Cholesterol lowering effects of a choleretic phloracetophenone in hypercholesterolemic hamsters.

The plasma cholesterol-lowering effect and mechanism thereof of a choleretic phloracetophenone or 2,4,6-trihydroxyacetophenone (THA) were investigated in hypercholesterolemic male hamsters. Intragastric administration of THA (300-600 micromol/kg) twice a day for 7 days to these animals caused a dose- and time-dependent decrease in both plasma cholesterol and triglyceride levels. THA at a dose of 400 micromol/kg reduced the cholesterol and triglyceride levels in plasma to 52% and 25% of the level in corresponding cholesterol-fed controls, respectively, with decreases in both plasma very low density lipoprotein and low density lipoprotein cholesterol but not in high density lipoprotein cholesterol.

Evaluation of the acute and subacute toxicity of a choleretic phloracetophenone in experimental animals.

Toxicity of a choleretic compound, phloracetophenone (2,4,6-trihydroxyacetophenone; THA) was investigated in mice, rats and hamsters. Acute toxicity of THA was observed to be dependent on species and route of administration, but not sex and age. LD(50) values for an acute toxicity of a single i.

Choleretic activity of phloracetophenone in rats: structure-function studies using acetophenone analogues.

The relationship between the chemical structure and choleretic activity of phloracetophenone (2,4,6-trihydroxyacetophenone) was investigated in adult male rats. Fourteen acetophenone analogues, with different substituents on the benzene nucleus, were intraduodenally administered and bile samples were collected via a bile fistula. All of the compounds tested immediately induced choleresis.

Hypocholesterolemic effect of vitamin E on cholesterol-fed rabbit.

Serum cholesterol level increased sharply in rabbits fed an atherosclerosis-promoting diet containing 0.25% or 0.5% cholesterol.

Comparison of sarcoplasmic reticulum Ca2+-adenosine triphosphatase from vitamin E-deficient dystrophic rabbit skeletal muscle with iron-ascorbate-treated and untreated enzyme.

Sarcoplasmic reticulum Ca2+-ATPase from rabbit skeletal muscle has an Arrhenius curve of enzyme activity with a discontinuity at about 20 degrees C. Preparations treated with FeSO4 and ascorbic acid and from a vitamin E-deficient dystrophic rabbit have 22% of the normal activity and a linear Arrhenius curve (Promkhatkaew, D., Komaratat, P.

Ascorbic acid-Fe2+ treatment mimics effect of vitamin E deficiency on sarcoplasmic Ca-ATPase of rabbit muscle.

After 90 min treatment with ascorbic acid and FeSO4 at 4 degrees C, the activity of rabbit sarcoplasmic reticulum Ca-ATPase was reduced to 22% and the Arrhenius plot of enzyme activity showed an absence of a discontinuity. The presence of vitamin E restored enzyme activity (60%) and the discontinuity in the Arrhenius plot. Ca-ATPase reconstituted with delipidated protein from ascorbic acid-Fe-treated preparation and normal lipid exhibited properties similar to the intact treated enzyme, whereas that reconstituted with delipidated normal protein and lipid from treated preparation exhibited reduced activity but retained the Arrhenius discontinuity.

Effects of vitamin E deficiency on the distribution of cholesterol in plasma lipoproteins and the activity of cholesterol 7 alpha-hydroxylase in rabbit liver.

Vitamin E-deficient rabbits with signs of muscular dystrophy showed accumulation of cholesterol in muscle as well as elevation of plasma cholesterol. The increase in plasma cholesterol was detected in low density lipoprotein (LDL) and very low density lipoprotein (VLDL) but not in high density lipoprotein (HDL) fractions of plasma lipoproteins. In liver, the activity of cholesterol 7 alpha-hydroxylase, the key enzyme involved in degradation of cholesterol, was approximately one-fifth that of control rabbits.

Effect of vitamin E on cholesterol plasma lipoprotein distribution and metabolism in rabbit.

In the rabbit, after nine weeks on a basal synthetic diet supplemented with stripped corn oil and varying amount of vitamin E, plasma cholesterol level was depressed as the supplementation of vitamin E was increased. This hypocholesterolemic effect was accompanied by an increase in hepatic cholesterol-7 alpha-hydroxylase activity and cytochrome P-450 level and by a redistribution of plasma lipoprotein-cholesterol resulting in the elevation of high density to low density lipoprotein-cholesterol ratio.

Altered property of sarcoplasmic Ca-ATPase from vitamin E-deficient dystrophic rabbit is associated with the protein and not the lipid component.

The effects of temperature on reconstituted sarcoplasmic Ca-ATPase preparations from vitamin E-deficient dystrophic and control rabbits were studied. Delipidated Ca-ATPase from vitamin E-deficient sarcoplasmic reticulum (SR) reconstituted with lipid of control SR exhibited properties similar to preparations reconstituted with lipid of vitamin E-deficient SR, namely low Ca-ATPase activity and a linear Arrhenius plot of enzyme activity. On the other hand, delipidated control SR Ca-ATPase reconstituted with lipid of vitamin E-deficient SR showed a reduction in activity but retained the discontinuity in the Arrhenius plot.

Effects of vitamin E deficiency on the activities of lipid-requiring enzymes in rabbit liver and muscle.

The effects of vitamin E deficiency on membrane integrity were studied by examining the temperature dependence of membrane-bound enzyme activities in liver mitochondria and microsome and in muscle sarcoplasmic reticulum. In vitamin E-deficient rabbits, the specific activities at 37 degrees of mitochondrial oligomycin-sensitive ATPase (EC 3.6.

Isolation and characterization of Actinopolyspora halophila, gen. et sp. nov., an extremely halophilic actinomycete.

An actinomycete, isolated as a contaminant of a culture medium containing 25% NaCl, has been classified as Actinopolyspora halophila gen. et sp. nov.

The lipid composition of a halotolerant species of Staphylococcus epidermidis.

Studies were carried out on the lipid composition of a halotolerant Staphylococcus epidermidis isolated in pure culture from a growth medium for extreme halophiles containing 25% NaCl. The four major polar lipid components in this bacterium were found to be: (a) glycerophosphoryl diglucosyl diglyceride (10% by weight) with structure 3(1)-O-(-sn-glycerol-1-phosphoryl-6'-O=(beta-D glucopyranosyl-(1 leads to 6)- O-beta-D-glucopyranosyl)-1(3),2-diacyl-sn-glycerol; (b) diglucosyl diglyceride (15% by weight) with structure 3(1)-O-(beta-D-glucopyranosyl (1 leads to 6)-O-beta-D-glucopyranosyl)-1(3),2-diacyl-sn-glycerol; (c) monoglucosyl diglyceride (3% by weight) with structure 3(1)-O-(beta-D-glucopyranosyl)-1(3),2-diacyl-sn-glycerol, and (d) phosphatidylglycerol (60% by weight) with structure 1,2 diacyl-sn-glycero-3-phosphoryl-1'-sn-glycerol. Phosphatidic acid, cardiolipin, lysophosphatidylglycerol and three unidentified phospholipids were also detected in small amounts.