1,4-Thienodiazepine-2,5-diones via MCR (I): Synthesis,Virtual Space and p53-Mdm2 Activity

1,4-Thienodiazepine-2,5-diones have been synthesized via the Ugi-Deprotection-Cyclization (UDC) approach starting from Gewald 2-aminothiophenes in a convergent and versatile manner. The resulting scaffold is unprecedented, cyclic, and peptidomimetic with four points of diversity introduced from readily available starting materials. In addition to eighteen synthesized and characterized compounds, a virtual compound library was generated and evaluated for chemical space distribution and drug-like properties. A small focused compound library of 1,4-thienodiazepine-2,5-diones has been screened for the activity against p53-Mdm2 interaction. Biological evaluations demonstrated that some compounds exhibited promising antagonistic activity.     

1,4]Benzoxazine-2,3-diones as antiallergic agents

The synthesis of a series of [1,4]benzoxazine-2,3-diones and a new class of compounds, benzobisoxazinetetrones, is described. These compounds were evaluated for their effect in the rat mast cell (RMC) test passively sensitized in vitro with rat antiovalbumin serum and for their effect in inhibitory passive cutaneous anaphylaxis (PCA) in the rat. Some of these compounds are of the same potency level as disodium cromglycate in the RMC test and some are effective orally in PCA.     

1,2,4-Triazolo[4,3-a]quinoxaline-1,4-diones as antiallergic agents

A series of new 1,4-dihydro-1,2,4-triazolo[4,3-]quinoxaline-1,4-diones has been prepared. These compounds were tested as inhibitors of antigen-induced release of histamine (AIR) in vitro from rat peritoneal mast cells (RMC) and as inhibitors of IgE-mediated rat passive cutaneous anaphylaxis (PCA). Most of this new class of antiallergic agents showed good activity in the RMC and PCA tests. The most potent compound, 2-acetyl-7-chloro-5-n-propyl-1,2,4-triazolo[4,3-a]quinoxaline-1,4-dione (1x), with an I50 value of 0.1 microM, is 30 times more potent than disodium cromoglycate (DSCG) in the RMC assay.     

Pyrrolidine-2,5-diones with basic substituents. 3. Anticonvulsant activity of racemic and optically active pyrrolidine-2,5-diones

Pyrrolidine-2,5-diones with Basic Substituents, III: Anticonvulsant Activity of Racem, and Optically Active Pyrrolidine-2,5-diones with Basic Substituents The anticonvulsant activity of racem. and optically active pyrrolidinediones with basic substituents was determined in mice. Against seizures induced by electrical stimulation the racemates 1c–3c possess the same activity. Against convulsions caused by pentetrazol, compounds 2c and 3c protect 90% of the animals whereas compound 1c is inactive. The (+)-enantiomer of 1b has a higher anticonvulsant activity than the (?)-enantiomer. The enantiomers of 2a, 3a and 3b , too, show stereoselective differences in anticonvulsant activity. The (+)-enantiomer of compound 1a possesses anticonvulsant activity, the (?)-enantiomer, however, shows the highest toxicity of all the investigated pyrrolidinediones with basic substituents.     

4-aryl-6,6-dimethyl-1,2,3,4,5,6,7,8-octahydroquinazoline-2,5-diones: synthesis, chromatographic resolution and pharmacological activity

In this study, a series of 4-aryl-6,6-dimethyl-1,2,3,4,5,6,7,8- octahydroquinazoline-2,5-diones were synthesized by condensing urea with 4,4-dimethyl-1,3-cyclohexanedione and appropriate aromatic aldehydes according to the Biginelli reaction. The structures of the compounds were characterized by spectroscopic methods. The racemic compounds were resolved into the enantiomers by HPLC on amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD). The compounds were tested in vitro for their calcium antagonistic activities. BaCl2-induced contractions of rat ileum were inhibited dose-dependently. Compounds 3 and 5 exerted weak calcium antagonistic activity on smooth muscles compared with the standard, nicardipine.     

1,4-Thienodiazepine-2,5-diones via MCR (II): Scaffold Hopping by Gewald and Ugi-Deprotection-Cyclization Strategy

A second scaffold of 1,4-thienodiazepine-2,5-diones was discovered and is synthetically accessible from Gewald 2-aminothiophenes via Ugi-Deprotection-Cyclization (UDC) strategy. This approach yielded hybrid peptidomimetic diazepine structures with six points of diversity introduced from readily available starting materials. A virtual compound library (N = 50 000) was generated and evaluated for chemical space distribution and drug-like properties.     

Anticoagulante 2,5-Diarylcyclopent-4-en-1,3-dione

Anticoagulant 2,5-Diarylcyclopent-4-ene-1,3-diones Seven title compounds were synthesized and tested for their anticoagulant activities. With five of them prothrombin levels below 25 % of normal were achieved in rats 12–48 h after a single oral dose. The most active compound 1a showed this effect after a dose of 43 mg/kg. By hydrogenation of the double bond, removal of the 4-hydroxy group and replacement of the carbonyl function at position 1 by a sulfonyl group, compounds without anticoagulant activity were obtained.     

Synthesis and antifungal activity of naphthalene-1,4-diones modified at positions 2, 3, and 5

A series of 2-arylamino-5-hydroxy-naphthalene-1,4-diones, 3-arylamino-5-methoxy-naphthalene-1,4-diones, and 2-arylamino-3chloro-5-hydroxy-naphthalene-1,4-diones were synthesized and tested for in vitro antifungal activity against the species Candida and Aspergillus niger. Among those tested, 3-arylamino-5-methoxy-naphthalene-1,4-diones exhibited potent antifungal activity. In general, the 3-arylamino-5-methoxy-naphthalene-1,4-diones showed more potent antifungal activity than the 2-arylamino-5-hydroxy-naphthalene-1,4-diones and the 2-arylamino-3-chloro-5-hydroxy-naphthalene-1,4-diones.     

Synthesis of 2,5-Disubstituted-1,4-benzoquinone Derivatives as Potential Antimicrobial and Cytotoxic Agents

A number of 2,5-disubstituted-1,4-benzoquinone derivatives were prepared and characterized by elemental analysis, infrared (IR), nuclear magnetic resonance (¹H-NMR), and mass spectra (MS). These compounds and their synthetic precursors were evaluated for their in vitro antimicrobial and cytotoxic activity. The most potent antimicrobial compound was the thiadiazolyl derivative 4b , which was 2- to 4 times more active than the antimicrobial drug sulfathiazole. All the tested compounds were active in the Brine Shrimp Lethality (BS) Test. Compound 4e which was the most active in the BS test was also found to possess a significant cytotoxicity against two tumor cell lines. Some of the compounds were found to be mutagenic at relatively high concentration.     

Design and synthesis of novel 1,4-benzodiazepine derivatives and their biological evaluation as cholinesterase inhibitors

A new series of 1,4-benzodiazepine-2,5-dione structurally related to cyclopenin has been synthesized. The new compounds were assayed in vivo and in vitro for their ability to inhibit acetylcholinesterase enzyme and were found to have potent reversible anticholinesterase activity when tested in vitro for isolated frog rectus abdominis and guinea pig ileum in addition to increasing brain cholinesterase level in rats when percentage inhibition were tested in vivo, moreover compounds 5a, 5b, 5c and 5g were the most active. LD(50) was performed for these derivatives and they displayed high safety margin.     

Synthesis and Anticonvulsant Properties of New Mannich Bases Derived from 3,3-Disubstituted Pyrrolidine-2,5-diones. Part IV

A library of 21 new N-Mannich bases of 3,3-diphenyl- (5a-g), 3-methyl-3-phenyl- (6a-g), and 3-ethyl-3-methylpyrrolidine-2,5-diones (7a-g) were synthesized and evaluated for their anticonvulsant activity in the maximum electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests after intraperitoneal injection into mice. The acute neurological toxicity was determined applying the rotarod screen. The results in mice showed that 13 compounds were effective in the MES or/and scPTZ screen. From these, seven molecules were tested in the MES seizures after oral administration in rats. The quantitative studies showed that N-[{4-(2-hydroxyethyl)-piperazin-1-yl}-methyl]-3-methyl-3-phenylpyrrolidine-2,5-dione (6c) and N-[(4-benzylpiperidin-1-yl)-methyl]-3-methyl-3-phenylpyrrolidine-2,5-dione (6f) revealed higher protection in the MES and scPTZ tests than valproic acid or ethosuximide which were used as reference antiepileptic drugs. Four compounds (5c, 6c, 6e, 6f) showed high effectiveness in the 6-Hz psychomotor seizure model of partial and therapy resistant epilepsy.     

Synthesis and in vitro calcium antagonist activity of 4-aryl-7,7-dimethyl/1,7,7-trimethyl-1,2,3,4,5,6,7,8-octahydroquinazoline-2,5-dione derivatives

In this study, a series of 4-aryl-7,7-dimethyl and 1,7,7-trimethyl-1,2,3,4,5,6,7,8-octahydroquinazoline-2,5-diones (1-25) were synthesized by condensing urea or N-methylurea with 5,5-dimethyl-1,3-cyclohexanedione and appropriate aromatic aldehydes according to the Biginelli reaction. The structures of the compounds were confirmed by spectral data and elementary analysis. The calcium antagonist activity of the compounds was tested in vitro on isolated rat ileum and lamb carotid artery. Compounds 16 and 19 were the most active derivatives on isolated rat ileum compared with the standard nicardipine. On isolated aortic strips of lamb the calcium antagonist activity of compound 16 (maximum relaxant effect: 38.83+/-5.84%) was found as high as that of nicardipine (maximum relaxant effect: 35.50+/-4.16%) used as a reference drug.     

Synthesis and antitumor activities of unsymmetrically substituted 1,4-bis[(aminoalkyl)amino]anthracene-9,10-diones and related systems

A number of unsymmetrically substituted 1,4-bis[(aminoalkyl)amino]anthracene-9,10-diones have been synthesized and evaluated for their antitumor activity against L1210 in vitro and in vivo. The high activity of several compounds observed in vitro was not paralleled by comparable activity in vivo. The activities of the substituted 1,4-bis[(aminoalkyl)amino]anthracene-9,10-diones as inhibitors of cell growth were generally much higher than those of the related 1-[(aminoalkyl)amino]-4-methoxyanthracene-9,10-diones, and this correlated with the relative abilities of compounds of the two types to interact with calf thymus DNA.     

Studies on the antibacterial and antifungal properties of 1,4-naphthoquinones

1. New halogenated 1,4-naphthoquinones were synthesized and together with other known 1,4-naphthoquinones, were screened for antibacterial activity by a turbidimetric method, and for antifungal activity by the diffusion method on agar plates.2. The half-wave potentials and the influence on the oxidative phosphorylation of some of these compounds were determined.3. 2-chloro-3,2'-chloro-ethyl-1,4-naphthoquinone (half-wave potential=-187 mV) was the most active compound, completely inhibiting cell respiration.4. While the natural active naphthoquinones, vitamin K and ubiquinones, possess, as substituent, the electron repelling methyl group, the microbiologically active 1,4-naphthoquinones are substituted, in the quinone moiety, with electron attracting groups such as OH or Cl.5. The half-wave potentials can give only an initial indication of the activity of the compounds studied; a good correlation, on the contrary, can be found between the ultraviolet spectra of such compounds and their activity which seems to depend on the ability of active compounds to exist in an extensively conjugated structure and to form hydrogen bonds.     

Angiotensin converting enzyme inhibitors: modifications of a tripeptide analogue

Modified nonhydrolyzable tripeptide analogues of (S)-1-[5-(benzoylamino)-1,4-dioxo-6-phenylhexyl]-L-proline (1), designed to impart oral angiotensin converting enzyme (ACE) inhibitory activity, were made and evaluated in vivo and in vitro. The N-methyl and C5-methyl analogues of 1 were inactive. Insertion of heteroatoms (O, S, NH) into the C--C chain of 1 gave a series of compounds with high in vitro activity in the guinea pig serum ACE assay. The O-analogue was the most potent with an IC50 = 4.4 x 10(-9) M compared to 1 with an IC50 = 3.2 x 10(-9) M. The structure-activity relationships in this series of compounds lead one to speculate that the heteroatom provides an additional binding site to the surface of the enzyme; however, these compounds were inactive when tested for antihypertensive activity in the renal hypertensive rat at 30 mg/kg by the oral route (captopril is active at 1.0 mg/kg po).     

Structure-activity relationships of 1,4-dihydro-(1H,4H)-quinoxaline-2,3-diones as N-methyl-D-aspartate (glycine site) receptor antagonists. 1. Heterocyclic substituted 5-alkyl derivatives

A series of 6,7-dichloro-1,4-dihydro-(1H, 4H)-quinoxaline-2,3-diones (1-17) were prepared in which the 5-position substituent was a heterocyclylmethyl or 1-(heterocyclyl)-1-propyl group. Structure-activity relationships were evaluated where binding affinity for the glycine site of the N-methyl-D-aspartate (NMDA) receptor was measured using the specific radioligand [3H]-L-689,560, and functional antagonism was demonstrated by inhibition of NMDA-induced depolarizations of rat cortical wedges. The ability to prevent NMDA-induced hyperlocomotion in mice in vivo was measured for selected compounds. Binding affinity increased significantly if the heterocyclic group, e.g. 1,2,3-triazol-1-yl could participate in accepting a hydrogen bond from the receptor. It was difficult to obtain compounds with adequate aqueous solubility and strategies to improve it were investigated. The most potent compound in this series, 6,7-dichloro-5-[1-(1,2,4-triazol-4-yl)propyl]-1,4-dihydro-(1H, 4H)-quinoxaline-2,3-dione (17) (binding IC50 = 2.6 nM; cortical wedge EC50 = 90 nM), inhibited NMDA-induced hyperlocomotion in mice (6/9 protected at 20 mg/kg iv). Pharmacokinetic parameters, including extent of brain penetration, for 11 and 17 are reported.     

The relative neurotoxicities of n-hexane,methyl n-butyl ketone, 2,5-hexanediol,and 2,5-hexanedione following oral or intraperitoneal administration in hens

The sensitivity of the hen to neurotoxicity produced by po and ip administration of n-hexane, methyl n-butyl ketone (MnBK), 2,5-hexanediol (2,5-HDOH), and 2,5-hexanedione (2,5-HD) was investigated. While po administration of one or two doses of these chemicals at a 21-day interval caused acute effects, it did not induce neuropathy in treated hens. Subchronic po or ip administration of n-hexane caused only weakness, which subsided after cessation of administration. By contrast, subchronic administration of the other three related compounds caused neurotoxicity characterized by ataxia, which progressed to paralysis in some hens. Severity of the neurotoxic effect was dependent on both the test compound and its route of administration of a similar dosage. Generally, ip injection caused more severe effects than po administration. Pathological examination of nervous system tissues of hens treated with the 2,5-HD, 2,5-HDOH, and MnBK showed giant paranodal axonal swelling followed by Wallerian degeneration of axons and myelin in peripheral nerve and spinal cord. Wallerian degeneration in the spinal cord was observed almost exclusively in the ventral columns of the lower spinal cord. n-Hexane failed to produce the characteristic pathological features produced by related compounds. The neurotoxic potency of these chemicals which considers onset and magnitude of clinical signs and severity of histopathologic changes was in descending order: 2,5-HD > 2,5-HDOH > MnBK > n-hexane when given by either method.     

Cytotoxicity of 2-ethenyl-2,3-dihydrophthalazine-1,4-diones in murine and human tumor cultured cells

2-Etheny1-2,3-dihydrophthalazine-1,4-diones were successfully synthesized and proved to be effective cytotoxic agents against the growth of suspended murine and human leukemias and lymphomas. Selected compounds were also active in human HeLa uterine carcinoma, suspended effusion breast MCF-7 and glioma HS683 screens. These agents suppressed P388 lymphocytic leukemia DNA synthesis after 60 min at 100 microM. Their target appeared to be the de novo synthesis pathway with significant inhibition of the activities of both regulatory enzymes of the pathway, i.e. PRPP-amide transferase and IMP dehydrogenase resulting in a reduction in the d[NTP] pool levels for DNA incorporation. The compounds did not affect de novo pyrimidine synthesis and its regulatory enzymes. Very minor reduction by the agents was noted for the nucleoside kinases and the DNA and RNA polymerase activities within 60 min. DNA was not a target of the agents in that there was no alkylation of the nucleotide bases, intercalation between base pairs or cross-linking of the DNA strands; however, the agents did cause P388 DNA strand scission after 24 h at 100 microM.     

Vasoconstriction and bronchoconstriction induced by 2,5-di-(tert-butyl)1,4-benzohydroquinone, an endoplasmic reticular Ca2+-ATPase inhibitor, in isolated and perfused rat lung.

The microsomal Ca(2+)-ATPase inhibitor 2,5-di-(tert-butyl)-1,4-benzohydroquinone (tBuBHQ) induced bronchoconstriction and vasoconstriction in the isolated perfused and ventilated rat lung. These effects were accompanied by increased levels of thromboxane and prostacyclin in the effluent perfusate. The effect of tBuBHQ was inhibited by L-655,240, a thromboxane receptor antagonist, indicating thromboxane-A2-mediated bronchoconstriction and vasoconstriction. Accordingly, the cyclooxygenase inhibitor indomethacin largely blocked the effects of tBuBHQ. The involvement of a phospholipase in the generation of thromboxane A2(TXA2) was supported by dibucaine protection on tBuBHQ effects. The results from this study indicate that tBuBHQ, probably by inhibiting the microsomal Ca(2+)-ATPase, can trigger the arachidonic acid cascade leading to the formation of TXA2, which in turn causes bronchoconstriction and vasoconstriction in rat lung.     

The abnormal cytotoxicities of 2,5-diaziridinyl-1,4-benzoquinone-3-phenyl esters

Several derivatives of 2,5-diaziridinyl-3-phenyl-1,4-benzoquinone have been synthesized and their cytotoxicities in six different human cancer cell lines (H460, H596, HT29, BE, K562 and A2780) have been determined. It was observed that certain phenol-ester derivatives were significantly more cytotoxic in all of the cell lines investigated. These esters were shown to be cleaved by esterases to form a stable meta-phenol and an unstable para-phenol. The meta-phenol was also highly cytotoxic. Several of these compounds were studied in detail using DNA cross-linking, clonogenic, apoptosis and flow cytometry assays. It is proposed that although the phenol-esters and the phenols can efficiently cross-link DNA, this mechanism alone is not sufficient to explain the toxicities of these compounds.