Physicochemical properties of bilirubin

Bilirubin is a bile pigment of dimethonol. It is a reddish-brown chromatophore, insoluble in water, difficult to dissolve in alcohol and ether, and easily soluble in alkali. The maximum absorption is 432 nanometers (in alkali) and 540 nanometers. (in chloroform). It is abundant in the bile of humans and carnivores. Blood bilirubin, in the red-purple Hijman van den Bergh reaction that occurs when diazo reagent is added, there are two types: one is the direct type that is positive without adding alcohol, and the other is the direct type that is positive after adding alcohol. Indirect type of color development. The first type is mono- or diglucuronic acid (ester), and the second type is the free type, which is a normal metabolite of hemoglobin. It can be formed through the reduction of biliverdin. If it is further reduced, it will become ethyl through vinyl. In mesobilirubin C30H40O6N, the methine groups are all saturated with hydrogen, forming mesobilirubin (urobilinogen).
Bilirubin is a pigment produced from hemoglobin in red blood cells. Red blood cells have a fixed lifespan (the average lifespan of normal red blood cells is about 120 days) and are destroyed every day. At this time, hemoglobin will decompose into haem and heme. Heme generates biliverdin, trivalent Fe ions and CO under the action of NADPH and H ions, and biliverdin generates bilirubin under the action of NADPH and H ions. Heme is then reformed into tissue protein.
Because bilirubin is toxic, bilirubin forms a bilirubin-albumin complex when it enters the blood. The bilirubin-albumin complex separates into bilirubin and albumin before entering the liver, i.e. indirect bilirubin. After entering the liver, bilirubin will combine with the Y protein and Z protein in the liver to form bilirubin-Y protein and bilirubin-Z protein. This reaction is reversible. Bilirubin-Y protein and bilirubin-Z protein generate glucuronide bilirubin, that is, conjugated bilirubin, under the action of UDP-glucuronide converting enzyme. Conjugated bilirubin enters the small intestine with bile, where it is stripped of glucuronic acid to generate bilirubin again. Bilirubin generates bilirubinogen, which is further oxidized into yellow-brown bile, which is the main color of feces. . The cholinogen in the small intestine can reach the liver again through the enterohepatic circulation, but most of the cholinogen is still excreted into the intestine in its original form. This part is called fecal bilinogen. A small portion of cholinogen enters the systemic circulation and is excreted in the urine. It is one of the sources of urine color and is the main pigment in urine. This part is called urobilinogen.
When red blood cells are destroyed and hemolysis occurs, indirect hyperbilirubinemia occurs. In addition, when liver cells are abnormal, direct and indirect hyperbilirubinemia will be caused. When the bile duct and biliary system are blocked, direct hyperbilirubinemia will be caused. When there are abnormal values, the treatment method is to cooperate with other examination results to truly understand the condition, and then treat the cause of the disease. Depending on the situation, methods such as acute liver failure treatment, hemodialysis, and extrahepatic biliary stasis emergency treatment can be adopted.
Except for newborns, the value for ordinary people is roughly fixed, and there is no difference in age. In addition, diet and exercise will hardly cause changes, but there will be an upward trend after a long period of fasting.