Lichen Substances Research Articles

Three new species of siphuloid lichens, with a first key to the genus Parasiphula

AbstractThe term ‘siphuloid’ is introduced for a suite of distinct lichen genera with a superficially similar foliose to fruticose morphology, notably Siphula, Siphulella, Siphulopsis, Parasiphula and Knightiellastrum. Three new species are described: Parasiphula squamosa Kantvilas (from Tasmania and New Zealand), characterized by a whitish grey, squamulose or minutely foliose thallus lacking lichen substances or containing traces of atranorin; Siphula capensis Kantvilas (from southern Africa), containing baeomycesic and squamatic acids, and characterized by robust, broadly flattened, rounded lobes with thickened apices; and S. crittendenii (from the Caribbean but with an outlying collection from Queensland, Australia), an epiphytic species containing thamnolic acid, with fragile, flattened lobes mostly to 10 mm long and 1−5 mm wide, with ragged or much-divided apices. Salient features of the species of Parasiphula are summarized and a first key for this genus is presented. Infrageneric problems in Siphula are also discussed briefly.

Unpigmented lichen substances protect lichens against photoinhibition of photosystem II in both the hydrated and desiccated states

Unpigmented lichen substances protect lichens against photoinhibition of photosystem II in both the hydrated and desiccated states

A review of the potential of lichen substances as antifungal agents: the effects of extracts and lichen secondary metabolites on Fusarium fungi

The present meta-analysis provides literature data on the effect of lichen extracts and single secondary metabolites used against Fusarium spp. moulds. Lichen extracts were obtained from 51 corticolous, 17 terricolous and 18 saxicolous lichen species and 37 secondary compounds were tested against eight fungal species, i.e., Fusarium acuminatum, F. avenaceum, F. culmorum, F. fujikuroi, F. oxysporum, F. roseum, F. solani and F. udum. The researchers used several test methods, mostly to determine MIC and IZ. Extracts were obtained using several solvents, mainly organic ones with use of the Soxhlet apparatus. The most frequently tested species was F. oxysporum, against which lichen substances from Alectoria sarmentosa, Cladonia mitis, C. rangiferina, Flavoparmelia caperata, Hypotrachyna cirrhata, Leucodermia leucomelos, Parmotrema austrosinense, P. reticulatum, Physcia aipolia, Pseudevernia furfuracea, Roccella montagnei and Umbilicaria nylanderiana and secondary metabolites such as 2-hydroxy-4-methoxy-3,6-dimethylbenzoic acid, atranorin, lecanoric and (+)-usnic acids showed the highest antifungal potential. These agencies could compete with the potential of fungicides, such as flucytosine and fluconazole. Other species have been poorly investigated. Statistical analysis of literature data showed that the fungistatic potential of lichen extracts is significantly different from individual secondary metabolites. Similarly, the potential of secondary metabolites often differs significantly from that of non-lichen substances. This meta-analysis indicates the potential of lichen substances as future anti-fusarial agents.

The genus Lambiella Hertel (lichenised fungi) in Tasmania: new combinations, new species and a revised key

Two new species of Lambiella Hertel from Tasmania are described and illustrated: L. parvipsephota Kantvilas, which is similar to the widespread L. psephota (Tuck.) Hertel but differs by lacking norstictic acid in the thallus and sedifolia-grey pigment in the apothecia, and by having smaller apothecia and ascospores, 8−13 × 5−7.5 µm; and L. plumbea Kantvilas, characterised by a grey thallus lacking lichen substances, minute apothecia 0.075−0.13 mm wide, and small ascospores 4−8.5 × 3−5 µm. Both are currently known only from Tasmania. A further 11 species of Rimularia are transferred to Lambiella: Lambiella albotessellata (Kantvilas) Kantvilas, Lambiella applanata (Kantvilas & Coppins) Kantvilas, Lambiella aspicilioides (Kantvilas) Kantvilas, Lambiella asteriphila (Kantvilas) Kantvilas, Lambiella campestris (Kantvilas & Elix) Kantvilas, Lambiella circumgrisea (Kantvilas) Kantvilas, Lambiella coppinsiana (Kantvilas) Kantvilas, Lambiella exigua (Hertel & Rambold) Kantvilas, Lambiella globulispora (Sipman & Aptroot) Kantvilas, Lambiella ramboldiana (Kantvilas & Elix) Kantvilas and Lambiella umbratilis (Kantvilas & Coppins) Kantvilas. The complexities of assigning many, chiefly Southern Hemisphere taxa to new generic concepts derived essentially from molecular data are discussed briefly. Lambiella is considered to be the genus of best fit for a suite of lichens that share many salient features, particularly with respect to apothecial anatomy and their Trapelia-type asci. An identification key to the 14 species of Lambiella in Tasmania is provided.

A new species of Halecania (Leprocaulaceae, Lecanoromycetes) from eastern North America1

Halecania robertcurtisii is described as new to science from dry sandstone cliffs and overhangs in Ohio, USA, in eastern North America. It has a smooth and continuous to rimose-areolate thallus, pseudolecanorine apothecia with reddish to rust colored disks, and lacks lichen substances. The species is similar to Halecania subsquamosa but lacks the diagnostic unidentified terpenoid present in that taxon.

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 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.

Evaluation of Antimicrobial Properties of Lichen Substances against Plant Pathogens

Plant pathogens pose major threats on agriculture and horticulture, causing significant economic loss worldwide. Due to the continuous and excessive use of synthetic pesticides, emergence of pesticide resistant pathogens has become more frequent. Thus, there is a growing needs for environmentally-friendly and selective antimicrobial agents with a novel mode of action, which may be used in combination with conventional pesticides to delay development of pesticide resistance. In this study, we evaluated the potentials of lichen substances as novel biopesticides against eight bacterial and twelve fungal plant pathogens that have historically caused significant phytopathological problems in South Korea. Eight lichen substances of diverse chemical origins were extracted from axenic culture or dried specimen, and further purified for comparative analysis of their antimicrobial properties. Usnic acid and vulpinic acid exhibited strong antibacterial activities against Clavibacter michiganensis subsp. michiganensis. In addition, usnic acid and vulpinic acid were highly effective in the growth inhibition of fungal pathogens, such as Diaporthe eres, D. actinidiae, and Sclerotinia sclerotiorum. Intriguingly, the growth of Rhizoctonia solani was specifically inhibited by lecanoric acid, indicating that lichen substances exhibit some degrees of selectivity to plant pathogens. These results suggested that lichen substance can be used as a selective biopesticide for controlling plant disease of agricultural and horticultural significance, minimizing possible emergence of pesticide resistant pathogens in fields.

Two New Fumarprotocetraric Acid Lactones Identified and Characterized by UHPLC-PDA/ESI/ORBITRAP/MS/MS from the Antarctic Lichen Cladonia metacorallifera

Lichens are symbiotic organisms between algae and fungi, which are makers of secondary compounds named as lichen substances. Hyphenated techniques have significantly helped natural product chemistry, especially UHPLC/ESI/MS/MS in the identification, separation, and tentative characterization of secondary metabolites from natural sources. Twenty-five compounds were detected from the Antarctic lichen Cladonia metacorallifera for the first time using UHPLC-PDA/ESI/Orbitrap/MS/MS. Compounds 5 and 7 are reported as new compounds, based on their MS/MS fragmentation routes, and considered as fumarprotocetraric acid derivatives. Besides, ten known phenolic identified as orsellinic acid, ethyl 4-carboxyorsellinate, psoromic acid isomer, succinprotocetraric acid, siphulellic acid, connorstictic acid, cryptostictic acid, lecanoric acid, lobaric acid and gyrophoric acid are noticed for the first time in the Cladonia genus.

In-vitro ANTICANCER ACTIVITY OF LICHEN Heterodermia boryi AND ITS SECONDARY METABOLITES

Lichens are symbiotic organisms that have been traditionally used for treating different kinds of ailments. Heterodermia boryi is a common foliose lichen found growing luxuriantly in the Western Ghats. It is clear from the literature survey that there are no reports on the isolation and biological activity of lichen substances from Heterodermia boryi, we thought of exploring the anticancer activity of its crude extract and isolated compounds. Fractionation of crude methanolic extract of Heterodermia boryi by column chromatography led to the isolation of three pure compounds. The crude methanolic extract and isolated compounds were screened for in vitro cytotoxic activity against three different human cancer cell lines such as breast (MCF-7), lung (H1975), and colon (HCT-116). Isolated compounds with the highest activity were further evaluated for their ability to induce apoptosis by dual staining method on the MCF-7 cell line. Molecular docking studies were carried out to study the ability of isolated compounds to interact with Mitogen-activated protein kinases- 2 (Mnk2). The isolated compounds were characterized as methyl haematommate (HKB-1), atraric acid (HKB-4), and zeorin (HKB-6) by spectral methods. Among the isolated compounds, HKB-1 and HKB-6 exhibited superior IC50 values of 11.1 µg/ml and 17.02 µg/ml respectively. Dual staining of MCF-7 cells treated with HKB-1 and HKB-6 at 10 µg/ml displayed early signs of apoptosis. Molecular docking studies revealed excellent binding affinity and interaction of HKB-1 with the binding site residues of Mnk2 and were comparable with that of the co-crystallized ligand staurosporine indicative of their possible role as Mnk2 inhibitors.

Natural Product Investigation in Lichens: Extraction and HPLC Analysis of Secondary Compounds in Mycobiont Cultures.

Chromatography techniques facilitate separation, purification, and identification of secondary compounds (natural products) in lichens and their mycobiont cultures. In particular, high-performance liquid chromatography (HPLC) plays a vital role in the identification of lichen substances because of its high sensitivity, speed, and reliability with theminimal sample. Therefore, we describe the extraction and HPLC protocol for the investigation of secondary compounds with a special focus on lichenmycobiont cultures.

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).

COMPUTATIONAL SCREENING AND MOLECULAR DOCKING OF LICHEN SECONDARY METABOLITES AGAINST SEVERE ACUTE RESPIRATORY SYNDROME-COV-2 MAIN PROTEASE AND SPIKE PROTEIN

Objective: At present, the coronavirus disease (COVID)-19 pandemic is increasing global health concerns. This coronavirus outbreak is caused by severe acute respiratory syndrome coronavirus (SARS-CoV)-2. Since, no specific antiviral for treatment against COVID-19, so identification of new therapeutics is an urgent need. The objective of this study is to the analysis of lichen compounds against main protease and spike protein targets of SARS-CoV-2 using in silico approach. Methods: A total of 108 lichen compounds were subjected to ADMET analysis and 14 compounds were selected based on the ADMET properties and Lipinski’s rule of five. Molecular docking was performed for screening of selected individual lichen metabolites against the main protease and spike proteins of SARS-CoV-2 by Schrodinger Glide module software. Results: Among the lead compounds, fallacinol showed the highest binding energy value of −11.83 kcal/mol against spike protein, 4-O-Demethylbarbatic acid exhibited the highest dock score of −11.67 kcal/mol against main protease. Conclusion: This study finding suggests that lichen substances may be potential inhibitors of SARS-CoV-2.

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 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. 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: The analysis of metabolites, mostly secondary metabolites, has 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.

Metabolic processes involved with sugar alcohol and secondary metabolite production in the hyperaccumulator lichen Diploschistes muscorum reveal its complex adaptation strategy against heavy-metal stress

The synthesis of various unique secondary metabolites by lichens is the result of mutualistic symbiotic association between the mycobiont and autotrophic photobiont. The function of these compounds and causal factors for their production are not fully understood. This paper examines the effect of heavy-metal bioaccumulation and physiological parameters related to photosynthesis and carbon metabolism on the production of lichen substances in hyperaccumulator Diploschistes muscorum. The obtained model of secondary metabolite concentrations in the thalli demonstrates that the carbon source provided by the photobiont and associated polyols produced by the mycobiont have positive impact on the production; on the contrary, the increased intracellular load of heavy metals and excessive loss of cell membrane integrity adversely affected secondary metabolite contents. Additionally, the production of secondary metabolites appears to be more dependent on intracellular metal concentrations than on soil pollution level. To compensate for metal stress, both efficient functioning of algal component and sufficient production of secondary metabolites are required. The balanced physiological functioning of mycobiont and photobiont constitutes the complex protective mechanism to alleviate the harmful effects of heavy metal stress on primary and secondary metabolism of lichens.

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.

Effect of several phenolic compounds of lichens on the physiological, cytological, and biochemical characteristics of Allium fistulosum seedlings

Abstract Here we report the effects of atranorin (ATR), gyrophoric acid (GPA), and thamnolic acid (TMA) on the physiological, biochemical, and cytological characteristics of Allium fistulosum L. seedlings for the first time. Of the lichen substances investigated, ATR and TAM had the highest phytotoxicity effects. ATR (4000 - 1000 μM) and TAM (4000 μM) inhibited the growth processes and increased the intensity of lipid peroxidation in A. fistulosum, and as a result the activities of the protective enzymes peroxidase, catalase, and superoxide dismutase increased, and the contents of photosynthetic pigments in the A. fistulosum seedlings decreased. ATR at concentrations 2000 and 4000 μM caused decrease of mitotic activity and increase of chromosomal aberrations frequency in root cells. The weakest phytotoxic properties were shown by GPA, which caused no changes in the physiological, cytological, or biochemical parameters of the A. fistulosum seedlings across the entire range of concentrations tested.

Analysis of Lichen Secondary Chemistry Doubled the Number of Cetrelia W.L. Culb. & C.F. Culb. Species (Parmeliaceae, Lichenised Ascomycota) in Hungary

The distribution patterns of lichen secondary metabolites are often taxon specific. They represent cryptic chemical diversity additional to morphological-anatomical biodiversity. Cetrelia W.L. Culb. & C.F. Culb. species (c. 200 specimens) were checked and revised by thin-layer chromatography. Soredia, pseudocyphellae, rhizines, features of lower surface are the main morphological characters analysed against the presence of cortical pigment, atranorin and medullary α-alectoronic acid, anziaic acid, α-collatolic acid, β-alectoronic acid, β-collatolic acid, imbricaric acid, 4-O-demethylimbricaric acid, olivetoric acid, perlatolic acid, physodic acid and 4-O-methylphysodic acid. The European occurrence of C. chicitae (W.L. Culb.) W.L. Culb. & C.F. Culb. – described from America – is confirmed on the basis of identical secondary metabolite composition by seven lichen substances. Four species were revealed and mapped in Hungary. Cetrelia chicitae and C. monachorum (Zahlbr.) W.L. Culb. & C.F. Culb. are new for the Hungarian lichen flora. From the originally known two taxa C. cetrarioides (Delise) W.L. Culb. & C.F. Culb. proved to be rare, C. olivetorum (Nyl.) W.L. Culb. & C.F. Culb. is less frequent than regarded earlier. Currently C. monachorum is the most frequent Cetrelia species in Hungary. Cetrelia chicitae and C. cetrarioides may need protection measures. Parmelia cetrarioides f. pseudofallax (Gyeln.) Gyeln. is lectotypified here.

Influence of secondary metabolites on surface chemistry and metal adsorption of a devitalized lichen biomonitor.

Despite the broad use of lichens as biomonitors of airborne trace elements, the surface chemistry and metal adsorption parameters of these organisms are still poorly known. The current investigation is aimed at (i) quantifying the acid-base surface properties and the first-order physical-chemical parameters of Cu2+ and Zn2+ adsorption of devitalized Pseudevernia furfuracea, a lichen commonly used in biomonitoring of airborne trace elements, and (ii) comparing the results with those available for moss biomonitors. Equilibrium constants and metal-binding site concentrations were calculated with a thermodynamic model by taking into account the presence/absence of ancillary extracellular cell wall compounds, namely melanin and acetone-soluble lichen substances. An acid-base titration experiment performed in the pH range of 3-10 showed that melanised and non-melanised P.furfuracea samples have lower pHPZC (3.53-3.99) and higher metal-binding site concentrations (0.96-1.20mmolg-1) compared to that of the mosses investigated so far at the same experimental conditions. Melanin biosynthesis increased the content of carboxyl and phosphoryl groups and reduces that of amine/polyphenols. Cu2+ and Zn2+ adsorption was unaffected by the degree of melanisation while the removal of extracellular lichen substances slightly decreased Zn2+ adsorption. Although Cu2+ and Zn2+ adsorption parameters related to P.furfuracea surfaces were 3 times lower than in the mosses, lichen samples adsorbed the same amount of Cu2+ and 30% more Zn2+. The present study contributes in understanding the role of ancillary cell wall compounds in Cu2+ and Zn2+ adsorption in a model lichen. It also provides a first comparison between the surface physico-chemical characteristics of lichens and mosses frequently used as biomonitors of trace elements.

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

Lichens are a composite consortium of a fungus and an 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 have known about the applications of lichens as major provenance of food/fodder, medicine, dyes, spices, perfumes, etc. Lichen substances have shown impressive antioxidant, antimicrobial, antiviral, anti-tumor, and antiinflammatory 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 antiproliferative 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. This study presents an overview of lichen-derived extracts and compounds showing anti-cancer (or related) properties. The review comprehends different studies (in vivo and in vitro) backing up the possibility of lichenextracts and metabolites towards their use as antioxidant, anti-proliferative, anti-inflammatory, and Epithelialmesenchymal transition (EMT) -inhibiting agents. Various studies carried out to date show that lichen-extracts and metabolites have a range of anti-cancer and related properties that include anti-oxidative, anti-inflammatory, anti-proliferative, pro-apoptotic, and the potential of inhibition of cancer-associated EMT that is responsible for drug resistance and metastasis of cancer cells in a substantial proportion of cases. Lichens are the repertoire of a plethora of lichen-metabolites with significant anti-cancer potential. However, some of the critical 'anti-cancer related' properties, such as the ability of EMT-inhibition and the potential of induction of apoptosis, are relatively less studied for several lichen compounds. Additionally, many lichen compounds need to be purified at a larger scale to explore their anti-cancer potential.