2,4-Dimethoxyphenylsemicarbazones with anticonvulsant activity against three animal models of seizures: synthesis and pharmacological evaluation

Design, Synthesis and Biological Activity of New Amides Derived from 3-Benzhydryl and 3-sec-Butyl-2,5-dioxo-pyrrolidin-1-yl-acetic Acid

The aim of this study was to design and synthesize two new series of pyrrolidine-2,5-dione-acetamides with a benzhydryl or sec-butyl group at position 3 as potential anticonvulsants. Their anticonvulsant activity was evaluated in standard animal models of epilepsy: the maximal electroshock (MES), the 6 Hz, and the subcutaneous pentylenetetrazole (scPTZ) tests. The in vivo studies revealed the most potent anticonvulsant activity for 15 (3-(sec-butyl)-1-(2-(4-(3-trifluoromethylphenyl)piperazin-1-yl)-2-oxoethyl)pyrrolidine-2,5-dione), with ED₅₀ values of 80.38 mg/kg (MES) and 108.80 mg/kg (6 Hz). The plausible mechanism of action was assessed in in vitro binding assays, in which 15 interacted effectively with voltage-gated sodium (site 2) and L-type calcium channels at a concentration of 100 μM. Subsequently, the antinociceptive activity of compounds 7 and 15 was observed in the hot plate test of acute pain. Moreover, compounds 7, 11 and 15 demonstrated an analgesic effect in the formalin test of tonic pain. The hepatotoxic properties of the most effective compounds (7, 11 and 15) in HepG2 cells were also investigated.

Thiazole-Based Thiosemicarbazones: Synthesis, Cytotoxicity Evaluation and Molecular Docking Study

INTRODUCTION

Hybrid drug design has developed as a prime method for the development of novel anticancer therapies that can theoretically solve much of the pharmacokinetic disadvantages of traditional anticancer drugs. Thus a number of studies have indicated that thiazole-thiophene hybrids and their bis derivatives have important anticancer activity. Mammalian Rab7b protein is a member of the Rab GTPase protein family that controls the trafficking from endosomes to the TGN. Alteration in the Rab7b expression is implicated in differentiation of malignant cells, causing cancer.

METHODS

1-(4-Methyl-2-(2-(1-(thiophen-2-yl) ethylidene) hydrazinyl) thiazol-5-yl) ethanone was used as building block for synthesis of novel series of 5-(1-(2-(thiazol-2-yl) hydrazono) ethyl) thiazole derivatives. The bioactivities of the synthesized compounds were evaluated with respect to their antitumor activities against MCF-7 tumor cells using MTT assay. Computer-aided docking protocol was performed to study the possible molecular interactions between the newly synthetic thiazole compounds and the active binding site of the target protein Rab7b. Moreover, the in silico prediction of adsorption, distribution, metabolism, excretion (ADME) and toxicity (T) properties of synthesized compounds were carried out using admetSAR tool.

RESULTS

The results obtained showed that derivatives 9 and 11b have promising activity (IC50 = 14.6 ± 0.8 and 28.3 ± 1.5 µM, respectively) compared to Cisplatin (IC50 = 13.6 ± 0.9 µM). The molecular docking analysis reveals that the synthesized compounds are predicted to be fit into the binding site of the target Rab7b. In summary, the synthetic thiazole compounds 1-17 could be used as potent inhibitors as anticancer drugs.

CONCLUSION

Promising anticancer activity of compounds 9 and 11 compared with cisplatin reference drug suggests that these ligands may contribute as lead compounds in search of new anticancer agents to combat chemo-resistance.

5-(Thiophen-2-yl)-1,3,4-thiadiazole derivatives: synthesis, molecular docking and in vitro cytotoxicity evaluation as potential anticancer agents

Background

Nowadays, cancer is an important public health problem in all countries. Limitations of current chemotherapy for neoplastic diseases such as severe adverse reactions and tumor resistance to the chemotherapeutic drugs have been led to a temptation for focusing on the discovery and development of new compounds with potential anticancer activity. The importance of thiophene and thiadiazole rings as scaffolds present in a wide range of therapeutic agents has been well reported and has driven the synthesis of a large number of novel antitumor agents.

Methods

A series of new 1,3,4-thiadiazoles were synthesized by heterocyclization of N-(4-nitrophenyl)thiophene-2-carbohydrazonoyl chloride with a variety of hydrazine-carbodithioate derivatives. The mechanisms of these reactions were discussed and the structure of the new products was elucidated via spectral data and elemental analysis. All the new synthesized compounds were investigated for in vitro activities against human hepatocellular carcinoma (HepG-2) and human lung cancer (A-549) cell lines compared with cisplatin standard anticancer drug. Moreover, molecular docking using MOE 2014.09 software was also carried out for the high potent compound 20b with the binding site of dihydrofolate reductase (DHFR, PDB ID (3NU0)).

Results

The results showed that compound 20b has promising activities against HepG-2 and A-549 cell lines (IC50 value of 4.37±0.7 and 8.03±0.5 μM, respectively) and the results of molecular docking supported the biological activity with total binding energy equals −1.6 E (Kcal/mol).

Conclusion

Overall, we synthesized a new series of 1,3,4-thiadiazoles as potential antitumor agents against HepG-2 and A-549 cell lines.

Synthesis, characterization, X-ray structure, computational studies, and bioassay of novel compounds combining thiophene and benzimidazole or 1,2,4-triazole moieties

BACKGROUND

Due to their interesting and versatile biological activity, thiophene-containing compounds have attracted the attention of both chemists and medicinal chemists. Some of these compounds have anticancer, antibacterial, antiviral, and antioxidant activity. In addition, the thiophene nucleus has been used in the synthesis of a variety of heterocyclic compounds.

RESULTS

In the present work, two novel thiophene-containing compounds, 4-phenyl-2-phenylamino-5-(1H-1,3-a,8-triaza-cyclopenta[α]inden-2-yl)-thiophene-3-carboxylic acid ethyl ester (3) and 5-(1H-Imidazo[1,2-b] [1,2,4] triazol-5-yl)-4-phenyl-2-phenylamino-thiophene-3-carboxylic acid ethyl ester (4), have been synthesized by reaction of 5-(2-bromo-acetyl)-4-phenyl-2-phenylaminothiophene-3-carboxylic acid ethyl ester (2) with 2-aminobenzimidazole and 3-amino-1H-1,2,4-triazole in the presence of triethylamine, respectively. Compound 2, on the other hand, was prepared by bromination of 5-acetyl-4-phenyl-2-phenylaminothiophene-3-carboxylic acid ester (1). Structures of the newly prepared compounds were confirmed by different spectroscopic methods such as ¹H-NMR, ¹³C-NMR, and mass spectrometry, as well as by elemental analysis. Furthermore, bromination of compound 1 led to the formation of two constitutional isomers (2a and 2b) that were obtained in an 80:20 ratio. Molecular structures of 2b were confirmed with the aid of X-ray crystallography. Compound 2 was crystallized in the triclinic, P-1, a = 8.8152 (8) Å, b = 10.0958 (9) Å, c = 12.6892 (10) Å, α = 68.549 (5)°, β = 81.667 (5)°, γ = 68.229 (5)°, V = 976.04 (15) Å³, Z = 2, and was found in two isomeric forms regarding the position of the bromine atom. The antibacterial and antifungal activities of the prepared compounds were evaluated.

CONCLUSIONS

Three new thiophene derivatives were synthesized in good yield. Antimicrobial screening revealed that compound 3 was a promising candidate as a potential antibacterial and antifungal agent; it exhibits remarkable activity against the studied bacterial strains, especially the gram negative bacteria E. coli in addition to some fungi. More work is needed to evaluate its safety and efficacy.

Synthesis, Molecular Structure Optimization, and Cytotoxicity Assay of a Novel 2-Acetyl-3-amino-5-[(2-oxopropyl)sulfanyl]-4-cyanothiophene

A novel thiophene-containing compound, 2-acetyl-3-amino-5-[(2-oxopropyl)sulfanyl]-4-cyanothiophene (4) was synthesized by reaction of malononitrile with CS₂ in the presence of K₂CO₃ under reflux in DMF and the subsequent reaction with chloroacetone followed by cyclization. This compound has been characterized by means of FT-IR, ¹H-NMR, (13)C-NMR, and mass spectrometry as well as elemental analysis. In addition, the molecular structures of compound 4 was determined by X-ray crystallography. The geometry of the molecule is stabilized by an intramolecular interaction between N1-H1···O1 to form S6 graf set ring motif. In the crystal, molecules are linked via N1-H2···O1 and C7-H7A···N2 interactions to form a three-dimensional network. Molecular structure and other spectroscopic properties of compound 4 were calculated using DFT B3LYP/6-31G (d,p) method. Results revealed a good agreement between the optimized geometric parameters and the observed X-ray structure. Furthermore, and by employing the natural bond orbital (NBO) method, the intramolecular charge transfer (ICT) interactions along with natural atomic charges at different sites, were calculated; results indicated strong n→π* ICT from LP(1)N5→BD*(2)C15-C16 (63.23 kcal/mol). In addition, the stabilization energy E(2) of the LP(2)O3→ BD*(1)N5-H6 ICT (6.63 kcal/mol) indicated the presence of intramolecular N-H···OH bonding. Similarly, calculations of the electronic spectra of compound 4 using, TD-DFT revealed a good agreement with the experimental data. Finally, compound 4 was evaluated for its in vitro cytotoxic effect against PC-3 and HeLa cell lines, as an anticancer agent, and found to be nontoxic.

Synthesis, in-vitro antibacterial, antifungal, and molecular modeling of potent anti-microbial agents with a combined pyrazole and thiophene pharmacophore

Ethyl 5-acetyl-4-methyl-2-(phenylamino)thiophene-3-carboxylate (2) and there derivatives 3a–c, 4, 6a–c and 9a–f were synthesized. The structure of compound 2 was deduced by ¹H-NMR, ¹³C-NMR, FT-IR, MS, microanalysis, and single-crystal X-ray crystallography. The compound crystallized in the monoclinic system, with space group P2₁/c and cell coordinates a = 8.5752(16) Å, b = 21.046(4) Å, c = 8.2941(12) Å, β = 101.131(6)°, V = 1468.7(4) ų, and Z = 4. Compounds 2, 3a–c, 4, 5a–c and 9a–f were subjected into in vitro antimicrobial activity tests. Compounds 3a and 3c were more potent than standard drug amphotericin B, showing MIC values of 23.8 ± 0.42 and 24.3 ± 0.68, respectively, against Aspergillus fumigatus while the standard drug MIC was 23.7 ± 0.1. Compound 3c was also more potent (MIC 24.8 ± 0.64) than the standard drug amphotericin B (MIC 19.7 ± 0.2) against Syncephalastrum racemosum. Compounds 4 and 9f also showed promising anti-microbial activity. Molecular modeling was performed for the most active compounds.

Synthesis and biological evaluation of benzothiazole derivatives bearing the ortho-hydroxy-N-acylhydrazone moiety as potent antitumor agents

A novel series of benzothiazole derivatives bearing the ortho-hydroxy-N-acylhydrazone moiety were designed, synthesized, and evaluated for their procaspase-3 kinase activation activities and antiproliferative activities against five cancer cell lines (NCI-H226, SK-N-SH, HT29, MKN-45, and MDA-MB-231). Most target compounds showed moderate to excellent cytotoxic activity against all five tested cancer lines. The most promising compound 18e (procaspase-3 EC50  = 0.31 µM) with IC50 values ranging from 0.24 to 0.92µM against all tested cell lines was 4.24-12.2 times more active than PAC-1 (procaspase-3 EC50  = 0.41 µM). Structure-activity relationship studies indicated that the phenyl group on the 2-hydroxyphenyl ring (moiety A) was critical for pharmacological activity in vitro. In addition, introduction of a benzyloxyl group on moiety A and a mono-electron-withdrawing group at the 4-position of the benzyloxyl group were more favorable for antitumor activity. Moreover, reduction of the electron density in the phenyl ring of the benzyloxy group led to a dramatic decrease in the procaspase-3 kinase activation activity.

Synthesis, anticonvulsant properties, and SAR analysis of differently substituted pyrrolidine-2,5-diones and piperidine-2,6-diones

Twenty-two differently substituted 1H-isoindole-1,3(2H)-diones (30-39), 8-azaspiro[4.5]decane-7,9-diones (40-45), and 3-azaspiro[5.5]undecane-2,4-diones (46-51) were synthesized and tested for anticonvulsant activity. These molecules were designed as analogs of previously obtained azaspirosuccinimides (1-24). Initial anticonvulsant screening was performed in mice using the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests. The acute neurological toxicity was determined applying the minimal motor impairment rotorod test. The preliminary pharmacological results showed that 15 new compounds were effective in at least one animal model of epilepsy, from which nine molecules showed protection against both MES and scPTZ seizures. The structure-activity relationship analysis revealed that anticonvulsant activity was connected closely with the structure of the imide fragment; the most favorable one was the hexahydro-1H-isoindole-1,3(2H)-dione core. 2-(2-Chlorophenyl)hexahydro-1H-isoindole-1,3(2H)-dione (31) showed activity in the 6-Hz psychomotor seizure model, which identifies substances effective in partial and therapy-resistant epilepsy. 3-[(4-Chlorophenyl)amino]-3-azaspiro[5.5]undecane-2,4-dione (47) was active in the in vitro hippocampal slice culture neuroprotection assay.

Design, synthesis, and structure-activity relationships of novel benzothiazole derivatives bearing the ortho-hydroxy N-carbamoylhydrazone moiety as potent antitumor agents

A series of novel benzothiazole derivatives bearing the ortho-hydroxy N-carbamoylhydrazone moiety were designed and synthesized and their cytotoxic activities against five cancer cell lines (NCI-H226, SK-N-SH, HT29, MKN45, and MDA-MB-231) were screened in vitro. Most of them showed moderate to excellent activity against all the tested cell lines. Among them, compounds 15g (procaspase-3 EC50 = 1.42 μM) and 16b (procaspase-3 EC50 = 0.25 μM) exhibited excellent antitumor activity with IC50 values ranging from 0.14 μM to 0.98 μM against all cancer cell lines, which were 1.8-8.7 times more active than the first procaspase activating compound (PAC-1) (procaspase-3 EC50 = 4.08 μM). The structure-activity relationship (SAR) analyses indicated that the introduction of a lipophilic group (a benzyloxy or heteroaryloxy group) at the 4-position of the 2-hydroxy phenyl ring was beneficial to antitumor activity, and the presence of substituents containing nitrogen that are positively charged at physiological pH could also improve antitumor activity. It was also confirmed that the steric effect of the 4-position substituent of the benzyloxy group had a significant influence on cytotoxic activity.

Design, synthesis and anticonvulsant properties of new N-Mannich bases derived from 3-phenylpyrrolidine-2,5-diones

The synthesis and anticonvulsant properties of new N-Mannich bases of 3-phenyl- (9a-d), 3-(2-chlorophenyl)- (10a-d), 3-(3-chlorophenyl)- (11a-d) and 3-(4-chlorophenyl)-pyrrolidine-2,5-diones (12a-d) were described. The key synthetic strategies involve the formation of 3-substituted pyrrolidine-2,5-diones (5-8), and then aminoalkylation reaction (Mannich-type) with formaldehyde and corresponding secondary amines, which let to obtain the final compounds 9a-d, 10a-d, 11a-d and 12a-d in good yields. Initial anticonvulsant screening was performed in mice (ip) using the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizures tests. The most effective compounds in mice were tested after oral administration in rats. The acute neurological toxicity was determined applying the minimal motor impairment rotarod test. The in vivo results revealed that numerous compounds were effective especially in the MES test (model of human tonic-clonic seizures). The most active in the MES seizures in rats was 1-[(4-benzyl-1-piperidyl)methyl]-3-(2-chlorophenyl)pyrrolidine-2,5-dione (10c) which showed ED50 value of 37.64mg/kg. It should be stressed that this molecule along with 9a, 9d and 10d showed protection in the psychomotor seizure test (6-Hz), which is known as an animal model of therapy-resistant epilepsy. Furthermore compounds 9a, 9d and 10d were also tested in the pilocarpine-induced status prevention (PISP) test to assess their potential effectiveness in status epilepticus. For the most promising molecule 9d an influence on human CYP3A4 isoform of P-450 cytochrome was studied in vitro.

Discovery and optimization of novel 4-phenoxy-6,7-disubstituted quinolines possessing semicarbazones as c-Met kinase inhibitors

A novel series of N(1)-(3-fluoro-4-(6,7-disubstituted-quinolin-4-yloxy)phenyl)-N(4)-arylidenesemicarbazide derivatives were synthesized and evaluated for their c-Met kinase inhibition and cytotoxicity against A549, HT-29, MKN-45 and MDA-MB-231 cancer cell lines in vitro. Several potent compounds were further evaluated against three other cancer cell lines (U87MG, NCI-H460 and SMMC7721). Most of compounds tested exhibited moderate to excellent activity. The studies of SARs identified the most promising compound 28 (c-Met IC50=1.4nM) as a c-Met kinase inhibitor. In this study, a promising compound 28 was identified, which displayed 2.1-, 3.3-, 48.4- and 3.6-fold increase against A549, HT-29, U87MG and NCI-H460 cell lines, respectively, compared with that of Foretinib.

Synthesis and biological properties of new N-Mannich bases derived from 3-methyl-3-phenyl- and 3,3-dimethyl-succinimides. Part V

Twenty four new 1-[(4-phenylpiperazin-1-yl)-methyl]- derivatives of 3-phenyl-3-methyl- (6-17) and 3,3-dimethyl-pyrrolidine-2,5-diones (18-29) have been synthesized and evaluated for their anticonvulsant activity in the maximum electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests after intraperitoneal injection in mice. The acute neurological toxicity was determined using the rotorod screen. Although no anti-seizure properties were found in the scPTZ screen, fourteen compounds revealed protection in electrically induced seizures. From these molecules seven compounds were tested in rats after oral administration (MES test). In the whole series the most effective in rats were 1-[{4-(4-fluorophenyl)-piperazin-1-yl}-methyl]-3-methyl-3-phenyl-pyrrolidine-2,5-dione (8) with ED₅₀ value of 7.78 mg/kg, it's 3-chlorophenyl- (10) and 3,4-dichlorophenyl- (12) analogs with ED₅₀ values of 27.93 mg/kg and 15.11 mg/kg, respectively. To explain the possible mechanism of action for the most active derivatives 8, 10 and 12 the influence on NaV1.2 sodium channel currents were evaluated in vitro. The results of electrophysiological studies showed higher inhibition of NaV1.2 currents in comparison with phenytoin used as a model antiepileptic drug active in electrically induces seizures. Additionally, eleven 3-phenyl-3-methyl-pyrrolidine-2,5-diones as more promising in the anticonvulsant screening were evaluated in the Vibrio harveyi test to estimate their anti/mutagenic activity.

Novel limonene and citral based 2,5-disubstituted-1,3,4-oxadiazoles: a natural product coupled approach to semicarbazones for antiepileptic activity

Two novel series of N(4)-(5-(2/3/4-substituted-phenyl)-1,3,4-oxadiazol-2-yl)-N(1)-(2-methyl-5-(prop-1-en-2-yl)cyclohex-2-enylidene)semicarbazide and N(4)-(5-(2/3/4-substituted-phenyl)-1,3,4-oxadiazol-2-yl)-N(1)-(3,7-dimethylocta-3,6-dienylidene)-semicarbazide were synthesized to meet structural prerequisite indispensable for anticonvulsant activity. The anticonvulsant activities of the compounds were investigated using maximal electroshock seizure (MES), subcutaneous pentylenetrtrazole (scPTZ) and subcutaneous strychnine (scSTY) models. The rotorod test was conducted to evaluate neurotoxicity. Some of the selected active compounds were subjected to GABA assay to confirm their mode of action. The outcome of the present investigations proved that the four binding sites pharmacophore model is vital for anticonvulsant activity. The efforts were also made to establish structure-activity relationships among test compounds.

Discovery of Fused Triazolo-thiadiazoles as Inhibitors of TNF-alpha: Pharmacophore Hybridization for Treatment of Neuropathic Pain

Introduction

Neuropathic pain is a complex, chronic pain state that is usually accompanied by tissue injury. With neuropathic pain, the nerve fibers themselves may be damaged, dysfunctional, or injured.

Methods

A series of pharmacophoric hybrids of substituted aryl semicarbazides incorporated into a fused triazolo-thiadiazole nucleus were synthesized and evaluated for neuropathic pain activity. After the assessment of neurotoxicity and peripheral analgesic activity, the compounds were evaluated in two peripheral neuropathic pain models, the chronic constriction injury and partial sciatic nerve ligation, to assess their antiallodynic and antihyperalgesic potential.

Results

Selected compounds exhibiting promising efficacies (4b, 6a, and 7e) revealed median effective dose (ED₅₀) values ranging from 7.62–28.71 mg/kg in four behavioral assays of allodynia and hyperalgesia (spontaneous pain, tactile allodynia, cold allodynia, and mechanical hyperalgesia). Studies carried out to assess the underlying mechanism revealed that compounds suppressed the inflammatory component of the neuropathic pain by inhibiting tumor necrosis factor (TNF)-alpha and preventing oxidative and nitrosative stress.

Conclusion

Using a hybrid design approach, the present study identified novel chemical compounds that could be a potential lead for the treatment of neuropathic pain.

Anticonvulsant activity of novel 1-(substituted benzylidene)-4-(1-(morpholino/piperidino methyl)-2,3-dioxoindolin-5-yl) semicarbazide derivatives in mice and rats acute seizure models

A series of novel 1-(substituted benzylidene)-4-(1-(morpholino/piperidino methyl)-2,3-dioxoindolin-5-yl) semicarbazides 6a-6t was designed and synthesized on the basis of semicarbazide-based pharmacophoric model to meet the structural requirements necessary for anticonvulsant activity. The compounds were subjected to in vivo antiepileptic evaluation using maximal electroshock test and subcutaneous pentylenetetrazole seizure test methods. The neurotoxicity was determined by rotorod test. In the preliminary screening, compounds 6c, 6d, 6g, 6h, and 6m were found active in maximal electroshock test model, while 6g, 6i, 6m, and 6o showed significant antiepileptic activity in subcutaneous pentylenetetrazole seizure test model. Further, the compounds 6c, 6d, 6g, 6h, 6i, and 6m were administered orally to rats, of which 6c and 6g showed better activity than phenytoin. Among the synthesized compounds, 6g revealed excellent protection in both models with lower neurotoxicity.

N-Phenyl-2-(propan-2-yl-idene)-hydrazine-carboxamide

In the title compound, C(10)H(13)N(3)O, the hydrazinecarboxamide N-N-C(=O)-N unit is nearly planar [maximum deviation = 0.018 (2) Å] and is inclined at a dihedral angle of 8.45 (10)° with respect to the plane of the phenyl ring. The mol-ecular structure is stabilized by an intra-molecular C-H⋯O hydrogen bond which generates an S(6) ring motif. In the crystal, mol-ecules are linked into an inversion dimer by pairs of N-H⋯O and C-H⋯O hydrogen bonds.

Synthesis and anticonvulsant activity of new N-Mannich bases derived from 5-cyclopropyl-5-phenyl- and 5-cyclopropyl-5-(4-chlorophenyl)-imidazolidine-2,4-diones

Synthesis, physicochemical and anticonvulsant properties of new N-Mannich bases derived from 5-cyclopropyl-5-phenyl- and 5-cyclopropyl-5-(4-chlorophenyl)-imidazolidine-2,4-diones have been described. Initial anticonvulsant screening was performed using intraperitoneal (ip.) maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests. The neurotoxicity was determined applying the rotarod test. The in vivo results in mice showed that all compounds were effective especially in the MES screen. The quantitative evaluation after oral administration in rats showed that the most active was 5-cyclopropyl-5-phenyl-imidazolidine-2,4-dione (1) with ED(50) values of 5.76 mg/kg (MES) and 57.31 mg/kg (scPTZ). This molecule was more potent than phenytoin and ethosuximide which were used as reference antiepileptic drugs. Additionally compound 1 with ED(50) of 26.06 mg/kg in psychomotor seizure test (6-Hz) in mice showed comparable activity to new generation anticonvulsant - levetiracetam.

Synthesis and antimalarial activity of novel dihydro-artemisinin derivatives

The Plasmodium falciparum cysteine protease falcipain-2, one of the most promising targets for antimalarial drug design, plays a key role in parasite survival as a major peptide hydrolase within the hemoglobin degradation pathway. In this work, a series of novel dihydroartemisinin derivatives based on (thio)semicarbazone scaffold were designed and synthesized as potential falcipain-2 inhibitors. The in vitro biological assay indicated that most of the target compounds showed excellent inhibition activity against P. falciparum falcipain-2, with IC₅₀ values in the 0.29–10.63 μM range. Molecular docking studies were performed to investigate the binding affinities and interaction modes for the inhibitors. The preliminary SARs were summarized and could serve as a foundation for further investigation in the development of antimalarial drugs.

Synthesis and anticonvulsant activity of new n-mannich bases derived from 5-cyclopropyl-5-phenyl-hydantoins

Synthesis, physicochemical and anticonvulsant properties of new N-Mannich bases 3-24 derived from 5-cyclopropyl-5-phenyl- and 5-cyclopropyl-5-(4-chlorophenyl)-hydantoins were described here. Initial anticonvulsant screening was performed using intraperitoneal (i.p.) maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizures tests. Selected derivatives were also screened in the 6-Hz test. The neurotoxicity was determined applying the rotorod test. The pharmacological results revealed that the majority of compounds were effective in MES and/or scPTZ tests. The quantitative studies after oral administration into rats showed that several molecules were more potent than phenytoin and ethosuximide which were used as reference antiepileptic drugs. From the whole series the most active was 3-[(4-phenylpiperazin-1-yl)-methyl]-5-cyclopropyl-5-phenyl-imidazolidine-2,4-dione (3) with the ED(50) value of 5.29 mg/kg in the MES test.

Synthesis and anticonvulsant properties of new Mannich bases derived from 3-aryl-pyrrolidine-2,5-diones. Part 1

A series of new Mannich bases of N-[(4-arylpiperazin-1-yl)-methyl]-3-(chlorophenyl)-pyrrolidine-2,5-diones 10-23 have been synthesized and evaluated for their anticonvulsant activity in maximum electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure threshold tests. Their neurotoxicity was determined using a rotorod screen. Several molecules showed a promising anticonvulsant profile especially in the MES-test. In this model of seizures, the most active were N-[{4-(4-chlorophenyl)-piperazin-1-yl}-methyl]-3-(3-chlorophenyl)-pyrrolidine-2,5-dione 16 and N-[{4-(3-trifluoromethylphenyl)-piperazin-1-yl}-methyl]-3-(3-chlorophenyl)-pyrrolidine-2,5-dione 17 with ED(50) values of 21.4 mg/kg and 28.83 mg/kg, respectively. Selected derivatives 10, 14, and 16 were tested in the psychomotor seizure 6-Hz test from which N-[{4-(2-chlorophenyl)-piperazin-1-yl}-methyl]-3-(2-chlorophenyl)-pyrrolidine-2,5-dione 10 revealed the highest protection with an ED(50) of 78 mg/kg. Compounds 10, 12, and 17 were also tested in the pilocarpine-induced status PIPS test. Furthermore, 17 was examined in the hippocampal kindling screen after i. p. administration to rats.