New Biocompatible β-Phosphorylated Linear Nitrones Targeting Mitochondria: Protective Effect in Apoptotic Cells

Area of Science:

• Biochemistry
• Cell Biology
• Medicinal Chemistry

Background:

• Mitochondria generate reactive oxygen species (ROS), crucial in cellular respiration but implicated in mitochondrial diseases when overproduced.
• Mitochondriotropic probes are needed to monitor in-situ ROS production, but existing probes like triphenylphosphonium (TPP) nitrones exhibit cytotoxicity.
• Developing safer, effective probes is essential for understanding and potentially treating mitochondrial dysfunction.

Purpose of the Study:

• To synthesize and evaluate novel, low-toxicity nitrone derivatives for detecting mitochondrial ROS.
• To assess the efficacy of these probes in targeting mitochondria and trapping free radicals.
• To identify promising alternatives to TPP-based nitrones for studying mitochondrial oxidative damage.

Main Methods:

• Synthesis of 13 N-benzylidene-1-diethoxyphosphoryl-1-methylethylamine N-oxide (PPN) derivatives with varying lipophilic cations (pyridinium, triethylammonium, berberinium).
• In vitro assessment of superoxide quenching activity and electron paramagnetic resonance (EPR)/spin-trapping efficiency against superoxide and hydroxyl radicals.
• Confirmation of mitochondrial penetration using 31P NMR spectroscopy and evaluation of anti-apoptotic properties in hydrogen peroxide-treated Schwann cells.

Main Results:

• The synthesized PPN derivatives demonstrated in vitro superoxide quenching and EPR/spin-trapping capabilities for biologically relevant radicals.
• Mitochondrial uptake of the PPN probes was confirmed via 31P NMR spectroscopy.
• Two pyridinium-substituted PPN derivatives exhibited low toxicity and anti-apoptotic properties, suggesting their potential as improved mitochondriotropic probes.

Conclusions:

• Novel PPN nitrones offer effective mitochondrial targeting and ROS detection with reduced cytotoxicity compared to TPP-based probes.
• Pyridinium-substituted PPNs are promising candidates for studying mitochondrial oxidative stress and related diseases.
• These findings pave the way for developing advanced diagnostic tools for mitochondrial disorders.