Nestorone Metabolites

Name Structure Notes
Segesterone (17α-deacetylnestorone) structure Minor metabolite. Also a degradant (see Nestorone Impurity 13). HPLC and MS.
4,5-dihydro-17α-deacetylnestorone structure Major metabolite as identified by Prasad et al. (19 total metabolites found but only 2 identified). HPLC and MS.
3β,5α-tetrahydronestorone structure Most abundant metabolite in mouse plasma at 1 h post administration.
3α,5α-tetrahydronestorone structure 120 times less potent PR activity than Nestorone in human PR (hPR) transactivation assay (EC50 = 24 pM for NES vs. 2850 pM for metabolite). GC/MS-MS.
5α-dihydronestorone structure Identified in vitro, detected in plasma and brain of mice. Most abundant metabolite in mouse brain at 30 min post administration. 17 times less potent PR activity than nestorone in human PR transactivation assay (EC50 = 410 pM vs. EC50 of Nestorone = 24 pM).