11,20-Dihy­droxy-3-oxopregna-1,4-dien-21-oic acid monohydrate

The title compound, C21H28O5·H2O, is the hydrate of a steroid derivative and was obtained by degradation of solid prednisolone sodium phosphate. The six C atoms in ring A are nearly co-planar with a mean deviation of 0.015 A. Rings B and C are both in chair conformations, while ring D has an envelope form. In the crystal, inter­molecular O—H⋯O hydrogen-bonding inter­actions occur between the hy­droxy groups, carbonyl O atoms and solvent water mol­ecules, resulting in an overall three-dimensional structure.