SS-31 (Elamipretide)

Various studies have explored the potential benefits of SS-31 on cellular health and physical performance. The following summarizes some of the main actions and potential effects attributed to this peptide:

• Mitochondrial Protection: SS-31 stabilizes the inner membranes of mitochondria, preserving their structure and function even under stress conditions. Thus, it helps prevent mitochondrial dysfunction associated with aging or disease[3].
• Increased Energy Production: By optimizing the efficiency of the electron transport chain, SS-31 increases ATP production in cells. This translates to better energy performance in high-demand tissues (such as cardiac and skeletal muscle) and reduced fatigue during physical activity[4][5].
• Reduction of Oxidative Stress: SS-31 decreases the generation of reactive oxygen species (free radicals) in mitochondria. Thereby, it protects cells from chronic oxidative damage, reduces cellular inflammation, and contributes to maintaining the integrity of cellular components (DNA, proteins, and lipids) over time[6].
• Potential Neuroprotection: Thanks to its mitochondria-targeted action, SS-31 may protect neurons from energy dysfunction. Research suggests it supports brain health by reducing oxidative stress in nerve cells, which could favor memory and cognitive function during aging[7].
• Improved Muscle Performance: SS-31 improves muscle bioenergetics, increasing efficient oxygen use and energy availability in muscle. As a result, studies indicate it could reduce fatigue during prolonged exercise and accelerate muscle recovery after intense activity[8].
• Anti-aging Potential: By counteracting one of the central factors of cellular aging (mitochondrial deterioration), SS-31 could contribute to healthier aging. It is postulated that its long-term use would promote more efficient cellular metabolism in multiple organs, delaying to some extent the onset of age-related functional declines[9].

Specifications

• Molecular Formula: C32H49N9O5[10]
• Molecular Weight: ≈639.8 daltones (g/mol)[10]
• Other known names: Elamipretide (code SS-31); also referred to in research as MTP-131 or Bendavia[10].

SS-31 belongs to a family of peptides known as Szeto-Schiller (SS), discovered in the early 2000s with the aim of improving mitochondrial function in disease and aging conditions[11]. These peptides were designed to be small and permeable enough to enter cells and concentrate in mitochondria, optimizing electron transport efficiency and energy production without negatively affecting healthy cells. In initial studies with isolated mitochondria and cell cultures, SS-31 was shown to restore cellular bioenergetics: it improved electron flow through the respiratory chain, elevated ATP synthesis, and reduced ROS (free radical) production within cells to near-normal levels[12]. Its mechanism of action is primarily attributed to its binding to cardiolipin in the inner mitochondrial membrane, thereby stabilizing mitochondrial cristae (the internal structure of mitochondria) and preventing membrane disruption under stress conditions[13]. Thanks to this targeted action, SS-31 keeps mitochondria functioning more efficiently and resistant to oxidative damage.

A prominent finding in preclinical research is SS-31's ability to protect skeletal muscle from disuse atrophy. In studies with immobilized mice (a model of muscle atrophy due to inactivity), treatment with SS-31 prevented the increase in mitochondrial oxidative stress and muscle mass loss that normally accompanies prolonged lack of muscle activity[14]. That is, mice subjected to immobilization maintained their musculature better when receiving SS-31 compared to those that did not. This effect suggests that SS-31 could counteract degenerative processes in muscle during periods of inactivity (e.g., in long convalescences or space travel), helping to preserve muscle integrity and functionality.

The decline in mitochondrial functional capacity contributes to age-related muscle weakening. In a notable study with aged mice (~26 months old, equivalent to advanced age), chronic administration of SS-31 for 8 weeks reversed several age-related muscle deficits[15]. Specifically, SS-31 improved maximal ATP production and restored redox balance (balance between oxidants and antioxidants) in the skeletal muscle of these old mice[15]. Notably, this improvement was achieved without increasing mitochondrial number, indicating that SS-31 made existing mitochondria more efficient rather than stimulating mitochondrial biogenesis. In functional terms, treated muscles showed greater fatigue resistance and some recovery of mass and strength compared to untreated controls. As a result, aged mice treated with SS-31 tolerated exercise better: they were able to run significantly longer on a treadmill than untreated aged mice[5]. These findings indicate that improving mitochondrial function via SS-31 can translate into more functional and resilient muscles in old age, pointing to possible applications for combating sarcopenia (age-associated muscle mass loss).

Given that the heart is an organ of incredibly high energy demand, mitochondrial function is critical for cardiovascular health. In preclinical studies of heart failure (e.g., in animal models with pressure overload inducing heart failure), SS-31 showed the ability to restore cellular bioenergetics of the heart: it improved the structure and function of mitochondria in the myocardium, increasing energy production and reducing ROS levels towards near-normal values[16]. As a consequence of this mitochondrial optimization, improvements in the heart's pumping function and a normalization in cardiolipin composition (a key phospholipid of the inner mitochondrial membrane) were observed in animal models of ventricular dysfunction and heart failure[17]. A significant advance is that this peptide has come to be evaluated in humans: the US FDA granted accelerated approval to elamipretide (SS-31) under the trade name Forzinity™ for the treatment of Barth syndrome[18]. Barth syndrome is a rare genetic disease in which mitochondria (especially in the heart) present abnormal functioning; in a clinical trial with patients of this condition, treatment with SS-31 managed to improve muscle strength and cardiac function of patients[18]. This marked the first therapy of its kind directed at mitochondrial repair in a human disease, highlighting the potential of SS-31 in the field of cardiomyopathies of mitochondrial origin.

Neurons, like muscle cells, depend heavily on the energy provided by their mitochondria. In models of neurodegenerative diseases and brain injury, SS-31 has demonstrated notable neuroprotective effects. For example, in cultures of neurons exposed to intense oxidative stress, treatment with SS-31 significantly reduced free radical production, restored mitochondrial membrane potential, and prevented apoptosis (programmed cell death) of vulnerable neurons[19]. These results suggest that SS-31 protects nerve cells by maintaining their mitochondrial function and preventing oxidative damage that triggers cell death. Similarly, in animal models of neurological disorders such as Alzheimer's and Parkinson's disease, the SS-31 peptide showed capacity to improve mitochondrial function in the brain and attenuate some of the impairments associated with the neurodegenerative process[20]. Taken together, these findings indicate that SS-31 could protect brain cells by sustaining their energy metabolism and reducing oxidative stress, opening the door to potential therapies for conditions where mitochondrial dysfunction plays a central role (e.g., neurodegenerative diseases, ischemic brain injury, etc.).

To date, SS-31 has shown a generally favorable safety profile in preclinical studies and initial human trials[21]. Due to its localized action in mitochondria and because it does not interact with the body's hormonal pathways, it tends to be well tolerated by test subjects[22]. Observed side effects are considered mild. The most common is a reaction at the injection site – since SS-31 is usually administered subcutaneously or intravenously in research settings – which may include redness, irritation, or local discomfort[23]. In some cases, transient symptoms such as slight fatigue, passing headache, or gastrointestinal discomfort (nausea) at the start of treatment have been reported, which remit spontaneously after a short time[24]. Important to note that no significant toxic effects have been identified in animals or humans during short to medium-term studies[25]. However, data on its long-term use in humans are still limited. As a precaution, experts recommend that SS-31 only be used within supervised research protocols. In special populations, such as pregnant women or people with pre-existing mitochondrial diseases, its use outside controlled clinical contexts is discouraged due to the lack of conclusive data on its safety in those cases.