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PubMed2004

Proof of the mysterious efficacy of ginseng: basic and clinical trials: metabolic activation of ginsenoside: deglycosylation by intestinal bacteria and esterification with fatty acid.

Orally ingested ginsenoside passes through the stomach and small intestine without decomposition by either gastric juice or liver enzymes into the large intestine, where ginsenoside is deglycosylated by colonic bacteria followed by transit to the circulation. Colonic bacteria cleave the oligosaccharide connected to the aglycone stepwise from the terminal sugar to afford the major metabolites, 20S-protopanaxadiol 20-O-beta-D-glucopyranoside (M1) and 20S-protopanaxatriol (M4). These metabolites are further esterified with fatty acids. The resultant fatty-acid conjugates are still active molecules that are sustained longer in the body than parental metabolites. Accumulating evidence strongly suggests that ginsenoside is a prodrug that is activated in the body by intestinal bacterial deglycosylation and fatty acid esterification.

Animals↗
PubMed2006

Application of multivariate curve resolution to chemical process control of an esterification reaction monitored by near-infrared spectroscopy.

Multivariate curve resolution-alternating least squares (MCR-ALS) methodology was applied to near-infrared spectroscopy (NIR) data for the esterification reaction between glycerol and a mixture of caprylic and capric acids. Batch reaction processes were conducted either at the laboratory scale or at an industrial plant, while NIR data were obtained from samples withdrawn during the reaction processes. The process has been monitored via two typical parameters for this type of reaction, namely, the acid value (AV) and the hydroxyl value (OHV). Spectral and concentration profiles were estimated by applying soft-modeling MCR-ALS to a column-wise augmented data matrix with pure spectra of the components, and concentration values for the acid were used as a soft-equality constraint. The estimated concentration profiles have been compared with the AV and OHV values, and the estimated spectral profiles were used to predict the concentration profiles for new batches. Good results have been obtained in terms of RMSE for the prediction of AV and OHV.

Journal Article↗
PubMed1999

Lipase immobilized on poly(VP-co-HEMA) hydrogel for esterification reaction.

Lipase from Candida rugosa was immobilized by entrapment on poly(N-vinyl- 2-pyrrolidone-co-2-hydroxyethyl methacrylate) (poly[VP-co-HEMA]) hydrogel, and divinylbenzene was the crosslinking agent. The immobilized enzymes were used in the esterification reaction of oleic acid and butanol in hexane. The activities of the immobilized enzymes and the leaching ability of the enzyme from the support with respect to the different compositions of the hydrogels were investigated. The thermal, solvent, and storage stability of the immobilized lipases was also determined. Increasing the percentage of composition of VP from 0 to 90, which corresponds to the increase in the hydrophilicity of the hydrogels, increased the activity of the immobilized enzyme. Lipase immobilized on VP(%):HEMA(%) 90:10 exhibited the highest activity. Lipase immobilized on VP(%):HEMA(%) 50:50 showed the highest thermal, solvent, storage, and operational stability compared to lipase immobilized on other compositions of hydrogels as well as the native lipase.

Journal Article↗
PubMed1986

Cholesterol esterification in mouse peritoneal macrophages in the presence of pathological human plasma lipoproteins.

Mouse peritoneal macrophages were incubated with abnormal lipoproteins (LP-X, HDL-E, VLDL-p, IDl-p and LDL-p) from a patient with secondary deficiency in phosphatidylcholine-sterol acyltransferase, or with phosphatidylcholine/cholesterol liposomes, and the stimulation of cholesteryl ester formation was studied. Acetylated low density lipoproteins served as a control. It was found that macrophages incubated with LP-X, the other pathological lipoproteins or with liposomes did not show an enhanced cholesterol esterification. Also HDL-E had no effect despite of its high apoE content and the fact that apoE has been postulated to be the agonist in beta-VLDL binding to macrophages.

Animals↗
PubMed1996

Troglitazone inhibits fatty acid oxidation and esterification, and gluconeogenesis in isolated hepatocytes from starved rats.

The effects of troglitazone and pioglitazone on glucose and fatty acid metabolism were studied in hepatocytes isolated from 24-h-starved rats. These thiazolidinediones inhibited long-chain fatty acid (oleate) oxidation and produced a very oxidized mitochondrial redox state. By contrast, thiazolidinediones did not affect the rate of medium-chain fatty acid (octanoate) oxidation or the activity of mitochondrial carnitine palmitoyltransferase (CPT) I. Thiazolidinediones inhibited selectively triglyceride synthesis but not phospholipid synthesis. The combined inhibition of oleate oxidation and esterification by troglitazone was due to a noncompetitive inhibition of mitochondrial and microsomal long-chain acyl-CoA synthetase (ACS) activities. It was suggested that troglitazone must be metabolized into its sulfo-conjugate derivative in liver cells to inhibit mitochondrial and microsomal ACS activities. Thiazolidinediones inhibited glucose production from lactate/pyruvate or from alanine. Analysis of gluconeogenic metabolite concentrations suggested that troglitazone would inhibit gluconeogenesis at the level of pyruvate carboxylase and glyceraldehyde-3-phosphate dehydrogenase reactions. It was concluded that 1) at a similar concentration, troglitazone was more efficient than pioglitazone to inhibit fatty acid metabolism and gluconeogenesis and 2) the inhibition of gluconeogenesis by troglitazone could be the result of the inhibition of long-chain fatty acid oxidation (decrease in acetyl-CoA, NADH-to-NAD+, and ATP-to-ADP ratios).

Animals↗
PubMed1998

Fractional esterification rate of HDL particles in patients with type 2 diabetes. Relation to coronary heart disease risk factors.

OBJECTIVE: To study the fractional esterification rate of cholesterol on HDL particles (FERHDL) in adults with type 2 diabetes and assess its correlation with serum lipids and other coronary heart disease (CHD) risk factors. RESEARCH DESIGN AND METHODS: FERHDL was measured in 90 adult (57 men, 33 women) patients by an isotopic assay method involving several steps, including preparation of VLDL- and LDL-depleted plasma, labeling of the sample with a trace amount of tritiated cholesterol, separation of free and esterified cholesterol fractions by chromatography post incubation, and subsequent counting of radioactivity in the individual fractions. RESULTS: Male patients have higher FERHDL values than their female counterparts. When HDL cholesterol was controlled for in a multivariate regression analysis, the sex factor was not significant. There was a significant positive correlation between FERHDL and plasma total cholesterol (r = 0.32), triglycerides (r = 0.82), apolipoprotein B (apo B; r = 0.48), insulin (r = 0.46), BMI (r = 0.31), and waist-to-hip ratio (WHR; r = 0.50). There was a negative correlation between FERHDL and HDL cholesterol (r = -0.76) and apolipoprotein AI (r = -0.60). When both HDL cholesterol and triglycerides were controlled for, the only significant correlation was between FERHDL and BMI. CONCLUSIONS: Non-insulin-requiring type 2 diabetic patients have FERHDL, which correlated positively with triglycerides and negatively with HDL cholesterol. The positive correlation of FERHDL with serum insulin, WHR, total cholesterol, and apo B, but not that with BMI, loses its significance when HDL cholesterol and triglycerides are controlled. The sex difference between men and women in FERHDL also loses its significance when HDL cholesterol is controlled.

Adult↗
PubMed1984

Familial hypercholesterolaemia: esterification of cholesterol in lymphocytes from homozygous and heterozygous subjects.

A comparative study of the rates of cholesterol esterification in lymphocytes from healthy subjects and patients with familial hypercholesterolaemia (25 heterozygotes and 10 homozygotes) was carried out. Freshly isolated lymphocytes were incubated at 37 degrees C in medium containing lipoprotein-deficient serum and [3H]oleate-albumin was extracted, isolated by thin layer chromatography and quantitated. Incorporation of [3H]oleate into cholesteryloleate was significantly higher in lymphocytes from both heterozygotes and homozygotes than in cells from normal subjects; there was no significant difference between the values for heterozygotes and homozygotes. For all three groups cholesteryloleate formation was dependent on the concentration of lipoprotein-deficient serum in the medium.

Adolescent↗
PubMed1987

Familial hypercholesterolaemia: effect of low density lipoproteins on esterification of cholesterol in lymphocytes from homozygous and heterozygous subjects.

The effect of low density lipoproteins on esterification of cholesterol was studied in lymphocytes from patients with familial hypercholesterolaemia; results were compared with those obtained using cells from normal individuals. Freshly isolated lymphocytes were maintained in lipoprotein-deficient medium for 48 h and the rate of formation of [3H] cholesteryl oleate from [3H] oleate was then determined in the presence or absence of low density lipoproteins. In the absence of low density lipoproteins, incorporation of [3H] oleate was higher in heterozygote and homozygote cells than in normal lymphocytes. Incorporation in the presence of low density lipoproteins was increased relative to that measured in their absence for all of the subjects studied; heterozygotes and homozygotes showed marked changes in some cases but not in others.

Adolescent↗
PubMed1999

Sugar Ester Modified Lipase Catalyzed Esterification in Organic Media.

The esterification reaction of a long-chain fatty acid and a fatty alcohol catalyzed by sugar ester-modified lipases in organic media was studied. The reaction activity was improved when the lipases were modified with sugar esters. Among four kinds of sugar esters and six kinds of lipases, lipase CES modified with sugar ester SE-7 showed the highest reaction activity. The pH, solvent and temperature on the reaction activity of SE-7 modified lipase CES were also studied.

Journal Article↗
PubMed1975

Esterification of cholesterol by the hepatopancreas of the mollusc Biomphalaria glabrata.

Homogenates of the hepatopancreas of the mollusc Biomphalaria glabrata, previously called Australorbis glabratus Say, 1818 (Pressoa, 1969), were incubated with cholesterol-4-C14 (dispersed on celite) at 37 degrees C for 24 hr. The lipids were extracted, separated into classes by thin-layer chromatography and the radioactivity associated with the different classes determined. Net esterfication of cholesterol was then obtained by calculating the percent of the total cholesterol radioactivity incorporated into the esterified cholesterol. The esterified cholesterol was also fractionated by thin layer chromatography, and the relative distribution of radioactivity associated with the different cholesterol ester groups was determined. The results showed the presence of cholesterol esterifying activity in the hepatopancreas with a percent esterification of 20.6%. It was found that the accumulation of radioactivity was higher in the polyunsaturated esters and lower in the monounsaturated esters.

Animals↗
PubMed2001

[A study on pathological changes of closed diffuse brain injury in rats with H.E., esterification-silver stain and albumin immunohistochemical stain].

OBJECTIVE: To observed the pathological changes of closed diffuse brain injury in the rats died immediately and 15 min to 5 days after the injury. METHODS: H.E. staind and esterification-silver stain were applied to investigate the closed diffuse brain injury. RESULTS: In rats died immediately after the concussive injury, a number of shrunken neurons(type I change), distended neurons(type II change) and wave-like nerve fibers were identified in the brain tissue, especially in brain-stem. At 2 h and 8 h after injury, brain edema and axonal swelling appeared clearly in the cortex and white matter, especially in brain-stem. At post-traumatic 8 h and 24 h, the axonal retraction balls began to appear. The amount of neurons undergoing type I and II changes and constraction balls increased along with the survivor time. After 4 days and 5 days, brain edema alleviated, but the retraction balls and axonal swelling still existed. With Esterifica-tion silver stain, the above changes of neurons and nerve fibers were more obvious. With ABC stain, the distribution of albumin(Al) was extended from the perio-vascular area to diffuse distribution. Al positive staining were more obvious in injuried neurons and nerve fibers. CONCLUSION: The distribution of the concussive damage in the brain are coup, contra-coup and centripental.

Albumins↗
PubMed2005

Relations between particle size of HDL and LDL lipoproteins and cholesterol esterification rate.

Particle size of low density (LDL) and high density (HDL) lipoproteins and cholesterol esterification rate in HDL plasma (FER(HDL)) are important independent predictors of coronary artery diseases (CAD). In this study we assessed the interrelations between these indicators and routinely examined plasma lipid parameters and plasma glucose concentrations. In 141 men, healthy volunteers, we examined plasma total cholesterol (TC), triglycerides (TG), HDL and LDL cholesterol (HDL-C, LDL-C) and HDL unesterified cholesterol (HDL-UC). Particle size distribution in HDL and LDL was assessed by gradient gel electrophoresis and FER(HDL) was estimated by radioassay. An effect of particle size and FER(HDL) on atherogenic indexes as the Log(TG/HDL-C) and TC/HDL-C was evaluated. Subjects in the study had plasma concentrations (mean +/- S.D.) of TC 5.2+/-0.9 mmol/l, HDL-C 1.2+/-0.3 mmol/l, TG 2.1+/-1.7 mmol/l, glucose 5+/-0.8 mmol/l. Relative concentration of HDL(2b) was 17.6+/-11.5 % and 14.6+/-11.8 % of HDL(3b,c). The mean diameter of LDL particles was 25.8+/-1.5 nm. The increase in FER(HDL) significantly correlated with the decrease in HDL(2b) and LDL particle size (r = -0.537 and -0.583, respectively, P<0.01) and the increase in HDL(3b,c) (0.473, P<0.01). Strong interrelations among TG and HDL-C or HDL-UC and FER(HDL) and particle size were found, but TC or LDL-C did not have such an effect. Atherogenic indexes Log(TG/HDL-C) and TC/HDL-C correlated with FER(HDL) (0.827 and 0.750, respectively, P<0.0001) and with HDL and LDL particle size.

Adult↗
PubMed1997

[Gas chromatographic analysis of methyl methacrylate and methanol in its esterification mixture].

A fast, simple and accurate gas chromatographic method is established for determining the content of methyl methacrylate (MMA) and methanol in the esterification mixture of methacrylic acid with methanol in the presence of sulfuric acid. In the measurement, polyethylene glycol-20M/sodium hydroxide was adopted as liquid phase, coated on the acid-washed 201 pink support. n-Heptane was used as the internal standard and the correction factors of MMA and methanol obtained were 1.65 and 4.10, respectively. It is significant for this method to be used to control MMA production by acetone cyanohydrin method and to improve the production technology.

English Abstract↗
PubMed1991

Interruption of the enterohepatic circulation of bile acids stimulates the esterification rate of cholesterol in human liver.

The activity of acyl CoA: cholesterol acyltransferase (ACAT), which catalyzes the esterification of cholesterol, was studied in liver microsomes obtained from cholestyramine-treated gallstone patients (n = 12) and patients with Crohn's disease who had undergone partial ileal resection (n = 11). Gallstone patients (n = 33) and gallstone-free subjects undergoing cholecystectomy because of polyps of the gallbladder (n = 8) served as controls. The mean levels of the ACAT activity were the same in the gallstone and the gallstone-free patient groups (6.0 +/- 0.4 and 6.1 +/- 1.1 pmol/min per mg protein, respectively). When exogenous cholesterol was added to the assay system the activities were increased four- to fivefold in both groups. The ACAT activity tended to be increased in the cholestyramine-treated patients (8.1 +/- 1.8 pmol/min per mg protein), and was significantly enhanced (P less than 0.005) in the ileal-resected patients (12.3 +/- 2.3 pmol/min per mg protein). When the enzyme activity was determined with added exogenous cholesterol, it was significantly higher compared to the controls in both the cholestyramine-treated patients and the patients with ileal resection (57.9 +/- 11.6 and 50.0 +/- 10.3 pmol/min per mg protein, respectively). The content of free and esterified cholesterol in liver homogenates and microsomes was not significantly different between the patient groups. We conclude that ACAT activity is increased in patients with interruption of the enterohepatic circulation of bile acids, and speculate that this reflects a stimulated uptake of lipoprotein cholesterol and may indicate that more cholesteryl esters are incorporated into very low density lipoproteins.

Adult↗
PubMedDate not supplied

[Cholesterol esterification in tissues and change in the apoprotein spectrum in rat blood under the effect of auto-oxidized cholesterol].

Influence of autooxidized cholesterol (Ch) products on accumulation of cholesterol esters (ChE) in liver and aorta tissues as well as alteration of the apolipoprotein spectrum in low density and very low density (LDL and VLDL) lipoproteins in blood plasma was studied in rats treated with purified Ch (ChP-rats) and with oxidized Ch containing 5% 25-hydroxyCh and 3% 7-ketoCh (ChO-rats). Increase of ChE content in liver tissue of ChO-rats resulted in two-fold activation of acyl-CoA-cholesterol-O-acyltransferase (ACAT) in liver microsomes as compared with the enzymatic activity rate in ChP-rats. As shown by polyacrylamide gel electrophoresis content of apoE in VLDL and LDL of ChO-rats was 1,5-fold higher as compared with that of ChP-rats. Content of apoIV was increased in LDL and VLDL of ChP-rats as compared with controls; this effect was not observed in ChO-rats. LDL and VLDL from ChO-rats stimulated incorporation of 14C-oleate into ChE of cultivated macrophages. Increase in content of ChE found in aorta of ChO-rats appears to occur due to activation of Ch esterification. Intensification of ChE synthesis in tissues and alterations in the spectrum of LDL and VLDL apolipoproteins caused by oxidized products of cholesterol may be one of the mechanisms involved in atherogenesis.

Animals↗
PubMed1991

Effects of different types of polyunsaturated fatty acids on cholesterol esterification in human fibroblasts.

We have enriched human fibroblasts with oleic acid, with linoleic acid and with eicosapentaenoic acid. The accumulation of cholesteryl esters in the cells and the rate of esterification of cholesterol by microsomal acyl-CoA:cholesterol acyltransferase (ACAT) were measured in these cells. Cholesteryl ester levels were lower in cells enriched with eicosapentaenoic acid compared with cells enriched with oleate or linoleate. We also observed significantly lower ACAT activities in the microsomes from fibroblasts enriched with the n-3 polyunsaturated fatty acids relative to cells enriched with oleic acid or linoleic acid. We suggest that the presence of n-3 polyunsaturated fatty acids might suppress cholesteryl ester accumulation and inhibit atherogenesis.

Cells, Cultured↗
PubMed1991

The degree of esterification and points of substitution by O-acetyl and O-(3-hydroxybutanoyl) groups in the acidic extracellular polysaccharides secreted by Rhizobium leguminosarum biovars viciae, trifolii, and phaseoli are not related to host range.

Rhizobium leguminosarum biovars viciae, trifolii, and phaseoli have been grown in the presence and absence of 4',5,7-trihydroxyflavonone (naringenin) or 4',5,7-trihydroxyflavone (apigenin), which induce the expression of nodulation genes of the bacteria. The acidic polysaccharides secreted by the Rhizobium were isolated from the culture media and purified. The polysaccharides were cleaved with a bacteriophage enzyme and the octasaccharide repeating units formed were isolated. The glycosyl sequence and type of nonglycosyl substituents of the repeating units derived from a number of these Rhizobium biovars were shown by fast atom bombardment-mass spectroscopy and proton nuclear magnetic resonance spectroscopy (1H NMR) to be identical. Minor variations in the degree of esterification of the repeating units by O-acetyl and O-(3-hydroxybutanoyl) substituents were observed when the Rhizobium were grown in the presence or absence of the flavonoids. The variation in content and the points of attachment of the O-acetyl and O-(3-hydroxybutanoyl) substituents were as great within each Rhizobium biovar as between different Rhizobium biovars and, contrary to two recent reports (Philip-Hollingsworth, S., Hollingsworth, R. I., and Dazzo, F. B. (1989) J. Biol. Chem. 264, 1461-1466; Philip-Hollingsworth, S., Hollingsworth, R. I., Dazzo, F. B., Djordjevic, M. A., and Rolfe, B. G. (1989) J. Biol. Chem. 264, 5710-5714), the O-acylation patterns were not correlated with the host specificity of the bacteria.

Acetylation↗