IN-VITRO SYNTHESIS OF 17,20-BETA,21-TRIHYDROXY-4-PREGNEN-3-ONE BY OVARIES OF TURBOT (SCOPHTHALMUS-MAXIMUS L) DURING OOCYTE MATURATION

Ovaries from female turbot (Scophthalmus maximus L.), a serial spawner , were incubated in vitro with 17-hydroxy[1,2,6,7-H-3]progesterone or [7-H-3(N)]pregnenolone (P-5-H-3) during the spawning season. Several m etabolites comigrated on TLC and HPLC with known reference steroids an d were identified after chemical reaction and crystallization. Incubat ion with P-5-H-3 generated many 4-ene steroids, accounting for 55% of total radioactivity, indicating strong 3 beta-HSD activity. The major steroids produced by ovaries were testosterone, androstenedione, and 1 7,21-dihydroxy-4-pregnene-3,20-dione. In addition, 17,20 alpha-dihydro xy-4-pregnen-3-one was also identified, while small quantities of 17,2 0 beta,21-trihydroxy-4-pregnen-3-one (20 beta-S) (maximum 1.7% of the total radioactivity) were also synthesized. The identity of 20 beta-S was confirmed in incubates with nonlabeled 17-hydroxyprogesterone by m ass spectrometry. Production of 17,20 beta-dihydroxy-4-pregnen-3-one w as not apparent. (C) 1997 Academic Press.