Sekikaic acid is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon- hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

in the structural class of chemicals known as depsides. It is found in some lichens. First isolated from '' Ramalina sekika'', it is a fairly common

lichen product 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 de ...

in ''

Ramalina ''Ramalina'' is a genus of greenish fruticose lichens that grow in the form of flattened, strap-like branches. Members of the genus are commonly called strap lichensField Guide to California Lichens, Stephen Sharnoff, Yale University Press, 20 ...

'' and ''

Cladonia ''Cladonia'' is a genus of moss-like lichens in the family Cladoniaceae. They are the primary food source for reindeer/caribou. ''Cladonia'' species are of economic importance to reindeer-herders, such as the Sami in Scandinavia or the Nenets ...

'', both

genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial ...

of lichen-forming fungi. The

species epithet Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany) A botanical name ...

of the powdery lichen ''

Lepraria sekikaica ''Lepraria sekikaica'' is a species of leprose (powdery) lichen in the family Lecanoraceae. Found in Western Australia, it was formally described as a new species by lichenologist John Elix. It was one of 100 new lichen species published in a ...

'' refers to the presence of this substance—a rarity in genus ''

Lepraria ''Lepraria'' is a genus of leprose crustose lichens that grows on its substrate like patches of granular, caked up, mealy dust grains.A taxonomic revision of the North American species of Lepraria s.l. that produce divaricatic acid, with notes ...

''.

Properties

In its purified form, sekikaic acid exists as colourless rectangular prisms or rhombic plates. Its

molecular formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

is C₂₂H₂₆0₈. It has a

melting point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...

of . An

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a h ...

ic solution of sekikaic acid reacts with

iron(III) chloride Iron(III) chloride is the inorganic compound with the formula . Also called ferric chloride, it is a common compound of iron in the +3 oxidation state. The anhydrous compound is a crystalline solid with a melting point of 307.6 °C. The colo ...

to produce a violet colour. Its

ultraviolet spectrum Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

has three peaks of maximum absorption (λ_max) at 219, 263, and 303 nm. Sekikaic acid has been demonstrated to have several biological activities in laboratory experiments. These include

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricants ...

activity, inhibition of the enzymes

α-glucosidase Glycoside hydrolases (also called glycosidases or glycosyl hydrolases) catalyze the hydrolysis of glycosidic bonds in complex sugars. They are extremely common enzymes with roles in nature including degradation of biomass such as cellulose (cel ...

and

α-amylase α-Amylase is an enzyme (EC 3.2.1.1; systematic name 4-α-D-glucan glucanohydrolase) that hydrolyses α bonds of large, α-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose: :Endohydr ...

hypoglycemic Hypoglycemia, also called low blood sugar, is a fall in blood sugar to levels below normal, typically below 70 mg/dL (3.9 mmol/L). Whipple's triad is used to properly identify hypoglycemic episodes. It is defined as blood glucose bel ...

activity, and lipid-lowering activity. It also has

antiviral Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do no ...

activity against

Respiratory syncytial virus Respiratory syncytial virus (RSV), also called human respiratory syncytial virus (hRSV) and human orthopneumovirus, is a common, contagious virus that causes infections of the respiratory tract. It is a negative-sense, single-stranded RNA virus. ...

, even more so than the standard antiviral medication

ribavirin Ribavirin, also known as tribavirin, is an antiviral medication used to treat RSV infection, hepatitis C and some viral hemorrhagic fevers. For hepatitis C, it is used in combination with other medications such as simeprevir, sofosbuvir, ...

Related compounds

The sekikaic acid contains similar compounds that are metabolically related to sekikaic acid. It comprises sekikaic acid as the major compound, and 4''O''-demethylsekikaic and homosekikaic acids as satellite metabolites.

References

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