Atranorin, a Secondary Metabolite of Lichens, Exhibited Anxiolytic/Antidepressant Activity in Wistar Rats.

Atranorin (ATR) is one of lichens' many known secondary metabolites. Most current studies have investigated the various effects of ATR in vitro and only sporadically in vivo. The latest data indicate that ATR may have anxiolytic/antidepressive effects. This study aimed to analyze the potential of ATR in a depression-like state in male Wistar rats. Pregnant females were stressed by restricting their mobility in the final week of pregnancy three times a day for 45 min each, for three following days. After birth, progeny aged 60 days was stressed repeatedly. The male progeny was divided into three groups as follows: CTR group as a healthy control (n = 10), DEP group as a progeny of restricted mothers (n = 10), and ATR group as a progeny of restricted mothers, treated daily for one month with ATR (n = 10; 10 mg/kg of body weight, p.o.). Our results show that ATR acts as an antioxidant and markedly changes animal behavior. Concomitantly, hippocampal neurogenesis increases in the hilus and subgranular zone, together with the number of NeuN mature neurons in the hilus and CA1 regions. Our results indicate a potential antidepressant/anxiolytic effect of ATR. However, further studies in this area are needed.

A Comparative Study of Isolated Secondary Metabolites from Lichens and Their Antioxidative Properties.

Free radicals play a critical role in the chemical processes that occur in all cells. Pharmaceutical companies manufacture a variety of synthetically prepared antioxidants, but it is known that many of these can be carcinogenic. As a result, efforts are being made to find natural antioxidants that do not have these side effects. Lichens may be suitable candidates because they contain secondary metabolites with proven antioxidant properties. This could be explained by the presence of compounds with phenolic groups in lichens. The radical scavenging reaction is a chemical reaction governed by stoichiometry, and our aim is to determine the efficacy of these reactions. The aim of this study is to compare metabolite activity based on the same amount of substance involved in radical scavenging, calculated in micromoles rather than weight concentration. This provides an accurate way of comparing radical scavenging activity. We tested superoxide anion scavenging activity and free radical scavenging activity of isolated lichen secondary metabolites and their mixtures in different ratios. The following compounds were isolated and tested for antioxidant activity: gyrophoric acid (Umbilicaria hirsuta), evernic acid (Evernia prunastri), physodic acid, 3-hydroxyphysodic acid, physodalic acid and atranorin (Hypogymnia physodes), and usnic acid (as a synthetic compound). Of all the tested compounds, 3-hydroxyphysodic acid, as well as mixtures containing this metabolite, showed the strongest scavenging activity. The results also demonstrated that calculation by amount of substance leads to a new consideration of antioxidant activity.

Investigation of Calcium Forms in Lichens from Travertine Sites.

Lichens are symbiotic organisms with an extraordinary capability to colonise areas of extreme climate and heavily contaminated sites, such as metal-rich habitats. Lichens have developed several mechanisms to overcome the toxicity of metals, including the ability to bind metal cations to extracellular sites of symbiotic partners and to subsequently form oxalates. Calcium is an essential alkaline earth element that is important in various cell processes. Calcium can serve as a metal ligand but can be toxic at elevated concentrations. This study investigated calcium-rich and calcium-poor sites and the lichen species that inhabit them (Cladonia sp.). The calcium content of these lichen species were analyzed, along with localized calcium oxalate formed in thalli collected from each site. The highest concentration of calcium was found in the lichen squamules, which can serve as a final deposit for detoxification. Interestingly, the highest content of calcium in Cladonia furcata was localized to the upper part of the thallus, which is the youngest. The produced calcium oxalates were species-specific. Whewellite (CaC2O4∙H2O) was formed in the case of C. furcata and weddellite (CaC2O4∙2H2O) was identified in C. foliacea.

Pro-Apoptotic Potential of Pseudevernia furfuracea (L.) Zopf Extract and Isolated Physodic Acid in Acute Lymphoblastic Leukemia Model In Vitro.

Acute lymphoblastic leukemia (ALL) is the most frequently diagnosed type of leukemia among children. Although chemotherapy is a common treatment for cancer, it has a wide range of serious side effects, including myelo- and immunosuppression, hepatotoxicity and neurotoxicity. Combination therapies using natural substances are widely recommended to attenuate the adverse effects of chemotherapy. The aim of the present study was to investigate the anti-leukemic potential of extract from the lichen Pseudevernia furfuracea (L.) Zopf (PSE) and isolated physodic acid (Phy) in an in vitro ALL model. A screening assay, flow cytometry and Western blotting were used to analyze apoptosis occurrence, oxidative stress, DNA damage and stress/survival/apoptotic pathway modulation induced by the tested substances in Jurkat cells. We demonstrate for the first time that PSE and Phy treatment-induced intrinsic caspase-dependent cell death was associated with increased oxidative stress, DNA damage and cell cycle arrest with the activation of cell cycle checkpoint proteins p53, p21 and p27 and stress/survival kinases p38 MAPK, JNK and PI3K/Akt. Moreover, using peripheral T lymphocytes, we confirmed that PSE and Phy treatment caused minimal cytotoxicity in normal cells, and therefore, these naturally occurring lichen secondary metabolites could be promising substances for ALL therapy.

Potential Effect of Pseudevernia furfuracea (L.) Zopf Extract and Metabolite Physodic Acid on Tumour Microenvironment Modulation in MCF-10A Cells.

Lichens comprise a number of unique secondary metabolites with remarkable biological activities and have become an interesting research topic for cancer therapy. However, only a few of these metabolites have been assessed for their effectiveness against various in vitro models. Therefore, the aim of the present study was to assess the effect of extract Pseudevernia furfuracea (L.) Zopf (PSE) and its metabolite physodic acid (Phy) on tumour microenvironment (TME) modulation, focusing on epithelial-mesenchymal transition (EMT), cancer-associated fibroblasts (CAFs) transformation and angiogenesis. Here, we demonstrate, by using flow cytometry, Western blot and immunofluorescence microscopy, that tested compounds inhibited the EMT process in MCF-10A breast cells through decreasing the level of different mesenchymal markers in a time- and dose-dependent manner. By the same mechanisms, PSE and Phy suppressed the function of Transforming growth factor beta (TGF-ß)-stimulated fibroblasts. Moreover, PSE and Phy resulted in a decreasing level of the TGF-ß canonical pathway Smad2/3, which is essential for tumour growth. Furthermore, PSE and Phy inhibited angiogenesis ex ovo in a quail embryo chorioallantoic model, which indicates their potential anti-angiogenic activity. These results also provided the first evidence of the modulation of TME by these substances.

Spatial and Temporal Patterns of Endopolyploidy in Mosses.

Somatic polyploidy or endopolyploidy is common in the plant kingdom; it ensures growth and allows adaptation to the environment. It is present in the majority of plant groups, including mosses. Endopolyploidy had only been previously studied in about 65 moss species, which represents less than 1% of known mosses. We analyzed 11 selected moss species to determine the spatial and temporal distribution of endopolyploidy using flow cytometry to identify patterns in ploidy levels among gametophytes and sporophytes. All of the studied mosses possessed cells with various ploidy levels in gametophytes, and four of six species investigated in sporophytic stage had endopolyploid sporophytes. The proportion of endopolyploid cells varied among organs, parts of gametophytes and sporophytes, and ontogenetic stages. Higher ploidy levels were seen in basal parts of gametophytes and sporophytes than in apical parts. Slight changes in ploidy levels were observed during ontogenesis in cultivated mosses; the youngest (apical) parts of thalli tend to have lower levels of endopolyploidy. Differences between parts of cauloid and phylloids of Plagiomnium ellipticum and Polytrichum formosum were also documented; proximal parts had higher levels of endopolyploidy than distal parts. Endopolyploidy is spatially and temporally differentiated in the gametophytes of endopolyploid mosses and follows a pattern similar to that seen in angiosperms.

Insights into physiological responses of mosses Physcomitrella patens and Pohlia drummondii to lichen secondary metabolites.

It is widely accepted that allelopathy among mosses and lichens do exist due to its similar ecological needs, though it is rarely documented. With an aim to test whether there is an effect of allelochemicals to mosses, we grow axenically two moss species (namely Physcomitrella patens and Pohlia drummondii) in controlled conditions and use them to test the effect of lichen Pseudevernia furfuracea acetone extracts containing active compounds: atranorin, chloratranorin, and physodic acid. The photosynthesis value and the biochemical parameters were measured to detect changes in moss organisms upon application of different concentration of lichen extract. The results obtained clearly showed that both moss species reacted to allelochemicals applied in test but to different extent. This suggests that tested moss species have various patterns on reaction to allelochemicals, and that the process of allelopathy is rather a recently coevolving one, than pre-defined. The lichen secondary metabolites are allelochemicals effective also to moss species that are not selected lichen cohabitants.

Usnic acid, as a biotic factor, changes the ploidy level in mosses.

Lichens and mosses often share the same environmental conditions where they compete for substrate and other essential factors. Lichens use secondary metabolites as allelochemicals to repel surrounding plants and potential rivals. In mosses, endoreduplication leads to the occurrence of various ploidy levels in the same individual and has been suggested as an adaptation to abiotic stresses. Here, we show that also biotic factors such as usnic acid, an allelochemical produced by lichens, directly influenced the level of ploidy in mosses. Application of usnic acid changed the nuclei proportion and significantly enhanced the endoreduplication index in two moss species, Physcomitrella patens and Pohlia drummondii. These investigations add a new aspect on secondary metabolites of lichens which count as biotic factors and affect ploidy levels in mosses.