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Abstract: In the present study, we have synthesized a series of novel 2-(3-substituted-4-oxo-3,4-dihydroquinazolin-2-yl)-2,3-dihydrophthalazine-1,4-diones by the reaction of 3-(substituted)-2-hydrazino-quinazoline-4(3H)-ones with phthalic anhydride. The starting material 3-(substituted)-2-hydrazino-quinazolin-4(3H)-ones were synthesized from various primary amines. All the synthesized compounds were screened for their antitubercular, anti-HIV and antibacterial activity against different gram positive and gram negative strains by agar dilution method. Among the test compounds, 2-(3-(4-chlorophenyl)-4-oxo-3,4-dihydroquinazolin-2-yl)-2,3-dihydrophthalazine-1,4-dione (QCT7) shown most potent antibacterial activity against E. coli, and S. aureus with the MIC of 3 μg/mL. The compound QCT7 exhibited the antitubercular activity with the MIC of 25 μg/mL and anti-HIV activity with the EC50 of 43.68 μM against HIV1 and HIV2 and offers potential lead for further optimization and development to new antitubercular and anti-HIV agents. The results obtained from this study confirm that the synthesized and biologically evaluated quinazolines showed promising antimicrobial, antitubercular and anti-HIV activities and are new scaffolds for antimicrobial activity.

Functionalized quinazolinone derivatives 1–30 were synthesized by two-step reaction. First, anthranilic acid was treated with substituted phenyl isothiocyanate to synthesize 3-aryl-2-thioxo-2,3-dihydroquinazolinone derivatives 1–8 which in turn reacted with different bromoacetophenone derivatives to obtain fully functionalized quinazolinone derivatives 9–30. Both reactions were catalyzed by triethylamine. All the products were characterized by EI-, HREI-MS, 1H-, and 13CNMR spectroscopic techniques. All compounds were subjected to their in vitro α-glucosidase inhibitory activity. Results showed that except compound 1–3, 5, 7, and 22, all compounds were found potent and showed many folds increased α-glucosidase enzyme inhibition as compared to standard acarbose (IC50 = 750.0 ± 10.0?μM). Compound 13 (IC50 = 85.0 ± 0.5?μM) was recognized as the most potent analog of the whole series, with ninefold enhanced inhibitory potential than the standard acarbose. Compounds 1–9, 11, 12, 22, and 26 were structurally known compounds, while remaining all are new. Kinetic study on compound 13 showed that the compound is following a competitive-type inhibition mechanism. Furthermore, in silico studies have also been performed to better rationalize the interactions between synthetic compound and active site of the enzyme. Graphic abstract: [Figure not available: see fulltext.]

In the present study, we have synthesized a series of novel 2-phenyl-3-(substituted quinazolinylamino)quinazolin-4(3H)-ones by the reaction of 3-(substituted)-2-hydrazinoquinazoline-4(3H)-ones with 2-phenyl-3,1-benzoxazin-4-one. The starting material 3-(substituted)-2-hydrazino-quinazolin-4(3H)-ones were synthesized from various primary amines. All the synthesized compounds were screened for their antitubercular, anti-HIV and antibacterial activity against different Gram-positive and Gram-negative strains by agar dilution method. Among the test compounds, 3-(4-nitrophenyl)-2-(4-oxo-2-phenylquinazolin-3(4H)-ylamino)quinazolin-4(3H)-one (BQZ6) and 3-(4-chlorophenyl)-2-(4-oxo-2-phenylquinazolin-3(4H)-ylamino)quinazolin-4(3H)-one (BQZ7) shown most potent antibacterial activity against E. coli, P. aeruginosa and S. aureus with the MIC of 3 μg/mL. The compound BQZ7 exhibited the antitubercular activity with the MIC of 25 μg/mL and anti-HIV activity with the MIC of 35.4 μg/mL against HIV1 and HIV2 and offers potential lead for further optimization and development to new antitubercular and anti-HIV agents. The results from this study confirm that the synthesized and biologically evaluated quinazolines showed promising antimicrobial, antitubercular and anti-HIV activities and are new scaffolds for antimicrobial activity.

A novel methodology is presented for the synthesis of 3-substituted 2-thioxo-2,3-dihydroquinazolin-4(1H)-one derivatives based on an efficient tandem multicomponent reaction using copper bromide as catalyst. This methodology is based on the multicomponent one-pot reaction of methyl 2-bromobenzoate, phenylisothiocyanate derivatives and sodium azide in the presence of copper bromide and l-proline under basic conditions. To show the generality of the method, various phenylisothiocyanates bearing electron-donating or electron-withdrawing functionalities were used and the desired products were obtained in high isolated yields.

A series of 4-(substituted-phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-ones (6a-x) with triazole and other heterocyclic substituents (7-14) were synthesized and the compounds were evaluated for their anticonvulsant activity and neurotoxicity by maximal electroshock (MES) and rotarod neurotoxicity tests. Among the compounds studied, 6o and 6q showed wide margins of safety with protective indices (PIs) that were much higher than those of currently used drugs (PI6o > 25.5, PI6q > 26.0). Compounds 6o and 6q showed significant oral activity against MES-induced seizures in mice, with ED50 values of 88.02 and 94.6 mg/kg, respectively. The two compounds were also found to have potent activity against seizures that were induced by pentylenetetrazole and bicuculline. A series of 4-(substituted-phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-ones with triazole and other heterocyclic substituents were synthesized and the compounds were evaluated for their anticonvulsant activity and neurotoxicity using maximal electroshock and rotarod neurotoxicity tests.

The synthesis of 2-thioxoquinazolinone derivatives was achieved by condensation of isatoic anhydride, primary amine, and carbon disulfide under microwave irradiation. This convenient and efficient method affords the desired products with good to excellent yields. Satisfactory infrared spectroscopy, 1H NMR, and high-resolution mass spectrometry (electrospray ionization) spectra were obtained for all compounds described.

A small library of new azomethine derivatives of 3-aryl-2-thioxo-2,3- dihydroquinazolin-4(1H)-ones was synthesized. The key intermediates 2-thioxo-quinazolinones (3a-e), obtained in 2 steps from the corresponding anilines, were treated with methyl chloroa

A series of novel 2-mercapto-4(3H)-quinazolinone derivatives have been synthesized and their inhibitory effects on PTP1B and TCPTP are evaluated for the first time. Most of these derivatives showed good inhibitory activity on PTP1B and reasonable selectivity for PTP1B over TCPTP, among them 32 was the most potent PTP1B inhibitor (IC50 = 1.50 μ ;g/mL), and 27 possessed the best selectivity of 3.0-fold.

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