1,720,971 research outputs found
Convenient synthesis of optically active deuterated primary alcohols via deuteride reduction of acetals derived from homochiral (1R*,2R*)-3,3,3-trifluoro-1-phenylpropane-1,2-diols
No full text(1R)-1-Deuterated alcohols with high enantiomeric excess were prepared via TiCl(4)/Et(3)SiD reduction of acetals arising from the reaction of aldehydes with (1S,2S)-3,3,3-trifluoro-1-phenylpropane-1,2-diol 9. Such a chiral auxiliary was synthesized in an enantiomerically pure form starting from L-mandelic acid. Due to its benzylic nature, it was easily removed from the reaction product of the reductive 1,3-dioxolane ring-cleavage to afford the desired alpha-deuterated alcohol
New Guanosine 5’-Phosphate Derivatives as Flavor Enhancers
No full textUmami (the fifth taste) is an essential element in our appreciation of food and is imparted by monosodium L-glutamate (MSG) and 5’-ribonucleotides such as disodium inosine 5’-monophosphate (IMP) and disodium guanosine 5’-monophosphate (GMP). These compounds are now used extensively as seasonings or condiments to supplement, enhance or round off the flavor of many savory-based processed foods. They are the best flavor enhancers that are in commercial use worldwide (Yamaguchi et al. 1998).
What is perhaps the most interesting property about MSG and 5’-ribonucleotides is their capacity to interact synergistically. This phenomenon of synergism is of the utmost importance, because it provides an opportunity for the food processor to use less MSG in the formulation without affecting flavor quality.
Although a molecular mechanism behind the synergism between MSG and IMP has been recently suggested (Zhang et al. 2008), a number of issues remain to be clarified including the structure/activity relationships (SARs) of 5’-nucleotide-related MSG enhancers. The aim of our current study is to gain further insight into the role played by substituents of the purine nucleus of 5’-ribonucleotides in eliciting a synergism with MSG.
In this regard, we synthesized a number of N2-acyl and N2-alkyl guanosine monophosphates, as shown in Scheme 1, and evaluated them for their capacity to enhance the taste intensity of MSG (Cairoli et al. 2008). Using a panel of tasters and the “Probit” method to make the responses of tasters statistically valid, we found that the synergistic activity of some N2-substituted GMPs was significantly higher than that of GMP and was related to the chain length of the alkyl or acyl substituent as well as to the position of a sulphur atom along the carbon chain
Chemo-enzymatic Synthesis of γ-Glutamyl Derivatives from Garlic with Kokumi and Flavor Enhancing Properties
No full textStudy on umami taste: the MSG taste‐enhancing activity of N2‐alkyl and N2‐alkanoyl‐5′‐guanylic acids having a sulfoxide group inside the N2‐substituent
No full textN2‐alkyl and N2‐alkanoyl derivatives of guanosine 5′‐phosphate bearing a sulfoxide group into the side chain (3b,e; 4b)were synthesized and tested for their synergistic effect with monosodium‐L‐glutamate (MSG), which is the prototypical substance
imparting umami taste to savoury‐based foods. Capacities to enhance the taste intensity of MSG were estimated (as γ values)
through subjective comparisons of MSG/5′‐nucleotide mixtures in water with appropriate solutions of MSG alone, followed by statistical treatment (Probitmethod) of the resulting responses. The synergistic activity of each sulfoxide toward MSG resulted to be lower than that of the corresponding sulfide
Peptidi derivati dall’endostatina con potenziale attività antitumorale:uno studio mediante dinamica molecolare
No full textChemo-enzymatic Synthesis of γ-Glutamyl S-alk(en)yl cysteines from garlic and onion with kokumi activity
No full textThe use of monosodium glutamate (MSG) in synergistic combination with the sodium salts of guanosine monophosphate (GMP) and inosine monophosphate (IMP) as flavor enhancers is well-established and industrially implemented. The japanese term umami (="delicious") refers to the characteristic taste of MSG, actually recognized as a fifth basic taste, and is commonly used even in the western countries. However, other substances supplement and modify, in part, the flavor of foods, enhancing mouthfulness, continuity, roundness and balance. The japanese term kokumi refers to all these flavor sensations. Kokumi is different from umami, in that it is not considered as a basic taste. -Glutamyl derivatives of natural or modified amino acids constitute a broad class of compounds and a lot of them show kokumi properties.
Sulfur-containing substances are often the candidate of kokumi taste. Among them, organosulfur metabolites of various Allium species, in particular -glutamyl derivatives of S-substituted cysteines, have been found to give characteristic kokumi flavor (Vermeulen et al., 2005).
In continuing our work in the field of the chemoreception of taste (Cairoli et. al., 2008), we developed a chemoenzymatic synthesis of -glutamyl-S-alk(en)yl cysteines (2) and their sulfoxides (3), which is based on the use of the enzyme -glutamyl-transpeptidase (GGT) as a catalyst to tranfer the -glutamyl group from glutathione (GSH) to S-substituted cysteines (1). Oxidation of the sulfur atom in 2 can be readily achieved with hydrogen peroxide in water at room temperature.
This synthesis is straightforward, involves readily accessible starting materials and requires no protective groups. It is carried out at room temperature using water as the only reaction solvent
Determination of the absolute configuration of tetralols by Vibrational Circular Dichroism(VCD), Electronic Circular Dichroism (ECD) and Density Functional Theory (DFT) calculations
No full textStudies on Umami Taste. Synthesis of New Guanosine 5'-Phosphate Derivatives and Their Synergistic Effect with Monosodium Glutamate
No full textA number of N-2-alkyl and N-2-acyl derivatives of guanosine 5'-phosphate (GMP) have been synthesized and tested for their synergistic effect with monosodium L-glutamate (MSG), the prototypical substance imparting umami taste to savory-based foods. Capacities to enhance the taste intensity of MSG (gamma values) were estimated through subjective comparisons of MSG/nucleotide mixtures in water with appropriate solutions of MSG alone. Assuming beta = gamma[nucleotide]/gamma[IMP], beta values of the N-2-substituted GMPs were found in the range 1.2-5.7. Such values appear to be related to the chain length of the substituent in the 2-position of the purine nucleus and dependent on the replacement of a CH2 group with an S atom and/or with an alpha-CO group. These findings indicate that the exocyclic NHR group of the guanine moiety is actively implicated in the synergism between GMP derivatives and MSG. Theoretical calculations suggest that an anti conformation is probably assumed by ribonucleotide molecules interacting with umami receptors
Purine nucleoside phosphorylases from B. subtilis and Aeromonas Hydrophyla: catalytic efficiency and substrate specificity
No full textRational Design of Cytotoxic peptides from analysis of Protein-Protein Interactions in Microtubules
No full text- …
