——Derived from Baidu Baike

The general term for toxic substances present in the bodies of Gram negative bacteria, such as typhoid and dysentery bacteria. It is a component of the cell wall of various Gram negative bacteria, and a toxin released after bacterial lysis, also known as a "pyrogen". Unit: EU/ml. Its chemical composition includes phospholipid polysaccharide protein complex, and its toxic component is mainly lipid A. Endotoxins are located on the outermost layer of the cell wall, covering the mucin of the cell wall. The toxic effects of various bacterial endotoxins are relatively weak and roughly the same, which can cause fever, microcirculation disorders, endotoxin shock, and disseminated intravascular coagulation. Endotoxins are heat-resistant and stable, with weak antigenicity. It can stimulate the body to produce antibodies, but has no neutralizing effect, forming an antitoxin. After formaldehyde treatment, it cannot become a toxoid.

Endotoxins are a component of the cell wall of Gram negative bacteria called lipopolysaccharides. Lipopolysaccharides are toxic to the host. Although endotoxins are tightly embedded in the cell wall, they continuously release into the surrounding environment. This release is not only caused by cell disintegration and death, but also occurs during normal cell growth and division.

Endotoxins are not proteins, so they are very heat-resistant. Heating at a high temperature of 100 ℃ for 1 hour will not destroy its biological activity. It can only be destroyed by heating at 160 ℃ for 2 to 4 hours, or boiling with strong alkali, strong acid, or strong oxidant for 30 minutes. The difference from exotoxins is that endotoxins cannot be detoxified by dilute formaldehyde solution to become toxoids; Although injecting endotoxins into the body can produce a certain amount of specific immune products (called antibodies), the effect of these antibodies on counteracting endotoxin toxicity is weak.