Crystal structure of 25-hydroxy-vitamin D3 monohydrate: a stereochemical analysis of vitamin D molecules

Abstract

A three-dimensional X-ray diffraction study on the monohydrate of the 25-hydroxy-vitamin D₃, the predominant metabolite of vitamin D₃ in the blood and the immediate precursor of 1α,25-dihydroxy-vitamin D₃, has provided the first high-precision molecular parameters for this class of molecules. A detailed comparative analysis of the solid state conformations of the rings and side-chain is made with those of other stucturally known vitamin D molecules, and the resulting stereochemical implications are discussed with respect to biological activities of various metabolites and active analogues. Crystals are monoclinic with Z= 2 in a unit cell of space group P2₁ and dimensions a= 10.600(1), b= 6.798(1), c= 18.142(2)Å, β= 103.75(2)°. The structure was solved by direct methods and refined to R 3.4% based on 2 012 independent intensities.