Studies On The Biotransformation Of 3β-Hydroxy-5-ene Steroidal Oximes By Mucor Silvaticus And Antitumor Activities

The investigations were undertaken of the microbial transformation of synthesized 3β-hydroxy-5-ene steroidal oximes with Mucor silvaticus, the biotransformation products were separated on silica gel column chromatography, the characterizations of the metabolites were identified by various spectroscopic methods and detected the antitumor activity of oxime derivatives of steroid on the LTEP-α-2 cell.This research afforded oxime derivatives of hydroxyl steroids, which provided the material foundation and the theoretical basis for the research and exploitation of new drugs, with great importance in application.3β-hydroxy-5-ene steroidal oximes were transformed with Mucor silvaticus.The products were separated on silica gel column chromatography. The characterizations of the metabolites were performed by various spectroscopic methods such as IR, 1H NMR, 13C NMR and 2D-NMR. The complete assignments of 13C NMR chemical shifts of these compounds were obtained, and the spectrum characterization of 7α,11β-dihydroxypregnenolone oxime was also analyzed in details.The biotransformations of 3β-hydroxy-5-ene steroidal oximes by Mucor silvaticus were carried out, in which the steroidal oximes mainly took place 7α-hydroxylation. 7α, 11α-dihydroxylation and hydrolyzation occurred in the transformation of pregnenolone oxime and 16-dehydro-pregnenolone oxime. A new stable 5-membered heterocyclic compound was obtained from the dehydration of hydroxyimino group with the hydroxyl group which resulted from hydrolization of 16α, 17α-epoxy in the biotransformation of 16α, 17α-epoxy-progesterone oxime.The results obtained in biotransformations of 3β-hydroxy-5-ene steroidal oximes indicated that the presence of C5-C6 double bond had a significant impact on the positions of hydroxylation, which mainly 7α-hydroxylated. Substrates were easily hydroxylated at 11αposition, depending on the stereo-hindrance of the acetyloxime at C-17 position. The C16-C17 double bond took no effect on the position of hydroxylation, while the interaction of 16α, 17α-epoxy with acetyloximel interferred the hydroxylation in C-ring and D-ring.The antitumor activity of oxime derivatives of steroid on the LTEP-α-2 cell was detected by MTT colorimetric assay. The results showed that the inhibitory effect of LTEP-α-2 cell strengthened with the increasing of concentration of the steroidal oximes. The antitumor activity of steroidal oximes was related to their chemical structures. The introduction of hydroxyl group decreased the antitumor activity of steroidal oximes. 16-dehydropregnenolone oxime could strongly inhibit the proliferation of LTEP-α-2 cell, which IC50 was 11.6μg/ml.