A series of fresh 1,3-dihydro-3-hydroxy-3-(2-phenyl-2-oxoethyl)-2H-indol-2-ones (1a-g) and 1,3-dihydro-3-(2-phenyl-2-oxoethylidene)-2H-indol-2-ones (2a-g) were synthesised

A series of fresh 1,3-dihydro-3-hydroxy-3-(2-phenyl-2-oxoethyl)-2H-indol-2-ones (1a-g) and 1,3-dihydro-3-(2-phenyl-2-oxoethylidene)-2H-indol-2-ones (2a-g) were synthesised by Knoevenagel condensation of substituted indole-2,3-diones (isatins) with numerous acetophenones. our study provides evidence that some newly synthesised isatin derivatives show considerable antioxidant activity at low concentrations. antioxidant activity of a new series of compounds synthesised by Knoevenagel reaction of substituted isatins with numerous acetophenones[14] using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. All chemicals and solvents used in this study were of analytical grade. All isatins were purchased from Sigma Chemicals, MO, USA. Additional chemicals used were from Himedia Chemicals, Mumbai, India. Plan 1 illustrates the preparation of fresh 3-substituted-2-oxindole derivatives. Characterization of the synthesised compounds was done on the basis of their elemental studies, IR, 1H NMR, 13C NMR and mass spectral analysis. The progress of the reaction was monitored by thin coating chromatography (TLC) by using Merck silica gel coated alumina plates and UV chamber. Melting points of newly synthesised compounds were determined by using open capillary tubes in medical melting point apparatus and are uncorrected. All spectral studies were carried out at Central Drug ABT-751 Study Institute, Lucknow. IR spectra were obtained on a Perkin-Elmer model 557 grating infrared spectrophotometer using KBr pellet. NMR and mass spectra of the synthesised compounds were recorded on Bruker Avance 400 spectrophotometer and Jeol SX-102 mass spectrometer, respectively. Plan 1 Synthetic route for the preparation of fresh 3-substituted-2-oxindole derivatives For synthesis of 1 1,3-dihydro-3-hydroxy-3-(2-phenyl-2-oxoethyl)-2H-indol-2-ones (1a-g), equimolar quantities (0.01 mol) of indole 2,3-dione (isatin) and acetophenone were refluxed on a steam bath in the presence of base, diethyl amine (0.5 ml), as catalyst in absolute ethanol (25-30 ml) for 40 min. The progress of reaction was monitored on TLC. After completion of reaction, mixture was remaining at room temp for 2-3 days when light yellow shining crystals precipitated (1) out, which were filtered, dried and purified by recrystallization from ethanol. Compound Ia: Cream coloured shining flakes; Yield 90%; melting point (MP) 172; IR (KBr, v/cm): 3420 (OH), 3260 (NHCO), 1715 (CO-Ar), 1685 (NHCO), 1617, 1475, 1363, 1216; 1H NMR (DMSO-antioxidant activity of the synthesised compounds was quantitatively measured by DPPH radical scavenging assay[15]. DPPH is definitely a stable free radical at space temperature and accepts an electron or hydrogen radical to become stable diamagnetic molecule. DPPH radical is definitely scavenged by antioxidants through the donation of proton forming the reduced DPPH. Solutions of synthesised 3-substituted oxindoles were prepared in complete ethanol at concentrations ranging from 10 to 500 g/ml. A DPPH blank was prepared without HDACA compound, and ethanol was utilized for the baseline correction. The well-known antioxidant, ascorbic acid was utilized for assessment or like a positive control. DPPH remedy was freshly prepared daily and was ABT-751 kept in dark at 4 between the measurements. Briefly, 2 ml of each compound remedy having different concentrations (10-500 g/ml) were taken in different test tubes and 2 ml of 0.1 mM ethanol solution of DPPH was added and shaken vigorously. The tubes were then incubated at 37 for 30 min. Changes in absorbance were measured at 517 nm using a UV/Vis spectrophotometer and the remaining DPPH was determined. Measurement was performed in triplicate. The radical scavenging activity was indicated as percentage inhibition of ABT-751 DPPH and was determined using the equation: Radical scavenging activity (%)[(antioxidant properties of the newly synthesised compounds at different concentrations were examined by a well-documented assay like DPPH free radical scavenging assay. The effect of antioxidants on DPPH radicals is considered because of the hydrogen donating ability[16]. Antioxidant molecule can quench DPPH free radicals and convert them to a colourless/bleached product ultimately resulting in a decrease in the absorbance. The antioxidant activity of the synthesised compounds Ia-g and compounds 2a-g compared to ascorbic acid as standard are demonstrated in figs. ?figs.11 and ?and2,2, respectively. Our results indicate that newly synthesised compounds showed moderate to good antioxidant activity at low concentrations as compared to ascorbic acid. Fig. 1 Fig. 2 In an attempt to establish some structure activity relationship based on the position and presence of different substituents and to understand as to how different functionalities have an effect on the antioxidant properties, a series of fresh 1,3-dihydro-3-hydroxy-3-(2-phenyl-2-oxoethyl)-2H-indol-2-ones (1a-g) and 1,3-dihydro-3-(2-phenyl-2-oxoethylidene)-2H-indol-2-ones (2a-g) were synthesised. These compounds were characterised by numerous physicochemical and spectroscopic techniques. As per chemical structural features, two different types of compounds were synthesised under the study area. It was observed that.