Oi T. Wong

Cytotoxicity of imides-N-alkyl semicarbazones, thiosemicarbazones, acetylhydrazones and related derivatives.

The semicarbazones, thiosemicarbazones and acetyl-hydrazones of phthalimide, o-benzosulfimide, naphthalimide and diphenimide demonstrated potent cytotoxicity against murine and human leukemia cell growth and cultured cell growth from human solid tumors. The major site of inhibition in L1210 leukemia cells was DNA synthesis after 60 min incubated with the agents at 25, 50 and 100 μM. De novo synthesis of purines at the regulatory enzyme sites of PRPP amidotransferase and IMP dehydrogenase were the major targets of the agent. Thymidylate synthetase, dihydrofolate reductase and ribonucleoside reductase activities were inhibited by the agents in a manner which would contribute to the overall reduction of DNA synthesis and cell death. d(NTP) pools were significantly reduced and the evidence suggests that the agents Interacted with DNA affording DNA strand scission which would interfere with both template utilization by the polymerases and also ultimately reduce nucleic acid synthesis.

Hypolipidemic activity of o-(N-phthalimido)acetophenone in Sprague Dawley rats

Abstracto-(N-Phthalimido)acetophenone has proven to be an effective hypolipidemic agent in rats at 20 mg/kg/ day orally. The agent suppressed the activity of the rate-limiting enzyme of the liver involved in de novo synthesis of triglycerides. The synthetic rate-limiting enzyme for cholesterol esters was also inhibited by the drug in vivo. o-(N-Phthalimido)acetophenone lowered cholesterol in the liver and the aorta wall and generally caused an increase in phospholipids in body tissues. Serum lipoproteins were modulated by the drug with a decrease in cholesterol and triglycerides in the chylomicron, very low-density lipoproteins (VLDL), and low-density lipoproteins (LDL) and an increase in high-density lipoprotein (HDL) cholesterol. The phospholipid content was increased in the chylomicron, VLDL, and LDL fractions. In hyperlipidemic rats, o-(N-phthalimido)acetophenone lowered elevated blood lipid levels at 20 mg/kg/day orally after 3 weeks of administration. The hypolipidemic rat after drug treatment had a lower LDL cholesterol and a higher HDL cholesterol content, which is therapeutically desirable to protect against cardiovascular disease.

Synthesis and hypolipidemic activity of 3-imino-1-oxoisoindolines in rodents

A series of substituted 3-imino-l-oxoisoindolines derivatives demonstrated significant hypolipidemic activity, lowering both serum cholesterol and triglycerides levels after 16 days of dosing at 20 mg/kg/ day ip in CF1 mice. 2-Butyl-3-butylimino-l-oxoisoindoline lowered serum cholesterol levels 52% and serum triglyceride 42%. 2-Pentyl-3-imino-l-oxoisoindoline lowered serum cholesterol levels 42% and serum triglyceride 61%. These derivatives resulted in better activity than the parent compound, 3-imino-1-oxoisoindoline. These studies showed that compounds with N-alkyl substitution of nitrogen atoms in the ring and outside the ring possessed potent hypolipidemic activity at the low dose of 20 mg/kg/day ip in normolipidemic CF1 mice. Studies with 2-butyl-3-butylimino-l-oxoisoinodine in rats showed that serum cholesterol was reduced 60% and serum triglyceride 43% after 14 days of dosing at 20 mg/kg/day, orally. Treatment with this agent lowered lipid levels in the liver and aorta tissue, with increases in lipid levels in the small intestine tissue. Higher levels of cholesterol and phospholipids were excreted in the feces of treated animals compared to the control. Cholesterol levels of the very low-density lipoprotein (VLDL) and high-density lipoprotein (HDL) fractions were reduced, whereas the HDL cholesterol levels were elevated significantly. This ratio of low-density lipoprotein (LDL) cholesterol:HDL cholesterol levels suggests that the agent may be effective in treating hyperlipidemic states in humans.

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 -Al, and HDL degradation in the hepatocytes, whereas in fibroblasts and aorta cells HDL receptor binding and degradation were suppressed. In parallel, activities of acyl Co A 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.

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.

The cytotoxicity of 3-imino-1-oxoisoindolines in murine and human tissue culture cells

Certain types of hypolipidemic agents have been observed to also function as cytotoxic agents. Previously reported hypolipidemic agents, 3-imino-1-oxoisoindolines, were evaluated for their anti-neoplastic activity. Selected agents were effective at inhibiting L1210, Tmolt3, HeLa-S3, KB nasopharynx, lung, osteosarcoma and glioma growth. 2-Propyl-3-imino-1-oxoisoindoline, (4), a representative compound of the class of agents, inhibited DNA and RNA syntheses of L1210 cells. The major site of inhibition was the purine pathway at IMP dehydrogenase. Other enzyme sites which were affected by (4) marginally were t-RNA and r-RNA polymerases, dihydrofolate reductase, aspartate transcarboxylase, and nucleoside kinases. d(NTP) pools of L1210 cells were reduced after 60 min. Incubation with (4).

The hypolipidemic activity of N(4-methyl-phenyl)diphenimide in rodents

N(4-Methyl-phenyl)diphenimide afforded potent hypolipidemic activity in rodents. Serum cholesterol levels were reduced 67% and serum triglyceride were lowered 66% in rats by the drug after two weeks administration orally at 20 mg/kg/day. Rate limiting enzymes in the de novo synthesis of lipids in the liver were suppressed by the drug. Cholesterol was also removed from the body due to the drug accelerating bile excretion. Lipids removed from the blood compartment were not deposited in the organs of the body. VLDL and LDL cholesterol content was significantly reduced in rats treated with the drug with marked increase in HDL cholesterol after two weeks of administration. These data suggest that the drug may be useful in hyperlipidemic states and atherosclerosis in man, thus, further investigation of this class of chemicals is warranted.

Investigation of 3,5-Isoxazolidinediones as Hypolipidemic Agents in Rodents

A series of 2-benzoyl-4,4-dialkyl-3,5-isoxazolidinediones proved to have potent hypolipidemic activity, lowering both serum cholesterol and triglyceride levels at 10 or 20 mg/kg/day, IP and orally in rodents. 2-(3,4,5-Trimethoxybenzoyl)-4,4-diethyl-3,5-isoxazolidinedione (4) afforded the best hypolipidemic activity lowering normolipidemic CFl mouse serum cholesterol levels 49% and serum triglyceride levels 34% at 20 mg/kg/day, IP. Compound 4 was selected as a typical derivative of the chemical class for further detailed studies. Serum cholesterol levels in normolipidemic Sprague Dawley male rats were reduced 45% after 8 weeks at 10 and 20 mg/kg/day of compound, orally. Serum triglyceride levels were reduced 38–49% at 10 and 20 mg/kg/day, orally. In vitro liver enzyme activities studies in normolipidemic CFl mice showed the compound inhibited mitochondrial citrate exchange, acetyl CoA synthetase, HMG CoA reductase, acyl CoA cholesterol acyl transferase, acetyl CoA carboxylase, sn-glycerol-3-phosphate acyl transferase, phosphatidylate phosphohydrolase and heparin-induced lipoprotein lipase activities with increases in the activities of cholesterol ester hydrolase and ATP-dependent citrate lyase. Similar enzyme activities were inhibited in vivo except HMG CoA reductase activity was not inhibited in rat liver or small intestinal mucosa after 8 weeks drug administration. Cholesterol levels were reduced in tissues after 8 weeks administration of compound 4 in normolipidemic rats. Bile cholesterol and triglyceride levels were elevated after two weeks administration to rats at 20 mg/kg/day. Serum lipoprotein levels in normolipidemic and hyperlipidemic rats showed the cholesterol levels in VLDL and LDL fractions after 4, 6 and 8 weeks at 10 and 20 mg/kg/day were reduced whereas HDL-cholesterol levels were significantly elevated. Studies demonstrated that 3H-cholesterol and 14C-palmitic acid incorporation into lipids of the lipoprotein fraction was reduced by the drug but 32P-incorporation was generally elevated. The agent demonstrated no observable toxicity in rats after 8 weeks administration, orally. The acute toxicity study in normolipidemic mice at 20, 40 and 100 mg/ kg/day, IP, demonstrated no observable harmful effects of the drug.

The cytotoxic activity of cyclic imido alkyl ethers, thioethers, sulfoxides, sulfones and related derivatives

Cyclic imides such as N-substituted alkyl ethers, thioethers, sulfoxides, sulfones and related derivatives were potent agents against human single cell tumors and selected solid tumor growths, eg adenocarcinoma of the colon and glioma. These agents in the L1210 lymphoid leukemia tumor model preferentially inhibited DNA synthesis. The regulatory enzyme sites in the purine pathway were targets of the agents. Other sites of inhibition were DNA polymerase alpha and thymidylate synthetase activities. d(NTP) pool levels were also reduced by the agents over 60 min.

The Hypolipidemic Activity of l-N-3-Methylphthalimido-butan-3-semicarbazone in Rodents

Abstractl-N-(3-Methylphthalimido)butan-3-one semicarbazone demonstrated potent hypolipidemic activity in normal rats and mice and hyperlipidemic diet-induced mice. The compound decreased tissue lipid 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 lipoprotein (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.