CONFORMATIONAL STUDIES OF VITAMINS D DERIVATIVES. Kinga Suwinska and Andrzej Kutner, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland Pharmaceutical Research Institute, Warsaw, Poland

The fat-soluble vitamins D play essential role in stimulation of intestinal calcium transport, bone calcification, bone calcium mobilization, and phosphate transport as well as stimulation of cell differentiation and inhibition of cell proliferation. Vitamins D2 and D3 were found to exist in two almost equimolar equilibrium conformations in both liquid and solid states. The biologically active form of vitamin D3 1,25-hydroxylated derivative was found to exist in solid state as the beta conformer only [1]. To explain the influence of 1-hydroxy substituent on the conformation of the vitamins D the 1-hydroxy vitamin D2 and 1-hydroxy vitamin D3 was crystallized and the structures of those two compounds were solved. For both compounds only one conformer was found in the solid state. The results of crystal structure determinations were compared with the semi-empirical calculations and will be discussed.

1. Suwinska K., Kutner A. (1996). Acta Cryst. B. in press.