Thionated aminofluorophthalimides reduce classical markers of cellular inflammation in LPS-challenged RAW 264.7 cells

Herein, we present the synthesis of several fluorinated pomalidomide derivatives and their thionated counterparts with subsequent biological evaluation against classical markers of cellular inflammation. Treatment in LPS-challenged cells effected varying reductions in levels of secreted TNF-α and nitrite relative to basal amounts. While arene fluorination and thioamidation had marginal and sporadic effects on TNF-α production, specific 7-position fluorination combined with subsequent increases in carbonyl thionation produced compounds 11, 14, and 15 which demonstrated corresponding and escalating anti-nitrite activities concurrent with minimal cellular toxicity. In this regard, compound 15 displayed roughly 96 % cell viability combined with a 65 % drop in nitrite production when supplied to RAW cells challenged with 60 ng/mL LPS. When a focused family of fluorinated isomers were directly compared, the analogous 5-fluorinated isomer 17 displayed comparable minimal toxicity but markedly less anti-nitrite activity versus 15 in RAW cells challenged with 70 ng/mL LPS. Compound 15 was subsequently screened in human liver microsomes for preliminary Phase 1 analysis where it demonstrated heightened stability relative to its non-fluorinated counterpart 3,6'-dithiopomalidomide 4, a result in line with the expected metabolic fortitude provided by fluorination at the sensitive pomalidomide 7-position.

A novel Cereblon E3 ligase modulator with antitumor activity in gastrointestinal cancer

Targeted protein degradation offers new opportunities to inactivate cancer drivers and has successfully entered the clinic. Ways to induce selective protein degradation include proteolysis targeting chimera (PROTAC) technology and immunomodulatory (IMiDs) / next-generation Cereblon (CRBN) E3 ligase modulating drugs (CELMoDs). Here, we aimed to develop a MYC PROTAC based on the MYC-MAX dimerization inhibitor 10058-F4 derivative 28RH and Thalidomide, called MDEG-541. We show that a subgroup of gastrointestinal cancer cell lines and primary patient-derived organoids are MDEG-541 sensitive. Although MYC expression was regulated in a CRBN-, proteasome- and ubiquitin-dependent manner, we provide evidence that MDEG-541 induced the degradation of CRBN neosubstrates, including G1 to S phase transition 1/2 (GSPT1/2) and the Polo-like kinase 1 (PLK1). In sum, we have established a CRBN-dependent degrader of relevant cancer targets with activity in gastrointestinal cancers.

Synthesis and pharmacological evaluation of pomalidomide derivatives useful for sickle cell disease treatment

Fetal hemoglobin (HbF) induction constitutes a valuable and validated approach to treat the symptoms of sickle cell disease (SCD). Here, we synthesized pomalidomide-nitric oxide (NO) donor derivatives (3a-f) and evaluated their suitability as novel HbF inducers. All compounds demonstrated different capacities of releasing NO, ranging 0.3-30.3%. Compound 3d was the most effective HbF inducer for CD34+ cells, exhibiting an effect similar to that of hydroxyurea. We investigated the mode of action of compound 3d for HbF induction by studying the in vitro alterations in the levels of transcription factors (BCL11A, IKAROS, and LRF), inhibition of histone deacetylase enzymes (HDAC-1 and HDAC-2), and measurement of cGMP levels. Additionally, compound 3d exhibited a potent anti-inflammatory effect similar to that of pomalidomide by reducing the TNF-α levels in human mononuclear cells treated with lipopolysaccharides up to 58.6%. Chemical hydrolysis studies revealed that compound 3d was stable at pH 7.4 up to 24 h. These results suggest that compound 3d is a novel HbF inducer prototype with the potential to treat SCD symptoms.

Chemical approaches to targeted protein degradation through modulation of the ubiquitin-proteasome pathway

Manipulation of the ubiquitin-proteasome system to achieve targeted degradation of proteins within cells using chemical tools and drugs has the potential to transform pharmacological and therapeutic approaches in cancer and other diseases. An increased understanding of the molecular mechanism of thalidomide and its analogues following their clinical use has unlocked small-molecule modulation of the substrate specificity of the E3 ligase cereblon (CRBN), which in turn has resulted in the advancement of new immunomodulatory drugs (IMiDs) into the clinic. The degradation of multiple context-specific proteins by these pleiotropic small molecules provides a means to uncover new cell biology and to generate future drug molecules against currently undruggable targets. In parallel, the development of larger bifunctional molecules that bring together highly specific protein targets in complexes with CRBN, von Hippel-Lindau, or other E3 ligases to promote ubiquitin-dependent degradation has progressed to generate selective chemical compounds with potent effects in cells and in vivo models, providing valuable tools for biological target validation and with future potential for therapeutic use. In this review, we survey recent breakthroughs achieved in these two complementary methods and the discovery of new modes of direct and indirect engagement of target proteins with the proteasome. We discuss the experimental characterisation that validates the use of molecules that promote protein degradation as chemical tools, the preclinical and clinical examples disclosed to date, and the future prospects for this exciting area of chemical biology.

Design and Synthesis of N-Arylphthalimides as Inhibitors of Glucocorticoid-Induced TNF Receptor-Related Protein, Proinflammatory Mediators, and Cytokines in Carrageenan-Induced Lung Inflammation

N-Arylphthalimides (1-10P) derived from thalidomide by insertion of hydrophobic groups were evaluated for anti-inflammatory activity, and (4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-N'-[(4-ethoxyphenyl)methylidene]benzohydrazide 6P was identified as a promising anti-inflammatory agent. Further testing confirmed that compared with the control, 6P treatment resulted in a considerable decrease in CD4(+), NF-κB p65(+), TNF-α(+), IL-6(+), GITR(+), and IL-17(+) cell populations and an increase in the Foxp3(+), CD4(+)Foxp3(+), and IκBα(+) populations in whole blood and pleural fluid of a mouse model of lung inflammation. Moreover, treatment with compound 6P decreased the proteins associated with inflammation including TNF-α, IL-6, IL-17, GITR, NF-κB, COX-2, STAT-3, and iNOS and increased the anti-inflammatory mediators such as IL-10 and IL-4. Further, histopathological examination confirmed the potent anti-inflammatory effects of compound 6P. Thus, the N-arylphthalimide derivative 6P acts as a potent anti-inflammatory agent in the carrageenan-induced lung inflammation model, suggesting that this compound may be useful for the treatment of inflammation in a clinical setting.

Design, synthesis and biological assessment of novel N-substituted 3-(phthalimidin-2-yl)-2,6-dioxopiperidines and 3-substituted 2,6-dioxopiperidines for TNF-α inhibitory activity

Eight novel 2-(2,6-dioxopiperidin-3-yl)phthalimidine EM-12 dithiocarbamates 9 and 10, N-substituted 3-(phthalimidin-2-yl)-2,6-dioxopiperidines 11-14 and 3-substituted 2,6-dioxopiperidines 16 and 18 were synthesized as tumor necrosis factor-α (TNF-α) synthesis inhibitors. Synthesis involved utilization of a novel condensation approach, a one-pot reaction involving addition, iminium rearrangement and elimination, to generate the phthalimidine ring required for the creation of compounds 9-14. Agents were, thereafter, quantitatively assessed for their ability to suppress the synthesis on TNF-α in a lipopolysaccharide (LPS)-challenged mouse macrophage-like cellular screen, utilizing cultured RAW 264.7 cells. Whereas compounds 9, 14 and 16 exhibited potent TNF-α lowering activity, reducing TNF-α by up to 48% at 30 μM, compounds 12, 17 and 18 presented moderate TNF-α inhibitory action. The TNF-α lowering properties of these analogs proved more potent than that of revlimid (3) and thalidomide (1). In particular, N-dithiophthalimidomethyl-3-(phthalimidin-2-yl)-2,6-dioxopiperidine 14 not only possessed the greatest potency of the analogs to reduce TNF-α synthesis, but achieved this with minor cellular toxicity at 30 μM. The pharmacological focus of the presented compounds is towards the development of well-tolerated agents to ameliorate the neuroinflammation, that is, commonly associated with neurodegenerative disorders, epitomized by Alzheimer's disease and Parkinson's disease.

Preliminary biological evaluations of new thalidomide analogues for multiple sclerosis application

The present work deals with the synthesis of a new series of thalidomide derivatives for therapeutic applications. These compounds were evaluated in vitro on a human endothelial cell line EA.hy926 for their antiproliferative potential and in vivo on an experimental animal multiple sclerosis model called EAE as angiogenesis inhibitors. The preliminary results obtained on EAE assays seem to validate that anti-angiogenesis compounds could be promising tools for the treatment of MS.

[Synthesis of 1,3-dihydro-1,3-dioxo-2H-isoindole derivatives]

OBJECTIVE

To synthesize a series of derivatives of Thalidomide.

METHODS

The N-Phthaloyl-L-glutamic anhydride was ammonolyzed with amino acid benzyl esters, followed by hydrogenization. The reaction between the hydogenized products and ammonia gas produced ammonium salt, 1,3-dihydro-1,3-dioxo-2H-isoindole derivatives.

RESULTS

Four new derivatives of Thalidomide were obtained and confirmed by spectral detection.

CONCLUSION

The derivatives of Thalidomide can be efficiently synthesized under mild conditions.

Synthesis and TNF expression inhibitory properties of new thalidomide analogues derived via Heck cross coupling

A library of new thalidomide analogues containing an olefin functionality were synthesised using a Heck cross coupling reaction from their aryl halogenated precursor. All analogues were tested for their ability to inhibit the synthesis of the proinflammatory cytokine Tumour Necrosis Factor (TNF). Compounds 22, 29, 33 and 37 were the most effective in this assay inhibiting TNF expression 50%, 69%, 52% and 50%, respectively.

Efficient asymmetric synthesis of novel 4-substituted and configurationally stable analogues of thalidomide

The preparation of new thalidomide derivatives 4-methyl-(3S,4R)-3a and 4-phenyl-(3S,4S)-3b starting from pyroglutamic acids (2R,3R)-7a and (2R,3S)-7b, possessing an inappropriate stereochemistry, was successfully realized due to stereochemically complete epimerization at the alpha-stereogenic center upon formation of the corresponding N-phthaloyl anhydrides 9a,b. The demonstrated conformational stability of these new thalidomide derivatives provides solid experimental evidence for practical feasibility of the approach described here to overcome the inherent problem of configurational instability of thalidomide by introducing an alkyl or aryl group in the C4 position. [reaction: see text].

Mono- and dihydroxylated metabolites of thalidomide: synthesis and TNF-alpha production-inhibitory activity

Mono- and dihydroxylated metabolites of thalidomide were efficiently prepared and characterized, and their inhibitory activity on tumor necrosis factor (TNF)-alpha production in the human monocytic leukemia cell line THP-1 was evaluated. 5,N-Dihydroxythalidomide was a much more potent TNF-alpha production inhibitor than thalidomide.

Thalidomide Analogs from Diamines: Synthesis and Evaluation as Inhibitors of TNF-.ALPHA. Production

Fourteen thalidomide analogs bearing two phthalimido units were prepared in high yields (83-94%) by condensation of different diamines with phthalic or 3-nitrophthalic anhydride. An in vitro investigation of the compounds as inhibitors of the TNF-alpha production was performed. The inhibition was higher for compounds bearing amino and nitro groups and was modulated by increasing the size of the spacers between the phthalimide groups.

Cell differentiation inducers derived from thalidomide

5-Hydroxy- and 4-amino-2-(2,6-diisopropylphenyl)-1H-isoindole-1,3-dione (5HPP-33 and 4APP-33, respectively) have been shown to possess cell differentiation-inducing activity toward human leukemia cell line HL-60.

[Search for new anti-angiogenic agents with structural analogy with thalidomide]

Despite its teratogenic effects, thalidomide has been reintroduced in human anticancer treatment for its anti-angiogenic activity, especially observed in patients with multiple myeloma. Here, we report the synthesis of new analogues designed to increase the thalidomide anti-tumour properties. The anti-angiogenic activity of the compounds was tested on EA.hy 926 endothelial cell lines. In this model, that is easier to manipulate than HUVEC cells, thalidomide is active in a similar dose range as reported on HUVEC cells and one of our compounds is more efficient.

Thiothalidomides: novel isosteric analogues of thalidomide with enhanced TNF-alpha inhibitory activity

Thalidomide is being increasingly used in the clinical management of a wide spectrum of immunologically-mediated and infectious diseases, and cancers. However, the mechanisms underlying its pharmacological action are still under investigation. In this regard, oral thalidomide is clinically valuable in the treatment of erythema nodosum leprosum (ENL) and multiple myeloma and effectively reduces tumor necrosis factor-alpha (TNF-alpha) levels and angiogenesis in vivo. This contrasts with its relatively weak effects on TNF-alpha and angiogenesis in in vitro studies and implies that active metabolites contribute to its in vivo pharmacologic action and that specific analogues would be endowed with potent activity. Our focus in the structural modification of thalidomide is toward the discovery of novel isosteric active analogues. In this regard, a series of thiothalidomides and analogues were synthesized and evaluated for their TNF-alpha inhibitory activity against lipopolysacharide (LPS)-stimulated peripheral blood mononuclear cells (PBMC), This was combined with a PBMC viability assay to differentiate reductions in TNF-alpha secretion from cellular toxicity. Two isosteric analogues of thalidomide, compounds 15 and 16, that mostly reflect the parent compound, together with the simple structure, dithioglutarimide 19, potently inhibited TNF-alpha secretion, compared to thalidomide, 1. The mechanism underpinning this most likely is posttranscriptional, as each of these compounds decreased TNF-alpha mRNA stability via its 3'-UTR. The potency of 19 warrants further study and suggests that replacement of the amide carbonyl with a thiocarbonyl may be beneficial for increased TNF-alpha inhibitory action. In addition, an intact phthalimido moiety appeared to be requisite for TNF-alpha inhibitory activity.

Inhibition of angiogenesis by THAM-derived cotelomers endowed with thalidomide moieties

The synthesis of a tris(hydroxymethyl)acrylamidomethane (THAM)-derived cotelomer endowed with thalidomide units and a preliminary assessment of its biological activity are described. 4-Carboxy thalidomide and 4-(N-acryloyl) lysine thalidomide derivatives were prepared. The polymerization of these compounds with THAM in the presence of octanethiol as transfer reagent provided a water-soluble telomer bearing several thalidomide units. The ability of this telomer to inhibit angiogenesis in a mouse model of corneal neovascularization was compared to 4-carboxy thalidomide and thalidomide. A significant inhibition in area of neovascularization stimulated by a bFGF pellet was observed only in the mice treated with the telomer.

Thalidomide metabolites and analogues. 3. Synthesis and antiangiogenic activity of the teratogenic and TNFalpha-modulatory thalidomide analogue 2-(2,6-dioxopiperidine-3-yl)phthalimidine

Versatile synthesis of the teratogenic, TNFalpha-modulatory, and antiangiogenic thalidomide analogue 2-(2,6-dioxopiperidine-3-yl)phthalimidine (1) and its direct antiangiogenic properties are described. With thalidomide or thalidomide derivatives as precursors, the synthesis involved either carbonyl reduction/thiation-desulfurization or carbonyl reduction/acyliminium ion reduction protocols. Compared to earlier studies with thalidomide, which was only active with microsomal treatment, 1 exhibited marginal inhibitory activity in the rat aortic ring assay, thereby demonstrating the requirement for metabolic activation.

Thalidomide and its analogues as cyclooxygenase inhibitors

Thalidomide showed cyclooxygenase (COX)-1/2 inhibitory activity with a potency comparable to that of aspirin. Structural development studies of thalidomide resulted in potent COX-1/2 inhibitors, and COX-1-selective and COX-2-selective inhibitors.

Solid-phase synthesis of thalidomide and its analogues

A novel solid-phase synthesis of thalidomide and its metabolites and analogues is described. The synthetic strategy involves the coupling of hydroxymethyl polystyrene with phthalic anhydride to form the resin-linked acid. The acid is then reacted with primary amines followed by acid or base treatment to form thalidomide and its analogues with either open or closed phthalimide rings. Most of the analogues are synthesized with high yields (40.3-98.1% in three steps) and purities (92.3-98.9%).

Aza analogues of thalidomide: synthesis and evaluation as inhibitors of tumor necrosis factor-alpha production in vitro

A synthetic entry to derivatives of the new classes of 5-phthalimidouracils and 5-phthalimidobarbituric acids is reported. These 5-phthalimidopyrimidines as well as phthalimido-2,4-difluorobenzenes were designed as analogues of thalidomide, a well known inhibitor of TNF-alpha production. A preliminary in vitro investigation of the compounds as inhibitors of the TNF-alpha production was performed. Among the compounds of the present series, 5-ethyl-1-phenyl-5-(tetrafluorophthalimido)barbituric acid and 2-(2,4-difluorophenyl)-4,5,6,7-tetrafluoro-1H-isoindole-1,3(2H)-dione were proved to be potent inhibitors. Both compounds showed inhibitory activity in the lower micromolar range on the LPS-induced TNF-alpha production in human monocytes.

Synthesis and immunological activity of water-soluble Thalidomide prodrugs

A series of new water-soluble thalidomide prodrugs was prepared. All compounds were derivatized on the nitrogen of the glutarimide ring. Esters of natural amino acids and succinic acid derivatives have been introduced by reaction with the hydroxymethyl thalidomide 2. Nicotinic acid derivatives were prepared from halomethyl derivatives. Additionally, a methoxymethyl derivative and a carboxymethyl derivative were prepared directly from thalidomide. Most compounds showed a very large increase in water solubility compared to thalidomide itself (0.012mg/mL). The amorphous hydrochlorides of the N-methylalanine ester 8, valine ester 9, and glycylglycine ester 10, respectively, were the most soluble compounds showing solubility greater than 300mg/mL, which equals an increase greater than 15,000-fold. The lipophilicity of the prodrugs has been determined by their HPLC capacity factors k'. The stability of selected compounds was determined. The hydrolysis rates follow pseudo-first order kinetics. In order to assess the immunological activity, the prodrugs were tested using tumor necrosis factor-alpha and interleukin-2 inhibition assays. Selected compounds were additionally investigated on their abililty to inhibit the local Shwartzman reaction, an assay to determine the vascular permeability. The prodrugs retained high effectiveness in the inhibition of TNF-alpha release. Our results indicated that the more stable prodrugs exhibited higher activity in the immunological assays. Some compounds showed higher activity than thalidomide itself, suggesting a high affine binding to the pharmacophore. In conclusion, the prodrugs exhibited high water solubility and high activity and might therefore be used in therapeutic applications.

Amino-substituted thalidomide analogs: potent inhibitors of TNF-alpha production

Thalidomide, (1), is a known inhibitor of TNF-alpha release in LPS stimulated human PBMC. Herein we describe the TNF-alpha inhibitory activity of amino substituted analogs of thalidomide (1) and its isoindolin-1-one analog, EM-12 (2). The 4-amino substituted analogs were found to be potent inhibitors of TNF-alpha release in LPS stimulated human PBMC.

Tumor necrosis factor-alpha production enhancing activity of substituted 3'-methylthalidomide: influence of substituents at the phthaloyl moiety on the activity and stereoselectivity

The synthesis and tumor necrosis factor (TNF)-alpha production enhancing activity of substituted 3'-methylthalidomides on human leukemia cell line HL-60 stimulated with 12-O-tetradecanoyl-phorbol 13-acetate (TPA) are described. Though the introduction of an electron-donating amino group at the phthaloyl moiety of alpha-methylthalidomides enhanced the activity, substituted alpha-methylthalidomides showed decreased stereoselectivity as compared to that of non-substituted alpha-methylthalidomide. The data indicates that the TNF-alpha production enhancing activity of thalidomide derivatives depends on both the electronic-state of substituents at the fused benzene ring and the stereochemistry of the glutarimide moiety.

Enhanced potency of perfluorinated thalidomide derivatives for inhibition of LPS-induced tumor necrosis factor-alpha production is associated with a change of mechanism of action

Perfluorination of phthalimides leads to dramatically increased potency as inhibitors of TNF-alpha production. We examined the enantiodependence for several tetrafluorophthalimides and alpha-methylthalidomide, 3. Only 3 exhibited strikingly enantiodependent activity. The key structural determinant for the enhanced activity is the tetrafluorophthaloyl group, which confers enhanced potency and a change in the mechanism of inhibition.

Binding of thalidomide to alpha1-acid glycoprotein may be involved in its inhibition of tumor necrosis factor alpha production

In addition to its well known sedative and teratogenic effects, thalidomide also possesses potent immunomodulatory and antiinflammatory activities, being most effective against leprosy and chronic graft-versus-host disease. The immunomodulatory activity of thalidomide has been ascribed to the selective inhibition of tumor necrosis factor alpha from monocytes. The molecular mechanism for the immunomodulatory effect of thalidomide remains unknown. To elucidate this mechanism, we synthesized an active photoaffinity label of thalidomide as a probe to identify the molecular target of the drug. Using the probe, we specifically labeled a pair of proteins of 43-45 kDa with high acidity from bovine thymus extract. Purification of these proteins and partial peptide sequence determination revealed them to be alpha1-acid glycoprotein (AGP). We show that the binding of thalidomide photoaffinity label to authentic human AGP is competed with both thalidomide and the nonradioactive photoaffinity label at concentrations comparable to those required for inhibition of production of tumor necrosis factor alpha from human monocytes, suggesting that AGP may be involved in the immunomodulatory activity of thalidomide.

Synthesis, central nervous system activity and teratogenicity of a homothalidomide

The optical isomers of alpha-phthalimidoadipinimide (1) were synthesized by a route based on D(+)- and L(-)-amino-epsilon-caprolactam (5) as synthon. The isomers of 1 were obtained in high yields by treating D(+)- and L(-)-amino-epsilon-caprolactam (5) with N-carboethoxyphthalimide (4), followed by oxidation with benzeneseleninic anhydride (7). The teratogenic potency of both isomers of 1 was studied by the HET-(Hen's Egg Test); 1 caused distinctly lower teratogenic effects in contrast to thalidomide (2). D(-)-1 and L(+)-1 showed sedative effects with a lower activity than 2. Both are more stable in alkaline solution at the same time with a smaller tendency for racemization.

[Stereoselective differences of central nervous system-depressive action of a homologous series of 3-alkyl-thalidomide analysis]

The racemates and the enantiomers of the 3-alkyl-thalidomide analogues 2a-c were synthesized via the lactams 1a-c. The absolute configuration of 1a-c and 2a-c was elucidated, their enantiomeric purity established. From racem. 2a 1,3-dimethylthalidomide (3) was synthesized. By means of the hexobarbital sleeping time prolongating effect in rats it was shown that racem. 2a and 3 were less CNS-depressant active than thalidomide; 3 caused a more prolonged sleeping time than 2a. Both enantiomers of 2a (i.p. 200 mg/kg) exceeded in their sleeping time prolongation action racem. 2a (same dose), whereby the (S)-enantiomer was to a factor of 1.8 more effective than the (R). With both enantiomers of 2a time and dose dependency of the effect were investigated. The enantiomers of 2b + c and 1a-c had also a prolongating effect on the hexobarbital sleeping time. Independently of the alkyl group the (S)-enantiomers were always more active than the respective (R)-enantiomers. (S)-1b (200 mg/kg) caused a long lasting loss of the righting reflexes as "own effect". Stereoselective differences between the enantiomers of 2a and 2b were observed only when a dose of 200 mg/kg was applied, whereas the higher activity of the (S)-enantiomers of 2c, 1b + c was obtained already with a lower dosage range.

[Synthesis of racemates and enantiomers of 3-alkylthalidomide analogs and determination of their absolute configuration]

The syntheses of the racemates and the enantiomers of the title compounds 7a-7c and of racem. 1,3-dimethyl-thalidomide (8) are reported. The absolute configuration of the optically active products is determined. The hypnotic activities of the analogs of thalidomide 7a - 7c and of the intermediates 6a - 6c are to be tested in animals.

Possible antineoplastic agents I

A few thalidomide and glutarimide derivatives were synthesized. Several compounds possessed significant antineoplastic activity against Ehrlich ascites carcinoma in Swiss albino mice.