Atranorin

Atranorin is a depside, a type of organic compound found in many lichens. It is a pale yellow crystalline solid and is a common secondary metabolite produced by lichen-forming fungi. Atranorin is soluble in organic solvents like ethanol and acetone but sparingly soluble in water. It is considered a universal compound in lichens, meaning it can be found in a wide variety of lichen species across different genera.

Chemically, atranorin is a di-O-methylated depside of orsellinic acid. It is often found in combination with its related compound, chloroatranorin, which differs by a chlorine atom. The presence of atranorin is frequently used as a chemical marker for identification in lichenology, particularly in field identification. It can be detected using chemical spot tests, such as the K-test (potassium hydroxide solution), which causes a yellow to orange reaction.

Atranorin has been the subject of research for its potential biological activities. Studies have investigated its antimicrobial, antioxidant, and anti-inflammatory properties. While some promising results have been observed in laboratory settings, further research is needed to determine its efficacy and safety for therapeutic applications. It is not currently used in mainstream medicine. Its primary significance remains in its role as a widespread lichen constituent and a tool for lichen identification.