摘要：The effect of bile alcohols on the microbial 7α-dehydroxylation of chenodeoxycholic acid was investigated. Bile alcohols isolated from urine of patients with cerebrotendinous xanthomatosis were added to anaerobic incubations of rat faecal microflora or isolated 'Strain II' with [14C]chenodeoxycholic acid, and the formation of labelled metabolites was measured by high-performance liquid chromatography after 7 d of incubation. The 7α-dehydroxylation by rat faecal microflora was inhibited by bile alcohols but not by bile acids. The inhibition started at a concentration of about 0.1 mM and was eight fold at 0-2 mM. In some experiments it was accompanied by an increased formation of 3α-hydroxy-7-oxo-5β-cholanoaicci d. The 7α-dehydroxylation by isolated 'Strain II' was stimulated by bile alcohols and cholic acid at concentrations of 0.05-0.2 mM. 5β-Cholane-3α,7α,12α,24-tetrol inhibited 7α-dehydroxylation in cultures of both rat faecal flora and isolated 'Strain II'. Bile alcohols at concentrations of 0.40.6 mM inhibited growth of isolated 'Strain IT. The results indicate that the low percentage or absence of deoxycholic acid in patients with cerebrotendinous xanthomatosis is due to an inhibitory action of the bile alcohols present in these patients on microbial 7α-dehydroxylation.Keywords: Bile alcohols; Bile acids; 7α-dehydroxylation; Intestinal bacteria.
