Galbinic acid is a depsidone lichen metabolite that has been found in
U. undulata.
1,2 It is active against the Gram-positive bacteria
B. cereus,
B. subtilis, and
S. aureus, but not
S. epidermidis (MICs = 62.5, 62.5, 250, and >250 μg/ml, respectively), as well as the Gram-negative bacterium
E. coli, but not
S. sonnei (MICs = 125 and >250 μg/ml, respectively).
3
1. Salgado, F., Albornoz, L., Cortéz, C., et al. Secondary metabolite profiling of species of the genus Usnea by UHPLC-ESI-OT-MS-MS Molecules 23(1),E54(2017).
2. Elix, J.A., and Engkaninan, U. The structure of galbinic acid. A depsidone from the lichen Usnea undulata Aust. J. Chem. 28(8),1793-1797(1975).
3. Sultana, N., and Afolayan, A.J. A new depsidone and antibacterial activities of compounds from Usnea undulata Stirton J. Asian Nat. Prod. Res. 13(12),1158-1164(2011).
