Cycobalamin is one of vitamin B complexes, which has a strong anti-pernicious anemia effect. It is the name given by the crystallization of vitamin B12, an indispensable factor for the development of bacteria and animals. Besides C, H, O, N, P and Co, the a-D- ribose conjugate of 5,6-dimethe-rbenzimidazole is a part of its structure. A. R. Todd et al. put forward the structural formula, which is called cyanocobalamin because cyano is coordinated on cobalt. The maximum absorption in aqueous solution is 278,361,548 nm. In 1948, E．L．Rickes of the United States and E．L．Smith of the United Kingdom independently extracted crystals from the liver. Since then, this substance has also been obtained from a certain actinomycete (StrePtomyces griseum).
Cyanocobalamin is also the growth factor of pigs and chicks, and it is the same substance as the animal protein factor necessary for egg hatching. Vitamin B12, given to patients with malignant diseases at 150 micrograms, can increase red blood cells by about 2 times, and 3-6 micrograms can also produce effects. In vivo, it is transported in the blood in the form of combination with trans-cobalamin protein (a- globular protein), and exists in the form of coenzyme in various tissues. Together with folic acid, it is involved in the metabolism of methyl transfer and active methyl generation. And become the essential factor of purine, pyrimidine and other biosynthesis.