Synthesis of 2-Oxacortexone and its Effect on Ca2+ Uptake in Bovine Spermatozoa

✍ Scribed by Aryeh A. Frimer; Gladis Aljadeff; Sara Rubinstein; Haim Breitart

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 519 KB
• Volume: 330
• Category: Article
• ISSN: 0365-6233
• DOI: 10.1002/ardp.19973300502

✦ Synopsis

Low temperature base catalyzed autoxidation (BCA) of the A-ring of 2 1 -acetoxypregn-5-ene-3,2O-dione 20-ethylene ketal (7) resulted in the saponification of the ester with the concomitant formation of 2,2 1 -dihydroxypregna-1,4-diene-3,2O-dione 20-ethylene ketal(8). Continued BCA at ambient temperature, converts the latter to 1,2 1-dihydroxy-2-oxaprogesterone 20-ethylene ketal (9), which is reduced by NB& to the 2-oxasteroid, 21-hydroxy-2-oxaprogesterone 20-ethylene ketal (10). Treatment of en01 8, lactol 9, and lactone 10 with aqueous acid generates the corresponding deprotected analogs 2,2 1 -dihydroxypregna-1 Pdiene-3.20-dione (enol ll), 1,2 1-dihydroxy-2-oxaprogesterone (lactol 12), and 2-oxacortexone (2-oxadesoxycorticosterone, 2 l-hydroxy-2-oxaprogesterone, lactone 13). In bovine spermatozoa, neither 2-oxasteroid ketal10 nor its deprotected analog 13 stimulated Ca2+ uptake. In high concentration (0.5 mM), the inhibition of Ca2+uptake is only 37% for 13, as compared to 83% found with the parent steroid, cortexone (desoxycorticosterone, 2 1 -hydroxyprogesterone, 5). The difference in molecular structure between 13 and 5 indicates the importance of the oxygen atom in ring A in achieving the protective effect of the steroid. Ketalization of the C-20 carbonyl is not important for protection. Thus it seems that by replacing C-2 by an oxygen atom we can reduce the biological damage caused by relatively high concentrations of steroid treatment. These results are highly significant when treatment of patients with high doses of steroids is considered.