ビューベリシン

Beauvericin is cytotoxic and increases ion permeability in cell membranes by forming complexes with essential cations (Ca2+, Na+, K+) and by forming cation-selective channels in lipid membranes. This may affect ionic homeostasis, increasing the intracellular calcium concentration, and lead to apoptosis. Beauvericin is also genotoxic and causes DNA damage, either by directly forming DNA adducts, through increased intracellular calcium levels influencing endonuclease activity, or through oxidative stress. Beauvericin induces lipid peroxidation and production of reactive oxygen species, producing cytotoxic effects and immunosuppressive activity. In addition, beauvericin is a potent inhibitor of the acyl-CoA:cholesterol acyltransferase (ACAT), which plays an important role in cholesterol ester accumulation in atherogenesis and in cholesterol absorption from the intestine. In isolated terminal ilea and heart muscles of guinea pig, beauvericin decreases the contractility, shortening the action potential duration and depolarizing the membrane resting potential. Beauvericin is also known to inhibit certain cytochrome P-450 enzymes. (A3015, A3016, A3017, A3018, A3077)

Free toxin may be removed by opsonization via the reticuloendothelial system (primarily the liver and kidneys) or it may be degraded through cellular internalization via the lysosomes. Lysosomes are membrane-enclosed organelles that contain an array of digestive enzymes, including several proteases.

Beauvericin is a mycotoxin with antibiotic and insecticidal effects. It was isolated from the fungus Beauveria bassiana, but is also produced by several other fungi, including several Fusarium species. It may therefore occur in grain (such as corn, wheat and barley) contaminated with these fungi. (L1962)