Antioxidant and antimicrobial activity of lichen Pseudevernia furfuracea (L.) Zopf

Abstract

Lichen Pseudevernia furfuracea (L.) Zopf. (Parmeliaceae) grows across Europe and northern Africa. Antioxidant and antimicrobial activity, as well as phenolic content of chloroformic (PFC), ethanolic (PFE) and water (PFW) extracts of P. furfuracea collected on Velebit mountain were investigated. Antioxidant activity of extracts was evaluated in three manners: β-carotene-linoleic acid model system, iron (III) to iron (II) reducing activity and DPPH radical-scavenging activity. PFC and PFE extracts demonstrated significant antioxidant activity. As it can be expected from the higher phenolic content, ethanolic extract exhibited higher antioxidant activity than the chloroformic extract in each of our three assays, especially in β-carotene-linoleic acid assay. Antimicrobial activity of PFE and PFW extracts was determinated using cylinder diffusion method, and macro-broth dilution method against standard and clinical isolates of 19 bacterial, 7 yeast and 4 dermatophyte species. Gram-positive bacterial species were highly susceptible to the PFE with inhibition zones (ZI) from 19 to 33mm, and MIC values between 0.15 and 3.1mg/mL (MMC under 4.8mg/mL), with the Bacillus spp. most resistant (MIC 9.95–114.6mg/mL). Dermatophytes showed ZI 13–17mm and MICs between 1.19 and 2.39mg/mL (MMC 2.39–4.78mg/mL). Susceptibility of Gram-negative bacterial species, as well as antifungal activity against yeasts, was specie-dependent. On the other hand, PFW did not show noticeable antimicrobial activity. Using bioactivity guided “bioassay in situ“ against Bacillus subtilis NCTC 8236, fraction rich in antimicrobial phenolic acids was isolated.