Synthesis and In vitro antioxidant activity of new 3-substituted-2-oxindole derivatives

Abstract

A series of new 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 various acetophenones. The synthesised compounds were characterised by their physical data, elemental, IR, 1H NMR, 13C NMR and mass spectral analyses and their in vitro antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl free radical scavenging assay. These compounds showed moderate to good antioxidant activities as compared with the standard, ascorbic acid. The antioxidant potential of 3-hydroxy-3-substituted oxindoles (1a-g) increased in a concentration-dependent manner from 10 to 500 μg/ml with 5-fluoro and 5-methyl analogues showing maximum activity. Of 3-aroyl methylene indol-2-ones (2a-g), majority of compounds with halogen substitution at position 5 of isatin ring exhibited good antioxidant activity within a concentration range of 5-100 μg/ml and the maximum activity was observed at 20 and 25 μg/ml concentrations. Thus, our study provides evidence that some newly synthesised isatin derivatives exhibit substantial antioxidant activity at low concentrations.

Hit optimization studies of 3-hydroxy-indolin-2-one analogs as potential anti-HIV-1 agents

“…Next, to enhance the yield, solvent and base was replaced with ethanol and diethyl amine, respectively and reaction mixture was stirred at room temperature. After six hours, reaction ended-up as single spot and desired compound 3a was obtained in 88% yield [31][32][33][34][35]. Rest of the compounds 3b-5j were synthesized in good to excellent yield (78-96%) using the optimized reaction conditions of compound a3.…”

“…After completion of reaction, ethanol was evaporated on rotary evaporator to half of its original volume and 15 ml of ice cold water was added to the reaction mixture. Resulting precipitates were filtered using vacuum filtration and twice washed with cold ethanol (2 × 10 ml), followed by diethyl ether (10 ml) and finally dried in oven at 45°C to get desired compounds 3a-5j [31][32][33][34][35]. Synthesized compounds were first characterized using non-spectral techniques like TLC and melting point and then by different spectral techniques like IR, 1 H NMR, 13 C NMR, ESI-MS and elemental analysis.…”

Synthesis, biological evaluation and molecular docking studies of Mannich bases derived from 1, 3, 4-oxadiazole- 2-thiones as potential urease inhibitors

“…DPPH scavenging activity was measured using a slight modification of the method in the literature [16,17].…”

DABCO-catalyzed synthesis of 3-substituted-3-hydroxyindolin-2-ones in aqueous media

“…This kind of structural framework is also found in many complex natural products like TMC-95A-D [6] , celogentin-K [7] , paratunamide [8] , and maremycins [9] . These molecules have been shown to display various pharmacological activities including anticancer [1] and antioxidant properties [10] .…”