Constituents of a fern, Davallia mariesii Moore. I. Isolation and structures of davallialactone and a new flavanone glucuronide.

A new gamma-lactone derivative named davallialactone (4) and the 7-O-beta-D-glucuronide of (+/-)-eriodictyol (5a) have been isolated from Davallia mariessi Moore along with caffeic acid (1), 4-beta-D-glucopyranosylcaffeic acid (2) and 4-O-beta-D-glucopyranosyl-p-coumaric acid (3). The structures of the new compounds were determined by chemical and spectroscopic methods including two-dimensional nuclear magnetic resonance (2D NMR) techniques, especially 1H-detected heteronuclear multiple-bond multiple-quantum coherence and long-range C-H J-resolved 2D NMR techniques.