Antioxidant phenolics from Lobaria pulmonaria (L.) Hoffm. and Usnea longissima Ach. lichen species

In this study, 1 steroidal and 8 phenolic compounds from Lobaria pulmonaria (L.) Hoffm. and Usnea longissima Ach. were isolated and their chemical structures were characterized by H-1-NMR, C-13-NMR, DEPT, H-1-H-1 COSY, HMQC, HMBC, IR, UV, and MS spectroscopic methods as stictic acid, isidiophorin, rhizonaldehyde, rhizonyl alcohol, pulmonarianin, vesuvianic acid, ergosterol peroxide, usnic acid, and diffractaic acid. Among these compounds, pulmonarianin, isolated from L. pulmonaria, was characterized for the first time as a natural compound. In addition to isolation and characterization, the lipid peroxidation inhibition and DPPH radical scavenging activities of the isolated compounds were investigated. Among these compounds, isidiophorin, rhizonaldehyde, rhizonyl alcohol, and pulmonarianin showed better lipid peroxidation inhibition in comparison to the other tested phenolics. However, usnic and diffractaic acids, which are phenolic compounds, did not have antioxidant potential.