Lichens as a potential natural source of bioactive compounds: a review

Biological activity of material whether known in folk medicine or observed in planned screening program has been the starting point in the drug research. The general pattern is the isolation of active principles, elucidation their structures, followed by attempts for modulation of its activity potential by chemical modification. Lichens are valuable plant resources and are used as medicine, food, fodder, perfume, spice, dyes and for miscellaneous purposes throughout the world. Lichens are well known for the diversity of secondary metabolites that they produce. Compounds isolated from various lichen species have been reported to display diverse biological activities. Here we review the medicinal efficacy of lichen substances, which intends to explore the pharmaceutical potential of lichen substances.     

Genetic diversity of algal and fungal partners in four species of Umbilicaria (Lichenized Ascomycetes) along a transect of the Antarctic peninsula

Lichens from the genus Umbilicaria were collected across a 5,000-km transect through Antarctica and investigated for DNA sequence polymorphism in a region of 480-660 bp of the nuclear internal transcribed spacer region of ribosomal DNA. Sequences from both fungal (16 ascomycetes) and photosynthetic partners (22 chlorophytes from the genus Trebouxia) were determined and compared with homologs from lichens inhabiting more temperate, continental climates. The phylogenetic analyses reveal that Antarctic lichens have colonized their current habitats both through multiple independent colonization events from temperate embarkation zones and through recent long-range dispersal in the Antarctic of successful preexisting colonizers. Furthermore, the results suggest that relichenization-de novo establishment of the fungus-photosynthesizer symbiosis from nonlichenized algal and fungal cells-has occurred during the process of Antarctic lichen dispersal. Independent dispersal of algal and fungal cultures therefore can lead to a successful establishment of the lichen symbiosis even under harsh Antarctic conditions.     

Some advances in the study of lichens since the time of E. M. Holmes

Some of the principal advances in our knowledge of lichens made since the time of E. M. Holmes are briefly reviewed. Floristic studies on British lichens have continued and distribution maps of particular species are now being produced. These studies have shown that many species have disappeared from areas affected by air pollution by sulphur dioxide. Lichen taxonomy has seen the acceptance of chemical characters as valid taxonomic criteria, and the realization that ascus types, ascocarp structure and ascocarp ontogeny are more important at the generic level than ascospore characters alone. Lichens are not now thought of as a single taxonomic group but as fungi related to various orders of non-lichenized Ascomycotina, united only in their common method of nutrition (symbiosis with algae); some lichenized and non-lichenized species with identical types of ascocarps are consequently being treated as members of the same genus. Considerable progress has been made in describing lichen communities characteristic of particular substrates and situations and in understanding the factors which may affect the occurrence of particular species. Lichens have proved to be particularly valuable indicators of mean air pollution levels and scales for the estimation of these levels based solely on the lichen vegetation have been devised. Physiological and ultrastructural studies on lichens have progressed rapidly in the last decade. Carbohydrates have been demonstrated to move from the algal to the fungal component and the mobile carbohydrates found to differ in lichens with different genera of algae. The algal and fungal partners have been isolated and studied in pure culture. Most attempts to synthesize lichens have met with little success but in 1970 a thallus was formed from its components in culture. It is now possible to grow some lichens under controlled conditions in the laboratory and these techniques, together with transplant experiments, will clearly assume considerable importance in the investigation of taxonomic and ecological problems in the future. Little progress has been made in the study of lichen cytology or the factors affecting the establishment of lichen thalli. Lichens constitute an important part of some ecosystems and their decline due to anthropogenic influences is consequently a matter of concern for all biologists.     

The complexity of symbiotic interactions influences the ecological amplitude of the host: A case study in Stereocaulon (lichenized Ascomycota)

Symbiosis plays a fundamental role in nature. Lichens are among the best known, globally distributed symbiotic systems whose ecology is shaped by the requirements of all symbionts forming the holobiont. The widespread lichen‐forming fungal genus Stereocaulon provides a suitable model to study the ecology of microscopic green algal symbionts (i.e., phycobionts) within the lichen symbiosis. We analysed 282 Stereocaulon specimens, collected in diverse habitats worldwide, using the algal ITS rDNA and actin gene sequences and fungal ITS rDNA sequences. Phylogenetic analyses revealed a great diversity among the predominant phycobionts. The algal genus Asterochloris (Trebouxiophyceae) was recovered in most sampled thalli, but two additional genera, Vulcanochloris and Chloroidium, were also found. We used variation‐partitioning analyses to investigate the effects of climatic conditions, substrate/habitat characteristic, spatial distribution and mycobionts on phycobiont distribution. Based on an analogy, we examined the effects of climate, substrate/habitat, spatial distribution and phycobionts on mycobiont distribution. According to our analyses, the distribution of phycobionts is primarily driven by mycobionts and vice versa. Specificity and selectivity of both partners, as well as their ecological requirements and the width of their niches, vary significantly among the species‐level lineages. We demonstrated that species‐level lineages, which accept more symbiotic partners, have wider climatic niches, overlapping with the niches of their partners. Furthermore, the survival of lichens on substrates with high concentrations of heavy metals appears to be supported by their association with toxicity‐tolerant phycobionts. In general, low specificity towards phycobionts allows the host to associate with ecologically diversified algae, thereby broadening its ecological amplitude.     

Ice encapsulation protects rather than disturbs the freezing lichen

Arctic and alpine terricolous lichens are adapted to harsh environments and are tolerant to extremely low temperatures when metabolically inactive. However, there are reports indicating that freezing can be lethal to metabolically active lichens. With a projected warmer and more unstable climate, winter precipitation at high latitudes will fall more frequently as rain, causing snowmelt and encapsulating terricolous lichens in ice or exposing them to large temperature fluctuations. Lichens are a major winter food source for reindeer in most parts of the circumpolar region. A laboratory experiment tested how three hydrated reindeer forage lichen species covered by snow, encapsulated in ice, or uncovered responded to storage at freezing temperatures and subsequent warming. Photosynthetic performance (maximal fluorescence of dark-adapted samples and net photosynthetic rates) was significantly lower in lichens not insulated by snow or ice, whereas there were few differences between the snow and ice treatments. It is suggested that snow and ice provide sufficiently moist environments to improve extracellular and reduce intracellular ice nucleation activity. Ice encapsulation, which is often lethal to vascular plants, did not have any negative effects on the studied lichens. The results indicate that complete snow and ice melt followed by refreezing can be detrimental to terricolous lichen ecosystems. Reduced lichen biomass will have a negative effect both on reindeer winter survival and the indigenous peoples who herd reindeer.     

Symbiosis as a successful strategy in continental Antarctica: performance and protection of Trebouxia photosystem II in relation to lichen pigmentation

Lichens as symbiotic associations consisting of a fungus (the mycobiont) and a photosynthetic partner (the photobiont) dominate the terrestrial vegetation of continental Antarctica. The photobiont provides carbon nutrition for the fungus. Therefore, performance and protection of photosystem II is a key factor of lichen survival. Potentials and limitations of photobiont physiology require intense investigation to extend the knowledge on adaptation mechanisms in the lichen symbiosis and to clarify to which extent photobionts benefit from symbiosis. Isolated photobionts and entire lichen thalli have been examined. The contribution of the photobiont concerning adaptation mechanisms to the light regime and temperature conditions was examined by chlorophyll a fluorescence and pigment analysis focusing on the foliose lichen Umbilicaria decussata from North Victoria Land, continental Antarctica. No photoinhibition has been observed in the entire lichen thallus. In the isolated photobionts, photoinhibition was clearly temperature dependent. For the first time, melanin in U. decussata thalli has been proved. Though the isolated photobiont is capable of excess light protection, the results clearly show that photoprotection is significantly increased in the symbiotic state. The closely related photobiont of Pleopsidium chlorophanum, a lichen lacking melanin, showed a higher potential of carotenoid-based excess light tolerance. This fact discriminates the two photobionts of the same Trebouxia clade. Based on the results, it can be concluded that the successful adaptation of lichens to continental Antarctic conditions is in part based on the physiological potential of the photobionts. The findings provide information on the success of symbiotic life in extreme environments.     

Functional diversity and traits assembly patterns of lichens as indicators of successional stages in a tropical rainforest

Understanding community assembly patterns with regard to functional traits, which may be common to different species, allows us to compare ecological communities in a wider range of environmental and phytogeographic conditions. Moreover, a functional approach may facilitate the comprehension of the relation between biotic changes and ecosystem functions in complex systems such as tropical forests. Considering the lack of information in relation to the influence of environmental conditions on lichen functional traits, on lichen functional patterns in tropical forests and the potential usage of this approach in bioindication studies, this paper aims at (i) determining the functional structure of the lichen communities along the forest succession gradient, (ii) assessing the relation of lichen functional traits to this gradient and (iii) verifying the potential of using lichen functional traits as indicators of successional stages in tropical rainforests. Lichens were sampled in 24 sampling units of three successional stages (6–10; 12–20; and 40–60 years of recovering). The results corroborated our main hypothesis that the functional structure of the lichen communities responds to structural changes along a forest regeneration gradient. Growth forms (foliose, fruticose and crustose) as well as some reproductive trait states (lirella, isidia and perithecia) were the most suitable lichen traits to be used as indicators of forest succession in the southern edge of the Atlantic Rainforest. Lirella, fruticose and foliose were more related to earlier successional stages; isidia was more related to intermediate stages, while perithecia and crustose were more related to older stages. These results reinforce the ability of lichens to be used as bioindicators of forest conditions.     

Algal switching among lichen symbioses

Lichens are intimate and long-term symbioses of algae and fungi. Such intimate associations are often hypothesized to have undergone long periods of symbiotic interdependence and coevolution. However, coevolution has not been rigorously tested for lichen associations. In the present study we compared the nuclear internal transcribed spacer (ITS) phylogenies of algal and fungal partners from 33 natural lichen associations to test two aspects of coevolution, cospeciation and parallel cladogenesis. Since statistically significant incongruence between symbiont phylogenies rejected parallel cladogenesis and minimized cospeciation events, we conclude that switching of highly selected algal genotypes occurs repeatedly among these symbiotic lichen associations.     

Rehydration of the Lichen Ramalina lacera Results in Production of Reactive Oxygen Species and Nitric Oxide and a Decrease in Antioxidants

Lichens are slow-growing associations of fungi and unicellular green algae or cyanobacteria. They are poikilohydric organisms whose lifestyle in many cases consists of alternating periods of desiccation, with low metabolic activity, and hydration, which induces increase in their metabolism. Lichens have apparently adapted to such extreme transitions between desiccation and rehydration, but the mechanisms that govern these adaptations are still poorly understood. In this study, the effect of rehydration on the production of reactive oxygen species and nitric oxide as well as low-molecular-weight antioxidants was investigated with the lichen Ramalina lacera. Rehydration of R. lacera resulted in the initiation of and a rapid increase in photosynthetic activity. Recovery of photosynthesis was accompanied by bursts of intracellular production of reactive oxygen species and nitric oxide. Laser-scanning confocal microscopy using dichlorofluorescein fluorescence revealed that formation of reactive oxygen species following rehydration was associated with both symbiotic partners of the lichen. The rate and extent of reactive oxygen species production were similar in the light and in the dark, suggesting a minor contribution of photosynthesis. Diaminofluorescein fluorescence, indicating nitric oxide formation, was detected only in fungal hyphae. Activities associated with rehydration did not have a deleterious effect on membrane integrity as assessed by measurement of electrolyte leakage, but water-soluble low-molecular-weight antioxidants decreased significantly.     

Corticolous lichens as environmental indicators in urban areas in southern Brazil

Lichens are considered bioindicators and, as such, are widely used for air quality monitoring, especially in urban-industrial areas. The present paper proposes an evaluation of lichen communities in urban areas. The corticolous lichen community was assessed at 29 sampling stations in the city of Porto Alegre, in addition to a reference area located in the State Park in the city of Viamão, southern Brazil. The rubber band method was used for lichen mapping; three hundred host-trees were analyzed, at 11 different height levels. Lichens were evaluated in terms of composition, richness, cover and diversity, and sampling stations were classified based on the Index of Atmospheric Purity (IAP) complemented by the Environmental Classification Factor (ECF). The inclusion of ECF as a complement to the original IAP formula is proposed in the present study and not only richness and cover components are considered, but also data on the lichenized mycota composition (considering its different morphological forms). One hundred and thirty-one (131) taxa have been identified, out of which 13 specimens may be considered as indicators of urban areas, and the predominance of taxa belonging to the crustose and foliose morphological group was verified. The sampling stations were classified into five zones, ranging from lichen-free zones to optimal zones for lichen development. The use of lichen proved to be efficient to both evaluate air quality and identify alterations of urban microclimates. The application of an ECF-based correction factor is expected to complement the use of IAP, making it a more sensitive index, since an analysis of a multivaried information profile was deemed necessary, especially in regions where specimen diversity is higher.     

Oxidoreductases and cellulases in lichens: Possible roles in lichen biology and soil organic matter turnover

Lichens are symbiotic associations of a fungus (usually an Ascomycete) with green algae and/or a cyanobacterium. They dominate on 8 % of the world's land surface, mainly in Arctic and Antarctic regions, tundra, high mountain elevations and as components of dryland crusts. In many ecosystems, lichens are the pioneers on the bare rock or soil following disturbance, presumably because of their tolerance to desiccation and high temperature. Lichens have long been recognized as agents of mineral weathering and fine-earth stabilization. Being dominant biomass producers in extreme environments they contribute to primary accumulation of soil organic matter. However, biochemical role of lichens in soil processes is unknown. Our recent research has demonstrated that Peltigeralean lichens contain redox enzymes which in free-living fungi participate in lignocellulose degradation and humification. Thus lichen enzymes may catalyse formation and degradation of soil organic matter, particularly in high-stress communities dominated by lower plants. In the present review we synthesize recently published data on lichen phenol oxidases, peroxidases, and cellulases and discuss their possible roles in lichen physiology and soil organic matter transformations.     

Invariant properties of mycobiont-photobiont networks in Antarctic lichens

Aim

Lichens are often regarded as paradigms of mutualistic relationships. However, it is still poorly known how lichen-forming fungi and their photosynthetic partners interact at a community scale. We explored the structure of fungus-alga networks of interactions in lichen communities along a latitudinal transect in continental Antarctica. We expect these interactions to be highly specialized and, consequently, networks with low nestedness degree and high modularity.

Location

Transantarctic Mountains from 76° S to 85° S (continental Antarctica).

Time Period

Present.

Major Taxa Studied

Seventy-seven species of lichen-forming fungi and their photobionts.

Methods

DNA barcoding of photobionts using nrITS data was conducted in 756 lichen specimens from five regions along the Transantarctic Mountains. We built interaction networks for each of the five studied regions and a metaweb for the whole area. We explored the specialization of both partners using the number of partners a species interacts with and the specialization parameter d'. Network architecture parameters such as nestedness, modularity and network specialization parameter H₂' were studied in all networks and contrasted through null models. Finally, we measured interaction turnover along the latitudinal transect.

Results

We recovered a total of 842 interactions. Differences in specialization between partners were not statistically significant. Fungus-alga interaction networks showed high specialization and modularity, as well as low connectance and nestedness. Despite the large turnover in interactions occurring among regions, network parameters were not correlated with latitude.

Main Conclusions

The interaction networks established between fungi and algae in saxicolous lichen communities in continental Antarctica showed invariant properties along the latitudinal transect. Rewiring is an important driver of interaction turnover along the transect studied. Future work should answer whether the patterns observed in our study are prevalent in other regions with milder climates and in lichen communities on different substrates.     

Fungal specificity and selectivity for algae play a major role in determining lichen partnerships across diverse ecogeographic regions in the lichen‐forming family Parmeliaceae (Ascomycota)

Microbial symbionts are instrumental to the ecological and long‐term evolutionary success of their hosts, and the central role of symbiotic interactions is increasingly recognized across the vast majority of life. Lichens provide an iconic group for investigating patterns in species interactions; however, relationships among lichen symbionts are often masked by uncertain species boundaries or an inability to reliably identify symbionts. The species‐rich lichen‐forming fungal family Parmeliaceae provides a diverse group for assessing patterns of interactions of algal symbionts, and our study addresses patterns of lichen symbiont interactions at the largest geographic and taxonomic scales attempted to date. We analysed a total of 2356 algal internal transcribed spacer (ITS) region sequences collected from lichens representing ten mycobiont genera in Parmeliaceae, two genera in Lecanoraceae and 26 cultured Trebouxia strains. Algal ITS sequences were grouped into operational taxonomic units (OTUs); we attempted to validate the evolutionary independence of a subset of the inferred OTUs using chloroplast and mitochondrial loci. We explored the patterns of symbiont interactions in these lichens based on ecogeographic distributions and mycobiont taxonomy. We found high levels of undescribed diversity in Trebouxia, broad distributions across distinct ecoregions for many photobiont OTUs and varying levels of mycobiont selectivity and specificity towards the photobiont. Based on these results, we conclude that fungal specificity and selectivity for algal partners play a major role in determining lichen partnerships, potentially superseding ecology, at least at the ecogeographic scale investigated here. To facilitate effective communication and consistency across future studies, we propose a provisional naming system for Trebouxia photobionts and provide representative sequences for each OTU circumscribed in this study.     

Rehydration of the lichen Ramalina lacera results in production of reactive oxygen species and nitric oxide and a decrease in antioxidants

Lichens are slow-growing associations of fungi and unicellular green algae or cyanobacteria. They are poikilohydric organisms whose lifestyle in many cases consists of alternating periods of desiccation, with low metabolic activity, and hydration, which induces increase in their metabolism. Lichens have apparently adapted to such extreme transitions between desiccation and rehydration, but the mechanisms that govern these adaptations are still poorly understood. In this study, the effect of rehydration on the production of reactive oxygen species and nitric oxide as well as low-molecular-weight antioxidants was investigated with the lichen Ramalina lacera. Rehydration of R. lacera resulted in the initiation of and a rapid increase in photosynthetic activity. Recovery of photosynthesis was accompanied by bursts of intracellular production of reactive oxygen species and nitric oxide. Laser-scanning confocal microscopy using dichlorofluorescein fluorescence revealed that formation of reactive oxygen species following rehydration was associated with both symbiotic partners of the lichen. The rate and extent of reactive oxygen species production were similar in the light and in the dark, suggesting a minor contribution of photosynthesis. Diaminofluorescein fluorescence, indicating nitric oxide formation, was detected only in fungal hyphae. Activities associated with rehydration did not have a deleterious effect on membrane integrity as assessed by measurement of electrolyte leakage, but water-soluble low-molecular-weight antioxidants decreased significantly.     

WHAT SHALL WE DO WITH THE BLUE-GREEN COUNTERPARTS?

Lichens are troublesome organisms for taxonomists because of their special ‘ double nature ’, i.e. being composed (normally) of two partners. Only recently has it been understood properly that the same fungus can take different photosynthetic partners and develop into quite different-looking organisms, for exampleLobaria amplissimaandDendriscocaulon umhausense. The taxonomic problem is to show that two totally different-looking lichens in fact contain the same fungus. This is possible to demonstrate when mixed stands are available, but is now best done with molecular methods. Since the international code of nomenclature rules that the name of a lichen species is the name of the fungus, two different organisms with the same fungus must under the Code carry the same name, which is most impractical. To remove this unintentional complication, one must either make an exception in the Code for these cases, or establish an informal system to take care of them. The latter seems to be preferable.     

The yeast lichenosphere: high diversity of basidiomycetes from the lichens Tephromela atra and Rhizoplaca melanophthalma

Lichens are well-known examples of complex symbiotic associations between organisms from different Kingdoms. Microfungi in particular, establish diverse associations with the hosting lichen thallus, as species-specific parasites or transient co-inhabitants. The whole community of lichen-associated fungi constitute the ‘lichen mycobiome’ comprising both ascomycetes and basidiomycetes, including filamentous and yeast taxa. Metabarcoding results and microscopy analyses show that in some thalli, basidiomycetes are frequent lichen-associated fungi but still only a few species could be axenically isolated and morphologically characterized. Within a broad project aiming at characterizing the mycobiome diversity by culture-dependent and independent approaches in two lichen species selected as reference models – Rhizoplaca melanophthalma and Tephromela atra, we succeed in isolating and culturing 76 new strains of basidiomycetous yeasts. The lichen thalli were collected in different mountain regions worldwide and at relatively high elevation. The yeast strains were isolated on different growth media and were studied for their morphological and genetic diversity. Nuclear internal transcribed spacer (ITS) and ribosomal large subunit (LSU) sequence analyses identified them to belong to ten families within the orders Agaricostilbomycetes, Cystobasidiomycetes, Microbotryomycetes, Tremellomycetes and Ustilaginomycetes. The yeasts here detected showed patterns of host-preference in a few cases and they are potentially related to the ecological conditions.     

Degradation of the disease-associated prion protein by a serine protease from lichens

The disease-associated prion protein (PrP(TSE)), the probable etiological agent of the transmissible spongiform encephalopathies (TSEs), is resistant to degradation and can persist in the environment. Lichens, mutualistic symbioses containing fungi, algae, bacteria and occasionally cyanobacteria, are ubiquitous in the environment and have evolved unique biological activities allowing their survival in challenging ecological niches. We investigated PrP(TSE) inactivation by lichens and found acetone extracts of three lichen species (Parmelia sulcata, Cladonia rangiferina and Lobaria pulmonaria) have the ability to degrade prion protein (PrP) from TSE-infected hamsters, mice and deer. Immunoblots measuring PrP levels and protein misfolding cyclic amplification indicated at least two logs of reductions in PrP(TSE). Degradative activity was not found in closely related lichen species or in algae or a cyanobacterium that inhabit lichens. Degradation was blocked by Pefabloc SC, a serine protease inhibitor, but not inhibitors of other proteases or enzymes. Additionally, we found that PrP levels in PrP(TSE)-enriched preps or infected brain homogenates are also reduced following exposure to freshly-collected P. sulcata or an aqueous extract of the lichen. Our findings indicate that these lichen extracts efficiently degrade PrP(TSE) and suggest that some lichens could have potential to inactivate TSE infectivity on the landscape or be a source for agents to degrade prions. Further work to clone and characterize the protease, assess its effect on TSE infectivity and determine which organism or organisms present in lichens produce or influence the protease activity is warranted.     

Does secondary chemistry enable lichens to grow on iron-rich substrates?

Lichen substances are shown to increase or to inhibit the adsorption of Fe at cation exchange sites. The influence on the adsorption strongly differs between individual lichen substances and is different for Fe²⁺ and Fe³⁺. These results add a new biological role to the known functions of lichen secondary metabolites. In an experiment with cellulose filters, which were soaked with acetone solutions of lichen substances and were then incubated with micromolar solutions of FeCl₂ or FeCl₃, many lichen substances were found to increase Fe³⁺ adsorption, whereas others had no effect. Most lichen substances had no effect on Fe²⁺ adsorption, but two were found to reduce and one to increase the level of adsorption. Lichens of Fe-poor and -rich sites contain lichen substances with different adsorption behavior towards Fe²⁺ and Fe³⁺. All the studied lichen substances, which only occur in lichens of Fe-poor sites, turned out to be effective Fe³⁺ adsorbents. Lichens of Fe-bearing rock and slag, however, were found to lack lichen substances, or to contain substances that did not adsorb Fe³⁺ and had no effect on Fe²⁺ adsorption, or thirdly, to contain substances that increased Fe³⁺ adsorption, but decreased Fe²⁺ adsorption. These results suggest that lichen substances do play a significant role in Fe adsorption in lichens and determine their tolerance to excess concentrations of Fe. Notwithstanding the strong correlation between the secondary chemistry of lichen species and their preference for Fe-rich or Fe-poor substrates, the postulated mechanism of temporary Fe adsorption by lichen substances has to be subject of future biochemical research.     

Flechten. Der Erfolg einer Symbiose

The success of a symbiosis: Lichens Lichens are a unique group of organisms composed of one or two alga and a fungus. Together they form species specific thalli. Their common eco‐physiological properties allow colonizing almost all terrestrial habitats, even the most hostile climatic zones on earth. However, as poikilohydrous organisms they also suffer from disadvantages related with their nature. As water content cannot be actively controlled, many lichens experience water‐oversaturation, thus being not able to gain full photosynthetic rates, even though they have otherwise optimal conditions. These eco‐physiological properties set up the frame for which microclimatic situation the realized thallus construction might do best. As all optimizations regarding water uptake also count for water loss, lichens are always at the edge of having either too much or not enough water for optimal carbon gain. So each habitat has its own challenge for the lichen thallus construction and lichens have to fit well into a specific ecological niche.     

New Insights into the Biological Activity of Lichens: Bioavailable Secondary Metabolites of Umbilicaria decussata as Potential Anticoagulants

This study reports the in vitro anticoagulation activity of acetonic extract (AE) of 42 lichen species and the identification of potential bioavailable anticoagulant compounds from Umbilicaria decussata as a competent anticoagulant lichen species. Lichens’ AEs were evaluated for their anticoagulant activity by monitoring activated partial thromboplastin time (APTT) and prothrombin time (PT) assays. A strong, positive correlation was observed between total phenolics concentration (TPC) of species and blood coagulation parameters. U. decussata was the only species with the longest clotting time in both APTT and PT assays. The research was moved forward by performing in vivo assays using rats. The results corroborated the dose-dependent impact of U. decussata’s AE on rats’ clotting time. Major secondary metabolites of U. decussata and their plasma-related bioavailability were also investigated using LC-ESI-MS/MS. Atranol, orsellinic acid, D-mannitol, lecanoric acid, and evernic acid were detected as possible bioavailable anticoagulants of U. decussata. Our findings suggest that U. decussata might be a potential anticoagulant lichen species that can be used for the prevention or treatment of coagulation-related issues such as cardiovascular diseases (CVDs).