title: Aromatization of 15 alpha and 16 alpha hydroxylated androgens in the human placental using [1,2-3H]-substrates.
abstract: This in vitro study reports data on the aromatization of [1,2-3H]-C19 steroids in the human term placenta [androstenedione (III), testosterone (IV), 15 alpha-hydroxy-androstenedione (V), 15 alpha-hydroxy-testosterone (VI), 16 alpha-hydroxy-androstenedione (VII)]. The hydroxylated androgens were microbiologically synthesized from commercially radiolabelled [1,2-3H]-androstenedione and testosterone. Androstenedione and testosterone were good substrates for the human placental aromatase (low Km values, high Vmax); they strongly inhibited the 15 and 16 hydroxylated androgens aromatizations. On the other hand, these hydroxylated compounds acted as poor substrates and were only non-competitive inhibitors of the androstenedione and testosterone aromatizations. However, 15 alpha-hydroxy-androstenedione could not be disregarded as a potential precursor of 15 alpha-hydroxylated estrogens in the human placenta.
mesh_terms: D000728:Androgens / Q000378:metabolism*; D000735:Androstenedione / Q000378:metabolism; D001141:Aromatase / Q000378:metabolism; D004953:Estetrol / Q000096:biosynthesis; D005260:Female; D006801:Humans; D006900:Hydroxylation; D066298:In Vitro Techniques; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D013739:Testosterone / Q000378:metabolism
chemical_list: D000728:Androgens; D013739:Testosterone; D000735:Androstenedione; D001141:Aromatase; D004953:Estetrol