Masaki Anetai

Psoralen and other linear furanocoumarins as phytoalexins in Glehnia littoralis

Inoculation of Glehnia littoralis root slices with Pseudomonas cichorii induced the production of four linear furanocoumarin phytoalexins, psoralen, xanthotoxin, bergapten and demethylsuberosin, of which the former three have been reported as constituents of the crude drug Glehnia root. A time-course study on the respective P. cichorri-inoculated, UV-irradiated and non-irradiated root slices showed greatly increasing concentrations of the furanocoumarins after stress treatment. Psoralen, xanthotoxin and bergapten in the crude drug were considered, at least in part, to be stress metabolites produced during processing.

Reducing Molecular Flexibility by Cyclization for Elucidation of Absolute Configuration by CD Calculations: Daurichromenic Acid

Circular dichroism (CD) calculations of flexible natural products have been difficult because of the large number of low-energy conformers and ambiguous Boltzmann distributions. In this article, through electronic (ECD) and vibrational (VCD) studies on a natural product, (+)-daurichromenic acid, we demonstrate that derivatization of a flexible molecule can dramatically reduce its flexibility. This work also shows the usefulness of derivatization for diminishing computational expenses required for optimization and CD calculations, and for increasing the reliability of the assignment of absolute configuration. Chirality 28:453-459, 2016.