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W C Burger

Publications and source records attributed to W C Burger.

At least 19 recordsLinked to original sources
PubMed1986

The structure of an inhibitor of cholesterol biosynthesis isolated from barley.

Purification of the oily, nonpolar fraction of high protein barley (Hordeum vulgare L.) flour by high pressure liquid chromatography yielded 10 major components, two (I, II) of which were potent inhibitors of cholesterogenesis in vivo and in vitro. The addition of purified inhibitor I (2.5-20 ppm) to chick diets significantly decreased hepatic cholesterogenesis and serum total and low density lipoprotein cholesterol and concomitantly increased lipogenic activity. The high resolution mass spectrometric analysis and measurement of different peaks of inhibitor I gave a molecular ion at m/e 424 (C29H44O2) and main peaks at m/e 205, 203, and 165 corresponding to C13H17O2, C13H15O2, and C10H13O2 moieties, respectively. which are characteristic of d-alpha-tocotrienol. This identification was confirmed against synthetic samples. The tocotrienols are widely distributed in the plant kingdom and differ from tocopherols (vitamin E) only in three double bonds in the isoprenoid chain which appear to be essential for the inhibition of cholesterogenesis.

Animals↗
PubMed1985

Suppression of cholesterogenesis by plant constituents: review of Wisconsin contributions to NC-167.

In animals, non-sterol metabolites of the mevalonate pathway act independently from receptor-mediated cholesterol uptake in the multivalent feedback regulation of mevalonate biosynthesis. Studies leading to the isolation and characterization of plant-borne suppressors of mevalonate biosynthesis are reviewed. We propose that one cardio-protective component of the vegetarian diet consists of a variety of non-sterol, post-mevalonate metabolites. These products of plant branches of the mevalonate pathway, discarded as animals evolved, continue to influence animal sterol metabolism. It is through this action, we propose, that the cholesterol-suppressive action of plant materials is expressed.

Animals↗
PubMed1984

Influence of culture filtrate of Trichoderma viride and barley on lipid metabolism of laying hens.

The suppression of hepatic 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase and cholesterol 7 alpha-hydroxylase, previously noted in studies of the influences of barley and the filtrate of Trichoderma viride culture (CF) on cholesterol metabolism in sexually immature birds, is shown in sexually mature birds. Barley, CF or both were fed in one study from the day of hatching, in another during the period of sexual maturation and, in a third study, CF was fed to mature layers. CF suppressed HMG CoA reductase by 30-50% and cholesterol 7 alpha-hydroxylase by 32-45% when added to the control diet. In birds fed barley rather than corn, the respective activities were 25-36% and 24-31% lower. These effects were expressed in the lowering of plasma cholesterol by 11-36%. Lipogenic activity based on the assays of 4 enzymes was increased 2-3 times by the treatments and plasma triglyceride elevated by 12-86%. The start of egg production by birds fed CF preceded the controls by 17 days. Birds fed barley trailed controls by 11-14 days. CF countered the barley-conditioned delay. Egg yolk cholesterol concentrations were lowered by both treatments. Eggs produced by hens fed barley were lower in weight; CF increased egg and yolk weights. Tissues from birds fed CF or barley for up to 30 weeks appeared to be normal.

Animal Feed↗
PubMed1984

Suppression of cholesterol biosynthesis by constituents of barley kernel.

Hepatic beta-hydroxy-beta-methylglutaryl CoA (HMG-CoA) reductase, cholesterol 7 alpha-hydroxylase (7 alpha-hyd), and fatty acid synthetase (FAS) activities and cholesterol levels were determined in chicks fed isonitrogenous corn- and high-protein barley flour (HPBF) based diets. HMG-CoA reductase (-27%), 7 alpha-hyd (-30%), and serum cholesterol (-13%) were reduced, whereas FAS increased (28%) in comparison to a corn-based (control) diet. fractions obtained by serial extractions of HPBF with solvents of increasing polarity were fed at levels equivalent to 20% HPBF in a corn-based diet to female White Leghorn (WHL) chickens for 3 weeks. A petroleum ether-soluble fraction of HPBF produced 3 effects: an increase in body weight (18%), a strong suppression of HMG-CoA reductase (-36%) and FAS (-40%) accompanied by decreases in serum triglyceride (-9%) and cholesterol levels (-23%). The methanol-soluble fraction produced a significant suppression of HMG-CoA reductase (-49%) and serum cholesterol level (-29%), and an increase in FAS activity (95%). These effects were duplicated in 7-week-old broiler chickens which also showed a significant decrease in chol-LDL (low density lipoprotein) levels by these fractions. The factor(s) lowering serum cholesterol concentration was about equally divided between the polar and nonpolar fractions, and each was significantly more effective than the 20% HPBF in the corn-based diet. The observed effects on lipogenesis and cholesterogenesis might be attributed to a number of chemical constituents of HPBF, but cannot be attributed to the water-insoluble plant fibers.

Animals↗
PubMed1983

Inhibition of cholesterol and fatty acid biosynthesis in liver enzymes and chicken hepatocytes by polar fractions of garlic.

Different concentrations of polar fractions, methanol-soluble (MESF), or water-soluble (WASF), of 1-8% equivalent to fresh garlic paste were added to yellow corn-soybean based diets and fed to 5-week-old male broiler chickens for 3 weeks to measure the inhibition of hepatic beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA) reductase, cholesterol 7 alpha-hydroxylase (7 alpha-hydroxy) and fatty acid synthetase (FAS). Dose-related decreases in the activities of these enzymes were obtained. Decreases in serum total cholesterol and in low density lipoprotein (LDL) levels were also observed. There was no effect on the level of cholesterol in high density lipoprotein (HDL). The most effective dose for these decreases was found 0.54% (MESF) and 1.2% (WASF) equivalent to 6% of the fresh garlic. The inhibition of HMG-CoA reductase and FAS by 25-300 micrograms of MESF or WASF for 15 min was tested in vitro, in male and female chicken hepatocytes. Inhibitions of activity were dose-dependent and the degree of inhibition increased with duration of incubation (150 micrograms of MESF or WASF 5 to 60 min). Dietary supplementation of odorless WASF of garlic was found to be very effective in lowering the total and LDL cholesterol levels compared to control chickens.

Animals↗
PubMed1983

Suppression of cholesterogenesis and reduction of LDL cholesterol by dietary ginseng and its fractions in chicken liver.

The effects of ginseng root powder and of serially extracted solvent fractions of ginseng on avian hepatic cholesterol metabolism and lipogenesis and on avian serum lipoprotein cholesterol levels were examined. In one study, White Leghorn females were fed for 4 weeks a corn-based diet (control) or an experimental diet in which was incorporated 0.25% Wisconsin ginseng or an equivalent quantity of a serial solvent fraction [petroleum ether (PESF), methyl alcohol (MESF), water (WASF)] or of the residue. beta-hydroxy-beta-methylglutaryl-CoA (HMG-CoA) reductase activity was significantly lower (P less than 0.01) in each of the treatment groups (31-37% of control activity) except that fed the extracted residue (90% of control, N.S.). Cholesterol 7 alpha-hydroxylase activity was lowered in parallel (45-64% of control, P less than 0.01) by all treatments except the residue (100% of control). Also with the exception of the residue treatment, each ginseng treatment effected a lowering of the serum total cholesterol level (67-83% of control, P less than 0.01) and of serum low density lipoprotein cholesterol level (53-81% of control, P less than 0.01). Lipogenic activities and serum triglycerides levels were lowered (P less than 0.01) by two of the ginseng treatments. The PESF treatment was the most effective suppressor of each parameter, 74% and 68% respectively, of the control values. The WASF also had significant impact. Not one of the experimental diets influenced the serum high density lipoprotein level. The PESF, the potent source of suppressors, effected a change in the ratio of low to high density lipoprotein cholesterol from 1.46 (control) to 0.88. The levels of cholesterol and triglycerides in liver under these conditions showed a similar pattern as that of serum. In companion studies, broiler females were fed 0.28% Chinese red ginseng root powder or its various fractions. The results confirmed those recorded above. The factor(s) responsible for lowering the serum total and low density lipoprotein cholesterol levels were generally more concentrated in the PESF and WASF of ginseng and each was significantly more effective than was ginseng root powder. Ginsenosides (saponins) are considered to be the active agents for the suppression of cholesterogenesis and lipogenesis.

Animals↗
PubMed1983

Effect of AMO 1618 on cholesterol and fatty acid metabolism in chickens and rats.

AMO 1618 (2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine carboxylate methyl chloride) was added to corn-soy based diets and fed to 9-week-old female chickens for 3 weeks to measure the inhibition of hepatic beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA) reductase and cholesterol 7 alpha-hydroxylase. Dose-related decreases in the activities of these two enzymes were obtained (2.5--15 ppm) of AMO 1618. Decreases in plasma total cholesterol, chol-HDL, and chol-LDL levels were observed, but the decreases in chol-LDL were substantially larger than those of chol-HDL in both chicken and rat. Assays of livers from rats fed 20 ppm AMO 1618 for 3 days had 24% less HMG-CoA reductase activity and 67% less cholesterol 7 alpha-hydroxylase activity than the controls. Plasma cholesterol in these animals was reduced 26%; the ratio of total cholesterol : chol-HDL was reduced from 3.27 to 2.67 and the chol-LDL : chol-HDL ratio was reduced from 1.96 to 1.14 as a result of the relatively brief treatment. Fatty acid synthetase (FAS) and other key lipogenic enzymes increased 1.5--4-fold in both the chicken and rat. The inhibition of HMG-CoA reductase and the induction of FAS by AMO 1618 were tested in vitro, using 10--100 micrograms (28--280 mumoles) for 15 min with isolated hepatocytes from chicken and rat. Linear responses in activity were dose-dependent and increased with duration of incubation (30 micrograms or 85 mumoles AMO 1618, 5--120 min) in both species. The results suggest the compound acts at the cellular level and AMO 1618 appears to possess several properties which recommend it for testing as a cholesterol-lowering agent in humans.

Animals↗
PubMed1983

Suppression of avian hepatic lipid metabolism by solvent extracts of garlic: impact on serum lipids.

The effects of garlic on lipid metabolism were examined in White Leghorn pullets that had been fed for 4 weeks either a control diet based on corn and soybean meal or an experimental diet containing either 3.8% garlic paste, a solvent extract (petroleum ether, methanol and water in sequence) of garlic paste, the residue or commercial garlic oil. Significant decreases in hepatic 3-hydroxy-3-methylglutaryl-CoA reductase (79-83%), cholesterol 7 alpha-hydroxylase (43-51%), fatty acid synthetase (17-29%) and in representative pentose-phosphate pathway (23-39%) activities accompanied the feeding of the petroleum ether-, methanol- and water-soluble fractions of garlic. Garlic paste and oil also suppressed these activities. Significant decreases in serum lipids occurred in response to the feeding of these garlic fractions: serum total cholesterol by 20-25%, low density lipoprotein cholesterol by 28-41% and triglycerides by 10-26%; but high density lipoprotein cholesterol failed to respond to these treatments. The residue remaining after solvent fractionation had little influence on these parameters. These findings were substantiated by a second study in which pullets of a commercial broiler line were fed the garlic fractions. The results confirm that garlic oil and odorous components of garlic lower cholesterol levels. An odorless water-soluble component of garlic also has this effect. The mechanism of the hypocholesterolemic action is at the level of the suppression of cholesterol biosynthesis.

Animals↗
PubMed1982

Effects of cereals and culture filtrate of Trichoderma viride on lipid metabolism of swine.

Swine were fed corn- or barley-based diets with, or without, culture filtrate (CF) of Trichoderma viride for 21 days. Weight gains were nonsignificantly but slightly increased by CF. The activities of beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA) reductase, cholesterol 7 alpha-hydroxylase, acetyl-CoA carboxylase (ACX), fatty acid synthetase (FAS) and other lipogenic enzymes in several tissues were determined. Significant decreases in the activities of HMG-CoA reductase and cholesterol 7 alpha-hydroxylase in all tissues of swine fed the CF-diets were observed. The major site for the regulation of cholesterol biosynthesis was adipose tissue followed by the intestine, liver, lung and muscle in order of activity. The concentrations of cholesterol in serum and muscle were decreased 27% and 23%, respectively, by CF. ACX and FAS activities increased ca. 2-fold when CF was fed with either of the cereal-based diets. The major sites for fatty acid synthesis was the adipose tissue and, to a lesser extent, the liver. Very low rates of synthesis were detected in intestine, lung and muscle. Similar distributions of activities were found for related lipogenic enzymes.

Adipose Tissue↗
PubMed1982

Effects of different fractions of the barley kernel on the hepatic lipid metabolism of chickens.

Various physical fractions of the barley kernel were fed to one-day-old female and male chickens to determine their effect on hepatic beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA) reductase, cholesterol 7 alpha-hydroxylase and the lipogenic enzymes, acetyl-CoA carboxylase (ACX), malic enzyme (ME), citrate-cleavage enzyme (CCE) and fatty acid synthetase (FAS) at the subcellular level. Significant inhibition (p less than 0.01) of cholesterol biosynthesis accompanied by significant decreases in plasma cholesterol concentrations and induction of fatty acid synthesis were found in diets based on pearled barley, barley pearlings and a high-protein barley flour (HPBF: aleurone and subaleurone layers of barley endosperm) separated from the pearlings when compared to corn. Lower weight gains in 1- to 4-week-old birds fed the high-protein barley flour were found to be the result of lower feed consumption; pair feeding of 12-week-old birds with diets based on corn and high-protein barley flour produced equal weight gains in both treatments and significant reductions in hepatic HMG-CoA reductase, plasma cholesterol and induction in several lipogenic enzymes in birds fed the high-protein barley flour. Substitutions of 5-20% high-protein barley flour for corn in a corn-based diet produced significant weight gains (p less than 0.01) of 10 to 20% in 2-week-old chickens, inhibited cholesterol biosynthesis by 45-65% and produced a 3-fold increase in a fatty acid synthetase. The results indicate that HPBF contains an inhibitor(s) of cholesterol biosynthesis and a growth factor(s) when compared to a corn-based diet.

Animals↗
PubMed1981

The viscosity interaction of barley beta-glucan with Trichoderma viride cellulase in the chick intestine.

A culture filtrate from Trichoderma viride was used as a source of cellulose degrading enzymes. This filtrate, when added to a barley ration fed to chicks, improved growth and feed efficiency by 19% and 8%, respectively. The response was saturable since increasing amounts of filtrate above 50 mg/kg produced no further improvement. Barley eta-glucan was added to a corn-based diet (10 g/kg) to evaluate the effect of the culture filtrate on the viscosity of beta-glucan in the chick intestinal contents. Barley beta-glucan increased the viscosity of the supernatant of the chick intestinal contents threefold and the culture filtrate reduced the viscosity to near control levels when combined with the diet containing beta-glucan. The presence of beta-glucan in barley probably limits growth of chicks by increasing viscosity of intestinal contents.

Animals↗
PubMed1980

Regulation of lipid metabolism in chicken liver by dietary cereals.

The activities of acetyl-CoA carboxylase (EC 6.4.1.2), fatty acid synthetase (FAS) and beta-hydroxy-beta-methylglutaryl-CoA (HMG-CoA) reductase (EC 1.1.1.88) were determined in subcellular fractions of livers from chicks fed different cereal-based diets. With a barley-based diet as compared to corn, the following was observed: body and liver weights decreased 31%; HMG-CoA reductase activity of liver decreased 79%; acetyl-CoA carboxylase activity increased 3-fold; fatty acid synthesis increased 5-fold, and plasma and liver cholesterol decreased 45% and 35%, respectively. The suppression and induction of activities of the two divergent pathways (cholesterol and fatty acid biosynthesis) persisted for at least 21 days. Wheat, oats and rye showed a similar but less pronounced effect. The pronounced decrease in plasma cholesterol level and HMG-CoA reductase activity have implications for human nutrition and possible control of the cardiovascular diseases in which cholesterol plays a key role.

Acetyl-CoA Carboxylase↗
PubMed1978

Development and Localization of Carboxypeptidase Activity in Embryo-less Barley Half-kernels.

Distal half-kernels of barley (Hordeum vulgare L.), after imbibition for 1 day, produced a carboxypeptidase that was active on N-carbobenzoxy-l-phenylalanyl-l-alanine and on N-carbobenzoxy-l-phenylalanyl-l-phenylalanine. For the ensuing 2 days, activity increased linearly and thereafter increased at reduced rates. Electrofocusing of an imbibed half-kernel homogenate produced coincident peaks of activity on both substrates. Experiments with dissected imbibed (3 days) half-kernels showed that the enzyme arose in the aleurone layer. Enzyme production was inhibited by 6-methylpurine, cordycepin, cycloheximide, and p-fluorophenylalanine, and activity was inhibited by phenylmethylsulfonylfluoride. The enzyme did not hydrolyze endopeptidase substrates over a range of pH.Gibberellic acid accelerated the rate of release from the aleurone, but was not essential for release and did not appreciably affect the ultimate amount of carboxypeptidase produced. In these respects, the carboxypeptidase appears to be unique among the known hydrolases produced by barley aleurone tissue.

Journal Article↗
PubMed1973

Multiple forms of acidic endopeptidase from germinated barley.

An endopeptidase preparation from germinated barley Hordeum vulgare L., cv. Trophy, purified by affinity chromatography and density-gradient electrofocusing, consisted of three or four components. The preparation was only partly resolved by electrofocusing, with evidence of three possible components (pI 4.15, 4.28, and 4.37). Gel filtration on Sephadex G-75 yielded an asymmetrical peak, the major part of which corresponded to a molecular weight of 14,100, with evidence of one larger and two smaller components. The activity of the preparation was sulfhydryl-dependent; cysteine was the most effective of several sulfhydryl compounds tested. The preparation was sensitive to O(2) in the absence of metal chelating agents and was inhibited by sulfhydryl reagents. It showed very narrow concentration tolerances for both cysteine and a substrate, N,N-dimethylhemoglobin. The Km value on N,N-dimethylhemoglobin at pH 3.8 was 0.064 to 0.067% (w/v) substrate; V(max) was 0.80 to 0.83 A(340) per hour. Normal enzyme activity and molecular-size distribution were observed when the endopeptidases were extracted in the inhibited state and subsequently reactivated, thus ruling out the possibility that the enzymes might be autolytic artifacts that arose during extraction and purification.

Journal Article↗