Occurrence of Z-2-oxo-4-methyl-3-pentene-1,5-dioic acid and its regioisomer 4-methylene-2-oxo-glutaric acid in tulip tissues

Abstract

Although Z-2-oxo-4-methyl-3-pentene-1,5-dioic acid (Z-OMPD) has been identified as a major dicarboxylic acid in tulip tissues, its biosynthetic pathway has not been elucidated. Herein, Z-OMPD was isolated from tulip leaves and chemically synthesized. Comparisons of these samples revealed that Z-OMPD exists as a tautomeric mixture at physiological pH. As a regioisomer of Z-OMPD, we enzymatically and chemically prepared 4-methylene-2-oxo-glutaric acid (4-MEOG) for the first time. Using these compounds as standards, the occurrence of Z-OMPD and 4-MEOG in various tissues of the tulip cultivar “Murasakizuisho” was evaluated directly and by 2,4-dinitrophenylhydrazone derivatization. Z-OMPD was found to be abundant in the aerial tissues, whereas 4-MEOG was almost absent from all tissues. Stability analyses of Z-OMPD and 4-MEOG revealed that no double bond isomerization occurred at physiological pH, suggesting that enzyme systems are responsible for Z-OMPD biosynthesis in tulip tissues.

Simultaneous magnetic resonance imaging of pH, perfusion and renal filtration using hyperpolarized 13C-labelled Z-OMPD

“…Here, out of this molecule class, previously introduced [1,5- 13 C 2 ]zymonic acid 41 exhibits a pK a in the physiological range and good hyperpolarization properties, but requires co-polarization and degrades. We identified Z-OMPD as the pyruvic acid dimer with the most favourable pH-sensing properties having the lowest energy level of OMPD isomers and high biocompatibility 43 , 47 , 49 . The C 1 - and C 5 -positions were considered to exhibit the most promising pH sensitivity and relaxation properties.…”