SS-31 is a synthetic, mitochondria-targeted peptide that primarily functions by improving mitochondrial function and reducing oxidative stress.

SS-31 selectively accumulates in the inner mitochondrial membrane where it interacts with a unique phospholipid called cardiolipin. This interaction helps in the following ways:

• Stabilizes Cardiolipin: SS-31 prevents the peroxidation and degradation of cardiolipin, which is essential for maintaining the structural integrity of the inner mitochondrial membrane.
• Optimizes Energy Production: By stabilizing cardiolipin, the peptide helps organize the components of the electron transport chain (respiratory complexes I, III, and IV) into "supercomplexes". This improves the efficiency of electron transfer and enhances the synthesis of adenosine triphosphate (ATP), the cell's main energy source.
• Reduces Reactive Oxygen Species (ROS): The improved efficiency of the electron transport chain leads to less electron leakage and, consequently, reduced production of harmful ROS (free radicals).
• Inhibits Apoptosis: SS-31 helps prevent the release of cytochrome c from the mitochondria into the cytosol, which is a key step in initiating programmed cell death (apoptosis). It also inhibits the opening of the mitochondrial permeability transition pore (mPTP), which can lead to mitochondrial swelling and cell death.