How to Store Peptides

Scientists may be interested in learning more about how to store peptides properly to maximize their success during experimentations.

Peptides are a popular research topic within the scientific community, as they are under active investigation for a wide range of potential applications. A small sample of them includes:

• Weight loss research
• Nootropics research
• Skincare research
• Recovery research
• Longevity research

However, research peptides often come in different forms that have specific storage and handling requirements. Considering the risk of contamination and how fragile the amino acid chains of peptides are, this further complicates the topic.

Therefore, we provide this comprehensive review of the most common types of peptides, the forms in which they are typically available, and how each form should be stored to preserve its potency throughout the entire duration of experimentation.

What are Research Peptides | Overview

Peptides are short chains of amino acids. They are formed by linking amino acids together, and depending on the number of amino acids involved, these chains can be classified as either peptides or proteins.

Peptides typically consist of 2 to 50 amino acids, making them much smaller than the chains of proteins [1]. 

The structure of peptides can vary significantly, with some being linear, non-linear, or even cyclic [2]. This structural diversity allows peptides to have a wide range of biological activities and functions.

These molecules are essential components of all living organisms, playing critical roles in various biological processes. 

Found in every cell of the body, peptides perform a wide range of functions that are crucial for maintaining life. In the human body, peptides serve numerous biological roles, acting as messengers, hormones, and antimicrobial agents, among other functions [1]. For example, some peptides function as: 

• neurotransmitters, facilitating communication between nerve cells
• hormones, such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), which regulate insulin and blood sugar levels
• antimicrobial peptides which are crucial in defending the body against infections by killing harmful bacteria and viruses

Considering the vast potential of peptides, scientists have created synthetic peptides, which are either identical to their natural counterparts or contain modifications.

However, one of the main challenges in researching peptides is their mode of administration. Due to their susceptibility to degradation in the digestive system and their inability to easily pass through the skin, most peptides require administration via injection [3, 4].

Nevertheless, the wide range of potential applications makes peptides a captivating area of scientific research with exciting implications for human health, and currently, there are hundreds of research peptides under investigation [5, 6]. 

Moreover, there are more than 60 peptide compounds that have already been approved for human use by the US Food and Drug Administration (FDA) [7, 8].

Below we have outlined some of the most notable research peptides based on their research objectives such as weight management, recovery, skin management research, etc, and we have also shared their specific form, obtainable for experimentation.

Research Peptides For Body Composition

Several peptides have shown promise in enhancing body composition, with some receiving approval for treating muscle-wasting conditions. These peptides often act on growth hormone-releasing hormone (GHRH) receptors in the pituitary gland, promoting the natural release of growth hormone (GH).

GH is known for its ability to reduce abdominal and visceral fat and stimulate the production of insulin-like growth factor 1 (IGF-1), which promotes muscle growth. Here are some of the peptides known to affect its synthesis:

• Tesamorelin has been approved since 2010 for treating HIV-associated lipodystrophy, a condition involving abnormal fat distribution [9]. Tesamorelin mimics GHRH, leading to increased GH and IGF-1 production [10]. Extensive studies have shown that this peptide can significantly enhance muscle density in HIV patients [11].
• Other peptides with potential for improving body composition include the GHRH analog sermorelin and the ghrelin mimetic MK-677, which also boost GH production. Sermorelin in particular is also shown to increase lean body mass without affecting fat mass in clinical trials [12].

They are currently available for researchers exploring their potential to improve body composition in specific subjects in the form of lyophilized powders that must be reconstituted with an appropriate solvent before use.

Research Peptides For Weight Management

The popularity of weight loss peptides has been on the rise, especially with compounds that activate the receptors for the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). These two molecules work to stimulate insulin release after food intake, but also significantly suppress appetite [13].

Consequently, the development of long-acting agonists for these receptors leads to prolonged appetite suppression and reduced energy intake, resulting in weight loss. 

Here are several notable examples:

• Semaglutide and liraglutide share 94-97% homology with the active form of the GLP-1 hormone [14, 15]. They are FDA-approved for weight management in overweight and obese individuals as phase 3 trials have shown 15.8% and 6.4% weight loss, respectively, after over 12 months [16].
• Tirzepatide is a new dual-incretin agonist mimicking the functions of both GLP-1 and GIP [17]. Clinical studies have shown that tirzepatide can also result in up to a 21% reduction in body weight in non-diabetic individuals [18].
• As of 2024, a novel peptide called retatrutide mimics both GLP-1 and GIP but also activates the receptors for the hormone glucagon and increases metabolic rate. The peptide is currently in phase 3 trials and preliminary research shows up to 24.2% weight loss [19].

All these peptides are typically shipped as lyophilized powders that require reconstitution.

Research Peptides For Recovery And Repair

Several peptides have garnered interest for their potential in tissue healing, with TB-500 (thymosin beta-4) and BPC-157 (body protection compound-157) being among the most prominent among researchers:

• TB-500 is an analog of the endogenous peptide thymosin beta-4 which may influence the ability of stem cells to move to a site of injury. Studies report accelerated wound healing, reduced inflammation, and the promotion of new blood vessel formation [20, 21, 22]. Additionally, TB-500 may possess antifibrotic properties and has been reported to aid in the healing of cardiac muscle tissues [23].
• BPC-157 is a synthetic compound, linked to wound healing and angiogenesis [24, 25, 26]. It is also noted for its ability to enhance collagen production and facilitate the healing of the gastrointestinal tract. Furthermore, it may support recovery and regeneration in injuries involving muscles, tendons, ligaments, and bones [27].

Despite these potential benefits, it is crucial to recognize that further research is necessary to determine their long-term safety and possible side effects, as human data is either scarce or non-existent. Neither TB-500 nor BPC-157 is currently FDA-approved.

These peptides are available for research as either lyophilized powders or already reconstituted and loaded into sprays.

Research Peptides For Cognitive Enhancement

Several nootropic peptides have been tested, with some of the most notable ones being Selank and Semax. Both peptides can readily pass the blood-brain barrier, and appear to be bioavailable when administered either via injections or intranasally.

Here is what researchers should know:

• Semax is a synthetic peptide that interacts with various neurotransmitters  and neurotrophic factors like BDNF that support the growth, survival, and maintenance of neurons [28]. It is approved in Russia for neuroprotective and cognitive-enhancing agents in settings of ischemic stroke and cognitive disorders [29]. This peptide also appears to provide nootropic effects in otherwise healthy individuals [30]. 
• Selank is another heptapeptide developed in the 1990s and approved as an anxiolytic by the Russian Federation Ministry of Health in 2009 [29]. Selank has a pronounced effect on opioid, serotonergic, and GABA signaling. These mechanisms are likely central to Selank's ability to reduce stress and anxiety levels [31, 32]. 

Neither of these peptides is approved for human use or clinically tested outside of Russia. They are available for research as either lyophilized powders or already reconstituted and loaded into sprays.

Research Peptides For Longevity 

Epithalon, also known as Epitalon or AEDG peptide, is among the most extensively studied peptides for its potential longevity benefits. It is a tetrapeptide derived from epithalamin, a crude extract of the pineal gland [33].

This peptide is believed to boost telomerase activity, which plays a key role in maintaining and lengthening telomeres—protective caps found at the ends of the chromosomes that store DNA. Longer telomeres are associated with increased cellular longevity [34, 35].

Research on epithalon is scarce with one notable trial involving 266 participants which reported that mortality was reduced by 1.6 to 1.8 times compared to the placebo group [36, 37, 38].

Moreover, preclinical research has examined Epithalon’s potential to inhibit tumor cell formation, reduce oxidative stress, and enhance the functioning of the endocrine and immune systems [39, 40, 41].

It is shipped to researchers as either a powder for reconstitution, or pre-reconstituted and preloaded into a spray bottle.

Research Peptides For Skin Care

Research peptides for skin care tend to work via a variety of mechanisms, including upregulating collagen synthesis, reducing facial muscle contractions, or inhibiting the production of pigments to lower hyperpigmentation.

One of the most notable ones is GHK-Cu (glycyl-l-histidyl-l-lysine-copper) also known as copper tripeptide. It is recognized for its ability to stimulate the synthesis and breakdown of the extracellular proteins that contribute to skin’s strength, structure, and elasticity such as collagen and glycosaminoglycans [42].

Preliminary studies report enhanced skin elasticity, tighter skin, reduced wrinkles, and protection against the photoaging effects of sun exposure [42]. Early studies also suggest that GHK-Cu might reduce oxidative stress, such as those caused by the pro-aging effects of UV exposure [43].

The peptide is often included in commercial skincare products, but it is not approved for any medical indication by the US FDA. It is also under active investigation as a research peptide.

This peptide available either as a lyophilized powder for reconstitution or formulated as a cream.

How to Store Peptides

Proper storage of research peptides is crucial for ensuring the success of future experiments. Improperly stored peptides may become inactive or contaminated, compromising their safety and effectiveness.

One of the key factors in peptide storage is the form in which the peptide is stored. Research peptides are typically produced through a process known as solid-phase peptide synthesis (SPPS). After synthesis, the peptides undergo purification and then freeze-drying (lyophilization) to remove the solvent.

The result is a lyophilized, or “raw,” peptide in powder form. This is the most common form of research peptide sent to scientists for experimentation. Before use, the peptide is reconstituted with a solvent, usually water-based, to create a liquid form suitable for research.

Therefore, there are two main forms of research peptides—”raw” and “reconstituted”—each requiring specific storage conditions to maintain their integrity.

How to Store “Raw” Peptides

The dry, lyophilized peptide powder in “raw” peptides is typically sealed in sterile vials, under an inert gas atmosphere. 

This packaging method significantly prolongs the shelf life of lyophilized peptides, often lasting several years if stored correctly in a cool, dark, and dry environment. Exposure to heat or direct sunlight should be avoided, as it can damage their structure. 

To extend their shelf life even further, potentially for decades, researchers can consider storing lyophilized peptides at low temperatures, particularly below -4°F (-20°C). 

Freezing is generally safe for “raw” peptides since they lack water molecules, eliminating risk of ice crystals that could harm their delicate structure. 

Before reconstitution, researchers must remember to allow “raw” peptides to reach room temperature over several hours to prevent ice crystal formation when a solvent is added.

How to Store Peptides Post-Reconstitution

The best way to store peptides following reconstitution depends primarily on the solvent used. 

One of the simplest, yet rarely used solvents is distilled water. This solvent lacks any preservatives and the peptide can be stored only for up to 24 hours, before expiring.

On the other hand, the most commonly used solvent is bacteriostatic water which contains 0.9% benzyl alcohol as a solvent. This is a solvent that is safe within this concentration and effectively suppresses bacterial growth, extending shelf-life [44].

Regardless of the chosen solvent, peptides should be protected from direct sunlight, heat, and mechanical stress (such as shaking or tapping), as these factors can degrade their structure.

When peptides are reconstituted in a solvent with a preservative such as bacteriostatic water, they should be refrigerated at 36 to 46 degrees F (2 to 8 degrees C), where they can remain stable for up to 4 weeks. 

Peptides that are shipped as already reconstituted solutions and preloaded into sprays should also be kept refrigerated at all times. The only form of ready-to-use peptides that do not require reconstitution are creams.

How to Freeze Research Peptides if Necessary

Freezing reconstituted peptides is also discouraged because it can compromise their integrity and functionality. Ice crystal formation during freezing can disrupt the peptide structure, potentially resulting in a loss of biological activity or altered properties. 

If freezing is absolutely necessary, the UK National Institute for Biological Standards and Control (NIBSC) advises freezing and storing peptides at -4°F (-20°C) or lower [45]. 

To minimize potential damage, slow freezing (to prevent the formation of large crystals), and rapid thawing methods may be beneficial, though the best approach can vary depending on the compound [46]. Additionally, using cryoprotectants or stabilizing agents can help mitigate damage during freezing and subsequent storage [47].

It is also crucial to avoid multiple freeze-thaw cycles, as these cause cumulative damage. Instead, it is better to freeze reconstituted peptides in separate aliquots and thaw them individually as needed.