CHEMICAL SYNTHESIS AND SOME BIOLOGICAL PROPERTIES OF THE COENZYME FORMS OF AN ALKANOLAMINE-TYPE B12-ANTIVITAMIN*†

Antivitamins for Medicinal Applications

Antivitamins represent a broad class of compounds that counteract the essential effects of vitamins. The symptoms triggered by such antinutritional factors resemble those of vitamin deficiencies, but can be successfully reversed by treating patients with the intact vitamin. Despite being undesirable for healthy organisms, the toxicities of these compounds present considerable interest for biological and medicinal purposes. Indeed, antivitamins played fundamental roles in the development of pioneering antibiotic and antiproliferative drugs, such as prontosil and aminopterin. Their development and optimisation were made possible by the study, throughout the 20th century, of the vitamins' and antivitamins' functions in metabolic processes. However, even with this thorough knowledge, commercialised antivitamin-based drugs are still nowadays limited to antagonists of vitamins B9 and K. The antivitamin field thus still needs to be explored more intensely, in view of the outstanding therapeutic success exhibited by several antivitamin-based medicines. Here we summarise historical achievements and discuss critically recent developments, opportunities and potential limitations of the antivitamin approach, with a special focus on antivitamins K, B9 and B12 .

High-performance liquid chromatographic separation of cobalamins

Physiological cobalamins were separated by means of high-performance liquid chromatography (HPLC). Optimal conditions for elution of methylcobalamin, adenosylcobalamin, hydroxycobalamin and cyanocobalamin were determined. Excellent separation and resolution of these physiological cobalamins by HPLC were achieved. In addition, several cobalamin analogues were also studied and shown to be separable from the physiological forms. HPLC provides a rapid, sensitive, reproducible means of characterizing physiological cobalamins.