Hypolipidemic activity of phthalimide derivatives V: Reduced and hydrolytic products of simple cyclic imides

Insights into the spontaneity of hydrogen bond formation between formic acid and phthalimide derivatives

We evaluated a group of phthalimide derivatives, which comprise a convenient test set for the study of the multiple factors involved in the energetics of hydrogen bond formation. Accordingly, we carried out quantum chemical calculations on the hydrogen bonded complexes formed between a sample of phthalimide derivatives with formic acid with the intent of identifying the most important electronic and structural factors related to how their strength and spontaneity vary across the series. The geometries of all species considered were fully optimized at DFT B3LYP/6-31++G(d,p), RM1, RM1-DH2, and RM1-D3H4 level, followed by frequency calculations to determine their Gibbs free energies of hydrogen bond formation using Gaussian 2009 and MOPAC 2012. Our results indicate that the phthalimide derivatives that form hydrogen bond complexes most favorably, have in their structures only one C=O group and at least one NH group. On the other hand, the phthalimide derivatives predicted to form hydrogen bonds least favorably, possess in their structures two carbonyl groups, C=O, and no NH group. The ability to donate electrons and simultaneously receive one acidic hydrogen is the most important property related to the spontaneity of hydrogen bond formation. We further chose two cyclic compounds, phthalimide and isoindolin-1-one, in which to study the main changes in molecular, structural and spectroscopic properties as related to the formation of hydrogen bonds. Thus, the greatest ability of the isoindolin-1-one compound in forming hydrogen bonds is evidenced by the larger effect on the structural, vibrational, and chemical shifts properties associated with the O-H group. In summary, the electron-donating ability of the hydrogen bond acceptor emerged as the most important property differentiating the spontaneity of hydrogen bond formation in this group of complexes.

Triphasic nanocolloids

Triphasic nanocolloids, that is, nanocolloids with three distinct compartments, were successfully produced by use of electrified co-jetting. Simultaneous manipulation of the three parallel liquid with laminar flows yielded a liquid droplet with three interfaces between the jetting liquids. Under a high electric potential, a single liquid jet was produced from the triple point of the droplet. Separation between the phases was maintained throughout the jetting process and resulted in triphasic nanocolloids. Poly(ethylene oxide), poly(acrylic acid), and poly(acrylamide-co-acrylic acid) solutions were used and verified to be compatible with the process. Fluorescent-labeled biomolecules were selectively incorporated in each phase of the nanocolloids, and confocal laser scanning microscopy was employed for the characterization. Scanning electron microscopy results verified that the sizes of the colloids are in the range of nanocolloids. This simple and versatile technique to fabricate multicompartment nanocolloids is expected to have great impact on drug delivery, molecular imaging, and smart displays.

Water-stable biphasic nanocolloids with potential use as anisotropic imaging probes

Electrified co-jetting of two aqueous polymer solutions followed by a thermal cross-linking step was used to create water-stable biphasic nanocolloids. For this purpose, aqueous solution mixtures of poly(acrylamide-co-acrylic acid) and poly(acrylic acid) were employed as jetting solutions. When the biphasic nanocolloids created by side-by-side electrified co-jetting were thermally treated, a cross-linking reaction occurred between amide groups and carboxylic groups to form stable imide groups. Infrared spectroscopy was employed to monitor the reaction. The quality and the integrity of the resulting biphasic nanocolloids were confirmed by confocal laser scanning microscopy, flow cytometry analysis, and dynamic light scattering. Selective encapsulation of two biomolecules in each phase of the biphasic colloids was maintained even after thermal reaction and suspension in aqueous environment. Well-dispersed spherical colloids with stable dye loadings in each hemisphere were kept intact without aggregation or dissolution for several weeks. Finally, biphasic nanocolloids were selectively surface-modified with a biotin-dextran resulting in water-stable particles to ensure binding of proteins only to a single hemisphere.

Synthesis and anticonvulsant evaluation ofN-substituted-isoindolinedione derivatives

A series of N-substituted-1,3-isoindolinedione derivatives (2-16) were synthesized for the purpose of defining the effect of N-substitution on the anticonvulsant activity of these derivatives. The target compounds (2-16) were obtained by condensation of phthalic anhydride with the corresponding amine derivative. The structures of the synthesized derivatives (2-16) were confirmed by means of IR, 1H-NMR, 13C-NMR, MS and elemental analyses. The anticonvulsant activity of all compounds (2-16) were evaluated by subcutaneous pentylenetetrazole seizure threshold test at doses of 0.2, 0.4 and 0.8 mmol/kg compared with sodium valproate as a positive control. Their neurotoxicity were determined by the rotorod test. Many of the present series of compounds showed good anticonvulsant activity at the tested doses, as compared to sodium valproate. Three of them (4, 6 and 11) exhibited 100% protection against convulsions, neurotoxicity and death at all tested doses. Out of the series, two compounds (12 and 13) were completely inactive with 100% mortality. 3-(p-chlorophenyl)-4-(1,3-dioxo-2,3-dihydro-1H-2-isoindolyl)butanoic acid derivative (11) has emerged as the most active compound which is 20 times more active than valproate with ED50 8.7, 169 mg/kg; TD50 413, 406 mg/kg and PI 47.5, 2.4. The results revealed the importance of the combination of baclofenic and phthalimide moieties (compound 11) as a promising anticonvulsant candidate.

Micropatterning of polymer thin films with pH-sensitive and cross-linkable hydrogen-bonded polyelectrolyte multilayers

Polyelectrolyte multilayers of poly(acrylic acid) (PAA) and polyacrylamide (PAAm) were prepared via hydrogen-bonding interactions. These multilayers as assembled were stable at low pH but dissolved quickly in neutral pH water. We developed methods for stabilizing these multilayers to high pH through cross-linking by heating or UV-irradiation. Thermal treatment of the multilayers, which resulted in a partial imidization between carboxylic acid and amide groups, gave the multilayer good stability at high pH. In addition, we introduced photoreactive groups in the multilayer, which rendered the film insoluble after UV irradiation. Using these selective stabilization approaches, we have succeeded in micropatterning these films by ink-jet printing and photolithography to create subtractive patterns.

Synthesis and hypolipidemic activity of N-phthalimidomethyl tetra-O-acyl-α-d-mannopyranosides

A facile synthesis of anomerically pure phthalimidomethyl 2,3,4,6-tetra-O-acetyl- and phthalimidomethyl 2,3-di-O-acetyl-4,6-di-O-benzoyl-alpha-D-mannopyranosides (6 and 9b) starting from N-hydroxymethylphthalimide and tri-O-acetyl-D-glucal is described. Compounds 3, 6, 8, 9a and 9b have been tested for their hypolipidemic activity in mice. All these compound showed significant reduction of plasma cholesterol and triglyceride levels. Compound 9b has been found to possess the highest activity.

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.

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.

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.

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.

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.

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

A series of substituted 3-imino-1-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-1-oxoisoindoline lowered serum cholesterol levels 52% and serum triglyceride 42%. 2-Pentyl-3-imino-1-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-1-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.

Hypolipidemic activity of 6-substituted 6,7-dihydro-5H-dibenz[c,e]azepine and the effects of 6,7-dihydro-5H-dibenz[c,e]azepine on lipid metabolism of rodents

A series of 6-substituted derivatives of 6,7-dihydro-5H-dibenz[c,e]azepine was found to be active hypolipidemic agents in rodents at doses of mg/kg per day. The parent drug was found to suppress the enzyme activity of ATP-dependent citrate lyase, sn-glycerol-3-phosphate acyl transferase, and phosphatidate phosphohydrolase. Treatment with 6,7-dihydro-5H-dibenz[c,e]azepine resulted in a reduction of cholesterol, neutral lipid, and triglyceride content in mouse and rat liver. The agent also afforded a reduction in cholesterol, triglycerides and neutral lipids in the chylomicron and very low density lipoprotein (VLDL) fractions. In the high density lipoprotein (HDL) fraction, the triglyceride, neutral lipids, and phospholipids were lowered but the cholesterol content was not. [H3]Cholesterol distribution studies showed that the 3H-content was lowered in the major organs but was elevated in the chyme and stomach, suggesting that the drug accelerated bile secretion of cholesterol or its metabolites.

The Hypolipidemic Activity of a Series of 2,3-Dihydrophthalazine-l,4-dione Derivatives in Rodents

A series of substituted 2,3-dihydrophthalazine-l,4-dione derivatives as well as the corresponding N,N-diaminophthalamides were prepared and were demonstrated to have potent hypolipidemic activity, lowering both serum triglyceride and cholesterol levels significantly at 20 mg/kg/day after 16 days of dosing in CF1 male mice. The parent compound, 2,3-dihydrophthalazine-l,4-dione, lowered serum cholesterol 51% and serum triglyceride 43%. 2-(2-Carboxyethyl)-2,3-dihydrophthalazine-l,4-dione demonstrated the best hypocholesterolemic activity, with a 66% reduction after 16 days. The 2-(p-chlorophenyl) derivative demonstrated good activity (>40% reduction) in both screens, as did the 6-methyl-2,3-dihydrophthalazine-l,4-dione derivative. Of the amides, 4-methyk N,N-diaminophthalamide demonstrated the best hypolipidemic activity, affording a greater than 40% reduction. 2,3-Dihydrophthalazine-l,4-dione was found to inhibit the enzyme activity of acetyl CoA synthetase, ATP-dependent citrate lyase, sn-glycerol-3-phosphate acyl transferase, phosphatidylate phosphohydrolase, and mitochondrial citrate exchange of liver. In mice after 16 days of dosing, there was a reduction of cholesterol, triglycerides, neutral lipids, and phospholipids in the liver. Cholesterol and neutral lipids were reduced in rat chylomicrons, very low-density lipoproteins, and low-density lipoproteins. The cholesterol content of the high-density lipoprotein fraction was slightly elevated, but reductions in the triglycerides and phospholipids were observed in this lipoprotein fraction. (3)H-Cholesterol distribution studies showed a lower concentration in the major organs and plasma, with a higher (3)H-cholesterol content in the stomach and large intestine.

The hypolipidemic activity of furoic Acid and furylacrylic Acid derivatives in rodents

2-Furoic acid, 3-furoic acid, 3,4-furan dicarboxylic acid and furyl-acrylic acid were evaluated for hypolipidemic activity in mice and rats. 2-Furoic acid was the most potent agent of the four tested, lowering serum cholesterol levels 41 % and serum triglyceride levels 56 % at 20 mg/kg/day in mice and serum cholesterol 50 % and serum triglyceride levels 42 % in rats. 2-Furoic acid effectively suppressed liver mitochondrial citrate exchange, ATP dependent citrate lyase, acetyl CoA synthetase, acyl CoA cholesterol acyl transferase, sn-glycerol-3-phosphate acyl transferase, phosphatidate phosphohydrolase and hepatic lipoprotein lipase enzymatic activities. Lipid levels after 16 days in mice were reduced in the liver. In the rat cholesterol content of the HDL fraction was elevated and lowered in the chylomicron fraction. 2-Furoic acid administration for 14 days resulted in a large portion of (3)H-cholesterol being excreted by the biliary route. The furoic acid derivatives appear to have promise as hypolipidemic agents and further studies on their ability to lower lipids are warranted.