REDUCTION OF ALDOSTERONE BY ANAEROBIC-BACTERIA - ORIGIN OF URINARY 21-DEOXY METABOLITES IN MAN

Aldosterone was incubated with pure cultures of human faecal micro-organisms and the products were analysed as methyloxime/trimethylsilyl ethers by gas chromatography/mass Spectrometry. Clostridium paraputrificum quantitatively reduced the A-ring of aldosterone to a 3α-hydroxy-5β group (tetrahydroaldosterone). In addition, aldosterone was quantitatively 21-dehydroxylated by culture no. 116 and Eubacterium lentum. Metabolism of aldosterone with mixed faecal flora yielded a single metabolite, 21-deoxy-tetrahydroaldosterone, reflecting the enzymatic action of both C. paraputrificum and culture no. 116. It is likely, therefore, that the 21-deoxymetabolites of aldosterone which have been identified in urine are formed by the action of these organisms during the passage of tetrahydroaldosterone through the gut following biliary excretion. The reduced metabolites are reabsorbed prior to urinary excretion. The specificity and high yield of the reactions carried out by these organisms suggest that they will prove useful for small scale production of reference compounds not yet commercially available, since almost all steroids with α-ketol side chain have been shown to be susceptible to transformation. © 1979.