The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Takayuki Shibamoto - One of the best experts on this subject based on the ideXlab platform.
-
Antioxidant activities of extracts from teas prepared from medicinal plants, Morus alba L., Camellia sinensis L., and Cudrania tricuspidata , and their volatile components.
Journal of agricultural and food chemistry, 2012Co-Authors: Sanghae Nam, Hae Won Jang, Takayuki ShibamotoAbstract:The antioxidant activity of essences of teas prepared from mulberry ( Morus alba L.), Camellia sinensis L., and Cudrania tricuspidata (Carr.) Burea plant was examined using two antioxidant assays. Selected volatile chemicals identified in these plants were also tested for antioxidant activity. All extracts exhibited antioxidant activity with a clear dose response in the aldehyde/carboxylic acid and the malonaldehyde/gas chromatography (MA/GC) assays. Antioxidant activity of extracts at the level of 500 μg/mL ranged from 77.02 ± 0.51% (stems of Burea plant) to 52.57 ± 0.92% (fermented tea of Camellia and stems of Mulberry tea) in the aldehydes/carboxylic acid assay. Their antioxidant activity at the level of 160 μg/mL ranged from 76.17 ± 0.27% (roots of Burea plant) to 59.32 ± 0.27% (stems of Mulberry tea) in the MA/GC assay. Among the positively identified compounds (11 terpenes and terpenoids, 15 alkyl compounds, 26 nitrogen containing heterocyclic compounds, 9 oxygen containing heterocyclic compounds, 18 aromatic compounds, 7 lactones, 6 acids, and 4 miscellaneous compounds), eugenol, 2,5-dihydroxyl acetophenone, and isoeugenol exhibited antioxidant activity comparable to that of BHT in both assays. Vanillin and 2-Acetylpyrrole showed potent antioxidant activity in the aldehydes/carboxylic acid assay but only moderate activity in the MA/GC assay. These results suggest that consumption of antioxidant-rich beverages prepared from these plants may be beneficial to human health.
-
role of roasting conditions in the profile of volatile flavor chemicals formed from coffee beans
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Joonkwan Moon, Takayuki ShibamotoAbstract:The volatile chemicals in dichloromethane extracts from green coffee beans, roasted at 230 degrees C for 12 min (light), at 240 degrees C for 14 min (medium), at 250 degrees C for 17 min (city), or at 250 degrees C for 21 min (French), were analyzed by gas chromatography and gas chromatography-mass spectrometry. Among the 52 volatile compounds identified, the major compounds were 5-hydroxymethylfurfural, furfuryl alcohol, and 6-methyl-3,5-dihydroxy-4H-pyran-4-one in light-roasted beans; furfuryl alcohol, 5-hydroxymethylfurfural, and gamma-butyrolactone in medium-roasted beans; furfuryl alcohol, gamma-butyrolactone, and 2-Acetylpyrrole in city-raosted beans; and gamma-butyrolactone, furfuryl alcohol, and catechol in French-roasted beans. Furfural derivatives and furanones were yielded in relatively high concentrations under mild roasting conditions and then reduced at higher roasting intensities. More pyridines and pyrroles were formed by high roasting intensities than by mild roasting intensities. Chlorogenic acid degradation products, phenols, and a lactone were produced more by high roasting intensities than by low roasting intensities. The results of the present study suggest that controlling the roasting conditions according to the formation of particular chemicals can prepare a roasted coffee with preferable flavor.
-
Antioxidative Activity of Heterocyclic Compounds Found in Coffee Volatiles Produced by Maillard Reaction
Journal of agricultural and food chemistry, 2002Co-Authors: Kenichi Yanagimoto, Hirotomo Ochi, Kwang-geun Lee, Takayuki ShibamotoAbstract:Typical heterocyclic compounds substituted with various functional groups found in Maillard reaction products were examined for antioxidant activity. Pyrroles exhibited the greatest antioxidant activity among all heterocyclic compounds tested. All pyrroles inhibited hexanal oxidation by almost 100% at a concentration of 50 microg/mL over 40 days. Addition of formyl and acetyl groups to a pyrrole ring enhanced antioxidative activity remarkably. Pyrrole-2-carboxaldehyde, 2-Acetylpyrrole, 1-methyl-2-pyrrolecarboxaldehyde, and 2-acetyl-1-methylpyrrole inhibited hexanal oxidation by >80% at 10 microg/mL. Unsubstituted furan exhibited the greatest antioxidant activity among furans tested. Addition of all functional groups used in this study to furan decreased antioxidative activity. The antioxidant activity of thiophene increased with the addition of methyl and ethyl groups, but the addition of formyl or acetyl groups to thiophene decreased antioxidant activity. Thiazoles and pyrazines were ineffective antioxidants at all concentrations tested. Reaction of all heterocyclic compounds with hydrogen peroxide resulted in the formation of various oxidized products.
-
Antioxidative activities of heterocyclic compounds formed in brewed coffee
Journal of agricultural and food chemistry, 2000Co-Authors: Marie Delores Fuster, Alyson E. Mitchell, Hirotomo Ochi, Takayuki ShibamotoAbstract:Typical volatile heterocyclic compounds found in brewed coffee extractspyrroles, furans, thiophenes, and thiazoleswere examined for antioxidative activity, which was determined by measuring the oxidative conversion of hexanal to hexanoic acid using gas chromatography. 2-Acetylpyrrole, 1-methylpyrrole, and pyrrole inhibited hexanal oxidation by 98, 87, and 78%, respectively, at a concentration of 500 μg/mL over a period of 30 days. 2-Methylfuran, which inhibited hexanal oxidation by 90% at all concentrations tested (500, 200, and 100 μg/mL) for a 30-day period, exhibited the greatest activity among furans tested. Similarly, 2-methylthiophene, which inhibited hexanal oxidation by almost 100% at a concentration of 500 μg/mL over 30 days, exhibited the greatest activity among the thiophenes tested. In general, thiazoles were ineffective antioxidants at all concentrations tested. However, 4,5-dimethylthiazole was able to inhibit hexanal oxidation by 50% at the highest level tested (500 μg/mL). 2-Acetylpyrrole,...
Teresa Pérez - One of the best experts on this subject based on the ideXlab platform.
-
Group 12 Metal Complexes of 2-Formylpyrrole-(4PL1) and 2-Acetylpyrrole-N(4)-phenylthiosemicarbazone (4Pl2), as Examples form Different Donor Modes. Crystal and Molecular Structures of [Hg(4PL1- H)Br]2 and [Zn(4PL2)2Br2] · 2 EtOH
Zeitschrift für Naturforschung B, 2001Co-Authors: Rosa Carballo, Alfonso Castiñeiras, Teresa PérezAbstract:Abstract The reactions of 4N-phenyl-2-[ 1 -(pyrrol-2-yl)methylidene]-hydrazine carbothioamide (4PL1) and 4N-phenyl-2-[l-(pyrrol-2-yl)ethylidene]-hydrazine carbothioamide (4PL2) with Group 12 metal halides afford complexes of types [M(L)2X2] [M = Zn, L = 4PL1 or 4PL2, X = Cl, Br or I; M = Cd, L = 4PL1, and X = Cl, or L = 4PL2 and X = Cl, Br or I] and [M(L)X2] [M = Cd, L = 4PL1, X = Br or I; M = Hg, L = 4PL1 or 4PL2, X = Cl, Br or I]. The new compounds were characterized by elemental analysis, FAB mass spectrometry, IR spectroscopy, and, in the case of sufficiently soluble compounds, 1H, 13C and, when appropriate, 113Cd or 199Hg NMR spectrometry. The structures of [Hg(4PL1-H)Br] and [Zn(4PL2)2Br2] · 2 EtOH were also studied by single-crystal X-ray diffractometry. In [Hg(4PL1-H)Br] crystallized from the mother liquor of its synthesis, 4PL1 behaves as a monodeprotonated S,N-bidentate ligand. Otherwise, with Hg(II), Zn(II) and Cd(II), 4PL1 and 4PL2 both behave as neutral S-monodentate ligands.
-
Synthesis and structural characterization of complexes of Zn(II), Cd(II) and Hg(II) halides with 2-formylpyrrole thiosemicarbazone and 2-Acetylpyrrole thiosemicarbazone
Polyhedron, 2001Co-Authors: Alfonso Castiñeiras, Rosa Carballo, Teresa PérezAbstract:Abstract Reaction of 2-[1-(pyrrol-2-yl)methylidene]hidrazine carbothioamide (L1) and 2-[1-(pyrrol-2-yl)ethylidene]hidrazine carbothioamide (L2) with zinc(II) cadmium(II) and mercury(II) halides afforded complexes with formulae [M(L1)X2] [M, X=Zn, Cl (1); Cd, Cl (4); Hg, Cl (7); Hg, Br (8); Hg, I (9)], [M(L1)2X2] [M, X=Zn, Br (2); Zn, I (3); Cd, Br (5); Cd, I (6)], [M(L2)X2] [M, X=Cd, Cl (13); Hg, Cl (16); Hg, Br (17); Hg, I (18)] and [M(L2)2X2] [M, X=Zn, Cl (10); Zn, Br (11); Zn, I (12); Cd, Br (14); Cd, I (15)]. Crystals of 5, 18 and 15·CH3CN were studied by X-ray diffractometry, and all the new compounds were characterized by elemental analysis, mass spectrometry, IR and 1H and 13C NMR spectroscopy and, when pertinent and allowed by the solubility of the compounds, 113Cd or 199Hg NMR spectroscopy. In these complexes, the metal atoms are tetra-coordinate and the ligands are neutral and S-monodentate.
Holger Zorn - One of the best experts on this subject based on the ideXlab platform.
-
Identification of potent odorants in a novel nonalcoholic beverage produced by fermentation of wort with shiitake (Lentinula edodes).
Journal of agricultural and food chemistry, 2014Co-Authors: Yanyan Zhang, Marco A. Fraatz, Felix Horlamus, Hendrich Quitmann, Holger ZornAbstract:Novel refreshments with pleasant flavors were developed by fermentation of wort with basidiomycetes. Among 31 screened fungi, shiitake (Lentinula edodes) produced the most pleasant flavor. It was perceived as fruity, slightly sour, and plum-like. Flavor compounds were isolated by liquid–liquid extraction (LLE) and by headspace solid phase microextraction (HS-SPME). The key odor-active compounds were analyzed by a gas chromatography system equipped with a tandem mass spectrometry detector and an olfactory detection port (GC-MS/MS-O) and aroma extract dilution analysis (AEDA). For HS-SPME, a revised method of increasing the GC inlet split ratio was used. Most of the key odor-active compounds (e.g., 2-Acetylpyrrole, β-damascenone, (E)-2-nonenal, and 2-phenylethanol) were detected with both extraction techniques. However, distinct differences between these two methods were observed.
-
Identification of Potent Odorants in a Novel Nonalcoholic Beverage Produced by Fermentation of Wort with Shiitake (Lentinula edodes)
2014Co-Authors: Yanyan Zhang, Marco A. Fraatz, Felix Horlamus, Hendrich Quitmann, Holger ZornAbstract:Novel refreshments with pleasant flavors were developed by fermentation of wort with basidiomycetes. Among 31 screened fungi, shiitake (Lentinula edodes) produced the most pleasant flavor. It was perceived as fruity, slightly sour, and plum-like. Flavor compounds were isolated by liquid–liquid extraction (LLE) and by headspace solid phase microextraction (HS-SPME). The key odor-active compounds were analyzed by a gas chromatography system equipped with a tandem mass spectrometry detector and an olfactory detection port (GC-MS/MS-O) and aroma extract dilution analysis (AEDA). For HS-SPME, a revised method of increasing the GC inlet split ratio was used. Most of the key odor-active compounds (e.g., 2-Acetylpyrrole, β-damascenone, (E)-2-nonenal, and 2-phenylethanol) were detected with both extraction techniques. However, distinct differences between these two methods were observed
Masood Parvez - One of the best experts on this subject based on the ideXlab platform.
-
Steric influences in the formation of complexes of Schiff base derivatives of 2-Acetylpyrrole with Cu(II)
Inorganica Chimica Acta, 1992Co-Authors: W. J. Birdsall, Bruce A. Weber, Masood ParvezAbstract:Abstract A series of Cu(II) complexes of Schiff base derivatives of 2-Acetylpyrrole with ammonia, n-butylamine and benzylamine have been synthesized, as well as the bis chelate complex of 2-Acetylpyrrole with Cu(II). The stoichiometry of each complex is shown to depend on the amine used. Small amines (NH3 and CH3NH2) produce trans bis ketimine Cu(II) chelates, while ethylamine and the larger primary amines effect mixed ligand products containing one 2-Acetylpyrrole chelate and one Schiff base chelate per metal center with pyrrole groups cis to one another. Cu(II) is shown to mediate Schiff base formation while also maintaining a square planar stereochemistry. Crystals of the trans bis Schiff base derivative of 2-Acetylpyrrole with ammonia, Cu(C6H7N2)2 (1a), are monoclinic with space group P21/n with a = 11.698(2), b = 5.406(1), c = 10.687(3) A, β = 115.92(1)°, V = 607.8 A3 and Z = 2. Crystals of the trans bis Schiff base adduct of 2-Acetylpyrrole with benzylamine, Cu(C13H13N2)2 (3b), are monoclinic with space group P21/c with a = 10.647(3), b = 12.737(4), c = 16.371(3) A, β = 90.31(2)°, V = 2220.1 A3 and Z = 4. Cu(C6H6NO)2 (4a), the bis Cu(II) chelate of 2-Acetylpyrrole, is monoclinic with space group P21/a with a = 8.143(2), b = 14.452(3), c = 5.189(1) A, β = 106.82(2)°, V = 584.5 A3 and Z = 2.
Devin G. Peterson - One of the best experts on this subject based on the ideXlab platform.
-
Identification of Hydroxycinnamic Acid-Maillard Reaction Products in Low-Moisture Baking Model Systems
Journal of agricultural and food chemistry, 2009Co-Authors: Deshou Jiang, Christopher R. Chiaro, Pranav Maddali, K. Sandeep Prabhu, Devin G. PetersonAbstract:The chemistry and fate of hydroxycinnamic acids (ferulic, p-coumeric, caffeic, sinapic, and cinnamic acid) in a glucose/glycine simulated baking model (10% moisture at 200 degrees C for 15 min) were investigated. Liquid chromatography-mass spectrometry analysis of glucose/glycine and glucose/glycine/hydroxycinnamic acid model systems confirmed the phenolics reacted with Maillard intermediates; two main reaction product adducts were reported. On the basis of isotopomeric analysis, LC-MS, and NMR spectroscopy, structures of two ferulic acid-Maillard reaction products were identified as 6-(4-hydroxy-3-methoxyphenyl)-5-(hydroxymethyl)-8-oxabicyclo[3.2.1]oct-3-en-2-one (adduct I) and 2-(6-(furan-2-yl)-7-(4-hydroxy-3-methoxyphenyl)-1-methyl-3-oxo-2,5-diazabicyclo[2.2.2]oct-5-en-2-yl)acetic acid (adduct II). In addition, a pyrazinone-type Maillard product, 2-(5-(furan-2-yl)-6-methyl-2-oxopyrazin-1(2H)-yl) acetic acid (IIa), was identified as an intermediate for reaction product adduct II, whereas 3-deoxy-2-hexosulose was identified as an intermediate of adduct I. Both adducts I and II were suggested to be generated by pericyclic reaction mechanisms. Quantitative gas chromatography (GC) analysis and liquid chromatography (LC) also indicated that the addition of ferulic acid to a glucose/glycine model significantly reduced the generation of select Maillard-type aroma compounds, such as furfurals, methylpyrazines, 2-acetylfuran, 2-acetylpyridine, 2-Acetylpyrrole, and cyclotene as well as inhibited color development in these Maillard models. In addition, adducts I and II suppressed the bacterial lipopolysaccharide (LPS)-mediated expression of two prototypical pro-inflammatory genes, inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, in an in vitro murine macrophage model; ferulic acid reported negligible activity.
-
Influence of epicatechin reactions on the mechanisms of Maillard product formation in low moisture model systems.
Journal of agricultural and food chemistry, 2007Co-Authors: Vandana M. Totlani, Devin G. PetersonAbstract:The influence of the polyphenolic compound epicatechin on Maillard chemistry was investigated under simulated roast conditions (10% moisture at 220 degrees C for 10 min). Quantitative gas chromatography (GC) analysis indicated that the addition of epicatechin to glucose or fructose/glycine model systems significantly reduced the generation of hydroxyacetone, 2-methylpyrazine, 2,3,5-trimethylpyrazine, furfural, 2-acetylfuran, 5-methylfurfural, 2(5H)-furanone, 2-Acetylpyrrole, and furfuryl alcohol. These analytes were reported to be primarily generated from intact C2, C3, C4, C5, and C6 sugar fragments based on gas chromatography/mass spectrometry quantitative isotopomeric analysis of a 1:1 13C6:12C6 hexose sugar/glycine model system. Liquid chromatography/mass spectrometry qualitative isotopomeric analysis of a 1:1 13C6:12C6 hexose sugar/glycine/epicatechin model systems confirmed epicatechin reacted with Maillard reactants in the model systems; two main reaction products were reported, epicatechin-C5 and -C6 sugar fragment adducts. In addition, LC/MS analysis of a model system consisting of only 3-deoxy-2-hexosulose and epicatechin identified 3-deoxy-2-hexosulose as a precursor of the epicatechin-C5 and -C6 sugar fragment adducts reaction products. These results imply that epicatechin quenched 3-deoxy-2-hexosulose (a key source C6 to C1 sugar fragments) and consequently inhibited Maillard product formation.