11 beta-substituted steroids, an original pathway to antihormones

11 beta-substituted steroids form a novel class of derivative for the study of ligand-receptor interactions. The present review describes the synthetic pathways leading to 11 beta-substituted norsteroids and the kinetics and specificity of their interaction with receptors of several hormone classes as determined in a routine screening programme. The biochemical data on the interaction of one of these compounds, RU 38486, a potent antihormone presently in clinical development, with the progestin (PR) and glucocorticoid (GR) receptors are briefly reviewed. The comparison of the 3D-structures of these antagonists with those of potent hormones can help to map the interaction sites with PR and GR and highlights the potential use of these molecules as labelling agents and molecular probes.