10639

Parietin, also known as physcion, is a distinctive orange-yellow pigment predominantly found in lichens, particularly those in the genus Caloplaca. It is a secondary product of the lichen Xanthoriaparietina and is also present in the roots of curled dock (Rumexcrispus). Parietin is notable for its absorption of blue light, contributing to the unique coloration of these organisms. In addition to its role as a pigment, parietin plays a significant protective role for lichens, especially against UV-B light. This is particularly important in high-altitude alpine regions, where exposure to UV-B can be intense. The presence of UV-B light stimulates the production of parietin, which in turn shields the lichens from potential damage caused by this radiation. Interestingly, lichens in arctic regions, such as Svalbard, also retain the ability to produce parietin despite the absence of harmful levels of UV-B light. This capability could be crucial for their survival in scenarios of ozone layer thinning, providing a protective mechanism against increased UV radiation. Parietin has also demonstrated anti-fungal properties, showing effectiveness against barley powdery mildew and cucumber powdery mildew. Notably, it has been more efficient in combating cucumber powdery mildew than certain commercial treatments like fenarimol and polyoxin B.  When reacted with potassium hydroxide (KOH), parietin forms a deep reddish-magenta compound. This reaction is indicative of the complex chemical interactions parietin can undergo and highlights its potential utility in various applications beyond its natural biological functions.

GHS Hazard Statements

• H315 (95.45%): Causes skin irritation [Warning Skin corrosion/irritation]

• H319 (95.45%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]

• H335 (100%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

Chemical and Physical Properties

Source: PubChem