Biomedical subjects

I H Hall

Publications and source records attributed to I H Hall.

At least 109 records · Page 6Linked to original sources

PubMed1990

Structure activity relationships of imido N-alkyl semicarbazones, thiosemicarbazones and acethydrazones as hypolipidemic agents in rodents.

A series of nitrogen substituted N-butan-3-one derivatives of cyclic imides (phthalimide, substituted phthalimide, o-benzosulfimide, 1,8-naphthalimide, 2,3-dihydrophthalazine-1,4-dione and diphenimide) and their semicarbazone, thiosemicarbazone and acethydrazone derivatives were investigated for hypolipidemic activity in rodents. These compounds were generally potent hypolipidemic agents, lowering serum cholesterol levels on an average of 37% and serum triglyceride levels on an average of 29% after 16 days dosing at 20 mg/kg day intraperitoneally (I.P.) in mice. Several analogs, most notably the semicarbazone and acethydrazone derivatives of 1-N-(1,8-naphthalimido)-butan-3-one, demonstrated improved hypocholesterolemic activity relative to their ketone precursors. Similarly, the acethydrazone derivatives generally resulted in improved hypotriglyceridemic activity in each series of 2-(3-oxobutyl)-2,3-dihydrophthalazone-1,4-dione analogs tested. The thiosemicarbazones in mice generally resulted in a loss in hypolipidemic activity. Select compounds, 1-N-3-methylphthalimido butan-3-semicarbazone (Ig) and 1-(4-methoxyphthalazine-1(2H)-one)yl butan-3(N-acetyl)hydrazone (IVg), at 10 mg/kg/day orally administered to rats demonstrated potent hypolipidemic activity after 14 days. These compounds lowered liver, small intestine mucosa and aorta wall tissue lipids, e.g. cholesterol and triglycerides, and raised fecal excretion of cholesterol moderately and of triglyceride significantly. Rat serum lipoprotein fractions after treatment for 14 days showed that the two agents lowered VLDL cholesterol and raised HDL cholesterol content.

Animals↗

PubMed1990

Substituted cyclic imides as potential anti-gout agents.

N-substituted cyclic imides of phthalimide, 2,3-dihydrohalazine-1,4-dione, and diphenimide were shown to reduce the serum uric acid levels in normal and hyperuric mice at 20 mg/kg/day I.P. for 14 days. The agents were potent inhibitors of commercial xanthine dehydrogenase and xanthine oxidase enzyme activities with IC50 values from 10(-7) to 10(-8) M concentrations of drug.

Allopurinol↗

PubMed1990

Renal, hepatic, cardiac and thymic acute toxicity afforded by bis(helenalinyl)malonate in BDF1 mice.

Bis(helenalinyl)malonate [BHM], a pharmacologically active sesquiterpene lactone potentially useful as an antineoplastic agent, proved to be less toxic than its parent compound, helenalin. Its LD50 in BDF1 mice, i.p. was more than twice that of helenalin. Its lower toxicity allowed a higher therapeutic dose (15 mg/kg/day vs. 8 mg/kg/day for helenalin) which, in turn, afforded a greater T/C% (261 vs. 161). When BHM was employed at its therapeutic dose of 15 mg/kg/day, no marked toxicity was evident after three daily doses. However, continuation of treatment at this level led to both kidney and liver toxicity as measured by clinical chemistry parameters. Histological lesions in the thymus and kidney were demonstrated within 48 h at 25 mg/kg as a single dose. Apparently the toxicity was delayed with BHM but accumulated over time. Transient cardiotoxicity occurred with the drug and the agent was suspected of causing intestinal blockage.

Animals↗

PubMed1990

The antineoplastic activity of trimethylamine carboxyboranes and related esters and amides in murine and human tumor cell lines.

Trimethylamine carboxyboranes including their esters and amides were shown to have antineoplastic activity in vivo against Ehrlich ascites carcinoma growth. The derivatization to the ester or amide did not necessarily improve activity. Cytotoxicity of the derivatives was observed against the growth of murine and human tumor cells. Selectivity was demonstrated by the boron derivatives in the human solid tumor screens. Almost all the compounds demonstrated cytotoxicity against single-cell suspension growths, eg Tmolt3, L1210, HeLa-S3. Selection of two compounds to examine their mode of action in L1210 lymphoid leukemia cells showed that the agents perferentially inhibited DNA synthesis followed by protein and RNA synthesis. The d(TTP) pools were markedly reduced because of inhibition of nucleotide kinase activity. The agents also inhibited regulatory enzymes in the de novo purine pathway and afforded DNA strand scission. These effects by the agents were probably additive to bring about tumor cell death.

Animals↗

PubMed1990

Inhibition of nucleic acid synthesis in P388 lymphocytic leukemia cells in culture by cis-platinum derivatives.

Cis-diaminedichloroplatinum(II) [cDDP] and three related derivatives Pt(mal)(NH3)2, PtCl2(dach) and Pt(mal) (dach) have been observed to possess cytotoxicity against the growth of P388 lymphocytic leukemia cells. DNA synthesis in P388 cells was inhibited by the agents in a manner which was consistent with their ED50 values for cytotoxicity. When P388 cells were treated with these platinum complexes in vitro at doses which caused more than 80% inhibition of DNA synthesis, no significant inhibition was observed for thymidine, kinase, thymidine monophosphate kinase, carbamoyl phosphate synthetase, or aspartate transcarbamoylase activities. Thus, there was no evidence that these agents inhibited de novo purine, pyrmidine, or deoxynucleotide synthesis. All of the agents did inhibit the nuclear DNA polymerase activity, but the extent of inhibition was 20% or less at doses which caused greater than 70% inhibition of DNA synthesis. Thus, the inhibition of DNA synthesis appeared to be due to cisplatinum(II) drug binding to the DNA bases. This was estimated to be 1 atom of platinum per 1500-3000 DNA base pairs which is consistent with other studies. The platinum complexes with chloro leaving ligands caused considerable DNA strand scission by 24 h at 10 times the ED50 dose, most likely a measure of impending cell death. In contrast, the platinum complexes with malonato leaving ligands did not cause significant strand scission by 24 h at similar doses. They also exhibited a significant delay in the inhibition of DNA synthesis. These data were interpreted as resulting from slower monoadduct to diadduct conversion, but it is not possible to eliminate the possibility of a different mode of interaction with DNA or a different mechanism of cytotoxicity for the malonato compounds.

Animals↗

PubMed1990

The anti-inflammatory activity of 5H-dibenz[c,e]azepine-5,7(6H)dione, 6,7-dihydro-5H-dibenz[c,e]azepine, N-benzoylbenzamide and 1H-benz[d,e]isoquinoline-1,3(2H)dione derivatives in rodents.

A series of N-substituted 5H-dibenz[c,e]azepin-5,7(6H)dione, 6-substituted 6,7-dihydro-5H-dibenz[c,e]azepine, 1H-benz[d,e]isoquinoline-1,3(2H)dione and N-benzoyl derivatives was shown to have anti-inflammatory and local analgesic activity in rodents. 6-(4-Chlorophenyl)-5H-dibenz[c,e]azepin-5,7(6H)dione demonstrated greater than 50% inhibition of induced edema and the writhing reflex at 25 mg/kg, I.P. in mice. 6-Methyl-6,7-dihydro-5H-dibenz[c,e]azepine and the N-butyl and N-pentyl derivatives of the dibenz-[c,e]azepine and N-benzoylbenzamide series demonstrated potent activity in both screens. The 1H-benz[d,e]isoquinoline-1,3(2H)diones were generally less active than the other three chemical classes of agents tested. However, the 2-(methylthio)ethyl derivative of this series demonstrates good activity in both screens. These agents appeared to be as potent as the standards, indomethacin and phenylbutazone, as anti-inflammatory agents in these animal models. Selected agents, e.g. 6-(4-methylphenyl)-5H-dibenz[c,e]azepin-5,7(6H)dione demonstrated anti-arthritic and anti-gout activities in rodents. The N-methyl and N-butyl derivatives of 6,7-dihydro-5H-dibenz[c,e]azepine afforded good anti-pleurisy activity in rats at 25 mg/kg x 2. The agents which demonstrated potent anti-inflammatory action were found to inhibit acid lysosomal hydrolytic enzyme activities in mouse liver and macrophages at 10(-5) M concentrations. Trypsin, elastase and collagenase activities were also inhibited by the derivatives. Prostaglandin synthetase activity of bovine seminal vesicles and mouse macrophages was inhibited by the compounds at 10(-5) M concentrations.

Animals↗

PubMed1990

Hypolipidemic activity of benzohydroxamic acids and dibenzohydroxamic acids in rodents.

A series of benzo- and dibenzohydroxamic acids were shown to have potent hypolipidemic activity in mice and rats lowering both serum cholesterol and triglyceride levels at 20 mg/kg/day. Selected derivatives lowered tissue lipids, i.e. liver, small intestine and aorta, and accelerated fecal lipid excretion in rats. The VLDL and LDL cholesterol content was reduced and HDL cholesterol was significantly elevated after 14 days administration, orally. The agents were not HMG CoA reductase inhibitors; however, other lipid regulator enzyme activities were inhibited, e.g. acyl CoA cholesterol acyl transferase, ATP-dependent citrate lyase and acetyl CoA synthetase. The triglyceride levels were probably reduced due to the derivatives inhibiting the enzymatic activities of sn-glycerol-3-phosphate acyl transferase and phosphatidylate phosphohydrolase.

Administration, Oral↗

PubMed1990

Hypolipidemic activity of a series of N-pyridinyl and N-quinolinyl substituted derivatives of phthalimide and succinimides in rodents.

N-Pyridinyl- and N-quinolinyl-ethyl substituted succinimide and phthalimide derivatives demonstrated significant hypolipidemic activity in rodents lowering both serum cholesterol and triglyceride levels at 20 mg/kg.day i.p. The pyridinyl, quinolinyl and tetrahydro-2-quinolinyl substitution improved the hypolipidemic activity of the succinimide derivatives. Whereas select N-quinolinylethylphthalimide derivatives demonstrated less activity than phthalimide, itself, in lowering serum cholesterol and triglyceride levels, they did cause significant increases in HDL cholesterol and lower LDL cholesterol levels after 14 days of drug administration. Phthalimide actually caused reductions of HDL cholesterol levels in rats. These new agents with heterocyclic substitution of the N atom of phthalimide increased fecal excretion of lipids and suppressed in vitro hepatic rate limiting enzyme activities for de novo synthesis of cholesterol, fatty acids and triglycerides. Acute toxicity studies of the N-quinolinylethylphthalimide derivatives indicated that the agents are safe as potential therapeutic agents at doses necessary for hypolipidemic activity.

Animals↗

PubMed1989

In vitro inhibition of mouse hepatic mixed-function oxidase enzymes by helenalin and alantolactone.

The sesquiterpene lactones (STL) helenalin and alantolactone were effective in vitro inhibitors of the mouse hepatic microsomal mixed-function oxidase (MFO) enzymes, aminopyrine demethylase (APD), aniline hydroxylase (ANH) and 7-ethoxyresorufin deethylase (ERD). Helenalin and alantolactone concentrations of 0.5 mM produced a 50-60% inhibition of APD and ERD, and a 20-30% inhibition of ANH. An increase in substrate (aminopyrine) concentration from 0.5 to 25 mM decreased STL inhibition of APD by 12-32%. APD was also inhibited at low aminopyrine concentrations (0.5 mM) by the helenalin derivative 2,3,11,13-tetrahydrohelenalin (tetrahydrohelenalin). The STL produced type I binding spectra with oxidized microsomes; Ks values for helenalin and alantolactone were 161 and 9 microM respectively. These results suggest that STL inhibition of the MFO system results, in part, from STL binding to the substrate-binding site of cytochrome P-450. It has been reported that the irreversible alkylation of protein cysteinyl residues is responsible for STL inhibition of several different enzymes, and second-order rate constants for the reaction of helenalin and alantolactone with glutathione were 25.1 and 1.80 mM-1.hr-1 respectively. Tetrahydrohelenalin did not react with glutathione. However, the subsequent addition of 3.0 mM thiols, i.e. L-cysteine, N-acetylcysteine or glutathione, to STL-treated (0.5 mM) microsomes reversed helenalin and alantolactone inhibition of APD and ERD by 50-80%. The ability of thiols to reverse STL inhibition of APD was decreased 20-43% by the coincubation of STL and microsomes with an NADPH-generating system. In addition, established effects of sulfhydryl-reactive compounds on the MFO system, i.e. inhibition of NADPH-cytochrome c reductase and conversion of cytochrome P-450 to cytochrome P-420, were not observed after addition of helenalin (1.0 mM) or alantolactone (0.5 mM) to mouse hepatic microsomes. These results suggest that STL inhibition of MFO enzymes may not be dependent upon the reactivity of the STL towards sulfhydryl groups. Instead, we suggest that STL binding to the substrate-binding site of cytochrome P-450 and subsequent metabolism of the STL may contribute to inhibition of the MFO system.

Aminopyrine N-Demethylase↗

PubMed1989

Hypolipidemic activity of cyclic imido alkyl ethers, thioethers, sulfoxides, and sulfones.

N-Substituted alkyl ethers, thioethers, sulfoxides, and sulfones of cyclic imides (e.g., phthalimide, saccharin, 1,8-naphthalimide, succinimide, and 2,3-dihydrophthalazine-1,4-dione) were shown to have potent hypolipidemic activity at doses of 10 and 20 mg/kg/d in rodents. These N-substitutions afforded no improvement over other known N-substitutions (e.g., butyl, 3-butanone, or the propionic acid derivatives of phthalimide, saccharin, and 2,3-dihydrophthalazine-1,4-dione) compared with the respective parent compounds. However, 2-(methoxyethyl)-1H-benz[de]isoquinoline-1,3-(2H)dione (3a), 2-[2-methylsulfinyl]ethyl-1H-benz[de]isoquinoline-1,3-(2H)dione (3c), 1-(2-methylsulfinyl)-2,5-pyrrolidenedione (4c), and 1-(2-methoxyethyl-2,5-pyrrolidenedione (4a) significantly improved activity compared with parent compounds, as well as previously reported N-substituted analogues, reducing serum cholesterol levels and serum triglyceride levels by 40%. The thioether of succinimide afforded a 54% reduction of serum cholesterol and a 41% reduction of serum triglyceride levels in mice after 16 d. The alkyl thioethers of 1,8-naphthalimide and succinimide significantly lowered cholesterol levels in serum VLDL and LDL, while the alkyl thioethers of succinimide elevated HDL cholesterol content. Tissue lipids were reduced in the liver and aorta by these selected derivatives. The activities of regulatory enzymes in de novo synthesis of hepatic cholesterol and triglyceride were inhibited by the selected 1,8-naphthalimide derivatives. In situ cholesterol and cholic acid reabsorption from intestines were suppressed by the presence of the agents.

Animals↗

PubMed1989

The hypolipidemic activity of 1-N-3-methylphthalimido-butan-3-semicarbazone in rodents.

1-N-(3-Methylphthalimido)butan-3-one semicarbazone demonstrated potent hypolipidemic activity normal rats and mice and hyperlipidemic diet-induced mice. The compound decreased tissue lip levels and increased the fecal excretion of cholesterol and triglycerides. After 2 weeks of administration, serum lipoprotein levels were modulated so that very low-density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol concentrations were reduced and high-density lipoproteins (HDL) cholesterol concentrations were elevated to levels unprecedented by the cyclic imide derivatives previously tested. The VLDL triglyceride content was also reduced. Hepatic in vitro enzymatic studies demonstrated that the compound suppressed the activity of enzymes in the early synthesis of fatty acids and cholesterol and the regulatory enzymes for the de novo synthesis of triglycerides.

Animals↗

PubMed1989

Role of thiol agents in protecting against the toxicity of helenalin in tumor-bearing mice.

Helanalin, a sesquiterpene lactone antineoplastic agent, is toxic at therapeutic doses in murine tumors. The toxicity has been assumed to be correlated with the binding of the drug to cellular thiol groups. Studies were undertaken to increase the intracellular level of GSH in the liver, kidney and other tissues to eliminate the toxicity of helenalin in vivo. Combination of helenalin 8 mg/kg/day i.p.) with L-cysteine (100 mg/kg/day), beta-mercaptoethanolamine (20 mg/kg/day), 18-beta-glycyrrhetinic acid (15 mg/kg/day), or 4,4'-diaminodiphenylsulfone (10 mg/kg/day) afforded improvement in survival of mice bearing P-388 lymphocytic leukemia. However, other thiol-elevating agents, anti-oxidants, intracellular buffering agents, and cardiac treatment drugs were not effective. Hydrocortisone, Cortef, treatment with helenalin afforded improvement in life expectancy. Reduced glutathione (GSH) and non-protein sulfhydryl (NPS) levels were not reduced in the liver, kidney, or circulating red blood cells (rbc) by helenalin treatment. After three days treatment of mice with helenalin, GSH levels were reduced and NPS levels elevated in P-388 tumor cells. Administration of L-cysteine, beta-mercaptoethanolamine, 4,4'-diaminodiphenylsulfone, or 18-beta-glycyrrhetinic acid alone caused no alteration in liver GSH but elevated NPS levels; P388 cell GSH and NPS levels were lowered. Combination of any of these agents, after three days, with helenalin afforded increases in P-388 cell GSH and NPS levels. This data would suggest that helenalin toxicity is not related to the lowering of GSH or NPS levels in critical tissues of mice.

Animals↗

PubMed1989

Disposition of the hypolipidaemic agent, 2,3-dihydrophthalazine-1,4-dione, in Sprague Dawley rats.

The disposition of [14C]2,3-dihydrophthalazine-1,4-dione, a potent hypolipidaemic agent, has been determined after both intravenous and oral administration. Both the routes of administration afforded multi-exponential disposition with an estimated t1/2 of approximately 75 h. After oral administration, the drug was observed to be absorbed rapidly from the intestine and distributed quickly to all tissues of the body. A large quantity of the 14C-radioactivity was found in the skin and carcass. Approximately 35% of the administered radioactivity was excreted in urine after oral administration and 11% in the faeces. Approximately 66% of the radioactivity excreted in urine was the parent drug. There was evidence of an additional metabolite which accounted for 28% of the urinary radioactive excretion. The parent drug has little serum protein binding, is highly water soluble, and is probably taken up by cells by passive diffusion.

Administration, Oral↗

PubMed1989

The effects of boron hypolipidemic agents on LDL and HDL receptor binding and related enzyme activities of rat hepatocytes, aorta cells and human fibroblasts.

Two boron-containing hypolipidemic agents, N,N-dimethyl-n-octadecylamine borane and tetrakis-mu-(trimethylamine-boranecarboxylato)bis-(trimethylamine- carboxyborane)-dicopper(II) were shown to reduce significantly serum cholesterol and triglyceride levels after 14 days administration in rats. Serum low density lipoprotein (LDL) cholesterol content was reduced by both agents; however, high density lipoprotein (HDL) cholesterol was elevated by N,N-dimethyl-n-octadecylamine borane but reduced by the dicopper (II) complex. The boron agents suppressed LDL binding and internalization in hepatocytes, fibroblasts and aorta cells and elevated HDL binding and degradation in hepatocytes. Enzyme activities were modulated by the boron derivatives which would favor less cholesterol deposition in peripheral tissues and further clearance from the plaque cells.

Animals↗

PubMed1989

Disposition of cisplatin derivatives -3H-cis-1,2-diaminocyclohexanedichloroplatinum (II) and 3H-cis-1,2-diaminocyclohexanemalonatoplatinum (II) in BDF1 mice.

The disposition of 3H-cis-1,2-diaminocyclohexanedichloroplatinum (II) and 3H-cis-1,2-diaminocyclohexanemalonatoplatinum (II) was investigated in P388 tumor-bearing BDF1 mice. Fifteen minutes after IP administration of the drugs, the serum contained 12% of the 3H-chloride derivative and 20% of the malonate derivative. Both drugs distributed to all organs of the body but were not sequestered in any major internal organ. However, substantial amounts of the drugs were found in the carcass and skin. After 24 hr, approximately 43% of the radioactivity was excreted in the urine. Only 5 to 8% of the radioactivity was eliminated in the feces. The radioactivity half-life (t1/2 beta) for the 3H-chloride derivative was estimated from urinary excretion data to be 22.7 hr, and 30.0 hr for the 3H-malonate derivative.

Animals↗

PubMed1988

Inhibition of nucleic acid synthesis in P-388 lymphocytic leukemia tumor cells by helenalin and bis(helenalinyl)malonate in vivo.

Although the parent sesquiterpene lactone, helenalin, and its derivative, bis(helenalinyl)malonate, are structurally related chemically, they demonstrate differences in their antineoplastic activity, with bis(helenalinyl)malonate being much more active against P-388 lymphocytic leukemia cell growth (T/C% = 261) compared with helenalin (T/C% = 162). Previous studies have shown that both agents strongly inhibit protein synthesis in vivo by greater than 70% after 3 d of administration and in vitro by 50% at a 100 microM concentration of drug. This inhibition of protein synthesis of P-388 cells may be partially responsible for the cytotoxicity of the drug. These agents also inhibit nucleic acid synthesis in vivo, with DNA synthesis being suppressed by greater than 90% after 2 d of administration of drugs at the therapeutic dose. Of the sulfhydryl-bearing enzymes involved in nucleic acid synthesis that were assayed, only the activities of inosine-5'-monophosphate (IMP) dehydrogenase and the ribonucleotide reductase complex were inhibited by greater than 50% by these sulfhydryl-reactive drugs, which would account for the observed inhibition of nucleic acid synthesis in the P-388 cells. The inhibition of the activities of these enzymes lowered the deoxyribonucleotide levels in P-388 cells, which would explain the overall suppression of DNA synthesis by the sesquiterpene lactones.

Animals↗

PubMed1988

Effects of 2-(2,4-dimethylphenyl)indan-1,3-dione on serum lipoprotein and lipid metabolism of rodents.

2-(2,4-Dimethylphenyl)indan-1,3-dione was shown to be a potent hypolipidemic agent in rodents, lowering significantly both serum cholesterol and triglyceride levels at 20 mg/kg/day. The agent in vivo inhibited the enzymatic activities of ATP-dependent citrate lyase, acetyl-CoA synthetase, cholesterol-7-alpha-hydroxylase, acyl-CoA cholesterol acyl transferase, sn-glycerol-3-phosphate acyl transferase and phosphatidylate phosphohydrolase. Tissue lipid levels of liver and small intestine also were reduced by the agent. The rat serum lipoprotein lipid content was modulated by the drug, which should be favorable for the removable of cholesterol from peripheral tissue for conduction to the liver for clearance from the body. Low density lipoprotein (LDL) cholesterol levels were reduced after treatment, which suggests that the agent potentially reduces deposition of cholesterol in plaques. If chemotherapy for atherosclerosis is to be successful, then the high density lipoprotein (HDL) cholesterol level needs to be elevated more than 16% to 25%, the level produced by current hypolipidemic agents. 2-(2,4-Dimethylphenyl)indan-1,3-dione offers a 75% increase in HDL cholesterol levels and a 30% reduction of LDL cholesterol levels with a suppression of de novo synthesis of lipids and a reduction of tissue cholesterol deposition.

Animals↗

PubMed1988

The effects of phthalimide and saccharin derivatives on low-density lipoprotein (LDL) and high-density lipoprotein (HDL) receptor activity and related enzyme activities.

The hypolipidemic agents, phthalimide, saccharin, o-(N-phthalimido) acetophenone, N-(p-chlorobenzoyl) sulfamate, and o-chlorobenzylsulfonamide affected low-density lipoprotein (LDL) and high-density lipoprotein (HDL) receptor activity and lipoprotein degradation. In isolated rat hepatocytes, rat aorta foam cells, and human fibroblasts, LDL receptor activity, which is dependent on apo-B and -E, was inhibited by the drugs in a dose-dependent manner. LDL degradation was accelerated in the hepatocytes, while it was inhibited in aorta cells and fibroblasts. The drugs enhanced HDL receptor activity, dependent on apo-E and -A1, and HDL degradation in the hepatocytes, whereas in fibroblasts and aorta cells HDL receptor binding and degradation were suppressed. In parallel, activities of acyl CoA acyl transferase, sn-glycerol-3-phosphate acyl transferase, and heparin-induced lipoprotein lipase decreased and activities of HMG-CoA reductase and cholesterol oleate-ester hydrolase increased. In fibroblasts the presence of drugs enhanced HDL binding of intracellular cholesterol. In vivo studies demonstrated that phthalimide and saccharin treatment enhanced the clearance of HDL and decreased the clearance of LDL from the serum of rats. The results suggest that the mode of action of the agents is to modulate the lipoprotein receptor and, thereby, the clearance of lipids from peripheral tissue as part of the hypolipidemic activity.

Animals↗