05 mol) and refluxed for over 20 h. The progress of the reaction was monitored by TLC analysis and after completion of the reaction, the reaction mixture was poured into ice cold water with constant stirring. Further, find more it was extracted with dichloromethane. The organic layer was collected and solvent was evaporated under reduced pressure. The crude product (3) was purified through silica gel column using petroleum ether: ethyl acetate as eluent. OXD-6: IR (cm−1) (KBr): C C (str) 1589.40, C N (str) 1558.54, Ar C–H (str) 3047.63, C–Br (str)
688.61; 1H-NMR (ppm) (CDCl3): δ 8.02 (s, 1H), 8.02–7.99 (dd, J = 6 Hz, 3 Hz, 1H), 7.86–7.82 (m, 2H), 7.75–7.72 (dd, J = 7.29, 1.32 Hz, 1H), 7.74–7.40 (m, 3H), 7.37–7.29 (m, 2H); MS (m/z): [M+]300. OXD-7: IR (cm−1) (KBr): C C (str) 1580.01, C N (str) 1548.89, Ar C–H (str) 3115.14, C–H (str) 2922.25; 1H-NMR (ppm) (CDCl3): δ 7.96–7.90
(m, 3H), δ 7.85–7.81 (m, 2H), δ 7.46–7.27 (m, 5H), δ 7.44 (m, 3H); MS (m/z): M+235. OXD-9: IR (cm−1) (KBr): C C (str) 1620.26, C N (str) 1566.25, Ar C–H (str) 3110.27, C–O (str) 1263.42, N O 1518.03; 1H-NMR (ppm) (CDCl3): δ 8.85 (d, J = 3 Hz, 1H), 8.31–8.27 (dd, J = 9Hz, 3 Hz, 1H), 7.97 (s, 1H), 7.83–7.79 (m, 2H), δ 7.47–7.49 (m, 2H), 7.47–7.42 (m, 2H), 7.38–7.32 (m, 1H), 4.04 (s, 3H); MS (m/z): M+296. OXD-11: IR (cm−1) (KBr): C C (str) 1604.83, C N (str) 1581.68, Ar C–H (str) 3026.41; 1H-NMR (ppm) (CDCl3): δ 8.05–8.02 (dd, J = 6 Hz, 3 Hz, 1H), 7.73–7.70 (m, 3H), 7.56–7.27 (m,
11H); MS (m/z): [M+1]+ 297, 165 (100%). The assay was carried out in a 96 well microtitre buy C646 plate. 100 μL of DPPH solution was added to 100 μL of each of the test sample of concentrations 500, 250, 125, 62.5, 31.25, 15.62 and 7.81 μg/ml or the standard solution i.e., ascorbic acid, separately in each well of the microtitre plate. The plates were incubated at 37 °C for 20 min and the absorbance of each solution was measured at 540 nm, using Enzyme Linked Immuno Sorbent Assay (ELISA) else microtitre plate reader. The absorbance of solvent control containing the same amount of methanol and DPPH solution was measured as well. The experiment was performed in triplicate and % scavenging activity was calculated using the formula given below. IC50 (Inhibitory Concentration) is the concentration of the sample required to scavenge 50% of DPPH free radicals and it was calculated from the graph, % scavenging vs concentration.9 The Nitric oxide scavenging activity of the compounds was tested at 500, 250, 125, 62.5, 31.25, 15.62 and 7.81 μg/ml concentrations.