Synthesis of 3-Arylmethyl-2-oxindole Derivatives and Their Effects on Neuronal Cell Death

Various 3-arylmethyl-2-oxindole derivatives were synthesized by the Knoevenagel condensation of oxindole and aromatic aldehydes followed by palladium-mediated hydrogenation or hydride-reduction. Further substituted derivatives at C-3 and/or N-1 of the oxindole skeleton were prepared from the condensation products. Their protective effect against neuronal cell death induced by oxidative stress was evaluated by lactate dehydrogenase assay. A structure–activity relationship study revealed that compounds with any of the dialkylamino, nitro or hydroxy groups on the 3-arylmethyl moieties elicit a superior potency to suppress cell death, while others are ineffective. Substitutions with less polar functional groups on the benzene or lactam ring of the oxindole skeleton positively, but not remarkably, affect the potency. In addition, the stereochemistry at C-3 of the oxindole core was not a crucial factor for the neuroprotective activity of the compounds.