Structure and Formation of the Fluorescent Compound of <i>Lignum nephriticum</i>

Abstract

The intense blue fluorescence of the infusion of Lignum nephriticum (Eysenhardtia polystachya), first observed in the sixteenth century, is due to a novel four-ring tetrahydromethanobenzofuro[2,3-d]oxacine which is not present in the plant but is the end product of an unusual, very efficient iterative spontaneous oxidation of at least one of the tree's flavonoids.