Synthesis, Characterization, and Biological Evaluation of 2-( p -Nitrophenyl)quinazolin-4(3 H )-one Derivatives
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ynthesis, Characterization, and Biological Evaluation of 2-(p-Nitrophenyl)quinazolin-4(3H)-one Derivatives V. N. Giradkara, U. D. Kabraa,b, R. S. Diwakara, R. T. Lohiyaa,*, and M. J. Umekarc b
a Department of Pharmaceutical Chemistry, Smt. Kishoritai Bhoyar College of Pharmacy, Nagpur, 441002 India Department of Pharmaceutical Chemistry, Parul Institute of Pharmacy, Parul University, Vadodara, 391760 India c Principal of Smt. Kishoritai Bhoyar College of Pharmacy, Nagpur, 441002 India *e-mail: [email protected]
Received February 24, 2020; revised February 29, 2020; accepted March 02, 2020
Abstract—A series of novel 2-(4-nitrophenyl)-3-(R-benzothiazol-2-yl)quinazolin-4(3H)-ones 4a–4g (R = Alk, AlkO, Hal, NO2) were synthesized from the corresponding substituted 2-aminobenzothiazoles and 2-(4-nitrophenyl)-4H-3,1-benzoxazin-4-one via a nucleophilic addition reaction. The structures of the novel compounds were assigned on the basis of the elemental analyses and FTIR, 1H NMR, and mass spectra. The synthesized compounds were tested for anticonvulsant, antimicrobial, and antioxidant activities. All the compounds increased the seizure latency compared to control. Compound 4b (R = 6-NO2) exhibited significant anticonvulsant activity, comparable to that of the standard drug Phenytoin. Antimicrobial activity testing revealed moderate to good activity in all the test compounds, and 4a (R = H) and 4b compared in activity with the standard drug Chloramphenicol. The antioxidant activity of compounds 4a, 4d (R = 5-Br), and 4f (R = 4,6-Me2) (IC50 39.30, 15.55, and 42.95 μg/mL, respectively) was found to be higher compared to the standard drug ascorbic acid (IC50 48.30 μg/mL). Keywords: quinazolinone, benzothiazole, anticonvulsant, antimicrobial, antioxidant
DOI: 10.1134/S1070428020080175 INTRODUCTION Quinazolinone belongs to the class of fused heterocycles, which have diverse biological activities, including antibacterial, antioxidant, antifungal, anticonvulsant, anticancer, antidiabetic, and antiinflammatory [1–6]. Therefore, the quinazolinone scaffold has been incorporated into variety of drugs: Diproqualone (analgesic), Gefitinib (anticancer), and Piriqualone (anticonvulsant) [7]. Inspection of the literature showed that different substituents at the N2 or N3 position of the quinazolinone nucleus modulate the biological activity [8]. Para substitution in the 2-phenyl group of quinazolinone was found to induce a higher biological activity than meta- or ortho-substitution; furthermore, electron-acceptors substituents, like NO2, F, or Cl, yielded more potent biologically active compounds [9–11]. One of the most useful moieties, which can be introduced in the N3 position of the quinazolinone ring to enhance the biological activity, is benzothiazole [12]. Alkyl, alkoxy, or halogen substituents at different positions of the benzothiazole
nucleus improved the activity and potency of the starting compounds. Benzothiazole and its derivatives showed such interesting biological activities, including anticonvulsant, antibacterial, anti-i
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