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.

Nephroma orvoi (Nephromatoideae, Peltigeraceae) – a new lichen species for Russia

The lichen species Nephroma orvoi is reported as new to Russia from two localities in Murmansk Region. Description and colour illustrations of the material studied are provided. The species was previously known from Norway, Sweden, Finland, Switzerland, Canada (Alberta and British Columbia), USA (Washington), and Greenland. In Russia, it grows on rock outcrops in open habitat along the shore of a Paz River (Pasvik Nature Reserve) and in the bed of a small unnamed stream (neighborhood of Fedorova Tundra Mt.). The specimens were identified by the morphology (mostly laminal, brown, corticate soredia; faveolate, wrinkle-ridged lobes; lower side with short pseudotomentum in middle and inner part) and the identification was confirmed by lichen substances (a series of specific triterpenoids).

High-performance thin layer chromatography: A powerful analytical technique in pharmaceutical drug discovery

HPTLC is an advanced type of planar chromatography used extensively in the recent years for fingerprinting of medicinal plants, products and for screening lichen substances, quantification of active ingredients and herbal drugs, phytochemical and biomedical analysis and also used to check of presence of adulterants in the formulation. It is more sensitive and possible to run more sample in a short period of time, by using small amount of solvent. It is one of the sophisticated instrumental techniques based on the full capabilities of thin layer chromatography. In this paper, a brief discussion of the type of instrument used in HPTLC, its entire approach, and how this procedure is superior to TLC is presented. This article attempts to concentrate on the use of HPTLC by including examples of medications, medicinal drugs, and formulations that have been analyzed using HPTLC.

Beneficial Effects of Liposomal Formulations of Lichen Substances: A Review

: Lichens are commonly used as essential traditional medicines to treat various conditions, including skin disorders, wounds, digestive, respiratory, obstetric, and gynecological problems in many cultures in Africa, Asia, Europe, Haitian, Oceania, and North and South America. Lichens have been deeply investigated for their phytochemical properties, and to date, numerous compounds (also known as substances) have been successfully isolated from the extracts. However, the low solubility and bioavailability of pure lichen substances have been widely recognized as the significant issues hindering their biological applications. Recently, several groups have investigated the properties and the potential applications of lichen metabolites-based liposomal formulations and revealed a substantial improvement in their solubility, bioactivity, and toxicity in the animal. Thus, in this topical review, we aimed to provide an overview of liposomal structures, the efficacy of liposomal formulations, as well as their beneficial effects as compared to the free compounds themselves.

A Review of Anti-Cancer and Related Properties of Lichen-Extracts and Metabolites

Background: Lichens are a composite consortium of fungus and alga. The symbiotic organisms are naturally equipped with distinct characteristics as compared to constituting organisms separately. Lichens due to their peculiar anatomy and physiology, are the reservoir of more than 600 unique secondary metabolites, also known as ‘lichen substances’. Since ancient times, many ethnic groups from various parts of the world had knowledge about the applications of lichens as major provenance of food/fodder, medicine, dyes, spices, perfumes, etc. Lichen substances have shown impressive antioxidant, antimicrobial, antiviral, antitumor, and anti-inflammatory activities under experimental conditions. Usnic acid, a well-known metabolite, found in several species of lichens, possesses potent antioxidant and anti-inflammatory activities. It also has significant anti-proliferative potential as revealed through testing in different cancer cell lines. Atranorin, Lecanoric acid, Norstictic acid, Lobaric acid, Stictic acid, Ramalin, Gyrophoric acid, Salazinic acid, Protolichesterinic, and Fumarprotocetraric acid are some of the other purified lichen metabolites with potent anti-cancer activities. Objective: This study presents an overview of lichen derived extracts/compounds augmenting the anti-cancer (related) properties. Method: The review comprehends different studies (in vivo and in vitro) backing up the possibility of lichen extracts and metabolites towards their use as antioxidant, anti-proliferative, anti-inflammatory and EMT-inhibiting agents. Results: The review focuses on anti-cancer and related properties of lichen extracts and metabolites that include their anti-oxidative, anti-inflammatory, anti-proliferative and pro-apoptotic, cancer stemness reduction, activities and, the potential of inhibition of cancer-associated Epithelial-mesenchymal transition (EMT) that is responsible for multiple drug-resistance and metastasis of cancer cells in a large proportion of cases. Conclusion: Lichens can be the repertoire of a plethora of lichen metabolites with putative bioactive potential, which is needed to be explored in order to find out novel anti-cancer drugs.

Lichentherapy: Highlights on the Pharmaceutical Potentials of Lichens

Lichens exist in every continent and have a history of being used as food, medicine, a source of dyes and animal feed. Lichens are now being used as natural indicators of climate change and for air quality monitoring worldwide. Lichens play an important role in many ecosystems and exist as a symbiotic association between fungi and algae or cyanobacteria. This symbiosis results in the production of unique secondary metabolites known as lichen substances, which arise within the thalli and are typically in crystal form on the surface of the fungal hyphae. Recently, lichens and their secondary metabolites have been receiving increased attention due to their nutritional value and pharmaceutical potential. This review aims to highlight on the importance and variety of common lichen substances (secondary metabolites). Finally, the commercialization of lichens is growing but, in the future, metabolic and biotechnological approaches can be used as an alternative product to overcome the limited availability of biologically active, commercially valuable and medicinally important secondary metabolite components.

Biodeterioration Patterns and Their Interpretation for Potential Applications to Stone Conservation: A Hypothesis from Allelopathic Inhibitory Effects of Lichens on the Caestia Pyramid (Rome)

The colonisation of stone by different organisms often leaves biodeterioration patterns (BPs) on the surfaces even if their presence is no longer detectable. Peculiar weathering patterns on monuments and rocks, such as pitting phenomena, were recognised as a source of information on past colonisers and environmental conditions. The evident inhibition areas for new bio-patinas observed on the marble blocks of the Caestia Pyramid in Rome, recognisable as tracks of previous colonisations, seem a source for developing new natural products suitable for restoration activities. To hypothesise past occurring communities and species, which gave rise to such BPs, we carried out both in situ observations and analyses of the rich historical available iconography (mainly photographs). Moreover, we analysed literature on the lichen species colonising carbonate stones used in Roman sites. Considering morphology, biochemical properties and historical data on 90 lichen species already reported in Latium archaeological sites, we suppose lichen species belonging to the genus Circinaria (Aspicilia s.l.) to be the main aetiological agent of such peculiar BPs. These results seem relevant to highlight the long-lasting allelopathic properties of some lichen substances potentially applicable as a natural product to control colonisation, improving the environmental and economical sustainability of stone restoration.

Mysterious World of Lichens: Highlights on Their History, Applications, and Pharmaceutical Potentials

Background: Lichens play an important role in many ecosystems and exist as a symbiotic association between fungi and algae or cyanobacteria. This symbiosis results in production of unique secondary metabolites known as lichen substances, which arise within the thalli and are typically in crystal form on the surface of the fungal hyphae. Recently, lichens and their secondary metabolites have been receiving increased attention due to their nutritional value and pharmaceutical potential. Objectives: This review aims to cast a light on the importance and variety of common lichen substances (secondary metabolites), which are investigated along with their historical and contemporary applications, use in environmental research and discussion of the commercialisation of lichens-based products. Methods: The literature, including research and reviews articles, was analysed and the information was compiled to provide a complete review of Lichens. A desk-based study to elucidate the role of lichens in commercial products was also undertaken. Results: Analysis of metabolites, mostly secondary metabolites, have yielded a wide range of interesting compounds with biological activities from antimicrobial to anticancer. 31 of these compounds are discussed in detail. Further, the nutritional value of lichens is identified alongside a role in environmental monitoring and a number of commercialised lichen-based products are located. Conclusions: Lichens are found on every continent and have a history of use as food, medicine, dyes and livestock feed. The pharmaceutical potential of lichens is high and several companies are now attempting to commercialise these unique attributes.

Arctoparmelia collatolica (Parmeliaceae), a new species from Siberia, Russia

Arctoparmelia collatolica is described as a species new to science based on morphological, chemical and molecular data. The species is similar to the usnic acid-deficient chemotype of A. centrifuga but differs in the grey-brown to brown upper surface in the central part of the thallus and ivory white to pale brown rhizines. The species contains collatolic acid and its derivatives. Seven secondary lichen substances are reported as new for the genus Arctoparmelia. A key to Arctoparmelia taxa is provided.