Sorption of cobalt and zinc from single and binary metal solutions by Evernia prunastri

Non-living lichen Evernia prunastri was studied as biosorbent material for zinc and cobalt removal from single and binary metal solutions. Sorption equilibrium of Zn2+ and Co2+ ions was reached within 1 hour. Both cobalt and zinc biosorption was not pH dependent within the range pH 4-6 and negligible at pH 2. The experimental results were fitted to the Langmuir, Freundlich, Redlich-Peterson and Langmuir-Freundlich adsorption isotherms to obtain the characteristic parameters of each model. The Langmuir, Redlich-Peterson and Langmuir-Freundlich isotherms were found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the maximum sorption capacities of metal ions onto lichen biomass were 112 μmol/g Zn and 97.2 μmol/g Co from single metal solutions. E. prunastri exhibited preferential uptake of zinc from equimolar binary Zn2+ - Co2+ mixtures within the range 50 – 4000 μM. Even thought mutual interference was seen in all Co-Zn binary systems. To evaluate the two-metal sorption system, simple curves had to be replaced by three-dimensional sorption surface. These results can be used to elucidate the behavior of lichens as bioindicators of cobalt and zinc pollution in water and terrestrial ecosystems.

The effect of lichen secondary metabolites on Aspergillus fungi

A systematic review of literature data on the antifungal potential of extracted lichen compounds and individual secondary metabolites against mold species of the genus Aspergillus is provided. Crude extracts from 49 epiphytic, 16 epigeic and 22 epilithic species of lichens and 44 secondary metabolites against 10 species, Aspergillus candidus, A. flavus, A. fumigatus, A. nidulans, A. niger, A. ochraceus, A. parasiticus, A. restrictus, A. stellatus and A. ustus, were analysed. Several measuring techniques were employed for such analyses. Lichen substances were extracted with alcoholic and other organic solvents mainly using the Soxhlet apparatus. Among the three most-studied mold species, the results showed that the crude extracts from the thalli of the lichens Cladonia foliacea, Hypotrachyna cirrhata, Leucodermia leucomelos, Platismatia glauca and Pseudevernia furfuracea against Aspergillus flavus, from C. foliacea, Nephroma arcticum and Parmelia sulcata against A. fumigatus and from Evernia prunastri, Hypogymnia physodes, Umbilicaria cylindrica and Variospora dolomiticola against A. niger have the greatest antifungal potential. The lichen secondary metabolites showed a higher inhibitory potential, e.g. protolichesterinic acid against A. flavus, lecanoric acid against A. fumigatus and orsellinic acid against A. niger; the other seven species of Aspergillus have been poorly studied and require further investigation. A comparison of the inhibitory potential of the tested mixtures of lichen substances and their secondary metabolites shows that they can compete with commonly used antifungal substances, such as ketoconazole and clotrimazole against A. flavus, A. nidulans, A. niger and A. parasiticus and fluconazole in the case of A. fumigatus.

Lichen-Derived Compounds and Extracts as Biologically Active Substances with Anticancer and Neuroprotective Properties

Lichens are a source of chemical compounds with valuable biological properties, structurally predisposed to penetration into the central nervous system (CNS). Hence, our research aimed to examine the biological potential of lipophilic extracts of Parmelia sulcata, Evernia prunastri, Cladonia uncialis, and their major secondary metabolites, in the context of searching for new therapies for CNS diseases, mainly glioblastoma multiforme (GBM). The extracts selected for the study were standardized for their content of salazinic acid, evernic acid, and (−)-usnic acid, respectively. The extracts and lichen metabolites were evaluated in terms of their anti-tumor activity, i.e. cytotoxicity against A-172 and T98G cell lines and anti-IDO1, IDO2, TDO activity, their anti-inflammatory properties exerted by anti-COX-2 and anti-hyaluronidase activity, antioxidant activity, and anti-acetylcholinesterase and anti-butyrylcholinesterase activity. The results of this study indicate that lichen-derived compounds and extracts exert significant cytotoxicity against GBM cells, inhibit the kynurenine pathway enzymes, and have anti-inflammatory properties and weak antioxidant and anti-cholinesterase properties. Moreover, evernic acid and (−)-usnic acid were shown to be able to cross the blood-brain barrier. These results demonstrate that lichen-derived extracts and compounds, especially (−)-usnic acid, can be regarded as prototypes of pharmacologically active compounds within the CNS, especially suitable for the treatment of GBM.

Accumulation and Release of Mercury in the Lichen Evernia prunastri (L.) Ach

This study investigated the dynamics of the accumulation and release of Hg2+ in lichens, using Evernia prunastri (L.) Ach. as a model species. Thalli were incubated with solutions containing 1, 10, and 100 µM Hg2+ and then exposed for 1, 2, 3, 6, 12, 18, and 24 months at the Botanical Garden of the University of Siena (a location free from local Hg sources). Lichen samples accumulated Hg proportionally to the exposure concentration, and after the exposure, reductions over time were evident, already starting from 1–2 months. After 24 months, samples released 72–74 (healthy thalli) to 94% (unhealthy thalli) of the accumulated Hg, but control values of untreated samples were never reached. Depending on the Hg content after the exposure, stable decreased concentrations were reached after 6–24 months. The results of this study highlight the ability of the lichen E. prunastri to reflect rapidly increasing environmental Hg concentrations, as well as to indicate an ameliorated situation (e.g., the closure of an Hg source). However, we have found evidence that an acute pollution episode can influence the content of Hg in lichens for several years.

Modifying the tumor effects in the lungs of laboratory mice with lichen extracts

The anti-tumor properties of common lichens of Belarus: Hypogymnia physodes, Ramalina pollinaria, Cladonia arbuscula, Evernia prunastri were studied using the models of spontaneous and induced carcinogenesis in mice Af lungs. Without exposing to a carcinogen in 20 weeks after taking aqueous lichen extracts (1 g/l) of 4 species for 28 days, only C. arbuscula showed the pro-carcinogenic properties almost doubling the average number of pulmonary adenomas per mouse. R. pollinaria and E. prunastri did not provoke spontaneous carcinogenesis and had a corrective effect significantly reducing the number of adenomas per mouse by 21 and 45 %, respectively. To carry out induced carcinogenesis, after 2 weeks of taking aqueous extracts, mice were injected intraperitoneally with urethane (1 g/kg). The analysis of the total number of adenomas per mouse showed a pro-tumor tendency for C. arbuscula, and the analysis of the number of adenomas of 1 mm and more showed that for H. physodes. The extracts do not affect the proportion of urethane adenomas of various sizes in their total number, but increase the incidence of high-yield adenomas of various sizes; at the same time, H. physodes has a much greater pro-carcinogenic activity according to the incidence of high-yield adenomas of 1 mm or more. The analysis of the total number of urethane adenomas per mouse, as well as adenomas of 1 mm showed an anti-tumor tendency for R. pollinaria and a pro-tumor tendency for E. prunastri. Taking E. prunastri increased the incidence of high-yield adenomas of various sizes, along with a notable increase in the incidence of low-yield adenomas. In the case of R. pollinaria, the increase in the incidence of low-yield adenomas was supplemented by a sharp decrease in the incidence of high-yield adenomas. As a result of the experiment, E. prunastri has exhibited both the pro-carcinogenic activity and the anti-tumor properties, but R. pollinaria has revealed a pronounced anti-tumor potential.

Environmental conditions influence on the accumulation of secondary metabolites of lichens of the genus Cladonia and the family Parmeliaceae

This paper gives the maximum absorption of 10 secondary metabolites of lichens in a 96% alcohol solution. An assessment of the content of lichen acids growing in the Muransky pine forest, the Buzuluk pine forest, the Krasnosamarsky Woodland and in the Bolshechernigovsky district of the Samara Region was also carried out. All the species studied by us accumulate more secondary metabolites when growing in the Krasnosamarsky Woodland in comparison with those in the Buzuluk pine forest by 1,12-5,47 times. From the point of view of medicine and agriculture, as a raw material for drugs, as well as for drugs with fungicidal and insecticidal activity, it is more expedient to collect material in the Krasnosamarsky Woodland and other areas in the steppe zone with similar contrasting ecological factors, where the total amount of active stuff is more. The total content of secondary metabolites decreases in the order: Evernia mesomorpha Hypogymnia physodes Evernia prunastri Xanthoparmelia camtschadalis Parmelia sulcata Pseudevernia furfuracea Cladonia arbuscula Cladonia furcata Cladonia fimbriata Cladonia rangiferina . In general, the studied representatives of the genus Cladonia accumulate secondary metabolites 2 times or more less than representatives of the Parmeliaceae family.

Biological Effects of Air Pollution on Sensitive Bioindicators: A Case Study from Milan, Italy

In this study, the physiological response of a sensitive lichen species (Evernia prunastri) exposed for three months in a complex urban area (Milan, Italy) was evaluated in order to verify if the air pollution abatement measures adopted over the years resulted in a suitable air quality for the survival of this sensitive species. Parameters investigated rely on the photosynthetic activity of the photobiont (Fv/Fm, PIabs, and OJIP curves), damage to mycobiont (membrane damage and antiradical activity), and the production of secondary metabolites involved in the protective functions of the organisms. Results showed that although air quality in Milan still suffers from heavy pollution from PM and NOx, the overall situation is not as severe as to induce the death of this sensitive biomonitor, at least in the short term. Nevertheless, the vital status of the samples exposed in the study area showed a significant impairment compared to that of samples exposed in a control area, indicating that the current air quality in Milan still prevents the optimal survival of E. prunastri.

Biologically Active Extracts from Different Medicinal Plants Tested as Potential Additives against Bee Pathogens

Honey bees (Apis mellifera) perform pollination service for many agricultural crops and contribute to the global economy in agriculture and bee products. However, honey bee health is an ongoing concern, as illustrated by persistent local population decline, caused by some severe bee diseases (e.g., nosemosis, AFB, EFB, chalkbrood). Three natural recipes are in development based on the bioactive compounds of different plants extract (Agastache foeniculum, Artemisia absinthium, Evernia prunastri, Humulus lupulus, Laurus nobilis, Origanum vulgare and Vaccinium myrtillus), characterised by HPLC-PDA. The antimicrobial activity of these recipes was tested in vitro against Paenibacillus larvae, Paenibacillus alvei, Brevibacillus laterosporus, Enterococcus faecalis, Ascosphaera apis and in vivo against Nosema ceranae. A mix of 20% blueberry, 40% absinthium, 10% oakmoss, 10% oregano, 10% Brewers Gold hops, 5% bay laurel and 5% anise hyssop extract showed the strongest antibacterial and antifungal activity. Combing several highly active plant extracts might be an alternative treatment against bee-disease-associated parasites and pathogens, in particular to replace synthetic antibiotics.

Antimicrobial and antioxidant potentials of non-cytotoxic extracts of corticolous lichens sampled in Armenia

Due to wide range of secondary metabolites, lichens were used from antiquity as sources of colorants, perfumes and medicaments. This research focuses on exploring the antioxidant, antimicrobial and cytotoxic activities of methanol, ethanol, acetone extracts and aqueous infusions of corticolous lichens sampled from Armenia. Methanol, ethanol and acetone extracts from all tested lichens were active against Gram-positive bacterial strains. The most effective solvent to retrieve antimicrobial compounds was methanol. Aqueous infusions of tested lichens didn’t show any significant antibacterial and antifungal activity. The highest antimicrobial activity was observed for methanol extract of Ramalina sinensis. The minimum inhibitory concentration of methanol extract of Ramalina sinensis were 0.9–1.8 mg mL− 1. Pseudevernia furfuracea demonstrated antifungal activity (Ø 12 mm). Methanol extract of Parmelia sulcata demonstrated largest 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging activity (71 %). The cytotoxicity was measured on human HeLa (cervical carcinoma) cell lines using microculture tetrazolium test assay. The IC50 values estimated for methanol extracts of Peltigera praetextata, Evernia prunastri, Ramalina sinensis and Ramalina farinacea species in HeLa cell line were within 1.8–2.8 mg mL− 1 and considered as non-cytotoxic. Obtained results suggest that studied lichens can be prospective in biotechnologies as alternative sources of antimicrobial and antioxidant substances.