A soy sauce sample was fractionated by gel filtration on a Sephadex G-15 column, then the fractions were subfractionated on the basis of acidity by ion exchange chromatography on a QAE-Sephadex A-25 column. The acidic subfractions with various acidities were further fractionated, using a preparative amino acid analyzer and by paper chromatography to separate the acidic peptide components.Four dipeptides and sugar derivatives of ten dipeptides and two tripeptides were isolated and characterized as the major acidic peptides in soy sauce. However, it was difficult to anticipate any direct contribution of these pep tides to the flavor construction in soy sauce on the basis of their contents and taste intensities.In the preceding work,I1 a soy sauce sample was fractionated by gel filtration on a Sephadex G-15 column, then the fractions were subfractionated on the basis of acidity by ion exchange chromatography on a QAE-Sephadex A-25 column. After the preliminary fractionation, the components in the neutral subfractions were converted to copper salts and chromatographed on a DEAE-Sephadex column to separate peptide substances from a large amount of free amino acids. The peptide fractions were further fractionated on a preparative amino acid analyzer and by paper chromatography to separate the peptide substances. Thus, three glycodipeptides and eight dipeptides were isolated and characterized as the major neutral peptide components in soy sauce. However, the practical contributions of these components to the flavor construction in soy sauce were evaluated as negligibly small.The present work deals with the peptide substances in the acidic subfractions obtained by the preliminary fractionation. Major acidic peptide components were isolated from the acidic subfractions and characterized, and their t
The rhizomes of Polygonatum odoratum represent a traditional Chinese medicine and functional food. A phytochemical investigation resulted in the isolation of eight steroidal glycosides (1-8), including two new compounds, polygonatumosides F (1) and G (2). The structures were elucidated by spectroscopic data and chemical reactions. Compound 7 showed antiproliferation activity against human hepatocellular carcinoma cell line HepG2 (IC of 3.2 μM). The chemical profile and contents of steroidal glycosides of P. odoratum rhizomes collected at different dates and geographical locations were also investigated, indicating that the rational harvest of P. odoratum in spring and autumn is preferable to obtain higher levels of steroidal glycosides. Compounds 1 and 7 showed the highest contents in all P. odoratum samples and have potential to serve as chemotaxonomic and chemical markers for quality control of this important plant material. 14-Hydroxylation may be a key step for the biosynthesis of compounds 1-7.
A soy sauce sample was fractionated by gel filtration on a Sephadex G-15 column, then the fractions were subfractionated on the basis of acidity by ion exchange chromatography on a QAE-Sephadex A-25 column. After preliminary fractionation, the components in the neutral subfractions were transformed to copper salts, and the salts were chromatographed on a DEAE-Sephadex A-25 column with a borate buffer and aqueous acetic acid to separate neutral peptide substances from a large amount of free amino acids. The peptide fractions were further fractionated on a preparative amino acid analyzer and by paper chromatography to separate the peptide substances. Three glycodipeptides and eight dipeptides were isolated and characterized as the major neutral peptide components in soy sauce. However, it was difficult to anticipate any direct contribution of these peptides to the flavor construction in soy sauce on the basis of their taste intensities and contents.
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