Dihydroxyoxocholestenoic acids are intermediates in bile acid biosynthesis. Here, using liquid chromatography – mass spectrometry, we confirm the identification of 7α,24-dihydroxy-3-oxocholest-4-en-26-oic and 7α,25-dihydroxy-3-oxocholest-4-en-26-oic acids in cerebrospinal fluid (CSF) based on comparisons to authentic standards and of 7α,12α-dihydroxy-3-oxocholest-4-en-26-oic and 7α,x-dihydroxy-3-oxocholest-4-en-26-oic (where hydroxylation is likely on C-22 or C-23) based on exact mass measurement and multistage fragmentation. Surprisingly, patients suffering from the inborn error of metabolism cerebrotendinous xanthomatosis, where the enzyme CYP27A1, which normally introduces the (25 R)26-carboxylic acid group to the sterol side-chain, is defective still synthesise 7α,24-dihydroxy-3-oxocholest-4-en-26-oic acid and also both 25 R- and 25 S-epimers of 7α,12α-dihydroxy-3-oxocholest-4-en-26-oic acid. We speculate that the enzymes CYP46A1 and CYP3A4 may have C-26 carboxylase activity to generate these acids. In patients suffering from hereditary spastic paraplegia type 5 the CSF concentrations of the 7α,24- and 7α,25-dihydroxy acids are reduced, suggesting an involvement of CYP7B1 in their biosynthesis in brain.

二羟基氧胆甾烯酸是胆汁酸生物合成的中间体。在这里，使用液相色谱-质谱法，我们确认了7α，24-二羟基-3-oxocholest-4-en-26-oic和7α，25-二羟基-3-oxocholest-4-en-26-oic酸的鉴定根据与真实标准品和7α，12α-二羟基-3-oxocholest-4-en-26-oic和7α，x-二羟基-3-oxocholestest-4-en-26-oic（ （根据C-22或C-23可能会发生羟基化反应）。令人惊讶的是，患有先天性代谢性脑黄瘤病的患者，其中通常将（25 R）26-羧酸基团引入固醇侧链的CYP27A1酶仍存在缺陷，仍会合成7α，24-dihydroxy-3-oxocholestest-4-en-26-oic acid以及7α，12α-dihydroxy-3-oxocholestest-4-en-26-oicacid的25个R-和25 S-受体。我们推测酶CYP46A1和CYP3A4可能具有C-26羧化酶活性以生成这些酸。在患有5型遗传性痉挛性截瘫的患者中，7α，24-和7α，25-二羟基酸的CSF浓度降低，表明CYP7B1参与了大脑的生物合成。