Synthesis of phthalimido-desmuramylpeptide analogues as potential immunomodulating agents

The preparation of immunologically active phthalimido desmuramylpeptide analogues 2e-h, 4c-d, and 7b is described. The N-acetylmuramic acid in the muramyl dipeptide has been replaced by a phthaloylated acyclic moiety such as N-phthaloylated amino acids 1a-c, 2-(2-phthalimidoethoxy)acetic acid 3, or by the carbocyclic rac. trans-2-(2'-phthalimidocyclohexyloxy)acetic acid 6.

The Gabriel-Colman rearrangement in biological systems: design, synthesis and biological evaluation of phthalimide and saccharin derivatives as potential mechanism-based inhibitors of human leukocyte elastase, cathepsin G and proteinase 3

The results of a structure-activity relationship study focusing on the interaction of a series of phthalimide and saccharin derivatives with leukocyte elastase, cathepsin G and proteinase 3 are described. The phthalimide derivatives were found to be inactive while some of the saccharin derivatives were found to be fair inhibitors of these enzymes.

Enhancement of 12-O-tetradecanoylphorbol-13-acetate-induced tumor necrosis factor alpha production by phenethylphthalimide analogs

Effects of phenyl-, benzyl-, phenethyl-, and phenylpropylphthalimides on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced tumor necrosis factor (TNF)-alpha production by human leukemia cell line HL-60 were examined. Among the four phthalimide derivatives, only phenethylphthalimide showed potent enhancing effect on TNF-alpha production.

Synthesis and anticonvulsant activity of some N-phenylphthalimides

The anticonvulsant potential of a series of N-phenylphthalimide derivatives has been screened in subcutaneous pentylenetetrazole seizure (scPTZ) and maximal electroshock seizure (MES) tests. Intraperitoneal 4-amino-N-phenylphthalimides were the most potent agents against MES in mice. Referring to the N-(2,6-dimethyl-phenyl)phthalimide structure, the order of anticonvulsant activity appears to correspond to the phthalimide ring substitution pattern of 4-amino > 4-nitro > 4-methyl; H > 3-nitro; 3-amino. The 4-amino-N-(2-methylphenyl)-phthalimide displays an anti-MES ED50 of 47.61 mumol/kg with a protective index (PI) of 4.2. Oral administration to rats of the compounds found to be active in mice showed that the 4-amino-N-(2,6-dimethylphenyl)phthalimide is the most potent anti-MES agent in rats, exhibiting an ED50 of 25.2 mumol/kg and a PI greater than 75. Regarding the nature of the 2 and 6 substituents of the N-phenyl ring, the anticonvulsant efficiencies may be ordered as follows: 2,6-dimethyl > 2-methyl > 2-ethyl > 2-ethyl-6-methyl > 2,6-diethyl > unsubstituted phenyl ring. N-Phenylphthalimide derivatives seem to have great potential as candidate anticonvulsant drugs.

Dianilinophthalimides: potent and selective, ATP-competitive inhibitors of the EGF-receptor protein tyrosine kinase

Dianilinophthalimides represent a novel class of inhibitors of the EGF-receptor protein tyrosine kinase with a high degree of selectivity versus other tyrosine and serine/threonine kinases. Steady-state kinetic analysis of compound 3, which showed potent inhibitory activity, revealed competitive type kinetics relative to ATP. Despite a highly symmetrical structure of compound 3, X-ray studies revealed an unsymmetrical propeller-shaped conformation of the molecule which differs clearly from that of the constitutionally related staurosporine aglycons. These conformational differences may explain the reversal of the selectivity profile of compound 3 relative to the staurosporine aglycons. In cellular assays compounds 3 and 4 have been shown to inhibit EGF-induced receptor autophosphorylation, c-fos induction and EGF-dependent proliferation of Balb/c MK cells. This inhibition was selective as compounds had no effect on PDGF-induced receptor autophosphorylation and c-fos induction. Furthermore, compound 3 showed potent antitumor activity in vivo at well-tolerated doses.

Synthesis and biological activity of C-3' ortho dihydroxyphthalimido cephalosporins

A series of C-3' ortho dihydroxyphthalimido cephalosporins 3-7 has been prepared by reaction of C-3' aminomethyl cephalosporin 41 with the corresponding N-carboethoxyphthalimides 23-25, 37, 38. These new cephalosporins exhibit excellent in vitro Gram-negative activities, including Pseudomonas aeruginosa, excellent beta-lactamases stability and pharmacokinetics equivalent or better than ceftriaxone.

beta-Lactamase inhibitors derived from N-tosyloxy-beta-lactams

Electrophilic N-tosyloxy-beta-lactams, N-tosyloxy-4-phenyl-2-azetidinone (2b) and N-tosyloxy-3-(S)-phthalimido-4-(S)-2-azetidinone (2c), are described. These agents are novel potent beta-lactamase inhibitors.

Synthesis and structure-activity relationships of acetylcholinesterase inhibitors: 1-benzyl-4-(2-phthalimidoethyl)piperidine and related derivatives

Following the discovery of a new series of 1-benzyl-4-[2-(N-benzoyl-N-methylamino)ethyl]piperidine (2) derivatives with a potent anti-acetylcholinesterase (anti-AChE) activity, we extended the structure-activity relationships (SAR) to rigid analogues (4) and 1-benzyl-4-[2-(N-benzoyl-N-phenylamino)ethyl]piperidine derivatives (3). Introduction of a phenyl group on the nitrogen atom of the amide moieties resulted in enhanced activity. The rigid analogue containing isoindolone (9) was found to exhibit potent anti-AChE activity comparable to that of 2. Furthermore, replacement of the isoindolone with other heterobicyclic ring systems was examined. Among the compounds prepared in these series, 1-benzyl-4-[2-[4-(benzoylamino)phthalimido]ethyl]piperidine hydrochloride (19) (IC50 = 1.2 nM) is one of the most potent inhibitors of AChE. Compound 19 showed a definite selectivity to AChE over the BuChE (about 34700-fold) and, at dosages of 10-50 mg/kg, exerted a dose-dependent inhibitory effect on AChE in rat brain.

Synthesis and evaluation of 2-pyridinone derivatives as HIV-1 specific reverse transcriptase inhibitors. 1. Phthalimidoalkyl and -alkylamino analogues

A potent (IC50 = 30 nM), specific nonnucleoside HIV-1 reverse transcriptase (RT) inhibitor 3-[N-(phthalimidomethyl)amino]-5-ethyl-6-methylpyridin-2(1H) -one (1), was discovered through an in vitro screening program. This compound did not inhibit (IC50 > 300 microns) other DNA and RNA polymerases, including HIV-2 RT and SIV-RT. Unfortunately, hydrolytic instability of this (aminomethyl)phthalimide precluded use as an antiviral agent. In the first paper of this series, preliminary development efforts are described which produced ethylphthalimide 20, a hydrolytically stable compound with reduced (100-fold) HIV-1 RT inhibitory activity and weak (CIC95 = 40 microM) antiviral activity in H9 cells. Structure-activity studies demonstrated the importance of the 5-ethyl, 6-methyl substituent pattern on the pyridinone ring and the need for a flexible two-atom linker between the pyridinone and phthalimide heterocycles. These leads, 1 and 20, provided a basis for the further development of this structural class of inhibitors from which several compounds, the subject of accompanying reports, were selected for clinical evaluation.

Synthesis and biological evaluation of a series of substituted N-alkoxyimides and -amides as potential atypical antipsychotic agents

In a continuing program to discover antipsychotic agents with a reduced propensity toward extrapyramidal side-effects, a series of N-alkoxyimides and -amides was prepared. Evaluation of these compounds in vitro revealed affinities for D2, 5HT2 and 5HT1A receptors. Several members of the series displayed a profile indicative of potential antipsychotic activity in preclinical assays. The most potent compound in these assays, 7, also displayed possible effectiveness for the negative symptoms of schizophrenia. The synthesis of these compounds and details of their structure-activity relationships are described.

N-(phthalimidoalkyl) derivatives of serotonergic agents: a common interaction at 5-HT1A serotonin binding sites?

Several classes of agents are known to bind at central 5-HT1A serotonin sites In order to challenge the hypothesis that these agents bind in a relatively similar manner (i.e., share common aryl and terminal amine sites), we prepared N-(phthalimidobutyl) derivatives of examples of several such agents. With regard to arylpiperazines, we had previously shown that introduction of this functionality at the terminal amine is tolerated by the receptor and normally results in a significant (greater than 10-fold) enhancement in affinity. The results of the present study show that this bulky functionality is also tolerated by the receptor when incorporated into examples of all other major classes of 5-HT1A agents (e.g., 2-aminotetralin, phenylalklamine, indolylalkylamine, and (aryloxy)alkylamine derivatives). The length of the alkyl chain that separates the terminal amine from the phthalimido group is of major importance, and a four-carbon chain appears optimal. Alteration of the length of this chain can have a significant influence on affinity; decreasing the chain length from four to three carbon atoms can reduce affinity by an order of magnitude, and further shortening can have an even more pronounced effect.

Antipsychotic properties of new N-(4-substituted-1-piperazinylethyl)- and N-(4-substituted-1-piperidinylethyl)-phthalimides

A series of N-(4-phenyl- and 4-pyridyl-1-piperazinylethyl)- and N-(4-phenyl-1-piperidinylethyl)-phthalmides were synthesized and tested for antipsychotic activity. All compounds suppressed the spontaneous motor activity and the apomorphine-induced climbing in mice and pergolide-induced locomotor activity in rats, demonstrating psychotropic properties equal to the corresponding properties of sulpiride. Although the compounds, like sulpiride, were less potent than haloperidol in blocking the locomotor activities, they caused no catalepsy, a major side effect following treatment with conventional antipsychotic agents. It is likely that the new compounds produce their neuroleptic activities through inhibition of limbic dopamine receptors.

Synthesis and application of derivatizable oligonucleotides

To investigate protein-DNA interactions, we have synthesized a versatile phthalimide-protected 5-(3-aminopropyl)-2'-deoxyuridine nucleoside probe. The modified residue was incorporated into deoxyoligonucleotides by automated synthesis. The standard oligonucleotide workup also exposed the pendent amino group, which was found to react with either fluorescent labelling agents or, as detailed below, a photoactivatable cross-linking agent. In the dark, a strand with a photolabile group adjacent to the 3' end served as a primer for synthetic template-directed DNA synthesis by the Klenow fragment of E. coli DNA polymerase I, by bacteriophage T4 DNA polymerase, and by avian myeloblastosis virus (AMV) reverse transcriptase. Brief illumination with 302 nm light afforded covalent complexes between DNA and the polymerases; labelling of AMV reverse transcriptase was predominantly in the beta subunit.

Acetohydroxyacid synthase inhibitors: N-phthalyl-L-valine anilide and related compounds

The potency of L-valine as an inhibitor of Zea mays acetohydroxyacid synthase (AHAS) is increased more than 8000-fold on conversion to its N-phthalyl anilide derivative which is active at 2 microM. The D-valine, alpha-aminobutyric acid, isoleucine and phenylalanine analogs are 11- to 43-fold less potent, and similar N-phthalyl anilide derivatives of other branched-chain amino acids are essentially inactive. Full potency is retained on replacing the phthalimide moiety of the valine anilide with cyclohexane-1,2-dicarboximide or 1-cyclohexene-1,2-dicarboximide groups and partial activity with 4-cyclohexene-1,2-dicarboximide and methyl- or dimethylmaleimide groups. Inhibition of the enzyme and of root growth by the valine derivatives may result from binding at or near the site involved in feedback control of AHAS by L-valine.

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

A series of cyclic imides and related compounds have previously been shown to possess hypolipidemic activity at the low dose level of 20 mg/kg/d. Hydrolytic and reduced products of the cyclic imides were synthesized and examined to discern if possible metabolic products were the active chemical species of these hypolipidemic agents. Phthalimide proved to be the most active cyclic imide tested. Unfortunately, the new products did not, in general, improve hypolipidemic activity in rodents. The exceptions were piperidine which demonstrated improved hypotriglyceridemic activity, and 3,4,5,6-dibenzohomopiperidin-2-one, which demonstrated improved hypocholesterolemic activity compared to phthalimide.

Hypolipidemic activity of phthalimide derivatives. 3. A comparison of phthalimide and 1,2-benzisothiazolin-3-one 1,1-dioxide derivatives to phthalimidine and 1,2-benzisothiazoline 1,1-dioxide congeners

Previously it has been observed that N-substituted phthalimide derivatives with chain lengths of four carbon or oxygen atoms showed potent hypolipidemic activity in rodents at 20 (mg/kg)/day ip. The 1,2-benzisothiazolin-3-one 1,1-dioxide (saccharin) nucleus, itself, had also been observed to be active at the same dose. An investigation was undertaken to examine a series of 1,2-benzisothiazolin-3-one 1,1-dioxide analogues for their hypolipidemic activity in mice and to compare them to their respective phthalimide congeners. In addition, a series of 1,2-benzisothiazoline 1,1-dioxide and phthalimidine analogues was prepared, and their hypolipidemic activity was compared to the phthalimide analogues. These studies show that the respective congeners of 1,2-benzisothiazolin-3-one 1,1-dioxide compared favorably to phthalimide congeners in reducing serum triglyceride and cholesterol levels in male CF1 mice at 20 (mg/kg)/day ip. Of the saccharin derivatives, 3-oxo-1,2-benzisothiazoline-2-propionic acid 1,1-dioxide was the most effective in lowering serum cholesterol levels by 53% after 16 days dosing and 3-oxo-1,2-benzisothiazoline-2-valeric acid 1,1-dioxide lowered serum triglycerides 56% after 14 days dosing. The 1,2-benzisothiazoline 1,1-dioxide and phthalimidine compounds were less active as hypolipidemic agents than their 1,2-benzisothiazolin-3-one 1,1-dioxide and phthalimide analogues, respectively.

Hypolipidemic activity of phthalimide derivatives. 2. N-phenylphthalimide and derivatives

A series of substituted N-phenylphthalimide derivatives was synthesized and examined for their ability to lower serum cholesterol and triglyceride levels in mice at 20 (mg/kg)/day, ip. Of the newly synthesized compounds, the most potent compound, o-(N-phthalimido)acetophenone, lowered serum cholesterol 57% after 16 days and lowered serum triglyceride levels 44% after 14 days. o-(N-Phthalimido)acetophenone was observed to be active in both normogenic (normal blood lipids levels) and hyperlipidemic mice and normogenic rats. In the latter, the reduction of serum lipids was reversible. The mode of this compound appeared to be multiple, including blockage of the de novo synthesis of lipids and acceleration of the excretion of lipids. The lipoprotein fractions of rat blood were reduced significantly in cholesterol, triglyceride, and neutral lipid content after 14 days treatment with o-(N-phthalimido)acetophenone.

Synthesis and application of cleavable photoactivable heterobifunctional reagents

Three different cleavable photoactivable heterobifunctional reagents have been synthesized and characterized by proton NMR, 13C NMR, mass spectroscopy, infrared spectroscopy, and thin-layer chromatography. They are the N-hydroxysuccinimide ester of 3-[(4-azidophenyl)dithio]-propionic acid, methyl 3-[(4-azidophenyl)dithio]propionimidate, and N-[(4-azidophenyl)thio]phthalimide. Concanavalin A was coupled with one of the reagents, the N-hydroxysuccinimide ester of 3-[(4-azidophenyl)dithio]propionic acid, and radioiodinated. The [125I]lectin derivative and [125I]lectin showed similar specific binding to the receptors on the human erythrocyte membrane. Upon photolysis, subunits of the [125I]lectin derivative were cross-linked to produce dimer, trimer, and tetramer. These cross-linked complexes were readily cleaved by reducing the disulfide bond of the reagent.

Hypolipidemic activity of phthalimide derivatives. 1. N-Substituted phthalimide derivatives

The general lipid-lowering action of the N-substituted phthalimide derivatives reported herein, as well as the activity of potassium phthalimide, implicates the phthalimide moiety as possessing hypolipidemic activity in rodents. Compounds containing substituents with chain lengths of four carbon or oxygen atoms showed the best hypolipidemic activity in the series tested. Tests involving 1-N-phthalimidobutan-3-one demonstrated a dose-dependent hypolipidemic action free of estrogenic side effects, with no apparent deposition of cholesterol in body organs, and with a high therapeutic index. Further work on the hypolipidemic activity of phthalimido, as well as other imido compounds, is underway.

Synthesis of antifungal 2-substituted phthalimidines

An improved synthesis of phthalimidine is reported. Two N-substituted phthalimidines were synthesized by alkylation of the parent compound, and they showed complete inhibition of Microsporum and Trichophyton species at 10-100 microgram/ml in an agar dilution test. Both compounds were inactive against Candida albicans at 100 microgram/ml or Aspergillus niger at 250 microgram/ml.