Steroidal free radicals as possible intermediates in the biosynthesis of C19-delta 16-steroids.
Treatment of deoxycorticosterone with reagents that abstract a hydrogen atom from the C-21-hydroxyl group leads to the formation of androsta-4,16-dien-3-one. In vitro incubations of [1,2-(3)H]deoxycorticosterone with homogenates of boar testis tissue produce the tritiated dienone. This reaction can be formulated as an abstraction of hydrogen from the C-21-hydroxyl group to form a C-21-alkoxy radical, followed by a 1,5-H.shift from the C-16 atom and beta-scission of the C-16-alkoxy radical leading to the loss of a C(2) fragment (C-20 and C-21) with the formation of the double bond between C-16 and C-17. Both the chemical model and the in vitro experiment support further the thesis [Lieberman, S., L. Bandy, V. Lippman, and K. D. Roberts, Biochem. Biophys. Res. Commun., 34, 367 (1969)] that biosynthetic reactions in which molecular oxygen reacts with steroids (for example, side-chain cleavage or hydroxylation) involve steroidal free radicals.
D000731:Androstanes / Q000096:biosynthesis; D000818:Animals; D001711:Biotransformation; D002855:Chromatography, Thin Layer; D003900:Desoxycorticosterone / Q000378:metabolism*; D005609:Free Radicals / Q000378:metabolism; D066298:In Vitro Techniques; D007854:Lead; D008297:Male; D008956:Models, Chemical; D011284:Pregnenolone / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism; D013256:Steroids / Q000096:biosynthesis*; D013552:Swine; D013737:Testis / Q000378:metabolism*; D014316:Tritium
D000731:Androstanes; D005609:Free Radicals; D013256:Steroids; D014316:Tritium; D007854:Lead; D003900:Desoxycorticosterone; D011374:Progesterone; D011284:Pregnenolone