Identification of bile alcohols in human bile

Isolation and Identification of a Urinary Biomarker for Lung Cancer: 27-Nor-5β-Cholestane-3α,7α,12α,24R,25S Pentol Glucuronide and Its Deuterated Analog

An untargeted metabolomic study identified four potential lung cancer diagnostic biomarkers in human urine. One of the potential biomarkers was an unidentified feature possessing a m/z value of 561+. "561+" was isolated from human urine and tentatively identified as 27-nor-5β-cholestane-3α,7α,12α,24,25 pentol glucuronide with unknown C24,25 stereochemistry using 1H NMR and mass spectrometry. In a prior report, the C24,25 stereochemistry of the aglycone, 27-nor-5β-cholestane-3α,7α,12α,24,25 pentol, was found to be 24S,25R through GC analysis of the acetonide-TMS derivative. An authentic sample was prepared and found not to have the same stereochemistry as "561+". To identify the C24,25 stereochemistry, four C24,C25 diastereoisomeric alcohols of 27-nor-5β-cholestane-3α,7α,12α,24,25 pentol were prepared from chiral amino acids. Using an LCMS method, the C24,C25 stereochemistry of the "561+" aglycone was determined to be 24R,25S. With the correct aglycone in hand, it was coupled with glucuronic acid to complete the first reported synthesis of 27-nor-5β-cholestane-3α,7α,12α,24R,25S pentol glucuronide. Deuterium labeled 27-nor-5β-cholestane-3α,7α,12α,24R,25S pentol was also synthesized for use as an internal standard for MS quantitation.

Using nontargeted LC-MS metabolomics to identify the Association of Biomarkers in pig feces with feed efficiency

Background

Improving feed efficiency is economically and environmentally beneficial in the pig industry. A deeper understanding of feed efficiency is essential on many levels for its highly complex nature. The aim of this project is to explore the relationship between fecal metabolites and feed efficiency-related traits, thereby identifying metabolites that may assist in the screening of the feed efficiency of pigs.

Results

We performed fecal metabolomics analysis on 50 individuals selected from 225 Duroc x (Landrace x Yorkshire) (DLY) commercial pigs, 25 with an extremely high feed efficiency and 25 with an extremely low feed efficiency. A total of 6749 and 5644 m/z features were detected in positive and negative ionization modes by liquid chromatography-mass spectrometry (LC/MS). Regrettably, the PCA could not classify the the samples accurately. To improve the classification, OPLS-DA was introduced. However, the predictive ability of the OPLS-DA model did not perform well. Then, through weighted coexpression network analysis (WGCNA), we found that one module in each positive and negative mode was related to residual feed intake (RFI), and six and three metabolites were further identified. The nine metabolites were found to be involved in multiple metabolic pathways, including lipid metabolism (primary bile acid synthesis, linoleic acid metabolism), vitamin D, glucose metabolism, and others. Then, Lasso regression analysis was used to evaluate the importance of nine metabolites obtained by the annotation process.

Conclusions

Altogether, this study provides new insights for the subsequent evaluation of commercial pig feed efficiency through small molecule metabolites, but also provide a reference for the development of new feed additives.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40813-021-00219-w.

A comparative study of the sulfation of bile acids and a bile alcohol by the Zebra danio (Danio rerio) and human cytosolic sulfotransferases (SULTs)

The current study was designed to examine the sulfation of bile acids and bile alcohols by the Zebra danio (Danio rerio) SULTs in comparison with human SULTs. A systematic analysis using the fifteen Zebra danio SULTs revealed that SULT3 ST2 and SULT3 ST3 were the major bile acid/alcohol-sulfating SULTs. Among the eleven human SULTs, only SULT2A1 was found to be capable of sulfating bile acids and bile alcohols. To further investigate the sulfation of bile acids and bile alcohols by the two Zebra danio SULT3 STs and the human SULT2A1, pH-dependence and kinetics of the sulfation of bile acids/alcohols were analyzed. pH-dependence experiments showed that the mechanisms underlying substrate recognition for the sulfation of lithocholic acid (a bile acid) and 5α-petromyzonol (a bile alcohol) differed between the human SULT2A1 and the Zebra danio SULT3 ST2 and ST3. Kinetic analysis indicated that both the two Zebra danio SULT3 STs preferred petromyzonol as substrate compared to bile acids. In contrast, the human SULT2A1 was more catalytically efficient toward lithocholic acid than petromyzonol. Collectively, the results imply that the Zebra danio and human SULTs have evolved to serve for the sulfation of, respectively, bile alcohols and bile acids, matching the cholanoid profile in these two vertebrate species.

Bile alcohols function as the ligands of membrane-type bile acid-activated G protein-coupled receptor

TGR5 is a G protein-coupled receptor that is activated by bile acids, resulting in an increase in cAMP levels and the subsequent modulation of energy expenditure in brown adipose tissue and muscle. Therefore, the development of a TGR5-specific agonist could lead to the prevention and treatment of various metabolic disorders related to obesity. In the present study, we evaluated the ability of bile alcohols, which are structurally and physiologically similar to bile acids and are produced as the end products of cholesterol catabolism in evolutionarily primitive vertebrates, to act as TGR5 agonists. In a cell-based reporter assay and a cAMP production assay performed in vitro, most bile alcohols with a side chain containing hydroxyl group(s) were highly efficacious agonists for TGR5 comparable to its most potent ligand in the naturally occurring bile acid, lithocholic acid. However, the abilities of the bile alcohols to activate TGR5 varied with the position and number of the hydroxyl substituent in the side chain. Additionally, the conformation of the steroidal nucleus of bile alcohols is also important for its activity as a TGR5 agonist. Thus, we have provided new insights into the structure-activity relationships of bile alcohols as TGR5 agonists.

Short-term toxicity of grass carp bile powder, 5alpha-cyprinol and 5alpha-cyprinol sulfate in rats

We compared the short-term toxicity of toxic components of grass carp bile juice (GCBJ) in rats. Twenty-four male Wistar rats were divided into four groups and treated orally every 3 days with 40 mg each of freeze-dried GCBJ powder, 5alpha-cyprinol and 5alpha-cyprinol sulfate for 19 days. After treatment, the relative ratio of liver and kidney weight to body weight, the concentrations of RBC, hemoglobin and hematocrit in the blood, the levels of aspartate amino transferase, alanine amino transferase, alkaline phosphatase, blood urea nitrogen and creatinine in the plasma, and the levels of urinary urea nitrogen and creatinine in the urine were significantly increased. Body weight of rats and the levels of Na+, K+, Ca2+ in the urine were significantly decreased, especially for groups treated with GCBJ powder and 5alpha-cyprinol sulfate. Pathological examination of liver and kidney also showed cell enlargement and lesions, especially for groups treated with GCBJ powder and 5alpha-cyprinol sulfate. The grass carp bile juice exhibited significant toxicity, and the short-term toxicity of 5alpha-cyprinol sulfate and GCBJ powder was similar to each other. Renal but not hepatic failure induced by grass carp bile juice could be prevented by pentoxifylline.

Urinary bile alcohol profiles in healthy and cholestatic children

BACKGROUND

Bile alcohols are normal constituents of urine.

METHODS

To better understand bile alcohol profile in childhood, urinary specimens from 41 healthy children and 10 children with cholestasis, and 3 healthy adults, were analyzed by GLC and GC-MS.

RESULTS

Five bile alcohols, 27-nor-5beta-cholestane-3alpha,7alpha,12alpha,24S,25R-pentol, 5beta-cholestane-3alpha,7alpha,12alpha,24S, 25-pentol, 5beta-cholestane-3alpha,7alpha,12alpha,24S,26-pentol, 5beta-cholestane-3alpha,7alpha, 12alpha,25,26-pentol, and 5beta-cholestane-3alpha,7alpha,12alpha,26,27-pentol were identified in all specimens. C(26)-Pentol was the most abundant constituent, constituting 29.5 to 65% of bile alcohols. Among healthy children (n=41), no significant relationship was seen between proportions of the C(26)-pentol and age, but older children (n=15, 6 to 14 years) showed a significantly greater mean percentage of the C(26)-pentol than young children (n=26, 0 to 5 years; 58.1+/-4.23% vs. 46.0+/-9.24%, p<0.001). In children with cholestatic liver diseases, the percentage of C(26)-pentol in urinary bile alcohols was significantly lower than age-matched controls.

CONCLUSIONS

There is an increased composition of C(26)-pentol in older children and relatively decreased composition of C(26)-pentol in children with cholestatic liver diseases.

Identification of cyprinol and cyprinol sulfate from grass carp bile and their toxic effects in rats

To elucidate the responsible toxic components of grass carp bile, the bile salt 5 alpha-cyprinol sulfate and its desalted form 5 alpha-cyprinol from grass carp bile were purified and identified by analyses of infrared spectrum, (1)H-, (13)C-nuclear magnetic resonance spectra and mass spectrum. The toxicity of grass carp bile powder, butanol extract of grass carp bile powder, 5 alpha-cyprinol and 5 alpha-cyprinol sulfate in rats were further determined. The kidney and liver functions were significantly affected by grass carp bile powder, butanol extract and 5 alpha-cyprinol sulfate. However, 5 alpha-cyprinol also significantly affected the kidney function, but the toxic effect was less.

Synthesis of 3 alpha, 7 alpha, 12 alpha-trihydroxy- and 3 alpha, 7 alpha-dihydroxy-5 beta-cholestan-26-oic acids by the use of beta-ketosulfoxide

The biosynthetic intermediates of bile acid, 3 alpha, 7 alpha, 12 alpha-trihydroxy- and 3 alpha, 7 alpha-dihydroxy-5 beta-cholestan-26-oic acids, were synthesized by means of the thermal elimination of beta-ketosulfoxides. The alpha, beta-unsaturated ketones as key compounds of the synthesis, 3 alpha, 7 alpha, 12 alpha-trihydroxy- and 3 alpha, 7 alpha-dihydroxy-5 beta-cholest-25-en-24-ones, were effectively derived from the beta-ketosulfoxides prepared from methyl cholate or chenodeoxycholate by reaction with methylsulfinylcarbanion. These unsaturated ketones were converted into 3 alpha, 7 alpha, 12 alpha, 26-tetrahydroxy- and 3 alpha, 7 alpha, 26-trihydroxy-5 beta-cholestanes by reductive deoxygenation and hydroboration, of which stereoisomers were chromatographically separated into 25S- and 25R- isomers. The oxidation of each of the above isomeric alcohols after the protection of the hydroxyl groups on the steroidal ring and the following hydrolysis gave the title 26-carboxylic acids.

Cerebrotendinous xanthomatosis: clinical and biochemical evaluation of eight patients and review of the literature

We present the clinical and laboratory findings of 8 patients with cerebrotendinous xanthomatosis. The clinical features consisted of a combination of bilateral Achilles tendon xanthomas, cataracts, low intelligence, pyramidal signs, cerebellar signs, convulsions, peripheral neuropathy, foot deformity, cardiovascular disease or atherosclerosis, EEG abnormality, and increased CSF protein. Increased cholesterol was present in the serum, CSF and red cell membrane of all 8 patients. The bile of one patient with late age onset of the disease showed an attenuated production of bile acids and bile alcohols. Three of the 7 had obstruction and/or marked narrowing of the coronary arteries. Data on 136 patients reported throughout the world are reviewed.

High-performance liquid chromatographic separation of bile acids and bile alcohols diastereoisomeric at C-25

The high-performance liquid chromatographic separation of the 25R and 25S diastereoisomers of the bile alcohols 5 beta-cholestane-3 alpha,7 alpha,26-triol and 5 beta-cholestane-3 alpha,7 alpha, 12 alpha, 26-tetrol and the bile acids, 3 alpha,7 alpha-dihydroxy-5 beta-cholestane-26-oic acid and 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestane-26-oic acid is described. A Radial-Pak microBondapak C18 reversed-phase cartridge was used for the separations and elutions were carried out with acetonitrile-water-methanol-acetic acid mixtures. All eight diastereoisomeric compounds showed baseline separation when up to 200 micrograms of the isomeric mixtures were injected into the column and the method can be used for isolation of pure diastereoisomers of these bile acids and bile alcohols.

Measurement of serum bile alcohol levels in liver dysfunction, using isotope dilution-mass spectrometry

We determined the concentration of two major serum bile alcohols, 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol, in healthy controls and patients with acute hepatitis, chronic hepatitis, and cirrhosis, using isotope dilution-mass spectrometry. In healthy controls the mean total amount of the two major bile alcohols was 9.6 +/- 3.4 ng/ml (mean +/- SD). In patients with liver diseases the mean values were as follows: acute hepatitis, 44.8 +/- 18.2 ng/ml; chronic hepatitis, 18.2 +/- 5.6 ng/ml; Child grade A cirrhosis, 37.9 +/- 26.0 ng/ml; Child grade B, 42.7 +/- 22.0 ng/ml; and Child grade C, 71.2 +/- 24.2 ng/ml. The mean ratio of 5 beta-cholestane-3 alpha,7 alpha,12 alpha,25,26-pentol to 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol in patients with Child grade C cirrhosis was significantly higher than that in healthy controls (1.42 +/- 0.92 versus 0.61 +/- 0.11; p less than 0.05).

Identification of bile alcohols in serum from healthy humans

Bile alcohol glucuronides present in human serum were isolated by ion exchange chromatography on piperidino-hydroxypropyl Sephadex LH-20. Following hydrolysis with beta-glucuronidase, the bile alcohols were analyzed by a combination of gas-liquid chromatography and mass spectrometry. Bile alcohols identified were 27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25-pentol, 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, and 5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,25,26-hexol. The bile alcohol composition in serum was similar to that in urine but not to that in bile. The concentration of total bile alcohols in serum was 59.5 +/- 24.6 micrograms/L.

Metabolism of C26 bile alcohols in the bullfrog, Rana catesbeiana

Metabolism of C26 bile alcohols in the bullfrog, Rana catesbeiana, was studied. [24-14C]-24-Dehydro-26-deoxy-5 beta-ranol (3 alpha,7 alpha,12 alpha-trihydroxy-27-nor-5 beta-cholestan-24-one) was chemically synthesized from [24-14C]cholic acid and incubated with bullfrog liver homogenate fortified with NADPH. 24-Dehydro-26-deoxy-5 beta-ranol was shown to be converted into both 26-deoxy-5 beta-ranol and 24-epi-26-deoxy-5 beta-ranol [(24S)- and (24R)-27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24-tetrols] in addition to 5 beta-ranol [(24R)-27-nor-5 beta-cholestane-3 alpha,7 alpha,12 alpha,24,26-pentol], which is the major bile alcohol of the bullfrog. [24-3H]-26-Deoxy-5 beta-ranol and [24-3H]-24-epi-26-deoxy-5 beta-ranol were prepared from 24-dehydro-26-deoxy-5 beta-ranol by reduction with sodium [3H] borohydride and administered respectively to two each of four bullfrogs by intraperitoneal injection. After 24 h, labeled 5 beta-ranol was isolated from the bile of the bullfrogs that received [24-3H]-26-deoxy-5 beta-ranol. In contrast little if any radioactivity could be detected in 5 beta-ranol or its 24-epimer after administration of [24-3H]-24-epi-26-deoxy-5 beta-ranol.