Synthesis and antioxidant activity of 2-indolinone bis(Mannich bases) and related compounds

Mannich bases attracted the interest of chemists and biologists due to their reactivity as a synthetic intermediate and their wide spectrum of biological activities. Based on the potent antioxidant, cytotoxic, and other biological properties of Mannich bases, there is a strong motivation for the continued synthesis of novel Mannich bases containing 2-indolinone core. In the present study 3-(phenacylidene)-1-(piperidin-1-ylmethyl)indolin-2-one, 3-(2-oxo-2-phenylethylidene)indolin-2-one, and 1,3-di(2-oxoindolin-3-ylidene)acetone were synthesized and used as a key intermediate in the synthesis of new 2-indolinone derivatives. All the synthesized compounds were characterized by IR, 1H NMR, 13C NMR, mass spectra, and elemental analysis. The synthesized compounds were tested for their antioxidant activity in vitro using ABTS and bleomycin-dependent DNA damage assays.