Synthesis and evaluation of 3-salicyloylpyridine derivatives as cytotoxic mitochondrial apoptosis inducers.

A series of novel 3-salicyloylpyridines (4a-h) were synthesized with good yield by modified Knoevenagel-Stobbel method; o-allylation with allyl bromide lead to formation of compounds (5a-h). The synthesized compounds were characterized by spectroscopic techniques and evaluated for cytotoxic activity against human cancer cell lines. Compounds bearing hydroxyl group displayed high cytotoxicity (4a-h) as compared to o-allylated molecules (5a-h). The most active compound 4b was selected for further investigation to look for mechanism of cell death in prostate cancer (PC-3) cells. The apoptotic bodies induced by 4b in PC-3 cells were scanned by confocal microscopy and confirmed by scanning electron microscopy (SEM). Further results obtained from spectrofluorimetric determination of mitochondrial membrane potential (ΔΨm) and intracellular reactive oxygen species (ROS) in treated PC-3 cells revealed that mitochondria dependent apoptosis was involved in the cell death.