Cantharidin
cantharidin is a poisonous chemical compound naturally produced by beetles of the Meloidae family, which includes more than 1,500 species commonly known as cantharids, such as Lytta vesicatoria (Spanish fly), which release small droplets of cantharidin-containing hemolymph from the joints of their legs or from their antennae when provoked. The males of these beetles also produce it in their oral fluid and store it in their alimentary tract.
Cantharidin is an inhibitor of protein phosphatase 1 and protein phosphatase 2.
It was first isolated by French chemist Pierre Jean Robiquet in 1812. Applied to the skin, cantharidin causes rashes, redness, and irritation. Consumed orally it produces irritations in the urinary system and the erection of the penis. For that reason, it was mistakenly believed that it was an aphrodisiac.
Several families of Coleoptera possess cantharidin in their body fluids. Cantharidin is mainly used as a pheromone for orientation and attraction (families Pyrochroidae, Anthicidae); the use of cantharidin as a defensive mechanism is an evolved condition (families Meloidae and Oedemeridae) and is frequently accompanied by warning colorations (aposematic)
In dermatological therapy
Cantharidin, the active irritant in the crude cantharid drug, is obtained from the dried insects Cantharis vesicatoria. Cantharidin was synthesized by Ziegler and colleagues in 1942., through a long series of reactions, starting with butadiene and dimethyl-maleic anhydride.
In human medicine, cantharidin is used for the removal of benign epithelial warts. Cantharids were formerly used as an anti-irritant and vesicant, but undesirable side effects were found. Still in 2021 it is used in veterinary medicine as a vesicant for the treatment of small umbilical hernias and as a counter-irritant in certain bone, joint, ligament and tendon diseases.
Gallery
The song, Lytta vesicatoria; its metallic green colour warns of its toxicity
Mylabris quadripunctata warning of its toxicity with a combination of red and black
Oedemera simplex warning of its toxicity with a combination of yellow and black
Pyrochroa coccinea; its intense red color warns of its toxicity
