The morphine-like and nonmorphine-like conformers of prodine opioids

The compounds alpha-, and beta-prodine and their meta hydroxylated analogs were synthesized, resolved, and screened for affinity at opioid receptor subtypes. The compounds primarily have affinity for mu-receptors. The mu-receptor affinities of the nonmorphine-like (+)-enantiomers, which have the greater antinociceptive activity, are reduced by the presence of a meta hydroxyl while the affinities for all opioid receptor subtypes of the morphine-like, but less active, (-)-enantiomers are enhanced or unchanged. Both enantiomers of meta-hydroxylated beta-prodine had antagonist activity in the guinea pig ileum assay.