Synthesis, Characterization and evaluation of antioxidant potential of 2, 6-diphenylpiperidine-4-one compounds and their novel imine derivatives.

In search of potent molecules having antioxidant activity the present work was designed to synthesize 2, 6-diphenylpiperidine-4-one compounds (1a and 1b) and their imine derivatives (2a, 2b, 3a, and 3b). Compounds 1a and 1b were synthesized by Mannich condensation reaction. The method was found to be simple, convenient with high yield and products were easily separated. Compounds 1a and 1b serves as an intermediate for the preparation of highly functionalized novel imine derivatives. Oxime (2a, 2b) and carbothioamide (3a, 3b) derivatives of 1a and 1b compounds were produced by condensation reaction with hydroxyl amine hydrochloride and thiosemicarbazide respectively. These compounds were characterized by IR, EI-mass and 1 HNMR spectroscopy. The antioxidant activity of compounds was analyzed by 1, 1- dipheny1-2-picrylhydrazyl (DPPH) assay method. It was found that substituted aryl derivatives containing phenol and methoxy groups (1b, 2b and 3b) showed better antioxidant activity (IC50 values rang from 1.84-4.53μg/ml) than unsubstituted aryl derivative (1a, 2a and 3a) (IC50 rang from 6.46-11.13μg/ml). Compound 1b exhibited excellent antioxidant activity (IC50 1.84±0.15μg/ml) comparable to standard ascorbic acid (IC50 1.65± 0.16μg/ml).