Phthalimide Analogues Research Articles

DISCOVERY OF NOVEL PHTHALIMIDE ANALOGOUS BASED ANTI-EPILEPTIC BY MOLECULAR DOCKING

Aim: The development of innovative compounds for managing seizures with greater therapeutic efficacy and fewer side effects by molecular docking.
 Introduction: One of the major global problems is epilepsy, a severe brain illness that affects around 1% of people globally. Vigabatrin, sodium valproate, phenytoin, and other strong medications for the treatment of epilepsy causes side effects and patient resistance. Despite the antiepileptic drug development process seems to be successful, more effective and safer, still antiepileptic drugs are needed, especially for the treatment of refractory seizures. The study’s focus was on phthalimide analogs with strong GABA-AT inhibitory effects by molecular docking. 
 Methodology: Since protein-ligand interactions are important for drug design, The protein data bank was used to retrieve the 3D structures of GABA-AT, and the Chem Office tool was used to dock the 3D structures of Novel Ligand (Chem Draw 16.0). 
 Result: By using Lipinski’s rule of five on the novel analogs to assess their anti-epileptic activity, and the drug-likeness property was verified. All the compounds had docking energies over 6.11 kcal/mol for the anti-epileptic GABA-AT receptors.
 Conclusion: These concluded that novel compounds can be the promising lead for further study as an Anti-Epileptic for the management and prevention of Epilepsy

Spectroscopic and Theoretical Analysis of the Interaction between Plasma Proteins and Phthalimide Analogs with Potential Medical Application

One of the groups of organic compounds with potential use in medicine and pharmacy is phthalimide derivatives. They are characterized by a wide range of properties such as antibacterial, antifungal, and anti-inflammatory. In this study, we focused on research on four phthalimide derivatives with proven non-toxicity, which are cyclooxygenase inhibitors. With the use of molecular docking study and spectroscopic methods, such as fluorescence, circular dichroism, and FT-IR spectroscopies, we analyzed the way the tested compounds interact with plasma proteins. Among the many proteins present in the plasma, we selected three: albumin, α1-acid glycoprotein, and gamma globulin, which play significant roles in the human body. The obtained results showed that all tested compounds bind to the analyzed proteins. They interact most strongly with albumin, which is a transport protein. However, interactions with serum albumin and orosomucoid do not cause significant changes in their structures. Only in the case of gamma globulins significant changes were observed in protein secondary structure.

Phthalimides Represent a Promising Scaffold for Multi‐Targeted Anticancer Agents

AbstractFrom the last two decades, phthalimide analogues received prime interest from scientists due to its potent inhibitory action on different cancer‐causing receptors. A variety of anticancer drugs are coming into the market but challenges of drug resistance, toxicities, and failure in therapy still remain. Cancer is a group of complex disorders it involves multiple receptors. So there is a need of targeting multiple receptors to get desired potent anticancer drugs with minimum harmful effects. Phthalimide scaffolds fit into these criteria as it is extensively reported for the inhibition of different cancer receptors such as VEGFR, HDAC, EGFR, TNF‐α, etc. The multi‐targeted mechanism of phthalimide derivatives plays a major role in anticancer therapy. Due to this advantage, there is the hope of developing some novel effective multi‐targeted anticancer agents. Consider structural features and pharmacological advancement of phthalimide analogues may fulfill the current need of cancer patients. In this review, we covered history, chemistry, SAR, anticancer mechanisms, and the current status of phthalimide derivatives reported till 2022. The article specifically focused on different cancer‐causing receptors inhibited by phthalimide derivatives and their mechanism of action in brief. Finally, we provided the future scope and role of phthalimide derivatives in multi‐targeted anticancer drug discovery.

Synthesis of 2-(2-(4-thioxo-3H-1,2-dithiole-5-yl) phenoxy)ethyl)isoindole-1,3-thione, a novel hydrogen sulfide-releasing phthalimide hybrid, and evaluation of its activity in models of inflammatory pain

Hydrogen sulfide (H2S) is a gaseous mediator that modulates several physiological and pathological processes. Phthalimide analogues, substances that have the phthalimide ring in the structure, belong to the group of thalidomide analogues. Both H2S donors and phthalimide analogues exhibit activities in models of inflammation and pain. As molecular hybridization is an important strategy aiming to develop drugs with a better pharmacological profile, in the present study we synthesized a novel H2S-releasing phthalimide hybrid, 2-(2-(4-thioxo-3H-1,2-dithiole-5-yl) phenoxy)ethyl)isoindole-1,3-thione (PTD-H2S), and evaluated its activity in models of inflammatory pain in mice. Per os (p.o.) administration of PTD-H2S (125 or 250 mg/kg) reduced mechanical allodynia induced by carrageenan and lipopolysaccharide. Intraperitoneal (i.p.) administration of PTD-H2S (25 mg/kg), but not equimolar doses of its precursors 5-(4-hydroxyphenyl)-3H-1,2-dithiole-3-thione (14.2 mg/kg) and 2-phthalimidethanol (12 mg/kg), reduced mechanical allodynia induced by lipopolysaccharide. The antiallodynic effect induced by PTD-H2S (25 mg/kg, i.p.) was more sustained than that induced by the H2S donor NaHS (8 mg/kg, i.p.). Previous administration of hydroxocobalamin (300 mg/kg, i.p.) or glibenclamide (40 mg/kg, p.o.) attenuated PTD-H2S antiallodynic activity. In conclusion, we synthesized a novel H2S-releasing phthalimide hybrid and demonstrated its activity in models of inflammatory pain. PTD-H2S activity may be due to H2S release and activation of ATP-sensitive potassium channels. The demonstration of PTD-H2S activity in models of pain stimulates further studies aiming to evaluate H2S-releasing phthalimide hybrids as candidates for analgesic drugs.

The 2-hydroxy-3-(4-aryl-1-piperazinyl)propyl Phthalimide Derivatives as Prodrugs-Spectroscopic and Theoretical Binding Studies with Plasma Proteins.

Many publications in databases deal with the interactions of new drugs with albumin. However, it is not only albumin that is responsible for binding pharmaceutical molecules to proteins in the human body. There are many more proteins in plasma that are important for the study of the ADME pathway. Therefore, in this study, we have shown the results of the interactions between the plasma proteins albumin, orosomucoid, and gamma globulins and non-toxic anti-inflammatory phthalimide analogs, which due to the promising obtained results, may be potential candidates in the group of analgesic and anti-inflammatory drugs. Using spectroscopic methods and molecular modeling, we showed that all four tested compounds form complexes with the analyzed proteins. The formation of a complex with proteins raises the pharmacological efficacy of the drug. Therefore, the obtained results could be a step in the study of the pharmacokinetics and pharmacodynamics of new potential pharmaceuticals.

Designing and development of phthalimides as potent anti-tubulin hybrid molecules against malaria

Constant emergence of drug-resistant Plasmodium falciparum warrants urgent need for effective and inexpensive drugs. Herein, phthalimide (Pht) analogs possessing the bioactive scaffolds, benzimidazole and 1,2,3-triazole, were evaluated for in vitro and in vivo anti-plasmodial activity without any apparent hemolysis, or cytotoxicity. Analogs 4(a-e) inhibited the growth of 3D7 and RKL-9 strains at submicromolar concentrations. Defects were observed during parasite egress from or invasion of the red blood cells. Mitochondrial membrane depolarization was measured as one of the causes of cell death. Phts 4(a-e) in combination with artemisinin exhibited two-to three-fold increased efficacy. Biophysical and biochemical analysis suggest that Pht analogs mediate plasmodial growth inhibition by interacting with tubulin protein of the parasite. Lastly, Phts 4(a-e) significantly decreased parasitemia and extended host survival in murine model Plasmodium berghei ANKA infection. Combined, the data indicate that Pht analogs should be further explored, which could offer novel value to the antimalarial drug development pipeline.

Borylated 2,3,4,5-Tetrachlorophthalimide and Their 2,3,4,5-Tetrachlorobenzamide Analogues: Synthesis, Their Glycosidase Inhibition and Anticancer Properties in View to Boron Neutron Capture Therapy.

Tetrachlorinated phthalimide analogues bearing a boron-pinacolate ester group were synthesised via two synthetic routes and evaluated in their glycosidase modulating and anticancer properties, with a view to use them in boron neutron capture therapy (BNCT), a promising radiation type for cancer, as this therapy does little damage to biological tissue. An unexpected decarbonylation/decarboxylation to five 2,3,4,5-tetrachlorobenzamides was observed and confirmed by X-ray crystallography studies, thus, giving access to a family of borylated 2,3,4,5-tetrachlorobenzamides. Biological evaluation showed the benzamide drugs to possess good to weak potencies (74.7–870 μM) in the inhibition of glycosidases, and to have good to moderate selectivity in the inhibition of a panel of 18 glycosidases. Furthermore, in the inhibition of selected glycosidases, there is a core subset of three animal glycosidases, which is always inhibited (rat intestinal maltase α-glucosidase, bovine liver β-glucosidase and β-galactosidase). This could indicate the involvement of the boron atom in the binding. These glycosidases are targeted for the management of diabetes, viral infections (via a broad-spectrum approach) and lysosomal storage disorders. Assays against cancer cell lines revealed potency in growth inhibition for three molecules, and selectivity for one of these molecules, with the growth of the normal cell line MCF10A not being affected by this compound. One of these molecules showed both potency and selectivity; thus, it is a candidate for further study in this area. This paper provides numerous novel aspects, including expedited access to borylated 2,3,4,5-tetrachlorophthalimides and to 2,3,4,5-tetrachlorobenzamides. The latter constitutes a novel family of glycosidase modulating drugs. Furthermore, a greener synthetic access to such structures is described.

Phthalimide Analogs Enhance Genotoxicity of Cyclophosphamide and Inhibit Its Associated Hypoxia.

Cyclophosphamide (CP) is a mutagen that is used in cancer chemotherapy, due to its genotoxicity and as an immunosuppressive agent. Thalidomide (TH) is another cancer chemotherapeutic drug. In this study, the cytogenotoxicity and hypoxia modulatory activities of two phthalimide analogs of TH have been evaluated with/without CP. Both analogs have increased CP-stimulated chromosomal aberrations than those induced by TH, including gaps, breaks/fragments, deletions, multiple aberrations, and tetraploidy. The analogs have elevated the cytotoxic effect of CP by inhibiting the mitotic activity, in which analog 2 showed higher mitosis inhibition. CP has induced binucleated and polynucleated bone marrow cells (BMCs), while micronuclei (MN) are absent. TH and analogs have elevated the CP-stimulated binucleated BMCs, while only analogs have increased the CP-induced polynucleated BMCs and inhibited the mononucleated BMCs. MN-BMCs were shown together with mononucleated, binucleated, and polynucleated cells in the CP group. Both analogs have elevated mononucleated and polynucleated MN-BMCs, whereas in presence of CP, TH and analogs have enhanced mononucleated and binucleated MN-BMCs. The analogs significantly induce DNA fragmentation in a comet assay, where analog 1 is the strongest inducer. The treatment of mice with CP has resulted in a high hypoxia status as indicated by high pimonidazole adducts and high HIF-1α and HIF-2α concentrations in lymphocytes. Analogs/CP-treated mice showed low pimonidazole adducts. Both analogs have inhibited HIF-1α concentration but not HIF-2α. Taken together, the study findings suggest that both analogs have a higher potential to induce CP-genotoxicity than TH and that both analogs inhibit CP-hypoxia via the HIF-1α-dependent mechanism, in which analog 1 is a more potent anti-hypoxic agent than analog 2. Analog 1 is suggested as an adjacent CP-complementary agent to induce CP-genotoxicity and to inhibit CP-associated hypoxia.

Synthesis, spectroscopic characterization of novel phthalimides derivatives bearing a 1,2,3-triazole unit and examination as potential SARS-CoV-2 inhibitors via in silico studies

In the present study, novel phthalimide derivatives 8(a-f) and 9(a-f) bearing a 1,2,3-triazole subunit were synthesized via CuAAC reactions and characterized by 1H, 13C NMR, HR-MS, and FT-IR analyses. To support the fight against SARS-CoV-2, in silico molecular docking studies were carried out to examine their interactions with the proteins of SARS-CoV-2 (Mpro and PLpro) and the protein-protein interactions (PPI) between the ACE2-spike (S1) in comparison with various inhibitors reported to be active by in vitro experiments. The ligand-protein stabilities of compounds 8a-Mpro, 8b-PLpro, and 9a-‘ACE2-S1’ showing the best binding energy and predicted inhibition constant values (Ki) were examined by molecular dynamics simulation studies. Finally, in silico ADMET properties of the target compounds were investigated using the Swiss ADME and ProTox-II web tools. According to in silico results, all phthalimide analogs may block the PPI between S1 and ACE2. The compounds may also inhibit the progression of the Mpro, and PLpro proteins of SARS-CoV-2. Additionally, it has been estimated that the compounds are suitable for oral administration and exhibit low levels of toxicity.

Theoretical Evaluation of 5, 6-Diaroylisoindoline-1,3-dione as Potential Carcinogenic Kinase PAK1 Inhibitor: DFT Calculation, Molecular Docking Study and ADMET Prediction

Background: The carcinogenic kinase PAK1 (p21-activated kinase 1) is associated with the progression of many disorders, including Alzheimer's disease, various cancers, type-2 diabetes and hypertension. Although few synthetic PAK1 inhibitors and herbal therapeutics, such as propolis and curcumin, are available in the market, a comprehensive remedy of PAK1 related ailments is still not studied in detail. Recently, several phthalimide-metal complexes (viz. Λ-FL172, Λ-FL411, called optically active octahedral ruthenium phthalimide complex) were shown as poor inhibition potency toward PAK1. However, for a full understanding of the inhibition of PAK1 about phthalimide analogues, this study has been designed. Methods: This manuscript presents density functional theory (DFT) based computational approaches of aryl derivatives of phthalimide. The DFT was used to calculate the equilibrium geometries, thermodynamic analysis, dipole moment, polarizability, electrostatic potential map, Mulliken, Hirshfeld, NBO population analysis, frontier molecular orbital contribution, reactivity descriptor, Fukui function analysis of phthalimide derivatives. Molecular docking and ADMET prediction were also performed. Result: The phthalimide derivatives were subjected to molecular docking studies, and binding affinities ranging from -7.3 to -7.7 kcal/mol against PAK1 kinase were determined. The docked ligands demonstrated stronger hydrogen bonding, electrostatic interactions, and hydrophobic interactions with PAK1 kinase. The magnitude of these contacts usually related with bond lengths and attraction forces. The derivatives with an elevated docking score were chosen against ADMET in silico, and they have an excellent oral bioavailability without observed carcinogenesis or mutagenicity affect. Conclusion: These results reveal that these phthalimide derivatives might be potential inhibitors for the protein kinase PAK1.

Advances in Synthesis and Medicinal Applications of Compounds Derived from Phthalimide.

Phthalimide derivatives have been presenting several promising biological activities in the literature, such as anti-inflammatory, analgesic, antitumor, antimicrobial and anticonvulsant. The most well-known and studied phthalimide derivative (isoindoline-1,3-dione) is thalidomide: this compound initially presented important sedative effects, but it is now known that thalidomide has effectiveness against a wide variety of diseases, including inflammation and cancer. This review approaches some of the recent and efficient chemical synthesis pathways to obtain phthalimide analogues and also presents a summary of the main biological activities of these derivatives found in the literature. Therefore, this review describes the chemical and therapeutic aspects of phthalimide derivatives.

Synthesis and Bioactivity of Phthalimide Analogs as Potential Drugs to Treat Schistosomiasis, a Neglected Disease of Poverty.

The neglected tropical disease, schistosomiasis, is caused by trematode blood flukes of the Schistosoma genus and infects approximately 200 million people worldwide. With just one partially effective drug available for disease treatment, new drugs are urgently needed. Herein, a series of 47 phthalimide (Pht) analogues possessing high-value bioactive scaffolds (i.e., benzimidazole and 1,2,3,-triazoles) was synthesized by click-chemistry. Compounds were evaluated for anti-schistosomal activity in culture against somules (post-infective larvae) and adults of Schistosoma mansoni, their predicted ADME (absorption, distribution, metabolism, and excretion) properties, and toxicity vs. HepG2 cells. The majority showed favorable parameters for surface area, lipophilicity, bioavailability and Lipinski score. Thirteen compounds were active at 10 µM against both somules and adults (6d, 6f, 6i–6l, 6n–6p, 6s, 6r’, 6t’ and 6w). Against somules, the majority caused degeneracy and/or death after 72 h; whereas against adult parasites, five compounds (6l, 6d, 6f, 6r’ and 6s) elicited degeneracy, tegumental (surface) damage and/or death. Strongest potency against both developmental stages was recorded for compounds possessing n-butyl or isobutyl as a linker, and a pentafluorophenyl group on triazole. Apart from five compounds for which anti-parasite activity tracked with toxicity to HepG2 cells, there was apparently no toxicity to HepG2 cells (EC50 values ≥50 µM). The data overall suggest that phthaloyl-triazole compounds are favorable synthons for additional studies as anti-schistosomals.

The phthalimide analogues N-3-hydroxypropylphthalimide and N-carboxymethyl-3-nitrophthalimide exhibit activity in experimental models of inflammatory and neuropathic pain.

Phthalimide analogues devoid of the glutarimide moiety exhibit multiple biological activities, thus making them candidates for the treatment of patients with different diseases, including those with inflammatory and painful disorders. In the present study, the activities of five phthalimide analogues devoid of the glutarimide moiety (N-hydroxyphthalimide, N-hydroxymethylphthalimide, N-3-hydroxypropylphthalimide, N-carboxy-3-methylphthalimide, N-carboxymethyl-3-nitrophthalimide) were evaluated in experimental models of acute and chronic inflammatory and neuropathic pain. The phthalimide analogues were administered per os (po) in Swiss mice or Wistar rats. Nociceptive response induced by formaldehyde and mechanical allodynia induced by chronic constriction injury (CCI) of the sciatic nerve or intraplantar (ipl) injection of complete Freund's adjuvant (CFA) were used as experimental models of pain. N-carboxymethyl-3-nitrophthalimide (700 mg/kg, -1 h) inhibited the second phase of the nociceptive response induced by the intraplantar injection of formaldehyde in mice. N-3-hidroxypropylphthalimide (546 mg/kg, -1 h) inhibited both phases of the nociceptive response induced by formaldehyde. Treatment of rats with N-carboxymethyl-3-nitrophthalimide (700 mg/kg) or N-3-hydroxypropylphthalimide (546 mg/kg) inhibited the mechanical allodynia induced by CCI of the sciatic nerve or ipl injection of CFA in rats. Intraperitoneal administration of the opioid antagonist naltrexone (10 mg/kg, -1.5 h) attenuated the antinociceptive activity of N-carboxymethyl-3-nitrophthalimide (700 mg/kg) in the model of nociceptive response induced by formaldehyde. N-3-hydroxypropylphthalimide and N-carboxymethyl-3-nitrophthalimide, two phthalimide analogues devoid of the glutarimide moiety, exhibited activities in different experimental models of pain, including models of chronic inflammatory and neuropathic pain.

Synergistic blending of high-valued heterocycles inhibits growth of Plasmodium falciparum in culture and P. berghei infection in mouse model

A series of phthalimide analogues, novelized with high-valued bioactive scaffolds was synthesized by means of click-chemistry under non-conventional microwave heating and evaluated as noteworthy growth inhibitors of Plasmodium falciparum (3D7 and W2) in culture. Analogues 6a, 6h and 6 u showed highest activity to inhibit the growth of the parasite with IC50 values in submicromolar range. Structure-activity correlation indicated the necessity of unsubstituted triazoles and leucine linker to obtain maximal growth inhibition of the parasite. Notably, phthalimide 6a and 6u selectively inhibited the ring-stage growth and parasite maturation. On other hand, phthalimide 6h displayed selective schizonticidal activity. Besides, they displayed synergistic interactions with chloroquine and dihydroartemisinin against parasite. Additional in vivo experiments using P. berghei infected mice showed that administration of 6h and 6u alone, as well as in combination with dihydroartemisinin, substantially reduced the parasite load. The high antimalarial activity of 6h and 6u, coupled with low toxicity advocate their potential role as novel antimalarial agents, either as standalone or combination therapies.

Synthesis and biological activity of new phthalimides as potential anti-inflammatory agents

The overproduction of nitric oxide (NO) plays an important role in a variety of pathophysiological processes, including inflammation. Therefore, the suppression of NO production is a promising target in the design of anti-inflammatory agents. In the present study, a series of phthalimide analogs was synthesized, and their anti-inflammatory activities were evaluated using lipopolysaccharide (LPS)-stimulated NO production in cultured murine macrophage RAW264.7 cells. A structure-activity relationship study showed that the free hydroxyl group at C-4 and C-6 and the bulkiness of the N-substituted alkyl chain are associated with biological activity. Among the series of phthalimide derivatives, compound IIh exhibited potent inhibitory activity, with an IC50 value of 8.7µg/mL. Further study revealed that the inhibitory activity of compound IIh was correlated with the down-regulation of the mRNA and protein expression of LPS-stimulated inducible nitric oxide synthase (iNOS). Compound IIh also suppressed the induction of the pro-inflammatory cytokines tumor necrosis factor-α and interleukin-1β in LPS-stimulated RAW 264.7 cells. The anti-inflammatory activity of compound IIh was also found to be associated with the suppression of the Toll-like receptor (TLR)4 signaling pathway by down-regulating the activation of interferon regulatory factor 3 (IRF-3) and interferon-β and signal transducer expression. These findings demonstrate that novel phthalimides might be potential candidates for the development of anti-inflammatory agents.

2-Phthalimidethanol and 2-phthalimidethyl nitrate inhibit mechanical allodynia, neutrophil recruitment and cytokine and chemokine production in a murine model of articular inflammation.

Phthalimide analogs have been shown to exhibit anti-inflammatory, analgesic and immunomodulatory activities in different preclinical assays. This study aimed to investigate the potential role of 2-phthalimidethanol (PTD-OH) and 2-phthalimidethyl nitrate (PTD-NO) in a murine model of antigen-induced articular inflammation. Articular inflammation was induced by intra-articular injection of methylated bovine serum albumin (mBSA) in the knee joint of immunized male C57BL/6J mice. The animals were pre-treated with PTD-OH or PTD-NO (500mg/kg, per os, - 1h). Nociceptive threshold was measured using an electronic von Frey apparatus. The total number of leukocytes in the synovial cavity was determined. Concentrations of tumor necrosis factor (TNF)-α and CXCL-1 and myeloperoxidase (MPO) activity were determined in periarticular tissue. Both PTD-OH and PTD-NO inhibited at similar extent the mechanical allodynia, neutrophil recruitment to the synovial cavity and periarticular tissue and TNF-α and CXCL-1 production induced by intra-articular challenge with mBSA in immunized mice. PTD-OH and PTD-NO exhibit a marked activity in a murine model of antigen-induced articular inflammation in immunized animals. These results reinforce the interest in the investigation of phthalimide analogs devoid of the glutarimide ring as candidates to analgesic and anti-inflammatory drugs.

Phthalimide analogs as probable 15-lipoxygenase-1 inhibitors: synthesis, biological evaluation and docking studies

BackgroundRecent studies have been explained the role of lipoxygenases (LOX) in the origin of cancer. Among the lipoxygenases, the 5-LOX, 12-LOX and 15-LOX are more important in the cause of neoplastic disorders. In the present investigation, a new series of anticancer agents with 1,3,4-thiadiazole and phthalimide substructures were synthesized and their in vitro cytotoxicity was evaluated by MTT assay. Moreover, enzyme inhibitory potency was also assessed by enzymatic protocol towards 15-LOX-1. Molecular docking was performed to explore in silico binding mode of the target compounds.ResultsTested compounds showed a better cytotoxic activity against HT29 cell line (colorectal cancer) in comparison with other cell lines (PC3: prostate carcinoma; SKNMC: neuroblastoma). Unfortunately, all of the tested derivatives rendered lower inhibitory potency than quercetin towards 15-LOX-1. Four hydrogen bonds were detected in docking studies for compound 4d as the most potent derivative in enzymatic assay.ConclusionsThe biological results of reported compounds in this research were not so satisfactory. But, further structural modifications are necessary to improve the bioactivity of these derivatives.

Activities of 2-phthalimidethyl nitrate and 2-phthalimidethanol in the models of nociceptive response and edema induced by formaldehyde in mice and preliminary investigation of the underlying mechanisms

The activities of 2-phthalimidethyl nitrate (PTD-NO) and 2-phthalimidethanol (PTD-OH) were recently demonstrated in models of pain and inflammation. We expanded our investigation by evaluating their activities in models of nociceptive and inflammatory pain and inflammatory edema, the preliminary pharmacokinetic parameter for PTD-NO and the role of opioid and cannabinoid pathways in the activity of analogs. Per os (p.o.) administration of PTD-NO or PTD-OH, 1h before intraplantar injection of formaldehyde, inhibited both phases of the nociceptive response (500 and 750mg/kg) and paw edema (125, 250, 500 and 750mg/kg). After p.o. administration of PTD-NO, peak plasma concentrations of PTD-NO and PTD-OH were found 0.92 and 1.13h, respectively. The plasma concentrations of PTD-NO were higher than those of PTD-OH. Intraperitoneal (i.p.) administration of CB1 (AM251) or CB2 (AM630) cannabinoid receptor antagonists (4 or 8mg/kg, −30min) or opioid antagonist naltrexone (5 or 10mg/kg, −30min) did not affect the antinociceptive activities of the analogs. AM251 (8mg/kg, i.p., −30min) attenuated the antiedematogenic activity of both analogs, while naltrexone (10mg/kg, i.p., −30min) only attenuated the antiedematogenic activity of PTD-NO. The antiedematogenic activities of both analogs were not affected by the CB2 cannabinoid antagonist AM630 (4 or 8mg/kg, i.p., −30min). Concluding, we expanded the knowledge on the activities of PTD-NO and PTD-OH by showing that these phthalimide analogs also exhibit marked activity in models of nociceptive and inflammatory pain and inflammatory edema. Opioid and cannabinoid mechanisms partially mediate the anti-inflammatory, but not the antinociceptive activity.

Activities of 2-phthalimidethanol and 2-phthalimidethyl nitrate, phthalimide analogs devoid of the glutarimide moiety, in experimental models of inflammatory pain and edema

The reintroduction of thalidomide in the pharmacotherapy greatly stimulated the interest in the synthesis and pharmacological evaluation of phthalimide analogs with new and improved activities and also greater safety. In the present study, we evaluated the activities of two phthalimide analogs devoid of the glutarimide ring, namely 2-phthalimidethanol (PTD-OH) and 2-phthalimidethyl nitrate (PTD-NO), in experimental models of inflammatory pain and edema in male C57BL/6J mice. Intraplantar (i.pl.) injection of carrageenan (300μg) induced mechanical allodynia and this response was inhibited by previous per os (p.o.) administration of PTD-OH and PTD-NO (750mg/kg) and also by thalidomide (500 or 750mg/kg). The edema induced by carrageenan was also inhibited by previous p.o. administration of PTD-OH (500 and 750mg/kg) and PTD-NO (125, 250, 500 or 750mg/kg), but not by thalidomide. Carrageenan increased tumor necrosis factor (TNF)-α and CXCL1 concentrations and also the number of neutrophils in the paw tissue. Previous p.o. administration of PTD-NO (500mg/kg) reduced all the parameters, while PTD-OH (500mg/kg) reduced only the accumulation of neutrophils. Thalidomide, on the other hand, was devoid of effect on these biochemical parameters. Plasma concentrations of nitrite were increased after p.o. administration of the phthalimide analog coupled to a NO donor, PTD-NO (500mg/kg), but not after administration of PTD-OH or thalidomide. In conclusion, our results show that small molecules, structurally much simpler than thalidomide or many of its analogs under investigation, exhibit similar activities in experimental models of pain and inflammation. Finally, as there is evidence that the glutarimide moiety contributes to the teratogenic effect of many thalidomide analogs, our results indicate that phthalimide analogs devoid of this functional group could represent a new class of analgesic and anti-inflammatory candidates with potential greater safety.

Efficient Synthesis of 2‐Substituted Phthalimides from Phthalic Acids in One Step

AbstractEfficient procedures for synthesizing 2‐substituted phthalimide (isoindole‐1,3‐dione) analogues starting from phthalic acids have been developed by using experimental design. The phthalimide central fragment frequently appears in biologically active compounds, materials, catalysts, and fluorescent probes, and therefore the development of general, fast, and convenient synthetic methods to this scaffold under neutral, acidic, and basic conditions would be attractive. After an initial screening, the use of acetonitrile, acetic acid, or pyridine in combination with microwave heating proved most promising. Experimental design was applied to these conditions to optimize the time, temperature, and concentration. This strategy has successfully generated synthetic methods that have been used to synthesize a series of phthalimides from phthalic acids and various amines or anilines in excellent yields. The developed methods have proven to be general, fast, convenient, and economic, and thus are expected to have broad utility to efficiently construct novel compounds for future biological and chemical applications.