Biomedical subjects

I H Hall

Publications and source records attributed to I H Hall.

At least 73 records · Page 4Linked to original sources

PubMed1993

Hypolipidemic effects of 6-amino-2-mercapto-5-methylpyrimidine-4-carboxylic acid in rats and tissue culture cells.

6-Amino-2-mercapto-5-methylpyrimidine-4-carboxylic acid (AMMPCA) was found to be a potent hypolipidemic agent at oral doses of 10 and 20 mg/kg/day in rodents. This agent was observed to affect de novo lipid synthesizing enzyme activities in a manner that resulted in lower lipid levels in tissues including the aorta wall. Very low density lipoprotein and low density lipoprotein cholesterol levels were reduced, whereas high density lipoprotein cholesterol levels were significantly increased. AMMPCA interfered with low density receptor activity, suggesting that the drug blocked lipid uptake by peripheral tissue while stimulating binding of lipid to the high density lipoprotein receptor, which should accelerate lipid clearance from the tissues and blood. A second mode of action of the drug is enhanced biliary excretion of lipids, but there was no evidence of a lithogenic effect. Acute toxicity studies in rodents support the fact that AMMPCA is safe in its therapeutic dose range.

Animals↗

PubMed1993

Synthesis and hypolipidemic activity of 4-substituted 1-acyl-1,2,4-triazolidine-3,5-diones in rodents.

A series of 4-substituted 1-acyl-1,2,4-triazolidine-3,5-diones demonstrated potent activity in CF1 mice when administered intraperitoneally at 20 mg/kg/day, lowering both serum cholesterol and triglyceride levels significantly. The 4-(4-chlorophenyl)-substituted compounds demonstrated better hypolipidemic activity in rodents than 4-methoxy-, 4-nitro-, and 4-t-butylphenyl substitutions. Aryl and alkyl substitutions rather than benzoyl substitutions at position 4 demonstrated good hypocholesterolemic activity. Selected compounds were examined for the mode of action in rats in which serum cholesterol and triglyceride levels were reduced after administration of 20 mg/kg/day orally; tissue lipids were reduced after 14 days of administration, and bile and fecal lipids were increased by 44-250%. Serum lipoprotein levels were also modulated by the agents, with cholesterol levels in very low density lipoprotein and low density lipoprotein fractions being reduced by 2-57%. Cholesterol levels in the high density lipoprotein fraction were elevated by 94-341%. Activities of mouse hepatic enzymes were suppressed by the agents in a manner that suggested that the compounds interfere with de novo synthesis of lipids.

Animals↗

PubMed1993

Comparison between 6,7-dihydro-5H-dibenz(c,e)azepine and lovastatin as hypolipidemic agents in rats.

6,7-Dihydro-5H-dibenz(c,e)azepine (azepine) and lovastatin were investigated for their hypolipidemic activity in Sprague-Dawley male rats. Azepine lowered both serum total cholesterol and serum triglyceride levels, whereas lovastatin only lowered serum total cholesterol levels significantly. Lovastatin also elevated lipid levels in tissues, whereas azepine in general did not have a similar effect. High-density lipoprotein cholesterol levels were significantly elevated and low-density lipoprotein cholesterol levels were reduced after treatment with both agents. Concentrations of ApoE and ApoAl of high-density lipoprotein were increased after treatment, a result that should enhance the reverse cholesterol transport process of returning cholesterol to the liver for excretion. Azepine appeared to be safe in its therapeutic range in rodents.

Administration, Oral↗

PubMed1993

Hypolipidemic activity of 6-alkoxycarbonyl-3-aryl-1,3,5- triazabicyclo[3.1.0]hexane-2,4-diones and 2-alkoxycarbonyl-5-aryl-1,3,5-triazine-4,6(1H,5H)-diones in rodents.

Significant hypolipidemic activity was demonstrated by 6-ethoxycarbonyl-1-3-phenyl-1,3,5-triazabicyclo[3.1.0]hexane-2,4-dione, 2-ethoxycarbonyl-5-phenyl-1,3,5-triazine-4,6(1H,5H)-dione and 2-ethoxycarbonyl-5-(4-chlorophenyl)-1,3,5-triazine-4,6(1H,5H)-dione in rodents at 20 mg/kg/day. These agents lowered serum cholesterol and triglyceride levels by approximately 40% in mice after 16 d. Tissue lipids in rat liver, small intestinal mucosa, aortic wall and feces were reduced by treatment with the agents. Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol levels were reduced in the rat; high density lipoprotein (HDL) cholesterol levels were elevated after 14 d of treatment. The activities of regulatory enzymes, e.g., acetyl-CoA synthetase, acyl-CoA:cholesterol acyltransferase, cholesterol 7 alpha-hydroxylase, sn-glycerol-3-phosphate acyltransferase, phosphatidylate phosphohydrolase and heparin-induced lipoprotein lipase, involved in de novo synthesis of hepatic lipids were affected by the agents. The new compounds may represent another class of potentially useful hypolipidemic agents for the treatment of atherosclerosis since HDL cholesterol levels were increased and VLDL and LDL cholesterol levels were lowered by some of the agents.

Administration, Oral↗

PubMed1993

Hypolipidemic activity of boronated nucleosides and nucleotides in rodents.

Base-boronated nucleoside and phosphate-boronated nucleotides were potent hypolipidemic agents in rodents, lowering both serum cholesterol and triglyceride levels. Rat VLDL and LDL cholesterol levels were generally reduced and HDL cholesterol levels were significantly elevated after 14 days dosing at 8 mg/kg/day. Tissue cholesterol, triglyceride and phospholipid levels were reduced by selected derivatives. Increased fecal excretion of lipids did not appear to be a mechanism by which these derivatives lowered serum lipids in rodents. Rather, the agents suppressed appetite and reduced the activities of rate-limiting enzymes for de novo lipid synthesis, specifically cytoplasmic acetyl CoA synthetase, squalene synthetase, and phosphatidylate phosphohydrolase with IC50 values of approximately 10(-5) m.

Animals↗

PubMed1993

The hypolipidemic effects of 1-acetyl-4-phenyl-1,2,4-triazolidine-3,5-dione in rodents.

1-Acetyl-4-phenyl-1,2,4-triazolidine,5-dione (APTD), a potent hypolipidemic agent, lowered both serum cholesterol and triglyceride levels in normo- and hyperlipidemic rats at 10 or 20 mg/kg/day. The agent effectively lowered VLDL-cholesterol (VLDL-C) and LDL-C content and raised HDL-C content in normal and hyperlipidemic rats treated from 4 to 8 weeks. Similar effects on the incorporation of cholesterol into the lipoprotein fractions were observed after drug treatment. Tissue lipids, e.g. cholesterol, were lowered, whereas fecal cholesterol levels were increased. APTD's primary targets were acyl CoA cholesterol acyl transferase (ACAT) for cholesterol ester synthesis and sn-glycerol-3-phosphate acyl transferase (GPAT) and phosphatidylate phosphohydrolase (PPH) for triglyceride synthesis.

Animals↗

PubMed1993

The cytotoxicity of heterocyclic thiosemicarbazones and their metal complexes on human and murine tissue culture cells.

Heterocyclic thiosemicarbazones, thioureas and 2-substituted pyridine N-oxides as well as representative nickel, cobalt and copper complexes were shown to be potent antineoplastic/cytotoxic agents. The cytotoxicity was demonstrated against single cell leukemia as well as cell lines derived from solid tissue (colon adenocarcinoma, HeLa, KB, skin, bronchogenic lung, bone osteosarcoma and glioma). In L1210 cells, DNA synthesis and subsequently RNA synthesis were particularly inhibited by the agents. IMP dehydrogenase activity and thus purine de novo synthesis was reduced significantly by the agents. Dihydrofolate reductase, ribonucleoside reductase, nucleoside kinase and DNA polymerase alpha activities were inhibited by the agents. d(NTP) pool levels were reduced by most of the agents. DNA strand scission was present with all of the derivatives; however, there was no evidence of intercalation, cross linking or alkylation/binding to bases of DNA. This new group of compounds may offer novel exploratory derivatives for future investigations in the treatment of cancer.

Animals↗

PubMed1993

The cytotoxicity of copper(II) complexes of heterocyclic thiosemicarbazones and 2-substituted pyridine N-oxides.

Thiosemicarbazone complexes of copper(II) were shown to be potent cytotoxic/antineoplastic agents against the growth of murine and human tumor cells. Selectivity of some agents was demonstrated against specific solid tumor growth. In L1210 lymphoid leukemia cells the copper complexes preferentially inhibited DNA synthesis with their major effects on the purine de novo pathway at PRPP amido transferase, IMP dehydrogenase and dihydrofolate reductase. The reductions of purines correlated positively with inhibition of DNA synthesis and cytotoxicity of the agents tested. DNA itself was fragmented after incubation with the drug; however, no binding of the agent to nucleotide bases or intercalation between base pairs was evident.

Animals↗

PubMed1993

The cytotoxicity of N-substituted indazolones in murine and human tumor cells.

N-Substituted indazolones are effective cytotoxic agents, causing cell death in a number of tissue culture lines, e.g. L1210, Tmolt3, colon adenocarcinoma and HeLa-S3. Selected agents were also active against the growth of KB, bronchogenic lung, osteosarcoma and glioma. The mode of action of the derivatives involves inhibition of de novo purine synthesis of L1210 cells, which reduces DNA and RNA syntheses. Agents lowered d(NTP) pools, further reducing DNA synthesis. DNA strand scission was evident after incubation with N-substituted indazolones for 24 h at 100 microM, lowering DNA synthesis and causing cell death.

Animals↗

PubMed1993

The cytotoxicity of N-substituted diphenimides and 6,7-dihydro-5H-dibenz[c,e]azepines.

N-substituted diphenimides and 6,7-dihydro-5H-dibenz[c,e]azepines demonstrated significant cytotoxic activity against the growth of murine and human cells. These derivatives were active against leukemias, carcinomas and sarcomas. Different derivatives with N-substitutions showed specific activity against the growth of several tumor types. These agents inhibited L1210 leukemia IMP dehydrogenase and PRPP amido transferase activities; this was reflected in the inhibition of purine and DNA synthesis. Other sites inhibited to a minor degree by these agents included DNA polymerase alpha, r- and tRNA polymerases, ribonucleoside reductase, dihydrofolate reductase, pyrimidine synthesis, and nucleoside kinase. d(NTP) pool levels were reduced after 24 h incubation with these derivatives. L1210 DNA strand scission was evident after drug treatment.

Animals↗

PubMed1993

Hypolipidemic activity of 1-acyl- and 1,2-diacyl-3,5-pyrazolidinediones.

A series of substituted 1-acyl- and 1,2-diacyl-3,5-pyrazolidinediones were found to have hypolipidemic properties lowering both serum cholesterol and triglyceride levels in rodents. For optimal activity of the pyrazolidinediones, both nitrogen atoms of the ring needed to be substituted preferentially with MeCO groups. This compound lowered rat VLDL but did not elevate HDL cholesterol content.

Animals↗

PubMed1992

Potential aldose reductase inhibitors: 1,2,4-triazolidine-3,5-diones and 2-(3,4,5-trimethoxybenzoyl)-4,4-diethyl-3,5-isoxazolidinedione .

1,2,4-Triazolidine-3,5-diones and the 3,5-isoxazolidinedione were observed to be potent inhibitors of rat lens aldose reductase activity. In vivo in streptozotocin-diabetic rats, selected agents at 20 mg/kg/day, orally for 21 days reduced significantly the sorbitol levels of rbc, lens and sciatic nerves, suggesting that these derivatives may have some usefulness to treat clinical complications of diabetes mellitus.

Aldehyde Reductase↗

PubMed1992

Relationship of hypolipidemic and antineoplastic activities of tricyclohexyl- and triphenylphosphine boranes, carboxyboranes, cyanoboranes, and related derivatives.

A series of tricyclohexyl- and triphenylphosphine boranes, carboxyboranes and cyanoboranes were synthesized. These compounds have potent hypolipidemic effects, antineoplastic and antiinflammatory activities in rodents. Furthermore, they demonstrated potent cyctotoxicity against standard human tissue culture lines. The compounds which afforded the best hypolipidemic activity, i.e. greater than 40% reduction of serum cholesterol and triglyceride levels, were diphenyl-(4-methylphenyl)-phosphine borane and triphenylphosphine carboxyborane. Other derivatives demonstrated more potent antineoplastic activity against the Ehrlich ascites carcinoma growth including triphenylphosphine cyanoborane, 2-amino-4-methyl-pyridine cyanoborane and 2-amino-pyridine cyanoborane. Most of the derivatives showed good activity against murine L1210 lymphoid leukemia, Tmolt3 human leukemia, uterine HeLaS cells, and human glioma cell growth. Select compounds were active against colon adenocarcinoma, KB nasopharynx, lung bronchogenic and osteosarcoma cell growth. Tricyclohexyl- and triphenylphosphine boranes and the carboxy derivatives of the latter borane demonstrated good antiinflammatory activity.

Animals↗

PubMed1992

Synthesis, cytotoxicity, hypolipidemic and anti-inflammatory activities of amine-boranes and esters of boron analogues of choline and thiocholine.

Boron analogues of carbamoylcholine and thiocholine and esters of these analogues were prepared. These compounds were fairly stable toward hydrolysis and demonstrated moderate anti-inflammatory and hypolipidemic activities in mice. The hypolipidemic activity of the compounds at a dose of 8 mg/kg/day was equivalent in reducing lipid levels in serum to those of clofibrate at 150 mg/kg/day and lovastatin at 8 mg/kg/day. The compounds demonstrated significant cytotoxic activity against the growth of murine and human tumor cells; all were active against the growth of human HeLa-S3 uterine suspended cells, and some were active against murine L1210 lymphoid leukemia, human Tmolt3 leukemia cells, colorectal adenocarcinoma, KB nasopharynx, osteosarcoma, and glioma. These studies demonstrated that antimetabolite analogues of acetylcholine exhibit the same types of pharmacological activity as other boron-substituted betaine and amino acids. Furthermore, a strong positive correlation exists between hypolipidemic activity and cytotoxicity for these new choline derivatives, as has previously been demonstrated for other boron-containing amino acids, amides, esters, and peptides.

Amines↗

PubMed1992

Hypolipidaemic activity in rodents of boron analogs of phosphonoacetates and cyanoborane adducts of dialkyl aminomethylphosphonates.

Boron analogues of phosphonoacetates proved to be potent hypolipidaemic agents in rodents, lowering both serum cholesterol and triglyceride levels. (C2H5O)3PBH2COOCH3 proved to be the most effective agent in mice, lowering serum cholesterol 46% and serum triglycerides 54% after 16 days. (C2H5O)3PBH2COOH and Na+H+(C2H5O)2(-O)PBH2COO- caused greater than a 40% reduction in lipids. The cyanoborane adducts of aminomethylphosphonates were generally less effective; (C6H5O)2P(O)CH2NH2BH2CN was the most effective, lowering serum cholesterol 32% and serum triglycerides 43% after 16 days. The phosphonoacetates appeared to lower lipid concentrations by several mechanisms. First, they lowered the de novo synthesis of cholesterol and triglycerides in the liver. Second, they accelerated the excretion of lipids into the bile and faeces. Thirdly, they modulated LDL and HDL-cholesterol contents in a manner which suggests they reduced the deposition of lipids in peripheral tissues, and accelerated the movement of cholesterol from tissues (e.g. plaques) to the liver for excretion into the bile.

Animals↗

PubMed1992

The effects of N(4-methylphenyl)diphenimide on lipid metabolism of Sprague Dawley rats.

N(4-Methylphenyl)diphenimide proved to be an effective hypolipidemic agent in rats at 10 and 20 mg/kg/day. Both serum cholesterol and triglyceride levels were reduced significantly. Decreases in tissue lipids as well as VLDL cholesterol levels were observed. HDL-cholesterol was elevated even at 10 mg/kg/day. The agent was equally effective in hyperlipidemic diet-induced rats, lowering serum lipids and VLDL- and LDL-cholesterol while elevating HDL-cholesterol levels. The drug interfered with the incorporation of 3H-cholesterol and 3H-palmitic acid into chylomicrons, VLDL, and LDL. The two precursors were incorporated at a higher rate into HDL. 3H-Leucine was incorporated into chylomicrons, VLDL, and LDL at a higher rate, but not into HDL. Reduced uptake of the precursor for lipid synthesis was noted in tissues after treatment with the drug.

Animals↗

PubMed1992

The anti-neoplastic activity of 2,3-dihydrophthalazine-1,4-dione and N-butyl-2,3-dihydrophthalazine-1,4-dione in human and murine tumor cells.

2,3-Dihydrophthalazine-1,4-dione derivatives demonstrated potent cytotoxicity against the growth of murine leukemia cells and human single cell suspension, i.e. Tmolt3 leukemia and HeLa-S3, as well as colon adenocarcinoma and KB nasopharynx. However, only select compounds demonstrated activity against bronchogenic lung, osteosarcoma and glioma growth. 2,3-Dihydrophthalazine-1,4-dione was active in vivo against L1210 leukemia, Lewis lung and Ehrlich ascites carcinoma growth. In L1210 cells the agents inhibited both DNA and RNA synthesis, and a few of the compounds were capable of inhibiting protein synthesis at 3 times their ED50 values. When 2,3-dihydrophthalazine-1,4-dione and N-butyl-2,3-dihydrophthalazine-1,4-dione were examined for their mode of action in the L1210 lymphoid leukemia cells, the sites of inhibition by the agents appear to be the de novo purine pathway at the enzymes IMP dehydrogenase and PRPP amido transferase. IMP dehydrogenase activity was inhibited at least 45% by 45 min at 100 microM concentration of drugs whereas the remaining enzymes that were affected by the drugs were not inhibited as early. Secondary sites were dihydrofolate reductase and thymidylate synthetase. The d(NTP) levels were also reduced specifically dATP and dCTP levels.

Animals↗

PubMed1992

The antineoplastic and cytotoxicity of benzohydroxamic acids and related derivatives in murine and human tumor cells.

Benzohydroxamic acids proved to be potent cytotoxic agents suppressing the growth of a number of murine and human cell lines grown in tissue culture, e.g. leukemia, colon, uterine and glioma. Selected compounds demonstrated activity against the growth KB nasopharynx, bronchogenic lung, osteosarcoma and skin cancer. In vivo activity against Ehrlich ascites carcinoma growth was shown with certain compounds. In L1210 cells compound 2 inhibited DNA synthesis significantly within 60 min. the site of action of the agent appears to involve the purine de novo synthesis pathway at PRPP amido transferase and IMP dehydrogenase. Dihydrofolate reductase and nucleoside kinase activities were inhibited by the agent. The levels of d(NTP)s in L1210 cells were reduced after drug treatment. The drug did not appear to affect the DNA template directly causing any damage which might alter transcription and replication nor was there any inhibition of HeLa topoisomerase activity by the drug. Thus the drug appears to be a metabolic inhibitor of nucleoside metabolism.

Animals↗