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. Graphical abstract: [Figure not available: see fulltext.]