Estrogen Biosynthesis - 2-Beta-Hydroxy-19-Oxoandrost-4-Ene-3,17-Dione Revisited

Current evidence is consistent with the view that biosynthesis of estrogens by human microsomal placental aromatase proceeds through several different pathways. One of the proposed mechanisms of aromatization of androgens involves the intermediacy of 2beta-hydroxy-19-oxoandrost-4-ene-3,17-dione 1a. It is shown that incubation of 2beta[(OH)-O-18]-1b with placental aromatase gave (HCOOH)-O-18 which differs from previous observations. The incorporation of isotopic oxygen in the formic acid is consistent with the view that one of the alternative routes of estrogen elaboration may involve a 2beta,19-dioxygenated androgen.