Isolation and Structure Determination of cis-OPDA-α-Monoglyceride from Arabidopsis thaliana.

cis-12-oxo-Phytodieneoic acid-α-monoglyceride (1) was isolated from Arabidopsis thaliana. The chemical structure of 1 was elucidated based on exhaustive 1D and 2D NMR spectroscopic measurements and supported by FDMS and HRFDMS data. The absolute configuration of the cis-OPDA moiety in 1 was determined by comparison of 1H NMR spectra and ECD measurements. With respect to the absolute configuration of the ß-position of the glycerol backbone, the 2:3 ratio of (S) to (R) was determined by making ester-bonded derivatives with (R)-(+)-α-methoxy-α-trifluoromethylphenylacetyl chloride and comparing 1H NMR spectra. Wounding stress did not increase endogenous levels of 1, and it was revealed 1 had an inhibitory effect of A. thaliana post germination growth. Notably, the endogenous amount of 1 was higher than the amounts of (+)-7-iso-jasmonic acid and (+)-cis-OPDA in intact plants. 1 also showed antimicrobial activity against Gram-positive bacteria, but jasmonic acid did not. It was also found that α-linolenic acid-α-monoglyceride was converted into 1 in the A. thaliana plant, which implied α-linolenic acid-α-monoglyceride was a biosynthetic intermediate of 1.

Isolation, structural elucidation, and biological activity of a novel isocoumarin from the dark septate endophytic fungus Phialocephala fortinii.

A novel isocoumarin was isolated from the mycelia of the dark septate endophytic fungus Phialocephala fortinii. The chemical structure was determined to be 8-hydroxy-6-methoxy-3,7-dimethyl-1H-2-benzopyran-1-one based on mass spectrometry, 1H-nuclear magnetic resonance (NMR), and 13C-NMR spectroscopic analyses, including 2D-NMR experiments. The isolated compound inhibited root growth of Arabidopsis thaliana, suggesting its potential as a plant growth regulator.

Isolation and Identification of the Antibacterial Compounds Produced by Maillard Reaction of Xylose with Phenylalanine or Proline.

Maillard reaction products (MRPs) of xylose with phenylalanine and xylose with proline exhibit high antibacterial activity. However, the active antibacterial compounds in MRPs have not yet been identified or isolated. This study aimed to isolate the active compounds in the two antibacterial MRPs. The organic layer of the MRP solution was separated and purified using silica gel chromatography and high-performance liquid chromatography. The chemical structures of the isolated compounds were determined by mass spectrometry and nuclear magnetic resonance spectroscopy. The compounds inhibited the growth of Bacillus cereus and Salmonella Typhimurium at 25 °C for 7 days at a concentration of 0.25 mM. Furthermore, the isolated compounds inhibited the growth of naturally occurring microflora of lettuce and chicken thighs at 25 °C for 2 days at a concentration of 0.5-1.0 mM. The antibacterial compounds found in MRPs demonstrated a wide range of effectiveness and indicated their potential as alternative preservatives.