ABSTRACT
A number of N2-alkyl and N2-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 N2-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 CH 2 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.
Subject(s)
Guanine Nucleotides/administration & dosage , Sodium Glutamate/administration & dosage , Taste , Acylation , Alkylation , Drug Synergism , Guanine Nucleotides/chemistry , Models, Molecular , Nucleic Acid Conformation , Purine Nucleotides/chemistryABSTRACT
Triethanolamine (TEA) is converted into acetate and ammonia by a strictly anaerobic, gram-positive Acetobacterium strain LuTria3. Fermentation experiments with resting cell suspensions and specifically deuterated substrates indicate that in the acetate molecule the carboxylate and the methyl groups correspond to the alcoholic function and to its adjacent methylene group, respectively, of the 2-hydroxyethyl unit of TEA. A 1,2 shift of a hydrogen (deuterium) atom from -CH2-O- to =N-CH2- without exchange with the medium was observed. This fact gives evidence that a radical mechanism occurs involving the enzyme and/or coenzyme molecule as a hydrogen carrier. Such a biodegradation appears analogous to the conversion of 2-phenoxyethanol into acetate mediated by another strain of the anaerobic homoacetogenic bacterium Acetobacterium.
Subject(s)
Acetobacterium/metabolism , Biodegradation, Environmental , Ethanolamines/chemistry , Acetaldehyde/chemistry , Acetates/chemistry , Acetobacterium/physiology , Ammonia/chemistry , Biochemical Phenomena , Biochemistry , Deuterium/chemistry , Ethanol/chemistry , Ethylene Glycols/chemistry , Free Radicals , Hydrogen/chemistry , Magnetic Resonance Spectroscopy , Models, ChemicalABSTRACT
Two triglycerides, both bearing polyunsaturated fatty acid residues, were isolated from the hexane extract of Urena lobata. One of them is characterized by the presence of three different polyunsaturated fatty acids. Their structures were studied with spectral methods.
