Candida albicans is a commensal coloniser of the human gastrointestinal tract and an opportunistic pathogen, especially thanks to its capacity to form biofilms. This lifestyle is frequently involved in infections and increases the yeast resistance to antimicrobials and immune defenses. In this context, 38 lichen acetone extracts have been prepared and evaluated for their activity against C. albicans planktonic and sessile cells. Minimum inhibitory concentrations of extracts (MICs) were determined using the broth microdilution method. Anti-biofilm activity was evaluated using tetrazolium salt (XTT) assay as the ability to inhibit the maturation phase (anti-maturation) or to eradicate a preformed 24 h old biofilm (anti-biofilm). While none of the extracts were active against planktonic cells, biofilm maturation was limited by 11 of the tested extracts. Seven extracts displayed both anti-maturation and anti-biofilm activities (half maximal inhibitory concentrations IC50_mat and IC50_biof ≤ 100 µg/mL); Evernia prunastri and Ramalina fastigiata were the most promising lichens (IC50_mat < 4 µg/mL and IC50_biof < 10 µg/mL). Chemical profiles of the active extracts performed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) have been analyzed. Depsides, which were present in large amounts in the most active extracts, could be involved in anti-biofilm activities. This work confirmed that lichens represent a reservoir of compounds with anti-biofilm potential.

A new chloro-depsidone (1) and five known compounds, variolaric acid (2), lecanoric acid (3), alpha-alectoronic acid (4), atranorin (5), and ergosterol peroxide (6), have been isolated from the lichen Ochrolechia parella. The structure of compound 1 was elucidated by spectroscopic analysis. Additionally, the tautomeric equilibrium of compound 4 was investigated. In the present study, two specimens of this lichen, growing under different light conditions, were analyzed. The major compound in both samples was found to be 2, but the amount of this metabolite was significantly higher in the shaded specimen (0.76% w/w). The new compound parellin (1) predominated in the specimen grown under shady conditions, while atranorin (5) was found only in the sunlit specimen. The cytotoxic activities of 2, 4, and 6 against B16 melanoma cells were evaluated.

A new diphenyl ether (1), along with 12 known compounds, was isolated from the lichen Diploicia canescens. The structure of compound 1 was elucidated by spectroscopic data analysis, and the biosynthetic origin of this product is discussed. Secalonic acids B (7), D (8), and F (9) were isolated for the first time from D. canescens. The cytotoxic activities of 1-3, 6-8, and 10 against the B16 murine melanoma and HaCaT human keratinocyte cell lines were evaluated.

Covering: up to 2016.When looking for dibenzofuran in the biochemical databases, most papers and reviews deal with pollutants and polychlorinated dibenzofurans like dioxins. But dibenzofurans are also biosynthetized by a wide diversity of organisms in nature. Even if dibenzofurans from natural sources represent a small class of secondary metabolites, compared to flavonoids, xanthones or terpenoids, they are often endowed with interesting biological properties which have been recently described. This review provides an update on papers describing dibenzofurans from lichens, ascomycetes and cultured mycobionts. Other sources, such as basidiomycetes, myxomycetes or plants produce sporadically interesting dibenzofurans in terms of structures and activities.