EXISTENCE OF VITAMIN-B12 ANALOGS IN BIOLOGICAL SAMPLES - A REALITY

Due to the fact that the existence of vitamin B12 analogs in biological materials has been much debated, we realized on plasma, bile, and feces series of experiences to demonstrate that analogs assayed by radioisotopic method in these biological media using intrinsic factor and haptocorrin as binders could not be extraction products or dosage artifacts. To this purpose, exposure to light was used to transform all corrinoids (true B12 + analogs) to their hydroxo forms. After that all corrinoids were transformed with KCN by cyanilation to their cyano forms. This permitted us to separate corrinoids on high performance liquid chromatography into only two peaks. These peaks will be subsequently identified by radioisotopic dilution assay as cyanocobalamin alpha and/or beta cyanocobinamides. Because the binding ability of an intrinsic factor to corrinoids is limited to its cobalamin forms, our method enabled us to emphasize the existence in biological materials of corrinoids that only recognize haptocorrin (analogs of vitamin B12) and not intrinsic factors.