[Anti-hyperlipidemic effect of iodine eggs: studies on the mechanism of its action]

The anti-hyperlipidemic effect of the iodine egg was found to be in the neutral lipid (NL) fraction in its yolk. For the purpose of clarifying the hypolipidemic effect of the iodine-containing NL fraction, the effect of clofibrate (CPIB) was investigated. CPIB was found to lower TC, atherogenic index [(TC-HDL cholesterol)/HDL cholesterol], TG and FFA, but not FC; while NL lowered TC, FC and the atherogenic index, but not TG and FFA. Cholesterol metabolites, probably metabolized in the liver, were examined. Hepatic cholesterol level was increased by NL and CPIB. The ratio of fecal bile acid of the excretion type, lithocholic acid (LCA) to deoxycholic acid (DCA), increased when NL and CPIB were administered, but the hepatic HMG-CoA reductase activity, responsible for the endogenous cholesterol synthesis, was not altered. Thus, the anti-hyperlipidemic mechanism of NL may be the mobilization of peripheral cholesterol to the liver, probably for the disposal by excretion as bile acids.

Urinary concentrations of bile acid glucuronides and sulfates in hepatobiliary diseases

Urinary bile acids in normal subjects and patients with obstructive jaundice and liver cirrhosis were quantitated by mass fragmentography after separation into nonglucuronidated-nonsulfated, glucuronidated and sulfated fractions. Mean values of total bile acids in urine were as follows: Control subjects (n = 7), 1.90 +/- 0.67; obstructive jaundice (n = 9), 77.90 +/- 40.39; liver cirrhosis, compensated (n = 6), 15.14 +/- 8.97, and decompensated (n = 6), 11.84 +/- 9.32 (mean +/- SD, mg/day). The percentages of each conjugate was 19-29% in the non-glucuronidated-nonsulfated fraction, 6-14% in the glucuronidated fraction and 60-74% in the sulfated fraction. Bile acids in urine and serum correlated well in each fraction (r = 0.82-0.84, p less than 0.001). The clearance of the three conjugates was the highest in the sulfates, and the clearance of glucuronides was higher than that of non-esterified bile acids. The glucuronidation and sulfation of bile acids play an important role in the detoxication of bile acids by excreting them into urine, especially in patients with elevated serum bile acids.

[Antihyperlipidemic effect of iodine egg: search for active ingredients and their iodine contents]

Active fractions that possess the hypocholesterolemic effect of iodine egg yolk lipid fraction have been investigated with male Wistar strain rats fed on a cholesterol-rich diet. Iodine egg yolk lipid was extracted by Folch's (chloroform: methanol) method and was refractionated into a neutral lipid (IEY-NL) fraction and a polar lipid (IEY-PL) fraction. The iodine content in each fraction was determined. The animals were kept on the cholesterol-rich diet for 5 days, and then they were fed the fractions in addition to the above diet for 10 more days. The hypocholesterolemic effect was seen most significantly with the IEY-NL fraction. The serum total cholesterol level in rats receiving this fraction was 70% as compared with that of the Ch group (fed on the cholesterol diet). However, the liver total cholesterol level was not affected or rather increased by the IEY-NL fraction. Another fraction (IEY-PL) showed no such effect. Iodine content in the IEY-NL fraction was quite low (0.2 ppm) compared with the other fractions. The daily dose in terms of iodine in the IEY-NL fraction was only the amount equivalent to 1/50 of the reported daily requirement for the rat. The IEY-NL fraction induced the hypocholesterolemic effect, though it contained only a trace of iodine.

[Antihyperlipidemic effect of iodine egg: Search for the screening method and active ingredients]

A screening method for the hypolipidemic effect of iodine egg and its active fractions have been investigated with Wistar strain male rats fed on a cholesterol-rich diet. The animals were kept on the cholesterol-rich diet for 5 days, and then iodine egg was fed to them in addition to the above diet for 10 more days. The present method was the most adequate for screening the hypolipidemic effect. Iodine egg yolk was fractionated into the following 3 fractions by Folch's method: Protein ( IEY -P), water-soluble ( IEY -A) and lipid ( IEY -L) fractions. The hypolipidemic effect of these fractions was determined with the screening method. The marked hypolipidemic effect was induced by the IEY -L fraction. The serum total cholesterol level in rats that received the fraction was 57% as compared with that of the ch group (fed on the cholesterol-rich diet). The other groups showed no such effect. Serum thyroid hormone levels were not affected by the IEY -L fraction which was found to be the active hypolipidemic fraction of iodine egg. The thyroid gland did not seem to participate directly in such a hypolipidemic effect.

The characterization of 2,3-alkanediol diacyl esters obtained from the Harderian glands of Mongolian gerbil (Meriones unguiculatus)

A major lipid class in the Harderian glands of the Mongolian gerbil was investigated. The IR and 1H-NMR spectra suggested that it was a wax-like compound. Fatty acids present were capric, lauric, myristic, palmitic, stearic, arachidic, and behenic acids in ratios of 3.0%, 16.3%, 16.5%, 29.5%, 5.1%, 16.4%, and 9.8%, respectively. Odd-numbered, branched chain and unsaturated fatty acids were not present in large amounts. The structure of the alcohol moiety was elucidated to be 2,3-alkanediol with carbon chain lengths from C12 to C22 by GC-MS of the TMS and isopropylidine derivatives. Lemieux-von Rudloff oxidation of these alcohols confirmed the 2,3-diol structure, giving fatty acids two carbon units shorter.

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.

Branched chain fatty acids in phospholipids of guinea pig Harderian gland

Fatty acid compositions of phosphatidyl ethanolamine and phosphatidyl choline extracted from the guinea pig Harderian gland were examined by gas chromatography and gas chromatography-mass spectrometry. Oleic acid was the major component of both phospholipids, but a large amount of saturated branched chain fatty acids was found: 34.5% in phosphatidyl ethanolamine, and 42.9% in phosphatidyl choline. On the other hand, linolenic and arachidonic acids were not found in these phospholipids. At the 1-position of phosphatidyl choline and phosphatidyl ethanolamine, 54.3% and 40.9% of fatty acids, respectively, had methyl branches. These methyl branches were located at the even-numbered carbon atoms. Branched chain fatty acids were also found at the 2-position of both lipids: 36.2% in phosphatidyl choline and 31.2% in phosphatidyl ethanolamine. The fatty acids of phosphatidyl ethanolamine and phosphatidyl choline from liver, cerebrum, cerebellum, erythrocytes, and plasma of the same animal were also analyzed. Saturated and unsaturated fatty acids, including arachidonic acid, were the major components. Branched chain fatty acids were also found in these lipids, but in very small amounts.

Quantitative determination of non-sulfated bile acids in the serum of patients with hepatobiliary diseases by mass fragmentography

Individual non-sulfated bile acids in the serum of 65 patients with hepatobiliary diseases were quantitated by mass fragmentography. Serum with deuterium labeled deoxycholic acid as an internal standard was hydrolyzed with strong alkali, extracted with ether after acidification under cooling, and quantitated by mass fragmentography as the hexafluoroisopropyl-trifluoracetyl derivatives. In obstructive jaundice, the ratio of cholic to chenodeoxycholic acid was significantly higher than others. Cholic or chenodeoxycholic acid levels were correlated with total bilirubin levels in obstructive jaundice and acute hepatitis. Lithocholic acid value was independent of the degree of liver injury. Total bile acid value was helpful in estimating the extent of liver cell injury and cholestasis, and these two pathological conditions can be distinguished to some extent by cholic to chenodeoxychoic acid ratio.

Serum concentrations of bile acid glucuronides in hepatobiliary diseases

Bile acid glucuronides in the serum in various hepatobiliary diseases (36 cases) were quantitated by mass fragmentography and their clinical significance was discussed. Serum was added to defined amounts of deuterium-labeled bile acids and their glucuronide and sulfate derivatives, and the bile acids were separated into unconjugated, glucuronidated and sulfated groups after enzymatic cleavage of amide bonds. The liberated bile acids were quantitated by mass fragmentography. Bile acid glucuronides comprised about 7-8% of the total bile acids in the serum of various patients. Chenodeoxycholic acid was the major glucuronidated bile acid while cholic acid was mostly unconjugated. Lithocholic acid was almost all either sulfated or glucuronidated. In patients with obstructive jaundice, glucuronidated bile acids also comprised about 5%, although their absolute amounts were increased. In patients with liver cirrhosis, bile acid glucuronides were decreased, especially in decompensated cases, possibly as a result of hepatocellular dysfunction.

Studies on the biosynthesis of cholestanol in cultured cells

The presence of cholestanol had never been reported in cultured cells, but in the present study cholestanol was detected both in human and rat skin fibroblasts. The present study has shown that the origin of cholestanol in these fibroblasts was derived from de novo synthesis in the cells rather than from the fetal calf serum used in the growth medium. The activity of 5 alpha-cholestan-3-one reductase which is the enzyme catalyzing the final step in the biosynthesis of cholestanol was measured by mass fragmentography using deuterium labeled 5 alpha-cholestan-3-one as a substrate. The activity of this enzyme was also detected in the microsomal fractions of rat cerebrum and cerebellum as well as in the liver. These results suggest that cholestanol can probably be synthesized in extra-hepatic tissues as well as in the liver.

Quantitative determination of bile acid glucuronides in serum by mass fragmentography

Individual non-glucuronidated . non-sulfated, glucuronidated and sulfated bile acids in serum were determined, i.e. lithocholic acid, deoxycholic acid, chenodeoxycholic acid, ursodeoxycholic acid, and cholic acid, by mass fragmentography. Glucuronic acid conjugates of lithocholic acid, deoxycholic acid, chenodeoxycholic acid, and cholic acid were synthesized via the Koenigs-Knorr condensation reaction. Deuterium labeled deoxycholic acid, lithocholic acid glucuronide, deoxycholic acid glucuronide, and deoxycholic acid sulfate were synthesized and used as internal standards. A serum sample of 1 ml including internal standards was purified with a Sep-Pak C18 cartridge. After the enzymatic cleavage of amino acid conjugates, bile acids were separated into three fractions, free, glucuronidated, and sulfated bile acids, using piperidinohydroxypropyl Sephadex LH-20 (Goto et al. (1978) Clin. Chim. Acta 87). Glucuronidated and sulfated bile acids were deconjugated by beta-glucuronidase treatment and solvolysis. Each fraction was converted to the hexafluoroisopropyl-trifluoroacetyl derivative and quantitated by mass fragmentography. The average concentrations of individual bile acid glucuronides from healthy fasting subjects (n = 9) were as follows; lithocholic acid 0.013 microgram/ml, deoxycholic acid 0.083 microgram/ml, chenodeoxycholic acid 0.078 microgram/ml, ursodeoxycholic acid 0.013 microgram/ml, and cholic acid 0.007 microgram/ml. Bile acid glucuronides occupied 7.8% of the total bile acids.

A case of cerebrotendinous xanthomatosis: effects of ursodeoxycholic acid administration on serum bile acids and cholestanol

Cerebrotendinous xanthomatosis (CTX) is a rare familiar disease characterized by tendon xanthomas, cataracts, cerebellar ataxia, dementia and an elevated serum cholestanol level. In this paper, a 50-year-old man with typical signs and symptoms of CTX is described. Serum cholestanol and chelesterol concentrations were 17.9-28.6 micrograms/ml and 109-153 mg/dl, respectively. The determination of non-sulfated bile acid concentration in the serum assayed by mass fragmentography disclosed an abnormal profile. The concentration of cholic acid (0.30-0.52 microgram/ml) was higher than normal, while those of chenodeoxycholic acid, ursodeoxycholic acid, deoxycholic acid and lithocholic acid were extremely low or undetectable. Administration of ursodeoxycholic acid (300 mg per day, orally) for 2 weeks resulted in a marked reduction of serum cholic acid concentration. However, serum cholestanol levels remained unchanged.

Serum bile acid profiles in cerebrotendinous xanthomatosis

Non-sulfated bile acid concentrations in sera of 10 cases of cerebrotendinous xanthomatosis (CTX) were determined by mass fragmentography. Total bile acid (TBA) in serum was 0.492 +/- 0.436 microgram/ml (mean +/- SD) which was significantly lower than that (1.481 +/- 0.571) in healthy control sera. Cholic acid was 0.342 +/- 0.291 microgram/ml and was the dominant bile acid, which constituted 69.5% of TBA in serum. Chenodeoxycholic acid was 0.111 +/- 0.133 microgram/ml being a minor component in CTX sera, although it was the major bile acid in healthy control sera. Other bile acids such as deoxycholic acid, lithocholic acid and ursodeoxycholic acid were scarcely detected. Subnormal TBA level and deranged bile acid composition in CTX sera may reflect the defect of bile acid biosynthesis in CTX patients. Determination of serum bile acid may be useful in the diagnosis of CTX.

Propionyl-Coa induced synthesis of even-chain-length fatty acids by fatty acid synthetase from Brevibacterium ammoniagenes

The product distribution of Brevibacterium ammoniagenes fatty acid synthetase has been investigated using propionyl-CoA instead of acetyl-CoA as the primer. The synthetase produces not only an odd-numbered fatty acid (heptadecanoic acid) but also even-numbered fatty acids (stearic and oleic acids) in the presence of propionyl-CoA. The amounts of heptadecanoic, stearic and oleic acids increased with increasing concentration of propionyl-CoA. However, the formation of heptadecenoic acid (C17:1) was not observed under any conditions tested. The failure of C17:1 synthesis suggested that the enzyme component catalyzing the beta, gamma-dehydration, which is responsible for the synthesis of unsaturated fatty acids, has a high degree of chain length specificity. Under standard assay conditions, stearic acid predominated and heptadecanoic and oleic acids were found in lesser amounts. Mass spectrometric analyses of fatty acids synthesized either from [2H]propionyl-CoA or in 2H2O revealed that propionyl-CoA is utilized as the priming substrate for the synthesis of heptadecanoic acid and that an acetyl residues, which is formed by the decarboxylation of malonyl-CoA, served as the priming substrate for the syntheses of stearic and oleic acids. No evidence was obtained for the direct decarboxylation of malonyl-CoA to acetyl-CoA in this reaction. It is concluded that the decarboxylation of the malonyl moiety bound to the synthetase occurs efficiently only in the course of fatty acid synthesis. A hypothetical scheme is presented to explain the propionyl-CoA-dependent decarboxylation of the malonyl moiety.

Steric course of deuterium incorporation from [2-2H2]malonyl-CoA into fatty acids by fatty acid synthetases

The steric course of the enoyl reduction catalyzed by fatty acid synthetase was investigated with the enzymes from bakers' yeast, rat liver and Brevibacterium ammoniagenes. The non-enzymic hydrogen-deuterium exchange of the methylene group of malonyl-CoA was studied by NMR spectroscopy. The half-life period of the methylene protons was 4.8 min at 37 degrees C and 12.2 min at 23 degrees C at p2H 7.5. Deuterium-labeled fatty acids were synthesized by incubating the synthetases with [2-2H2]malonyl-CoA for 8 min. The deuterium-labeled fatty acids thus produced were extracted and subjected to the action of acyl-CoA oxidase, which had been previously shown to catalyze the anti elimination of the pro-2R and pro-3R hydrogens of acyl-CoA. The resulting products, 2,3-dehydroacyl-CoAs, were methylated and converted to 3-chlorofatty acid methyl esters by addition of hydrogen chloride. The deuterium contents of saturated fatty acids and 3-chlorofatty acids were analyzed by gas chromatography-mass spectrometry. The oleic acid produced by the enzyme from B. ammoniagenes was oxidized to nonanoic acid and azelaic acid. The resulting nonanoic acid was also subjected to the action of acyl-CoA oxidase. The deuterium contents of nonanoic acid and trans-2-nonenoic acid were analyzed. The results suggested that fatty acid synthetase from yeast and rat liver incorporated hydrogen from water via a 2-Si attack and the enzyme from B. ammoniagenes incorporated hydrogen via a 2-Re attack during enoyl reduction. The partial racemization of the C-2 position was observed and the magnitude of this racemization was correlated with the deuterium content of synthesized fatty acids. This phenomenon may be attributed to the non-stereospecific hydrogen exchange of the C-2 position of the elongating acyl residue catalyzed by fatty acid synthetases.