Studies On The Biotransformation Of 4-Ene-3-One Steroids By Mucor Genevensis And Antitumor Activities

In this thesis, the biotransformation of 4-ene-3-one and 3-hydroxyl-5-ene steroids were studied by Mucor genevensis which was screened from 20 fungal strains purchased. The strain Mucor genevensis had the capability of biotransformation of steroids with high selectivity. The antitumor activities of the biotransformation products on the HepG2 cell line were detected.The studies on the biotransformation of 4-ene-3-one steroids in the Mucor genevensis AF 93221 culture were undertaken. The results showed that the Mucor genevensis strain was a suitable biocatalyst for hydroxylations at some specific sites in steroids. The biotransformation products obtained were predominantly hydroxylation at the 7αposition, and the 6β-, 14α-hydroxylation of steroids, reduction of 20-carbonyl group of 16α,17α-epoxy-progesterone were also observed. The relationships between the substrate structures and the hydroxylated positions had been discussed in detail. The hydroxylation positions and configuration of the biotransformation products depended on the structure of the substrate. The adaptable conditions for the biotransformation were determined.The biotransformation of 3-hydroxyl-5-ene steroids by Mucor genevensis AF 93221 were carried out.The results showed that the substrates were mainly hydroxylated at the C-7αposition, the mixtures of 7α-, 11α-, 11β-hydroxyl and 7-oxo derivatives were formed. 7α-OH-DHEA and 7-OXO-DHEA were obtained from the biotransformation products of DHEA. The biotransformation products of pregnenolone were 7α,11α-dihydroxypregnenolone and 7α,11β-dihydroxypregnenolone, which were isomeric structures.The biotransformation products were separated on silica gel column chromatography. The characterization of the metabolites was performed by various spectroscopic methods such as IR, MS, 1H NMR, 13C NMR and 2D-NMR.The spectrum characterization of compound 14 and 17 was analysed in detail.The antitumor activities of twelve biotransformation products on the HepG2 cell line were detected by MTT colorimetric assay. The results showed that the antitumor effects of the hydroxylated steroids were related to their chemical structures.Compound 17 had definite Inhibition (IC50) on HepG2 cell, which was 60.8μg/mL.The research work will expend the applications of Mucor genevensis, the hydroxyl steroid derivatives from the biotransformation can be used for the research and exploitation of new drugs, which is of great importance in application.