Biomedical subjects
Publications and source records attributed to Hiroyuki Tazaki.
The biosynthesis of fukinolic acid, which had been isolated from the Japanese fuki vegetable, Petasites japonicus, was investigated by feeding selected (13)C-labeled compounds to axenic cultures of P. japonicus. [1,2-(13)C(2)] sodium acetate and [1-(13)C] L-tyrosine were incorporated into the fukiic acid sub group, while [3-(13)C] L-phenylalanine was incorporated into the caffeic acid moiety.
Higher alcohols with a carbon length ranging from 16 to 30 found in the lipophilic fraction from potato pulp were shown to be present as ferulate and in a free form, but not as wax. Thin-layer chromatography of the neutral lipids in potato pulp indicated a few spots with scavenging activity toward the 1,1-diphenyl-2-picrylhydrazyl (DPPH) stable radical, the major active component being characterized as alkyl ferulate which showed almost the same level of activity as gamma-oryzanol.
Thermally decomposed products of (+/-)-linalyl beta-D-glucoside were analyzed by GC and GC/MS. 2,6-dimethyl-2,6-octadienes produced by mild pyrolysis of linalyl beta-D-glucopyranoside under a vacuum were detected and characterized by MS and NMR spectroscopy. This suggests that 2,6-dimethyl-2,6-octadienes are produced during thermal decomposition of the glucoside via proton transfer from the anomeric position to C-6 in the aglycon moiety. A stable isotope labeling experiment directly indicated the new reaction mechanism.
The novel Diels-Alder adduct, dicaffeoyl quinone as its hydrate, was formed from the oxidation of 3,4-dihydroxycinnamic acid (caffeic acid) with NaIO4. The structure of this hydrate was determined by spectroscopic methods.
The new caffeic acid derivative, subulatin (1), was isolated from in vitro cultured liverworts, Jungermannia subulata, Lophocolea heterophylla, and Scapania parvitexta. The structure of 1 involved two caffeic acids, D-glucose, and 2-carboxy-6-(1,2-dihydroxy-ethyl)-4,5-dihydroxy-5,6-dihydro-4H-pyran. The connectivity of those and the absolute stereochemistry of 1 were elucidated on the basis of spectroscopic evidence. The antioxidative activity of 1 was comparable to that of alpha-tocopherol. (2'R)-Phaselic acid (2a) and (-)-9,2''-epiphylloyl-L-malic acid (4) were also isolated from J. subulata and L. heterophylla, respectively. A chiral HPLC analysis of the p-bromobenzoyl-malic acids derived from 2a showed that 2a from J. subulata was unusual (+)-trans-caffeoyl-D-malic acid.