Soichi Tanabe

4-Hydroxy-3-nitrophenylacetic and Sinapic Acids as Antibacterial Compounds from Mustard Seeds

A methanol extract from yellow mustard seeds had antibacterial activity against Escherichia coli, Salmonella enteritidis, and Staphylococcus aureus. Two compounds with such activity were isolated from the extract. By instrumental analysis, the compounds were identified as 4-hydroxy-3-nitrophenylacetic and sinapic acids. Examination of the structure-activity relationship showed that the hydroxyl and nitro groups of the first compound were involved in the activity against all three species. The two methoxyl groups and the hydroxyl group in sinapic acid were effective against E. coli and all of the substituents of the benzene ring were effective against S. enteritidis. The presence of the propenoic group of the second compound was effective against S. aureus.

NMR analysis of a model pentapeptide, acetyl–Gln–Gln–Gln–Pro–Pro, as an epitope of wheat allergen.

NMR analysis of a model pentapeptide, acetyl (Ac)–Gln–Gln–Gln–Pro–Pro, as an epitope of a wheat allergen was performed. The problem of severe signal overlapping in the 1H NMR spectrum was overcome by elaborate two‐dimensional methods using 13C information. HMQC‐TOCSY allowed the assignments of the 1H and 13C NMR signals except the γ‐glutamylamide parts. E‐HSQC‐ROESY, which was constructed by modification of the E‐HSQC, could serve for discriminating ROEs of protons whose δH values were close to each other. Although the sensitivity of HSQC‐ROESY itself was low, selecting only CH carbons by adjusting the proper delay and flip angle of a pulse allowed a narrow F1 spectral width and hence the collection of numerous transients. As a result, the configurations of the amide bonds of the backbone were determined as all‐trans. ©1998 John Wiley & Sons, Ltd.

Occurrence of Bound Salt in Freeze-concentrated Soy Sauce

Part of the salt in soy sauce formed no eutectic H2O•2NaCl crystals at sub-zero temperatures and remained in a freeze-concentrated product. NMR line width of (23)Na was broader in the concentrated soy sauce than in the material. A broad line width of (23)Na was also observed in an aqueous solution of NaCl and a non-diffusible soy sauce fraction. The data indicate that part of the salt in soy sauce interacted with its non-diffusible fraction and that such bound salt formed no eutectic crystals.