanism of action is not yet understood. The aims of this clinical study were to determine whether plant sterols affect the bioavailability of beta-carotene and alpha-tocopherol in normocholesterolemic men and to compare the effects of plant sterol esters and plant free sterols on cholesterol absorption. Twenty-six normocholesterolemic men completed the double-blind, randomized, crossover study. Subjects consumed daily, for 1 wk, each of the following 3 supplements: a low-fat milk-based beverage alone (control) or the same beverage supplemented with 2.2 g plant sterol equivalents provided as either free sterols or sterol esters. During this 1-wk supplementation period, subjects consumed a standardized diet. Both of the milks enriched with plant sterols induced a similar (60%)...
Isotopes in Environmental and Health Studies, 2003
Hypercholesterolemia is a major health risk. Dietary cholesterol absorption is one important fact... more Hypercholesterolemia is a major health risk. Dietary cholesterol absorption is one important factor affecting levels of plasma and tissue cholesterol. Considerable effort has thus been devoted to develop reliable in vivo clinical methodologies to determine dietary cholesterol absorption in humans. The present paper summarises radiolabelled experiments and major advances in stable isotope technologies to determine cholesterol absorption. Initially, direct methods employing gastro-intestinal intubation were developed. Later, indirect methods using oral-faecal cholesterol balance permitted calculation of cholesterol mass absorption. Once the use of radiolabelled [3H, 14C]cholesterol balance was developed in healthy humans, it was finally possible to distinguish exogenous and endogenous cholesterol. Non-invasive and safer stable isotope (2H, 13C, 18O) labelled cholesterol tracers then replaced radioisotopes for use in infants and adults. Stable isotopes and radioisotopes showed identical cholesterol kinetics. The most promising contemporary stable isotope assessment of cholesterol absorption is a dual stable isotope dual tracer approach based on simultaneous administration of oral and intravenous differentially labelled cholesterol tracers, followed by plasma sampling for 3-4 d. Online GC/Combustion/IRMS and GC/Pyrolysis/IRMS allow minimal amounts of dual stable isotope cholesterol tracers to be detected. Using the dual stable isotope dual tracer approach, the percent cholesterol absorption in adult volunteers has been determined to be 50-70%.
The mass spectrometric behaviour of four new macrocyclic compounds, all containing the 13,Striazi... more The mass spectrometric behaviour of four new macrocyclic compounds, all containing the 13,Striazine moiety, was studied with the aid of different ionization methods and mass-analysed ion kinetic energy spectrometry. Extensive fragmentation of the oligoethylene glycol side-chains is observed, with the usual loss of C2H,0 units. The favoured cleavage of the ethereal bond nearest to the etherocyclic ring gives rise-to both complementary ions.
Journal of Agricultural and Food Chemistry, Nov 1, 1995
... Miriam Amrani-Hemaimi,+ Christoph Cerny,*Bt and Laurent B. Fay ... pyrazine this result was i... more ... Miriam Amrani-Hemaimi,+ Christoph Cerny,*Bt and Laurent B. Fay ... pyrazine this result was in accordance with a proposed mechanism in which acet-aldehyde is added to an intermediate dimethyldihydro-pyrazine (Shibamoto et al., 1979; Milic and Piletic, 1984), the origin of the ...
The heterocyclic aromatic amines (HAAs) 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2... more The heterocyclic aromatic amines (HAAs) 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) and 2-amino alpha carboline (A alpha C) were quantitated in grilled bacon and beef. The levels of PhIP in bacon ranged from &amp;amp;lt; 0.1 to 52 p.p.b., MeIQx was detected at levels ranging from 0.9 to 18 p.p.b. Both 4,8-DiMeIQx and A alpha C were found at &amp;amp;lt; 1 p.p.b. In grilled meat patties, MeIQx and PhIP were detected at levels ranging from 0.8 to 3.2 p.p.b., while 4,8-DiMeIQx and A alpha C were below the limit of detection (approximately 0.5 p.p.b.). HAAs were below the limit of detection in grilled fish. The bacon fat drippings and the pan scrapings obtained from grilled meat and fish also contained significant amounts of HAAs and indicated that either these carcinogens are released with the fat during grilling or that HAAs are formed directly in the released fat and juices. Several of these carcinogens were detected in the pan scrapings at concentrations 10- to 100-fold higher than in cooked meats. PhIP was detected at 144 p.p.b. in combined grilled meat and fish scrapings, followed by A alpha C at 77 p.p.b., MeIQx at 29 p.p.b. and 4,8-DiMeIQx at 4 p.p.b. The co-mutagens harman and norharman were also detected in cooked meats and fish at amounts ranging from 5 to 30 p.p.b. Fat drippings and grill residue scrapings are often used as a base for gravies and sauces. Thus, cooking practices and dietary habits have a strong impact on HAA exposure.
www.molecularsystemsbiology.com Probiotic modulation of symbiotic gut microbial–host metabolic in... more www.molecularsystemsbiology.com Probiotic modulation of symbiotic gut microbial–host metabolic interactions in a humanized microbiome mouse model
The metabolism of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo[4,... more The metabolism of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), two carcinogenic heterocyclic aromatic amines (HCAs) formed in cooked meats and fish, was studied in animal models and in vitro with human tissues to develop strategies for human biomonitoring. Both IQ and MeIQx are rapidly absorbed from the gastrointestinal tract of rodents and transformed into a number of products which are excreted in urine and feces. Detoxification occurs via cytochrome P450 mediated ring hydroxylation at the C-5 position followed by conjugation to sulfuric or beta-glucuronic acid. Other routes of detoxification include N2-glucuronidation and the uncommon pathway of sulfamate formation; N2-acetylation, however, appears to be a minor pathway. Metabolic activation by N-oxidation was demonstrated through formation of the metastable N2-glucuronide conjugate of the mutagenic N-hydroxy metabolites. These conjugates are excreted preferentially in ur...
www.molecularsystemsbiology.com Top-down systems biology integration of conditional prebiotic mod... more www.molecularsystemsbiology.com Top-down systems biology integration of conditional prebiotic modulated transgenomic interactions in a humanized microbiome mouse model
Thiols are important constituents of the flavour of many foods and beverages. They were produced ... more Thiols are important constituents of the flavour of many foods and beverages. They were produced efficiently by enzymatic hydrolysis of thioacetates, which are commercially available or easily accessible, by reaction of thioacetic acid with alkenes. Enzymatic ...
Abstract: The present invention is directed to procedures for the controlled natural bioprocessin... more Abstract: The present invention is directed to procedures for the controlled natural bioprocessing of naturally occurring biological molecules by processing activities present in select organisms, extracts of such organisms or other natural processing agents. The invention also covers the methods for developing these procedures and compositions prepared by the procedures.
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