Synthesis and pharmacological investigation of novel 4-(4-Ethyl phenyl)-1-substituted-4H-[1,2,4]triazolo[4,3-a]-quinazolin-5-ones as new class of H1-antihistaminic agents

Synthesis, X-ray Structure, Hirshfeld, DFT and Biological Studies on a Quinazolinone-Nitrate Complex

The reaction of 4-hydroxyquinazoline (4HQZ) with aqueous solution of nitric acid afforded the corresponding quinazolinone-nitrate (4HQZN) complex in very good yield. The crystal structure of 4HQZN was determined and its structural and supramolecular structural aspects were analyzed. 4HQZN crystallized in the space group P2₁/c and monoclinic crystal system with one [4HQZ-H]⁺[NO₃]⁻ formula and Z = 4. Its supramolecular structure could be described as a 2D infinite layers in which the 4HQZN molecules are connected via N-H…O and C-H…O hydrogen bridges. Using DFT calculations, the relative stability of five suggested isomers of 4HQZN were predicted. It was found that the medium effects have strong impact not only on the isomers’ stability but also on the structure of the 4HQZN. It was found that the structure of 4HQZN in DMSO and methanol matched well with the reported X-ray structure which shed the light on the importance of the intermolecular interactions on the isomers’ stability. The structure of 4HQZN could be described as a proton transfer complex in which the nitrate anion acting as an e-donor whiles the protonated 4HQZ is an e-acceptor. In contrast, the structure of the isolated 4HQZN in gas phase and in cyclohexane could be described as a 4HQZ…HNO₃ hydrogen bonded complex. Biological screening of the antioxidant, anticancer and antimicrobial activities of 4HQZ and 4HQZN was presented and compared. It was found that, 4HQZN has higher antioxidant activity (IC₅₀ = 36.59 ± 1.23 µg/mL) than 4HQZ. Both of 4HQZ and 4HQZN showed cell growth inhibition against breast (MCF-7) and lung (A-549) carcinoma cell lines with different extents. The 4HQZ has better activity with IC₅₀ of 178.08 ± 6.24 µg/mL and 119.84 ± 4.98 µg/mL, respectively. The corresponding values for 4HQZN are 249.87 ± 9.71 µg/mL and 237.02 ± 8.64 µg/mL, respectively. Also, the antibacterial and antifungal activities of 4HQZN are higher than 4HQZ against all studied microbes. The most promising result is for 4HQZN against A. fumigatus (MIC = 312.5 μg/mL).

Novel 3-Substituted-2, 3-Dihydro-2-Thioxoquinazolin-4-(1H)-one derivative as Anticonvulsants: Synthesis, Molecular Docking and Pharmacological Screening

Background:

According to the World Health Organization, 50 million people worldwide are suffering from epilepsy, making it one of the most common neurological diseases globally. 2,3 disubstituted quinazolinone-4-one derivatives endowed with various pharmacological activity, particularly having anticonvulsant action.

Objectives:

The aim of this study was to synthesize 3-Substituted-2,3-Dihydro-2-thioxoquinazolin- 4-(1H)-one derivative and evaluate for anticonvulsant activity and neurotoxicity in order to find an efficient, compound with lesser side effects.

Methods:

A novel series of 3-[4-(2-amino-5, 6-dihydro-4(substituted phenyl)-4H-1, 3-oxazin /thiazin-6yl) phenyl]-2, 3-dihyro-2-thioxoquinazolin-4(1H)-one derivatives (4a-4p) were synthesized. The structures of the synthesized compounds were assigned on the basis of spectral data (UV, IR, 1HNMR, 13CNMR and MS) and performed anticonvulsant activity against maximal electroshock test and Subcutaneous Pentylenetetrazole model. Neurotoxicity was assessed using a rotarod apparatus test. The molecular docking study was performed to assess their binding affinities towards Gamma-Aminobutyric Acid type A receptor. A quantitative estimate of drug-likeness was also performed, which calculates the molecular properties and screen the molecules based on drug-likeness rules.

Results:

Compounds 4b, 4e, 4j and 4m have shown the highest anticonvulsant activity against tonic seizure with decreased mean duration of tonic hind leg extension of 8.31, 7.35, 8.61 and 8.99 s, respectively in maximal electroshock model and increased onset time clonic convulsion duration of 94.45, 96.65, 93.51 and 91.86 s in Subcutaneous Pentylenetetrazole model. Molecular docking study revealed a better binding affinity with Gamma-Aminobutyric Acid type A receptor.

Conclusion:

The compound 4b and 4e emerged out as the pilot molecule with a better anticonvulsant activity without any neurotoxicity. The obtained results showed that compounds 4b and 4e could be useful as a template for future design, optimization, and investigation to produce more active analogs.

Novel 3-{4-[2-Amino-4-(Substitutedphenyl)-2H-[1, 3] Oxazin/Thiazin-6-Yl} -2-Phenyl-3H-Quinazolin-4-One Derivatives as Enhancer of GABA Mediated Inhibition: Synthesis, Molecular Modeling and Pharmacological Studies

Background:

According to WHO, the 50 million people worldwide are suffering from epilepsy, making it one of the most common neurological diseases globally. Epilepsy is often characterized by neurobiological, cognitive, psychological and behavioral changes and that may enhance the susceptibility to seizures and affect the quality of life.

Objective:

The aim of the present work was to develop 2, 3 disubstituted 4-(3H)-quinazolinone derivatives in order to find an effective and highly lipophilic compound with lesser side effects and to evaluate them for anticonvulsant and neurotoxic activity.

Methods:

A novel series of 3-4-[2-amino-4-(substitutedphenyl)-2H-[1.3] oxazin/thiazin-6-yl 2- phenyl-3H-quinazolin-4-one derivatives were synthesized and evaluated for their anticonvulsant activity. The structures of the compound have been confirmed by spectral analysis. The molecular docking study was performed for finding the binding affinity with GABAA receptor in order to rationalize their anticonvulsant activities in a qualitative way. Quantitative estimate of drug-likeness was also performed which calculate the molecular properties and screen the molecules based on drug-likeness rules. Anticonvulsant activities of synthesized compounds were done by using (Maximal electroshock) MES induced seizures and subcutaneous pentylenetetrazole (scPTZ) induced seizure models in Wistar rats of either sex. None of the compounds demonstrated any sign of neurotoxicity.

Results:

Compounds 3-4-[2-amino-4-(fluorophenyl)-2H- [1, 3] oxazin-6-yl 2-phenyl-3H quinazolin-4-one (5i) and 3-4-[2-amino-4-(fluorophenyl)-2H- [1, 3] thiazin -6-yl 2-phenyl-3H quinazolin-4-one (5n) have shown significant activity against tonic seizure by the MES model and clonic seizure by scPTZ induced seizure model.

Conclusion:

These ten novels synthesized compounds had significant anticonvulsant activity. As a result, the compound (5i) and (5n) emerged out as the pilot molecule with a better anticonvulsant activity without any neurotoxicity, while the other compounds have moderate activity. QED analysis of compounds (5i) and (5n) also indicated that these compounds will have good oral absorption. The proposed work is to make efforts towards the development and identification of novel molecules as anticonvulsant agents by the synthesis of some novel quinazolinone derivatives with improved biological activity.