A lichen is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. Lichens are important actors in nutrient cycling and act as producers which many higher trophic feeders feed on, such as reindeer, gastropods, nematodes, mites, and springtails. Lichens have properties different from those of their component organisms. They come in many colors, sizes, and forms and are sometimes plant-like, but are not plants. They may have tiny, leafless branches (fruticose); flat leaf-like structures (foliose); grow crust-like, adhering tightly to a surface (substrate) like a thick coat of paint (crustose); have a powder-like appearance (leprose); or other growth forms.
Cladonia rangiferina, also known as reindeer cup lichen, reindeer lichen or grey reindeer lichen, is a light-colored fruticose, cup lichen species in the family Cladoniaceae. It grows in both hot and cold climates in well-drained, open environments. Found primarily in areas of alpine tundra, it is extremely cold-hardy.
In organic chemistry, polyketides are a class of natural products derived from a precursor molecule consisting of a chain of alternating ketone and methylene groups: [−C(=O)−CH2−]n. First studied in the early 20th century, discovery, biosynthesis, and application of polyketides has evolved. It is a large and diverse group of secondary metabolites caused by its complex biosynthesis which resembles that of fatty acid synthesis. Because of this diversity, polyketides can have various medicinal, agricultural, and industrial applications. Many polyketides are medicinal or exhibit acute toxicity. Biotechnology has enabled discovery of more naturally-occurring polyketides and evolution of new polyketides with novel or improved bioactivity.
Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C18H16O7. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933 and 1937 by Curd and Robertson. Usnic acid was identified in many genera of lichens including Usnea, Cladonia, Hypotrachyna, Lecanora, Ramalina, Evernia, Parmelia and Alectoria. Although it is generally believed that usnic acid is exclusively restricted to lichens, in a few unconfirmed isolated cases the compound was found in kombucha tea and non-lichenized ascomycetes.
Cannabigerol (CBG) is one of more than 120 identified cannabinoid compounds found in the plant genus Cannabis. Cannabigerol is the decarboxylated form of cannabigerolic acid, the parent molecule from which other cannabinoids are synthesized.
Retinoic acid receptor beta (RAR-beta), also known as NR1B2 is a nuclear receptor that in humans is encoded by the RARB gene.
Cannabichromene (CBC), also called cannabichrome, cannanbichromene, pentylcannabichromene or cannabinochromene, exhibits anti-inflammatory properties in vitro, which may, theoretically, contribute to cannabis analgesic effects. It is a phytocannabinoid, one of the hundreds of cannabinoids found in the Cannabis plant. It bears structural similarity to the other natural cannabinoids, including tetrahydrocannabinol (THC), tetrahydrocannabivarin (THCV), cannabidiol (CBD), and cannabinol (CBN), among others. CBC and cannabinols are present in cannabis. It is not scheduled by the Convention on Psychotropic Substances.
Vulpinic acid is a natural product first found in and important in the symbiosis underlying the biology of lichens. It is a simple methyl ester derivative of its parent compound, pulvinic acid, and a close relative of pulvinone, both of which derive from aromatic amino acids such as phenylalanine via secondary metabolism. The roles of vulpinic acid are not fully established, but may include properties that make it an antifeedant for herbivores. The compound is relatively toxic to mammals.
Lobaria pulmonaria is a large epiphytic lichen consisting of an ascomycete fungus and a green algal partner living together in a symbiotic relationship with a cyanobacterium—a symbiosis involving members of three kingdoms of organisms. Commonly known by various names like tree lungwort, lung lichen, lung moss, lungwort lichen, oak lungs or oak lungwort, it is sensitive to air pollution and is also harmed by habitat loss and changes in forestry practices. Its population has declined across Europe and L. pulmonaria is considered endangered in many lowland areas. The species has a history of use in herbal medicines, and recent research has corroborated some medicinal properties of lichen extracts.
A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an ester group. Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, Lamiaceae, Papaveraceae and Myrtaceae.
Canoparmelia is a genus of lichen-forming fungi in the family Parmeliaceae. The widespread genus contains about 35 species. Canoparmelia, a segregate of the parmelioid lichen genus Pseudoparmelia, was circumscribed by John Elix and Mason Hale in 1986.
Olivetolic acid cyclase is an enzyme with systematic name 3,5,7-trioxododecanoyl-CoA CoA-lyase (2,4-dihydroxy-6-pentylbenzoate-forming). This enzyme catalyses the following chemical reaction
Cannabidiolic acid (CBDA), is a cannabinoid found in cannabis plants. It is most abundant in the glandular trichomes on the female seedless flowers or more accurately infructescence often colloquially referred to as buds. CBDA is the chemical precursor to cannabidiol (CBD). Through the process of decarboxylation cannabidiol is derived via a loss of a carbon and two oxygen atoms from the 1 position of the benzoic acid ring. Cannabinoids are a class of compounds that are essentially unique to the cannabis genus. Both marijuana and hemp belong to this genus.
John Alan (Jack) Elix emeritus professor in chemistry at the Australian National University, is an organic chemist who has contributed in many fields: lichenology, lichen chemotaxonomy, plant physiology and biodiversity and natural product chemistry. He has authored 2282 species names, and 67 genera in the field of mycology.
Atranorin is a chemical substance produced by some species of lichen. It is a secondary metabolite belonging to a group of compounds known as depsides. Atranorin has analgesic, anti-inflammatory, antibacterial, antifungal, cytotoxic, antioxidant, antiviral, and immunomodulatory properties. In rare cases, people can have an allergic reaction to atranorin.
Cetrelia sayanensis is a species of foliose lichen in the family Parmeliaceae. Found in Europe, it was formally described as a new species in 2009 by lichenologists Tatyana Otnyukova, Nikolay Stepanov, and John Alan Elix. The type was collected along the Kulumys ridge on the West Sayan Mountains of southern Siberia. Here it was found growing on the bark of an old stem of Sorbus sibirica, at an altitude of 800 m (2,600 ft). It has also been collected in several neighbouring areas, all at altitudes between 400–930 m (1,310–3,050 ft), with the bark of Abies, Betula, Salix, and Sorbus as the typical substrates. In 2019, the lichen was recorded from Austria, its first reported occurrence in middle Europe.
Anziaic acid is a depside found in lichens. It gives a red reaction in the C test. The two phenolic rings have a pentyl side chain. It is an ester dimer of olivetolic acid.
Salazinic acid is a depsidone with a lactone ring. It is found in some lichens, and is especially prevalent in Parmotrema and Bulbothrix, where its presence or absence is often used to help classify species in those genera.
Lichexanthone is an organic compound in the structural class of chemicals known as xanthones. Lichexanthone was first isolated and identified by Japanese chemists from a species of leafy lichen in the 1940s. The compound is known to occur in many lichens, and it is important in the taxonomy of species in several genera, such as Pertusaria and Pyxine. More than a dozen lichen species have a variation of the word lichexanthone incorporated as part of their binomial name. The presence of lichexanthone in lichens causes them to fluoresce a greenish-yellow colour under long-wavelength UV light; this feature is used to help identify some species. Lichexanthone is also found in several plants, and some species of fungi that do not form lichens.
Lichen products, also known as lichen substances, are organic compounds produced by a lichen. Specifically, they are secondary metabolites. Lichen products are represented in several different chemical classes, including terpenoids, orcinol derivatives, chromones, xanthones, depsides, and depsidones. Over 800 lichen products of known chemical structure have been reported in the scientific literature, and most of these compounds are exclusively found in lichens. Examples of lichen products include usnic acid, atranorin, lichexanthone, salazinic acid, and isolichenan, an α-glucan. Many lichen products have biological activity, and research into these effects is ongoing.
