Cyclopiazonic acid

Cyclopiazonic acid (α-CPA), a mycotoxin and a fungal neurotoxin, is made by the molds Aspergillus and Penicillium. It is an indole-tetramic acid that serves as a toxin due to its ability to inhibit calcium-dependent ATPases found in the endoplasmic and sarcoplasmic reticulum. This inhibition disrupts the muscle contraction-relaxation cycle and the calcium gradient that is maintained for proper cellular activity in cells.

Cyclopiazonic acid is known to contaminate multiple foods because the molds that produce them are able to grow on different agricultural products, including but not limited to grains, corn, peanuts, and cheese. Due to this contamination, α-CPA can be harmful to both humans and farm animals that were exposed to contaminated animal feeds. However, α-CPA needs to be introduced in very high concentrations to produce mycotoxicosis in animals. Due to this, α-CPA is not considered a potent acute toxin.

Chemically, CPA is related to ergoline alkaloids. CPA was originally isolated from Penicillium cyclopium and subsequently from other fungi including Penicillium griseofulvum, Penicillium camemberti, Penicillium commune, Aspergillus flavus, and Aspergillus versicolor. CPA only appears to be toxic in high concentrations. Ingestion of CPA causes anorexia, dehydration, weight loss, immobility, and signs of spasm when near death. CPA can be found in molds, corns, peanuts, and other fermented products, such as cheese and sausages. Biologically, CPA is a specific inhibitor of SERCA ATPase in intracellular Ca²⁺ storage sites. CPA inhibits SERCA ATPase by keeping it in one specific conformation, affecting both the catalytic and transport domains of the protein. CPA also binds to SERCA ATPase at the same site as another inhibitor, thapsigargin (TG). In this way, CPA reduces the ability of SERCA ATPase to bind an ATP molecule.