SS-31 (Elamipretide / MTP-131)

The Mitochondrial Membrane Problem

As mitochondria age, their inner membrane undergoes progressive structural deterioration. The key target is cardiolipin — a unique phospholipid found almost exclusively in the inner mitochondrial membrane that serves as a structural scaffold for the electron transport chain (ETC) complexes.

With age and oxidative stress, cardiolipin is oxidised and degraded. This causes:

• Cristae unfolding — the inner membrane loses its characteristic folded structure
• ETC complex dissociation — Complexes I–IV separate, reducing electron transfer efficiency
• Cytochrome c release — pro-apoptotic signal, contributes to cell death
• ROS overproduction — damaged ETC generates more reactive oxygen species

SS-31 (Elamipretide) addresses this at the source.

Mechanism: Cardiolipin Stabilisation

SS-31 has the chemical sequence D-Arg-Dmt-Lys-Phe-NH₂ — an alternating cationic/aromatic pattern that allows it to penetrate the mitochondrial membrane and bind directly to cardiolipin via electrostatic and hydrophobic interactions.

This binding produces several effects: ^[]

• Stabilises cristae structure, preventing unfolding
• Maintains ETC Complex assembly
• Reduces cytochrome c release
• Suppresses mitochondrial ROS production
• Restores ATP synthesis efficiency

Clinical Evidence

Heart failure (MOTH trial): A Phase 2 RCT in 71 patients with heart failure with reduced ejection fraction (HFrEF) showed SS-31 significantly improved exercise capacity and quality of life markers, with a trend toward improved cardiac function. ^[]

Barth syndrome: SS-31 demonstrated functional improvements in patients with this rare mitochondrial cardiomyopathy caused by cardiolipin deficiency — providing direct mechanistic validation. ^[]

Ageing models: In aged mice, SS-31 restored mitochondrial function, improved exercise capacity, and reversed vascular ageing phenotypes — even when started late in life.

SS-31 as the Foundation of the Mitochondrial Stack

The sequencing logic is critical: SS-31 repairs damaged mitochondrial infrastructure first. Then MOTS-c (or PGC-1α activators like PQQ) drive biogenesis of new, healthy mitochondria. Building more mitochondria without first repairing the structural defects of existing ones is suboptimal — akin to constructing new buildings in a city with broken utilities.