Structural and biosynthetic studies of a principal bile alcohol, 27-nor-5beta-cholestane-3alpha,7alpha,12alpha,24,25-pentol, in human urine

The stereochemistry at C-24 and C-25 of 27-nor-5beta-cholestane-3alpha,7alpha,12alpha,24 ,25-pentol, a principal bile alcohol in human urine, and its biosynthesis are studied. Four stereoisomers of the C(26)-24,25-pentols were synthesized by reduction with LiAlH(4) of the corresponding epoxides prepared from (24S)- or (24R)-27-nor-5beta-cholest-25-ene-3alpha, 7alpha,12alpha,24-tetrol. The stereochemistries at C-25 were deduced by comparison of the C(26)-24,25-pentols with the oxidation products of (24Z)-27-nor-5beta-cholest-24-ene-3alpha,7alpha, 12alpha-triol with osmium tetraoxide. On the basis of this assignment, the principal bile alcohol excreted into human and rat urine was determined to be (24S,25R)-27-nor-5beta-cholestane-3alpha,7alpha, 12alpha,24,25-pentol, accompanied by a lesser amount of (24R, 25R)-isomer. To elucidate the biosynthesis of the C(26)-24,25-pentol, a putative intermediate, 3alpha,7alpha, 12alpha-trihydroxy-27-nor-5beta-cholestan-24-one, derived from 3alpha,7alpha, 12alpha-trihydroxy-24-oxo-5beta-cholestanoic acid by decarboxylation during the side-chain oxidation of 3alpha,7alpha, 12alpha-trihydroxy-5beta-cholestanoic acid, was incubated with rat liver homogenates. The 24-oxo-bile alcohol could be efficiently reduced to yield mainly (24R)-27-nor-5beta-cholestane-3alpha,7alpha, 12alpha,24-tetrol. If a 25R-hydroxylation of the latter steroid occurs, it should lead to formation of (24S,25R)-C(26)-24,25-pentol. Now it has appeared that a major bile alcohol excreted into human urine is (24S,25R)-27-nor-5beta-cholestane-3alpha,7alpha, 12alpha, 24, 25-pentol, which might be derived from 3alpha,7alpha, 12alpha-trihydroxy-27-nor-5beta-cholestan-24-one via (24R)-27-nor-5beta-cholestane-3alpha, 7alpha,12alpha,24-tetrol.     

Occurrence of both (25R)- and (25S)-3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acids in urine from an infant with Zellweger's syndrome

Urine from a patient with Zellweger's syndrome was examined for bile acids after fractionation into three groups according to mode of conjugation. 3 alpha,7 alpha,12 alpha-Trihydroxy-5 beta-cholestanoic acid was the predominant bile acid of the unconjugated and glycine-conjugated bile acid fractions. Smaller amounts of cholic acid and 1 beta-, 6 alpha-, 24-, and 26-hydroxylated derivatives of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid were found in both fractions in similar proportions. The bile acid spectrum of the taurine-conjugated bile acid fraction was different from those of the other two fractions in the occurrence of two new compounds as the major constituents. These compounds were tentatively identified as two epimers at C-23 of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestano-26,23-lactone, which were probably artifacts formed from the corresponding tetrahydroxycholestanoic acids during the procedures for extraction after hydrolysis. High-performance liquid chromatographic analysis revealed that 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid excreted into the urine as the unconjugated form consisted of a mixture of (25R)- and (25S)-isomers in the ratio of about 7:3.     

Identification of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25,26-hexol in human urine

A new bile alcohol, 5 beta-cholestanehexol, was identified in the urine of healthy humans as the glucuronide. The bile alcohol glucuronide fraction was isolated by an ion exchange chromatography on piperidinohydroxypropyl Sephadex LH-20. After enzymatic hydrolysis, the bile alcohols were converted into trimethylsilyl ether derivatives and analyzed by a combination of gas-liquid chromatography and mass spectrometry. The major bile alcohol was 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol. As minor constituents the following C26 and C27 bile alcohols were identified: 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25,26-hexol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,26-pentol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol. In addition to these bile alcohols, a new bile alcohol was identified as a sixth component of the urinary bile alcohols. The structure was assigned as (24S)-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25,26-hexol by the direct comparison of mass spectral data and chromatographic properties with synthetic standard. The average daily excretion of the new bile alcohol was 28.6 micrograms and 3.0% of the total bile alcohols. The presence of 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol and 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25,26-hexol suggests that 26-hydroxylation of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol is most likely for the biosynthesis of this new bile alcohol.     

Absolute configuration at carbon 23 of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol excreted by patients with cerebrotendinous xanthomatosis

Absolute configuration at C-23 of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,23,25-pentol, one of the bile alcohols isolated from the patients with cerebrotendinous xanthomatosis, was unequivocally determined as 23S by conversion of a key intermediate, (23S)-5 beta-cholest-25-ene-3 alpha,7 alpha,12 alpha,23-tetrol to either the bile alcohol of known absolute configuration, (23R)-5 beta-cholestane-3 alpha,7 alpha,12 alpha,23-tetrol, or the naturally occurring 23,25-pentol.     

Identification of 3 alpha, 6 alpha, 7 alpha, 12 alpha-tetrahydroxy-5 beta-cholestanoic acid in Zellweger's syndrome

In order to confirm the occurrence of 3 alpha, 6 alpha, 7 alpha, 12 alpha-tetrahydroxy-5 beta-cholestanoic acid in Zellweger's syndrome, the nature of tetrahydroxycholestanoic acids present in a patient with this disease was studied. Urinary bile acids were extracted with a Sep-pak C18 cartridge and methylated after alkaline hydrolysis. The methyl esters were purified by silica gel column chromatography, and the methyl tetrahydroxycholestanoate fraction was analyzed by gas liquid chromatography-mass spectrometry. Along with already known side chain hydroxylated derivatives of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid, 3 alpha, 7 alpha, 12 alpha, 24- and 3 alpha, 7 alpha, 12 alpha, 26-tetrahydroxy-5 beta-cholestanoic acids, three nuclear hydroxylated derivatives of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid were found. One of them was identified as 3 alpha, 6 alpha, 7 alpha, 12 alpha-tetrahydroxy-5 beta-cholestanoic acid by direct comparison with the authentic standard which was chemically synthesized from 3 alpha, 6 alpha, 7 alpha, 12 alpha-tetrahydroxy-5 beta-cholanoic acid by side chain elongation.     

Bile alcohol profiles in bile, urine, and feces of a patient with cerebrotendinous xanthomatosis

Bile alcohols in bile, urine, and feces of a patient with cerebrotendinous xanthomatosis have been analyzed by a combination of capillary gas-liquid chromatography and mass spectrometry after fractionation into groups according to mode of conjugation. The presence of at least 18 bile alcohols, which were excreted mainly as glucurono-conjugates in bile and urine, and as unconjugated forms in feces, was demonstrated. The following bile alcohols were identified with certainty by direct comparison with reference compounds: 5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol; (23R)-5 beta-cholestane-3 alpha,7 alpha,12 alpha,23-tetrol; 5 alpha- and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24-tetrols; 5 alpha- and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrols; 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol; (22R)-5 beta-cholestane-3 alpha,7 alpha,12 alpha,22,25-pentol; (23R)- and (23S)-5 beta-cholestane-3 alpha,7 alpha, 12 alpha,23,25-pentols; 3 alpha,12 alpha,25-trihydroxy-5 beta-cholestane-7-one; (24R)- and (24S)-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentols; 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol. Although the bile alcohol profile in urine was quite different from those in bile and feces, the determination of urinary bile alcohols as well as of biliary and fecal bile alcohols could be used for diagnosis of cerebrotendinous xanthomatosis.     

Identification of pentahydroxy bile alcohols in cerebrotendinous xanthomatosis: characterization of 5beta-cholestane-3alpha, 7alpha, 12alpha, 24xi, 25-pentol and 5beta-cholestane-3alpha, 7alpha, 12alpha, 23xi, 25-pentol.

This paper describes studies dealing with the nature of the C27 pentahydroxy bile alcohols present in the bile and feces of two patients with cerebrotendinous xanthomatosis (CTX). The presence of a bile alcohol having the structure 5beta-cholestane-3alpha,7alpha,12alpha,24alpha,25-pentol was confirmed by separation of the two 24-hydroxy epimers of 5beta-cholestane-3alpha,7alpha,12alpha,24,25-pentol and characterization of the dpimers by gas-liquid chromatography and infrared and mass spectrometry. Tentative assignment of the 24alpha and 24beta configuration was made on the basis of molecular rotation differences. A second major bile alcohol excreted by the CTX subjects was 5beta-cholestane-3alpha,7alpha,12alpha,23xi,25-pentol. Its structure was determined by infrared spectrometry, proton magnetic resonance spectrometry, and mass spectrometry because a reference compound was not available.     

Configurational assignment of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23, 25-pentol excreted by patients with cerebrotendinous xanthomatosis (a circular dichroism study).

The absolute configuration of the C27 pentahydroxy bile alcohol present in bile and feces of two patients with cerebrotendinous xanthomatosis (CTX) was determined by circular dichroism (CD) spectroscopy. Under anhydrous conditions CD spectra of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23, 25-pentol in the presence of Eu (fod) 3[tris (1, 1, 1, 2, 2, 3, 3-hepta fluoro-7, 7-dimethyl-octane-4, 6-dionato) europium (III)] exhibited a large induced split Cotton effect at ca. 310 nm. From the induced circular dichroism of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23, 25-pentol with Eu(fod) 3 it was concluded that the CTX bile alcohol has the 1, 3 glycol structure with carbon 23 having the R configuration. This information will be useful in elucidating a structural mechanism for the conversion of 5 beta-cholestranepentols into bile acids in man and rat.     

C26-analogs of naturally occurring bile alcohols-II. Preparation of 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,23-tetrols (23R and 23S) and 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,26-tetrols (25R and 25S) by a hydroboration procedure

A convenient procedure for the synthesis of 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,23-tetrol (23R and 23S) and 24-nor-5 beta-cholestane-3 alpha,7 alpha,12alpha,26-tetrol (25R and 25S) starting from 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol was developed. Dehydration of 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha, 25-tetrol with glacial acetic acid and acetic anhydride yielded a mixture of 24-nor-5 beta-cholest-23-ene-3 alpha,7 alpha,12 alpha-triol and the corresponding delta 25 compound. Hydroboration and oxidation of the mixture of unsaturated nor-triols resulted in the formation of 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,23-tetrols (23R and 23S) and 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,26-tetrols (25R and 25S). In addition, smaller amounts of 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,22 xi-tetrol and 24-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha-triol were also obtained. The C26 bile alcohols epimeric at C-23 and C-25 were resolved by analytical and preparative TLC and characterized by gas-liquid chromatography and mass spectrometry. Provisional assignment of the configurations of the C-23 and C-25 hydroxyl groups were made on the basis of molecular rotation differences. These C26 alcohols will be used to test the stereospecificity of the hepatic enzymes that promote oxidation of the cholesterol side chain.     

Synthesis and structure of 26 (or 27)-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24S,25 xi-pentol isolated from the urine and feces of a patient with sitosterolemia and xanthomatosis

The urine and feces of a patient with the rare inherited lipid storage disease, sitosterolemia and xanthomatosis, were analyzed. Substantial quantities of C26-bile alcohol, 26 (or 27)-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24S,25 xi-pentol along with 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24-tetrol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25-tetrol, 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24R,25-pentol, and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol were found. The structure of the C26-bile alcohol was confirmed by direct comparison (gas-liquid chromatography-mass spectrometry and thin-layer chromatography) with a standard sample synthesized from cholic acid. The configurational assignment at C-24 was determined by lanthanide-induced circular dichroism Cotton effect measurements. The increased excretion of these C26- and C27-bile alcohols suggests an abnormality of bile acid biosynthesis in this disease.     

Synthesis of 3 alpha,7 alpha,12 alpha,25-tetrahydroxy-5 beta-cholestan-24-one, an intermediate in the 25-hydroxylation pathway of cholic acid biosynthesis from cholesterol

This paper describes the chemical synthesis of 3 alpha,7 alpha,12 alpha,25-tetrahydroxy-5 beta-cholestan-24-one via selective oxidation of 5 beta-cholestane-3 alpha,7 alpha,12 alpha, 24 xi,25-pentol with silver carbonate on celite. The structure of this 24-keto bile alcohol was confirmed by gas-liquid chromatography and mass spectrometry. Synthesis of this compound via pyridinium chlorochromate oxidation of the triacetoxy derivative of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24 xi,25-pentol followed by saponification further established its structure. 3 alpha,7 alpha,12 alpha,25-Tetrahydroxy-5 beta-cholestan-24-one was required for the in vivo and in vitro studies of side-chain oxidation and cleavage in the 25-hydroxylation pathway of cholic acid biosynthesis.     

New bile alcohols - synthesis of (22R)- and (22S)-5beta-cholestane-3alpha,7alpha,12alpha,22,25-pentols.

The synthesis of (22R)- and (22S)-5beta-cholestane-3alpha,7alpha,12alpha,22,25-pentols is described. Bisnorcholyl aldehyde was prepared from cholic acid and converted into the cholestane-pentols by a Grignard reaction with 3-methyl-3-(tetrahydropyran-2-yloxy)-butynylmagnesium bromide followed by hydrogenation and acid hydrolysis. One of the synthetic pentols, the 22R-isomer was identical with a metabolite of 5beta-cholestane-3alpha,7alpha,25-triol formed in the rabbit.     

Synthesis of 5beta-cholestane-3alpha, 7alpha, 12alpha, 25-tetrol and 5beta-cholestane-3alpha, 7alpha, 245, 25-pentol.

This paper describes syntheses of 5beta-cholestane-3alpha, 7alpha, 12alpha, 25-tetrol and 5beta-cholestane-3alpha, 7alpha, 12alpha, 24xi, 25-pentol which give higher yields than previously published methods. In addition, 5beta-cholestane-3alpha, 7alpha, 12alpha, 24xi, 25-pentol was synthesized by a different procedure, namely via performic acid oxidation of the correspinding unsaturated triol, which gave a lower yield but avoided the formation of 5beta-cholestane-3alpha, 7alpha, 12alpha, 25, 26-pentol, which normally tends to contaminate the final product. Structures were confirmed by gas-liquid chromatography, infrared-, proton magnetic resonance- and mass spectrometry, 5beta-Cholestane-3alpha, 7alpha, 12alpha, 25-tetrol and 5beta-cholestane-3alpha, 7alpha, 12alpha, 24xi, 25-pentol were required for in vivo and in vitro studies of the (hypothetical) 25-hydroxylation pathway of cholic acid biosynthesis.     

Identification of 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24 xi, 25 xi,26-hexol and partial characterization of the bile alcohol profile in urine

The nature of the bile alcohols present in urine of an infant with neonatal cholestasis has been investigated. Urine was extracted with Sep-Pak C18 cartridges and a glucuronide fraction was isolated by ion exchange chromatography on Lipidex-DEAP. Following enzymatic hydrolysis and purification on Lipidex-DEAP, the bile alcohols were isolated by high performance liquid chromatography. Fourteen compounds were studied by a combination of microchemical reactions and capillary column gas-liquid chromatography-mass spectrometry. Both C26 and C27 bile alcohols were present. Among the former, three additional isomers of the previously identified 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24 xi,25 xi-pentol were detected. A new C26 bile alcohol, 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24 xi,25 xi,26 -hexol, was identified, and a 27-norcholestane-pentolone with hydroxyl groups at C-24 and C-25 and a keto group in the ring system was partially characterized. The C27 bile alcohols consisted of cholestanepentols, -tetrolones, and -pentolones. 5 beta-Cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol (5 beta-bufol), one of its isomers and an isomer of cholestane-3,7,12,24,26-pentol were present. Two cholestanetetrolones and two cholestanepentolones having the keto group in the ring system were partially characterized. The hydroxyl groups in the side chain of the tetrolones were at C-24,26 and C-25,26, respectively, whereas the pentolones had hydroxyl groups at C-24,25 and C-25,26, respectively. The excretion of glucuronidated bile alcohols in urine is suggested to reflect an alternative metabolism of intermediates in the normal biosynthesis of bile acids.     

Identifications of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23 beta-tetrol, 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 24 alpha-tetrol, and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 24 beta-tetrol in cerebrotendinous xanthomatosis

The bile alcohols present in the feces of a patient with cerebrotendinous xanthomatosis were studied. Three bile alcohols which are different from any known natural bile alcohol were isolated as minor components of the fecal bile alcohol fraction. The structures of these compounds were established as 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23 beta-tetrol, 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 24 alpha-tetrol, and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 24 beta-tetrol by comparison with synthetic samples.     

Conversion of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 26-tetrol into 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid by rabbit liver mitochondria

Rabbit liver mitochondria in the presence of NAD+ were found to catalyze the conversion of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 26-tetrol into 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid. The peroxisomal fraction did not catalyze the reaction. Sonication of the mitochondria or dialysis overnight against a hypotonic buffer increased the rate of oxidation twofold. Most of the enzyme activity was recovered in the supernatant fraction after centrifugation at 100,000xg of sonicated mitochondria. 4-Heptylpyrazole, an inhibitor of cytosolic ethanol dehydrogenase, inhibited the mitochondrial formation of 3 alpha, 7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid by 70%. Disulfiram, an inhibitor of cytosolic acetaldehyde dehydrogenase, did not inhibit the reaction. The role of the mitochondrial dehydrogenase system in bile acid biosynthesis is discussed.     

Identification of new C27 and C24 bile acids in the bile of Alligator mississippiensis

Biliary bile acids of Alligator mississippiensis were analyzed by gas-liquid chromatography-mass spectrometry after fractionation by silica gel column chromatography. It was shown that the alligator bile contained 12 C27 bile acids and 8 C24 bile acids. In addition to the C27 bile acids, such as 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid, 3 alpha,7 alpha,12 alpha-trihydroxy-5 alpha-cholestanoic acid, 3 alpha,7 alpha-dihydroxy-5 beta-cholestanoic acid, 3 alpha,12 alpha-dihydroxy-5 beta-cholestanoic acid, 7 alpha,12 alpha-dihydroxy-3-oxo-5 beta-cholestanoic acid, and 3 alpha,12 alpha-dihydroxy-7-oxo-5 beta-cholestanoic acid, identified previously in the bile of A. mississippiensis, 3 alpha,7 beta-dihydroxy-5 beta-cholestanoic acid, 3 alpha,7 beta,12 alpha-trihydroxy-5 beta-cholestanoic acid, 7 beta,12 alpha-dihydroxy-3-oxo-5 beta-cholestanoic acid, 3 alpha,7 alpha,12 alpha,24-tetrahydroxy-5 beta-cholestanoic acid, 3 alpha,7 alpha,12 alpha,26-tetrahydroxy-5 beta-cholestanoic acid, and 1 beta,3 alpha,7 alpha,12 alpha-tetrahydroxy-5 beta-cholestanoic acid were newly identified. And in addition to the C24 bile acids, such as chenodeoxycholic acid, ursodeoxycholic acid, cholic acid, and allocholic acid, identified previously, deoxycholic acid, 3 alpha,7 alpha-dihydroxy-5 beta-chol-22-enoic acid, 3 alpha,7 alpha,12 alpha-trihydroxy-5 alpha-chol-22-enoic acid, and 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-chol-22-enoic acid were newly identified.     

Oxidation of 5 beta-cholestane-3 alpha,7 alpha, 12 alpha-triol into 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid by cytochrome P-450(26) from rabbit liver mitochondria

The mitochondrial cytochrome P-450(26), previously shown to catalyze 26-hydroxylation of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha-triol, was found to convert this substrate also into 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid. The formation of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid increased with increasing incubation time and enzyme concentration. Addition of NAD+ to the incubation mixture did not increase the formation of the acid. Incubation with 5 beta-cholestane-3 alpha,7 alpha,12 alpha,26-tetrol, cytochrome P-450(26), ferredoxin, ferredoxin reductase and NADPH resulted in one major product, 3 alpha,7 alpha, 12 alpha-trihydroxy-5 beta-cholestanoic acid. The cytochrome P-450 required both ferredoxin, ferredoxin reductase and NADPH for activity. NADPH could not be replaced by NAD+ or NADP+.     

Configuration at C-25 in 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol excreted by patients with cerebrotendinous xanthomatosis: circular dichroism and 13C-NMR studies

The configuration at C-25 in 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha,25,26-pentol isolated from the bile and feces of patients with cerebrotendinous xanthomtosis (CTX) was determined from the lanthanide-induced circular dichroism (CD) Cotton effects and 13C-NMR measurements. Under anhydrous conditions, CD spectra of 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha,25,26-pentol in the presence of Eu(fod)3 exhibited a large induced negative Cotton effect at 320 nm. On the basis of the empirical rule (primary-tertiary-alpha-diols) in which R compounds have positive Cotton effects and S compounds have negative Cotton effects at 320 nm, it was concluded that 25,26-pentol has the 1,2,glycol structure with C-25 having the S-configuration. This assignment was based upon comparison with model compounds, 25(R and S),26-dihydroxy cholesterols and 25(R and S),26-dihydroxy cholecalciferols whose single-crystal X-ray structure and 13C-NMR studies have been performed. It is suggested that these data may be helpful to clarify the stereospecificity of the hydroxylation of the terminal methyl group of the cholesterol side chain in CTX.     

Effect of chenodeoxycholic acid on biliary and urinary bile acids and bile alcohols in cerebrotendinous xanthomatosis; monitoring by high performance liquid chromatography

Biliary and urinary bile alcohol and bile acid composition has been determined by high performance liquid chromatography in patients with cerebrotendinous xanthomatosis before and after treatment with chenodeoxycholic acid. Most of the bile acids and bile alcohols in the bile and urine were separated in less than 30 min using a radial pack C18 muBondapak 5 micron particle size column with a mobile phase of acetonitrile-water-methanol-acetic acid 70:70:20:1 (v/v/v/v) at a flow rate of 2 ml/min, and a refractive index detector. Before treatment, cholic acid (49%) and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 25-tetrol (27%) were the major biliary bile acid and bile alcohol, respectively, but were not detected in the urine of five patients. 5 beta-Cholestane-pentols were, instead, the major urinary bile alcohols with 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 23 xi, 25-pentol (56%) predominating. Whereas 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 24S,25-pentol was not detected in the bile, it was isolated in the urine of all patients (27%). The only urinary bile acid isolated by high performance liquid chromatography was nor-cholic acid. After 1 month of treatment with chenodeoxycholic acid, 0.75 g/day, chenodeoxycholic acid became the major bile acid in the bile of all patients (71%) along with its metabolite, ursodeoxycholic acid (21%). Cholic acid and 5 beta-cholestane-3 alpha, 7 alpha, 12 alpha, 25-tetrol were drastically reduced and were only 3% each. The excretion of 5 beta-cholestane-pentols in the urine was also drastically reduced from 130 mg/day to 15 mg/day.