Figure 2.

Extracted ion chromatogram of the metabolites formed (m/z 445) by human placental mitochondria as revealed by LC-MS. Incubation of 17HPC in the presence of human placental mitochondria resulted in the formation of 6 metabolites. Three of them were identical to M₁₂, M₁₃, and M₁₅ formed by human placental microsomes as determined by their retention times and mass spectra.⁴ One metabolite was identified as M₁₆′ based on the identical retention time and similar mass spectra of M₁₆′ formed by human placental microsomal fractions.⁴ Metabolite MM was unique to placental mitochondrial fraction. The retention time and mass spectra of M₁₉ were identical to the previously described M₁₉ metabolite formed by human hepatic microsomes.⁴ LC-MS indicates liquid chromatography–mass spectrometry; 17HPC, 17-alpha-hydroxyprogesterone caproate.