Chemical constituents of the lichen Usnea lapponica Vain., Parmeliaceae

Abstract

Introduction: The lichen Usnea lapponica Vain. belonging to the Usnea genus (family Parmeliaceae) grow hanging from tree branches in the damp forest at Bidoup Nui Ba National Park, Dam Rong district, Lam Dong province. In addition, this lichen has not yet been chemically and biologically studied. The primary goal of the present work was to study the chemical constituents of the lichen Usnea lapponica Vain. Methods: A dried powder of thalli Usnea lapponica Vain. was extracted by maceration with MeOH at ambient temperature to prepare the crude MeOH extract. This crude extract was subjected to silica gel column chromatography with gradient polar solvent including n-hexane, CHCl3, EtOAc, and MeOH to separate into different polar fractions. The chemical structures of the isolated compounds were elucidated through the interpretation of their 1D and 2D NMR and HRESIMS data. Results: In this paper, we reported the isolation of six known compounds, including two depsides lecanorin (1) and isolecanoric acid (2), two depsidones norstictic acid (3) and methylstictic acid (4), an ergosterol, 22E,24R-5α,6α-epoxyergosta-8,22-diene-3β,7α-diol (5), and lupeol (6). Conclusion: This is the first time that these compounds have been reported from Usnea lapponica Vain.