Diosgenone: a second P2(1) polymorph.

ABSTRACT

Diosgenone [(20S,22R,25R)-spirost-4-en-3-one, C(27)H(40)O(3)] has been proposed as a new therapeutic alternative for the treatment of malaria. The first X-ray structure report for diosgenone was by Piro et al. [(2002). Z. Naturforsch. Teil C, 57, 947-950] in the space group P2(1) (Z' = 2). We now report a new polymorph in the same space group, with two mol-ecules in the asymmetric unit. Both mol-ecules have similar conformations, characterized by a skewed envelope A ring, which contains the C=C bond conjugated with the ketone functionality at C3. The dimorphism results from a modification of the relative orientation of the mol-ecules in the asymmetric unit two independent mol-ecules were arranged anti-parallel in the Piro report, while they are parallel in the present determination.