Bile acid sulfates in serum bile acids determination

Overcoming environmental problems of biocides: Synthetic bile acid derivatives as a sustainable alternative

Marine biofouling represents a global economic and ecological challenge. Some marine organisms produce bioactive metabolites, such as steroids, that inhibit the settlement and growth of fouling organisms. The aim of this work was to explore bile acids as a new scaffold with antifouling (AF) activity by using chemical synthesis to produce a series of bile acid derivatives with optimized AF performance and understand their structure-activity relationships. Seven bile acid derivatives were successfully synthesized in moderate to high yields, and their structures were elucidated through spectroscopic methods. Their AF activities were tested against both macro- and microfouling communities. The most potent bile acid against the settlement of Mytilus galloprovincialis larvae was the methyl ester derivative of cholic acid (10), which showed an EC₅₀ of 3.7 μM and an LC₅₀/EC₅₀ > 50 (LC₅₀ > 200 μM) in AF effectiveness vs toxicity studies. Two derivatives of deoxycholic acid (5 and 7) potently inhibited the growth of biofilm-forming marine bacteria with EC₅₀ values < 10 μM, and five bile acids (1, 5, and 7-9) potently inhibited the growth of diatoms, showing EC₅₀ values between 3 and 10 μM. Promising AF profiles were achieved with some of the synthesized bile acids by combining antimacrofouling and antimicrofouling activities. Initial studies on the incorporation of one of these promising bile acid derivatives in polymeric coatings, such as a marine paint, demonstrated the ability of these compounds to generate coatings with antimacrofouling activity.

Serum concentrations of unconjugated and conjugated cholic acid in portal venous and systemic venous blood of fasting man

The fasting concentrations of unconjugated and conjugated cholic acid were determined in the peripheral venous serum of 15 healthy subjects, eight patients with ileal resection and six patients with known bacterial overgrowth of the upper small intestine. In addition, the estimated hepatic uptake of unconjugated and conjugated cholic acid was determined in 15 gallstone patients undergoing cholecystectomy. A highly accurate and specific mass-fragmentographic technique with high sensitivity was used. The proportion of unconjugated cholic acid averaged 34% in the healthy subjects. The estimated fractional hepatic uptake of unconjugated cholic acid was lower than that of conjugated cholic acid, 71% and 87%, respectively (means). Patients with ileal resection had an increased proportion of unconjugated cholic acid in their peripheral venous serum, 49% (mean). The patients with bacterial overgrowth of the upper small intestine also displayed a high proportion of unconjugated cholic acid, 63% (mean). It is suggested that determination of the proportion of unconjugated cholic acid in peripheral venous blood may possibly be used for detection of bacterial contamination of the upper small intestine.

Diagnostic sensitivity of fasting and postprandial serum bile acids determined by different methods

The diagnostic sensitivities of serum bile acids determined by three different methods in the fasting and in the postprandial state were compared in 43 patients with cirrhosis of the liver. When a method with high analytical sensitivity (capillary gas-liquid chromatography, GLC, or radioimmunoassay, RIA) was used, the serum concentrations of bile acids exhibited similar diagnostic sensitivities in the fasting state (GLC, 98%; RIA, 93%) and in the postprandial state (GLC, 95%; RIA, 93%). By contrast, when an enzymatic method with limited analytical sensitivity was employed, the diagnostic sensitivity of fasting serum bile acids was lower (79%) than that of postprandial serum bile acids (93%). The measurement of individual serum bile acids by GLC did not add any further diagnostic information. The results of this study demonstrate that the diagnostic sensitivity of serum bile acids strongly depends on the analytical method used.

Portal venous bile acids in cholesterol gallstone disease: effect of treatment with chenodeoxycholic and cholic acids

We determined the serum concentrations of cholic, chenodeoxycholic and deoxycholic acids in portal and peripheral venous blood in 9 gallstone-free patients and 39 patients with cholesterol gallstones during standardized cholecystectomy. An accurate and specific gas chromatographic-mass spectrometric technique was used. The portal venous concentration of total bile acids was similar in gallstone-free and untreated gallstone patients (n = 20); there was no evidence of a reduced hepatic uptake of bile acids in the latter. Treatment with cholic acid (n = 10) was associated with a 70% increase in cholic acid and normal concentration of total bile acids. In chenodeoxycholic acid-treated patients (n = 9), the portal venous concentration of this bile acid was increased 3-fold; total bile acids were increased about 60%. The estimated hepatic uptake of cholic acid was slightly decreased during chenodeoxycholic acid treatment. The results indicate that neither bile acid inflow to the liver nor hepatic bile acid uptake is reduced in fasting patients with cholesterol gallstones, and treatment with chenodeoxycholic acid increases fasting inflow of bile acids to the liver. The latter may contribute to unsaturation of fasting hepatic bile during treatment with chenodeoxycholic acid.

The diagnostic value of fasting individual serum bile acids in anicteric alcoholic liver disease: relation to liver morphology

The aim of the present study was to evaluate the diagnostic value of measuring individual serum bile acids in patients with suspected alcoholic liver disease. A highly accurate and specific mass-fragmentographic technique with high sensitivity was used. Anicteric patients with fatty liver (n = 10) and liver cirrhosis (n = 9) were compared with healthy controls (n = 27). The measurement of serum bile acids did not discriminate patients with fatty liver from controls. In general, an increased serum level of cholic acid indicated more serious liver disease. Determination of chenodeoxycholic acid and deoxycholic acid did not add any further diagnostic information.

Determination of sulfated and nonsulfated bile acids in serum by mass fragmentography

A Sep-Pak C18 cartridge was used for purification of bile acids from serum. Three kinds of deuterium labeled internal standards were required for accurate measurement of individual sulfated and nonsulfated bile acids. These internal standards were added to the serum before its application to the cartridge. Separation of sulfated and nonsulfated bile acids was performed on piperidinohydroxypropyl Sephadex LH-20 column chromatography. The nonsulfate fraction was submitted to alkaline hydrolysis, and the sulfate fraction to solvolysis followed by alkaline hydrolysis. Each fraction was converted to the hexafluoroisopropyl-trifluoroacetyl derivatives and quantitated by mass fragmentography. The recovery of each bile acid sulfate was quite satisfactory. In fasting healthy subjects the mean of total nonsulfated bile acids in serum was 1.324 micrograms/ml, and that of total sulfated bile acids was 0.450 micrograms/ml. Sulfated lithocholic acid comprised a large part of sulfated bile acids in healthy subjects.

Ion-pair extraction of bile acids with Lipidex gel

A new method for the extraction of bile acids from aqueous solutions, urine, plasma, and bile is described. A buffered solution of decyltrimethylammonium bromide is added to the sample to give a 0.03 M concentration of the counter-ion. The mixture is passed through a bed of Lipidex 1000, which is then washed with the buffered solution of counter-ion followed by water. The decyltrimethylammonium salts of bile acids are sorbed by the Lipidex and are eluted with methanol. Recoveries of unconjugated, taurine- and glycine-conjugated, sulfated, and glucuronidated bile acids are close to 100%. Unconjugated bile acids can also be quantitatively extracted from aqueous solutions and urine after acidification with acetic acid.

Serum bile acid analysis

Routine and research techniques are outlined for the analysis of bile acids in serum. The basis of these techniques is the use of liquid-solid extraction and liquid-gel chromatography coupled with the measurement of bile acids by gas chromatography using high resolution glass capillary columns and mass spectrometry which provides increased sensitivity compared with conventional methods of measurement. Problems associated with the isolation and purification of bile acids from serum are discussed and rapid and flexible methods for their metabolic profiling are described. The advantages and applicability of these procedures are illustrated with examples of profiles of bile acids in the serum from normal subjects, patients with liver disease and a patient with an ileal resection.

A rapid method for the quantitative extraction of bile acids and their conjugates from serum using commercially available reverse-phase octadecylsilane bonded silica cartridges

Described is a rapid semi-automated technique for the quantitative extraction of bile acids and their conjugates from serum samples using commercially available reverse-phase octadecylsilane bonded silica cartridges. Serum is diluted with 4 volumes of 0.1 mol/l sodium hydroxide and the sample heated to 64 degrees C before application to the cartridge. Bile acids and their conjugates are adsorbed to the octadecylsilane bonded silica particles and reproducibly recovered by elution with a small volume of methanol. The technique is superior to extraction procedures using either Amberlite XAD resins or liquid-liquid partitioning, and gives a quantitative recovery of polar bile acid sulphates. The method is convenient and rapid and by using a specially designed apparatus it is possible to extract up to 60 samples/hour.