Advances in Synthesis and Medicinal Applications of Compounds Derived from Phthalimide

Phthalimides: developments in synthesis and functionalization

Phthalimides, an important class of biologically active N-heterocycles, are not only found in pharmaceuticals, natural products, agrochemicals, polymers, and dyes, but also serve as building blocks in organic transformations. Many synthetic methods, including metal catalysis and metal-free systems, have been developed to prepare functionalized phthalimides. In this review, we describe the developments in the synthesis and functionalization of phthalimides over the past two decades.

N-heterocyclic carbene-catalyzed atroposelective synthesis of N-Aryl phthalimides and maleimides via activation of carboxylic acids

Traditionally, N-aryl phthalimides are synthesized by the condensation of phthalic anhydride and aniline derivatives, usually proceeding under harsh conditions. The alternative mild and organocatalytic strategies for their synthesis are underdeveloped. Herein, we demonstrate the organocatalytic atroposelective synthesis of N-aryl phthalimides via the traditional N-CC=O disconnection under mild conditions. The in-situ acid activation of phthalamic acid and subsequent N-heterocyclic carbene (NHC)-catalyzed atroposelective amidation allowed the synthesis of well-decorated N-aryl phthalimides in excellent yields and enantioselectivities. Mechanistic studies reveal the addition of NHC to the in situ generated isoimides, thus introducing a unique mode of generating acylazoliums. Interestingly, both enantiomers of the product can be accessed from the same phthalic anhydride and aniline using the same NHC pre-catalyst. Moreover, this strategy has been extended to the atroposelective synthesis of N-aryl maleimides.

Thiazole, Isatin and Phthalimide Derivatives Tested in vivo against Cancer Models: A Literature Review of the Last Six Years

BACKGROUND

Cancer is a disease characterized by the abnormal multiplication of cells and is the second leading cause of death in the world. The search for new effective and safe anticancer compounds is ongoing due to factors such as low selectivity, high toxicity, and multidrug resistance. Thus, heterocyclic compounds derived from isatin, thiazole and phthalimide that have achieved promising in vitro anticancer activity have been tested in vivo and in clinical trials.

OBJECTIVE

This review focused on the compilation of promising data from thiazole, isatin, and phthalimide derivatives, reported in the literature between 2015 and 2022, with in vivo anticancer activity and clinical trials.

METHODS

A bibliographic search was carried out in the PUBMED, MEDLINE, ELSEVIER, and CAPES PERIODIC databases, selecting relevant works for each pharmacophoric group with in vivo antitumor activity in the last 6 years.

RESULTS

In our study, 68 articles that fit the scope were selected and critically analyzed. These articles were organized considering the type of antitumor activity and their year of publication. Some compounds reported here demonstrated potent antitumor activity against several tumor types.

CONCLUSION

This review allowed us to highlight works that reported promising structures for the treatment of various cancer types and also demonstrated that the privileged structures thiazole, isatin and phthalimide are important in the design of new syntheses and molecular optimization of compounds with antitumor activity.

Benzothiazole-Phthalimide Hybrids as Anti-Breast Cancer and Antimicrobial Agents

The benzothiazole nucleus is a major heterocyclic scaffold whose therapeutic potential has been thoroughly explored due to its structural simplicity and ease of synthesis. In fact, several benzothiazole derivatives have been synthesized over time, demonstrating numerous pharmacological properties such as anticancer, antimicrobial, anti-inflammatory, and antioxidant activities. Herein, we propose a new series of benzothiazole-phthalimide hybrids obtained by linking the phthalimide moiety to differently substituted benzothiazole nuclei through the N atom. These compounds have been screened for their anticancer properties against two human breast cancer cell lines. Furthermore, we delved into the mechanism of action of the most active hybrid, compound 3h, by assessing its capability to damage the nuclear DNA, trigger the apoptotic process in the high metastatic MDA-MB-231 cells, and prevent cellular migration. Moreover, in view of the documented antimicrobial activities of the two scaffolds involved, we explored the antibacterial and antifungal effects of the studied compounds by means of the broth microdilution method. Among the studied compounds, 3h showed the highest antimicrobial activity, both against gram-positive and gram-negative bacterial strains belonging to the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) and against fungal strains of the Candida species with MICs values ranging from 16 to 32 µg/mL.

Phthalimide as a versatile pharmacophore scaffold: Unlocking its diverse biological activities

Phthalimide, a pharmacophore exhibiting diverse biological activities, holds a prominent position in medicinal chemistry. In recent decades, numerous derivatives of phthalimide have been synthesized and extensively studied for their therapeutic potential across a wide range of health conditions. This comprehensive review highlights the latest developments in medicinal chemistry, specifically focusing on phthalimide-based compounds that have emerged within the last decade. These compounds showcase promising biological activities, including anti-inflammatory, anti-Alzheimer, antiepileptic, antischizophrenia, antiplatelet, anticancer, antibacterial, antifungal, antimycobacterial, antiparasitic, anthelmintic, antiviral, and antidiabetic properties. The physicochemical profiles of the phthalimide derivatives were carefully analyzed using the online platform pkCSM, revealing the remarkable versatility of this scaffold. Therefore, this review emphasizes the potential of phthalimide as a valuable scaffold for the development of novel therapeutic agents, providing avenues for the exploration and design of new compounds.

Direct synthesis of phthalimides via palladium-catalysed double carbonylation of o-dihaloarenes with nitroarenes

The direct carbonylation of readily available nitro compounds is more attractive and straightforward than the use of traditional amines as nucleophiles. Herein, a practical palladium-catalysed double carbonylation of nitroarenes with o-dihaloarenes has been developed for the construction of various N-aryl phthalimides. Key to the success of this transformation is the use of Mo(CO)6, which acts as both a reducing agent and a solid carbonyl source. A wide range of nitroarenes and o-dihaloarenes as well as o-iodobenzoic acids reacted smoothly to give phthalimides in 27-94% yields.

CT2-3 induces cell cycle arrest and apoptosis in rheumatoid arthritis fibroblast-like synoviocytes through regulating PI3K/AKT pathway

Rheumatoid arthritis (RA) is a kind of chronic autoimmune disease. The existing therapies encountered several challenges. Therefore, continued novel anti-RA drug discovery remains necessary for RA therapy. Recently, our group reported a novel compound named CT2-3, which could be realized as a hybrid of the natural product magnolol and phthalimide and exhibited anti-lung cancer activity. However, the effect of CT2-3 on RA is unclear. Here, we aim to explore the effect and potential mechanism of CT2-3 on the abnormal functions of RA-fibroblast-like synoviocytes (RA-FLSs). In this study, we identified the important role of the dysregulated cell cycle and apoptosis of RA-FLSs in RA progression. Interestingly, we found that CT2-3 inhibited the proliferation and DNA replication of primary RA-FLSs and immortalized RA-FLSs namely MH7A. In addition, CT2-3 downregulated the mRNA and protein expression of cyclin-dependent kinase 2 (CDK2), cyclin A2, and cyclin B1, resulting in cell cycle arrest of primary RA-FLSs and MH7A cells. Also, CT2-3 downregulated the level of B-cell lymphoma-2 (Bcl-2), and increased the level of Bcl-2 associated X (Bax), contributing to apoptosis of primary RA-FLSs and MH7A cells. Furthermore, differential analyses of RNA-sequencing, Western blot, and network pharmacological analysis confirmed that CT2-3 inhibited phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway of primary RA-FLSs and MH7A cells. In conclusion, CT2-3 induces cell cycle arrest and apoptosis in RA-FLSs through modulating PI3K/AKT pathway, which may serve as a potential lead compound for further novel small molecule anti-RA drug development.

Anti-Hyperuricemic, Anti-Arthritic, Hemolytic Activity and Therapeutic Safety of Glycoconjugated Triazole-Phthalimides

Hyperuricemia, the metabolic alteration that leads to gout or gouty arthritis, is increasing worldwide. Glycoconjugated triazole-phthalimides show potent anti-inflammatory activity. The aim of this study was to evaluate the anti-hyperuricemia effect of glycoconjugated triazole-phthalimides. To develop hyperuricemia, groups of mice received orally potassium oxonate (250 mg/kg) for 7 days, and F2, F3 and F4 glycoconjugated triazole-phthalimides (20 mg/kg), allopurinol (300 mg/kg), and 1% carboxymethylcellulose; indomethacin (2 and 4 mg/kg) was the positive control for anti-arthritic effect. Genotoxic and mutagenic effects were evaluated by the comet and micronucleus assays, respectively. The hemolytic action of the compounds was evaluated. Phthalimides F2, F3 and F4 significantly reduced the levels of serum uric acid, creatinine and urea in hyperuricemic animals. In addition, the compounds were efficient in reducing protein denaturation in a dose-dependent manner. In an interesting way, the histopathological analysis of kidneys from groups treated with F2, F3 and F4 showed a glomerular architecture, with the Bowman's capsule and renal tubules having a normal appearance and without inflammatory changes. Also, F2 and F4 showed a small increase in micronuclei, indicating a low mutagenic effect, whilst by comet assay only, we could infer that F4 affected the frequency and damage index, thus indicating a very small genotoxic action. Similarly, the phthalimides showed a low degree of erythrocyte hemolysis (<3%). Our data demonstrate that the new glycoconjugate triazole-phthalimides have potential to treat hyperuricemia and its secondary complications, such as gouty arthritis, with a low to non-significant rate of erythrocytes hemolysis, genotoxicity and mutagenicity making these molecules strong candidates as pharmaceutical agents for treatment requiring uric-acid-lowering therapy.

Novel N-α-amino acid spacer-conjugated phthalimide-triazine derivatives: synthesis, antimicrobial and molecular docking studies

To design and develop novel antimicrobial agents, a series of phthalimide-triazine-based derivatives (6a-6e) were synthesized, characterized and evaluated for their potential antibacterial activities. The compounds were prepared through reaction of 6-phenyl-1,3,5-triazine-2,4-diamine with phthalimide moiety containing aliphatic amino acid. Structural analysis of the synthesized compounds was carried out by various characterization techniques such as FT-IR, ¹H and ¹³C-NMR and mass spectroscopy. After the confirmation of the structure, the antibacterial screening of the synthesized compounds was performed against two strains of Gram-positive (Staphylococcus aureus, and Bacillus subtilis) and two strains of Gram-negative (Escherichia coli and Salmonella enteritidis) bacteria. The results of antimicrobial activity showed that compound 6d was the most active against all the tested strains of microorganisms with the MIC value 1.25 µg/µl. The synthesized compounds were docked into the binding sites of E. coli-DNA gyrase B and S. aureus-DNA gyrase complex to explore their theoretically binding mode and possible interactions of these ligands with these two targets. Docking study showed the importance of both hydrogen bonding and hydrophobic interactions as a key interaction with the targets. Based on the obtained results, the hybrid derivatives of triazine and phthalimide could be regarded as efficient candidates for further molecular developments of antimicrobial agents.

(µ2-η4-N-(2-Butynyl)phthalimide)(hexacarbonyl)dicobalt

The reaction of [Co2(CO)8] with an equimolar amount of the internal alkyne N-(2-butynyl)phthalimide (1-Phthalimido-2-butyne) 1 in heptane solution yields the title compound [Co2(CO)6(µ-phthalimidoCH2C≡CMe)] 2. Compound 2 has been characterized using IR, 1H and 13C NMR spectroscopy; the tetrahedrane-type cluster framework has been ascertained using a single-crystal X-ray diffraction study performed at 100 K.

Antihyperlipidemic activity of glycoconjugated phthalimides in mice submitted to a model of dyslipidemia and insulin resistance

Alterations in lipid and lipoprotein metabolism are factors that trigger several negative metabolic complications. Hyperlipidemia is the starting point for the development of comorbidities of the cardiovascular system, such as atherosclerosis. The search for compounds that reduce high levels of total cholesterol and triglycerides has been widely reported in several publications in the literature. Phthalimide derivatives have been extensively researched with various biological actions. In this study we evaluated the antihyperlipidemic ability of three phthalimide derivatives (FGT-2, FGT-3 and FGT-4) on a model of obesity and insulin resistance in mice. The animals were submitted to a hyperlipid diet for 60 days. On the thirtieth day they were treated with phthalimides (20 mg/kg). The positive control group was treated with Simvastatin (20 mg/kg) and the negative control received only the carboxymethylcellulose vehicle. Biochemical and histological analyzes of all groups were analyzed. The animals treated with phthalimidic derivatives had a reduction in total cholesterol, low density and very low density lipoproteins (LDL-c and VLDL-c), triglycerides and fasting glycemia when compared to the negative control group. The treated animals also showed good results when analyzing the atherogenic indexes Castelli i and II and the ratio Triglycerides/HDL-c. In the oral glucose tolerance test and in the insulin tolerance test, animals treated with phthalimides were more sensitive to the action of the hormone regulating carbohydrate uptake. In the evaluation of the transaminases (AST/ALT), the animals of the group treated with phthalimides presented a lower elevation than the other groups of the experiment, the same observed with the uric acid evaluation. Histological analyzes were performed on liver, kidney, heart and pancreas samples. The groups treated with the compounds FGT-2 and FGT3 presented discrete alterations in the liver and kidney. FGT-4 did not present histological alterations for both tissues and the three phthalimide derivatives did not cause alterations in the other organs. These results suggest that the phthalimides tested can act as antihyperlipidemic agents and have a pleiotropic action, by acting also reducing glycemia in insulin resistance model mimicking diabetes mellitus type 2. These compounds may appear as a new approach in the treatment of obesity and complications, which are multifaceted.

Design, synthesis, in vitro α-glucosidase inhibition, docking, and molecular dynamics of new phthalimide-benzenesulfonamide hybrids for targeting type 2 diabetes

In the present work, a new series of 14 novel phthalimide-benzenesulfonamide derivatives 4a-n were synthesized, and their inhibitory activity against yeast α-glucosidase was screened. The obtained results indicated that most of the newly synthesized compounds showed prominent inhibitory activity against α-glucosidase. Among them, 4-phenylpiperazin derivative 4m exhibited the strongest inhibition with the IC50 value of 52.2 ± 0.1 µM. Enzyme kinetic study of compound 4m proved that its inhibition mode was competitive and Ki value of this compound was calculated to be 52.7 µM. In silico induced fit docking and molecular dynamics studies were performed to further investigate the interaction, orientation, and conformation of the target compounds over the active site of α-glucosidase. Obtained date of these studies demonstrated that our new compounds interacted as well with the α-glucosidase active site with the acceptable binding energies. Furthermore, in silico druglikeness/ADME/Toxicity studies of compound 4m were performed and predicted that this compound is druglikeness and has good ADME and toxicity profiles.

Synthesis of novel thiazolidinic-phthalimide derivatives evaluated as new multi-target antiepileptic agents

Epilepsy is a disease that affects millions of people around the globe and has a multifactorial cause. Inflammation is a process that can be involved in the development of seizures. Thus, the present study proposed the design and synthesis of new candidates for antiepileptic drugs that would also control the inflammatory process. Nine new derivatives of the substituted thiazophthalimide hybrid core were obtained with satisfactory purity ≥99% and yields between 27% and 87%. All compounds showed cell viability values greater than 90% in the culture of PBMC cells from healthy volunteers and, therefore, were not considered cytotoxic. These compounds modulated proinflammatory cytokines IFN-y and IL-17A and can mitigate inflammation. Acute toxicity studies of compound 7i in an animal model indicated that the compound has low toxicity and an LD50 greater than 2 g/kg in healthy adult rats. The same compound did not show positive results for anticonvulsant activity through the PTZ test. However, 7i demonstrates the interaction with the target GABA-A receptor in silico, indicating a possible activity as an agonist of that receptor. Thus, further studies are needed to investigate the anticonvulsant activity, in particular, using models in which the inflammatory process triggers epileptic seizures.

Synthesis, anticancer activity and mechanism of action of new phthalimido-1,3-thiazole derivatives

In this work, 22 new compounds were obtained and evaluated for their cytotoxic activity on peripheral blood mononuclear cells (PBMC) and eight different tumor cell lines. All compounds displayed IC₅₀ values above 100 μM when assayed against PBMCs. The cytotoxic assays in tumor cell lines revealed that sub-series of phthalimido-bis-1,3-thiazoles (5a-f) exhibited the best anti-tumor activity profile, presenting viability values below 59 %. As a result, the IC₅₀ value was calculated for compounds 5a-f and 4c, and compounds 5b and 5e were selected for further assays due to their best IC₅₀s. Considering the results presented by the sub-series 5a-f, the importance of the 1,3-thiazole ring in improving the anti-tumor activity was pointed out. Together, the results highlighted the anti-tumor activity of phthalimido-bis-1,3-thiazole derivatives.

Design of molecular hybrids of phthalimide-triazole agents with potent selective MCF-7/HepG2 cytotoxicity: Synthesis, EGFR inhibitory effect, and metabolic stability

This study reports an efficient and convenient click chemistry synthesis of a novel series of phthalimide scaffold linked to 1,2,3 triazole ring and terminal lipophilic fragments. Structures of newly synthesized compounds were well characterized by different spectroscopic tools. In vitro MTT cytotoxicity assay was performed comparing the cytotoxic effects of newly synthesized compounds to staurosporine using three different types: human liver cancer cell line (HepG2), Michigan cancer foundation-7 (MCF-7) and human colorectal carcinoma cell line (HCT116). The initial screening showed excellent to moderate anticancer activity for these newly synthesized compounds with high degree of cell line selectivity with micromolar (µM) half maximal inhibitory concentration (IC₅₀) values against tumor cells. The SAR analysis of these derivatives confirmed the role of molecular fragments including phthalimide, linker, triazole, and terminal tails in correlation to activity. In addition, enzymatic inhibitory assay against wild type EGFR was performed for the most active compounds to get more details about their mechanism of action. In order to further explore their binding affinities, molecular docking simulation was studied against EGFR site. The results obtained from molecular docking study and those obtained from cytotoxic screening were correlated. One of the most prominent analogs is (6f) with terminal disubstituted ring and amide linker showed selective MCF-7 cytotoxicity profile with IC₅₀ 0.22 µM and 79 nM to EGFR target. Extensive structure activity relationship (SAR) analyses were also carried out. The pharmacokinetic profile of (6f) was studied showing good metabolic stability and long duration behavior. This design offered a potent selective anticancer phthalimide-triazole leads for further optimization in cancer drug discovery.