12 Common Peptides Explained: Types, Research Uses, and Key Differences

1. Semaglutide — GLP-1 Signaling

Semaglutide activates the glucagon-like peptide-1 receptor, usually shortened to GLP-1. This pathway connects nutrient-related signaling with processes including appetite regulation and glucose control.

Its clinical evidence explains much of the wider interest in peptide-based medicines. In the STEP 1 trial, 1,961 adults with overweight or obesity, without diabetes, received the tested pharmaceutical regimen or placebo alongside lifestyle intervention. Average body-weight change at 68 weeks was −14.9% versus −2.4%. [1]

The useful takeaway is its receptor-mediated role in metabolic regulation. Calling it simply a “fat-burning peptide” hides that biology.

Semaglutide is a molecular name; individual medicines containing it have their own formulations, indications, and prescribing information.

2. Tirzepatide — GIP and GLP-1 Signaling

Tirzepatide acts at GIP and GLP-1 receptors. Unlike semaglutide’s GLP-1-focused approach, it combines activity at two hormone-receptor targets within one molecule.

In SURMOUNT-1, 2,539 adults with obesity, or overweight with a weight-related complication, excluding diabetes, participated in a 72-week randomized trial. Mean weight reductions across the tested tirzepatide groups ranged from 15.0% to 20.9%, compared with 3.1% for placebo. [2]

These findings make tirzepatide important in metabolic drug development. However, receptor count alone is not a performance score.

When comparing it with another compound, distinguish the mechanism from the actual clinical comparison: populations, treatment regimens, duration, and statistical analyses can all differ.

3. Retatrutide — A Triple-Receptor Research Approach

Retatrutide activates GIP, GLP-1, and glucagon receptors. Adding glucagon-receptor activity introduces another pathway relevant to metabolic regulation.

Published Phase 3 TRIUMPH-2 results involved 1,152 adults with overweight or obesity and type 2 diabetes. At 80 weeks, the highest studied group showed 18.8% mean weight reduction versus 5.1% with placebo, using the treatment-regimen analysis. [3]

Status checked October 29, 2026: Lilly’s October 28 update described retatrutide as investigational and not approved by the FDA or another regulatory organization. Its newer announcement reported additional Phase 3 topline findings, which should be distinguished from fully published results. [4]

The next useful question is how the extra receptor pathway changes outcomes—not whether “three” automatically means better than “two.”

4. Tesamorelin — Visceral Fat Research

Tesamorelin is a growth hormone–releasing hormone analogue. It stimulates a hormone-signaling pathway rather than acting like a GLP-1 receptor agonist.

Its distinctive research focus is visceral fat: fat within the abdominal cavity around internal organs. This differs from subcutaneous fat beneath the skin.

A 26-week randomized study of 412 people with HIV and abdominal fat accumulation used CT imaging to assess visceral adipose tissue. Visceral fat decreased by 15.2% with tesamorelin, compared with a 5.0% increase with placebo. Subcutaneous fat did not show the same pattern. [5]

That makes fat distribution the key point to remember. The result concerns a specific tissue compartment and population, rather than a universal reduction in all forms of abdominal fat.

5. AOD-9604 — Fat Mobilization and Utilization

AOD-9604 was developed from a modified region related to the C-terminal portion of human growth hormone. Its research appeal concerns lipid metabolism rather than the full range of growth hormone activity.

A mouse study reported reduced body weight and body fat after repeated experimental administration. It also investigated lipolytic sensitivity and found increased fat oxidation and energy expenditure under particular acute experimental conditions. [6]

These observations did not establish corresponding human weight-loss benefits. FDA’s review describes a larger human obesity program that failed to demonstrate the intended weight-loss effect. [7]

AOD-9604 therefore illustrates an important distinction: fat mobilization, oxidation, and sustained changes in body fat are separate measurements.

6. GHK-Cu — Copper Peptides and Skin Biology

GHK-Cu is a copper complex of the tripeptide glycyl-histidyl-lysine. In cosmetic ingredient terminology, it is commonly associated with Copper Tripeptide-1.

Its research background includes extracellular-matrix biology—the network of molecules surrounding cells and contributing to tissue structure.

An original laboratory study reported that GHK-Cu stimulated collagen synthesis in cultured fibroblasts, without the increase being explained by a change in cell number. [8]

This gives a concrete reason for interest in skin biology. It does not, by itself, predict how much a finished serum will change wrinkles or skin firmness.

For further evaluation, keep three identities separate: the peptide complex, the supplied ingredient preparation, and the complete skincare formula.

7. SNAP-8 — Expression-Line Research

SNAP-8 is a trade name commonly associated with Acetyl Octapeptide-3. Its development concept concerns signaling involved in expression-related lines.

One published study evaluated a dissolving patch containing Acetyl Octapeptide-3, hyaluronic acid, and other active ingredients in 24 participants. Over 28 days, the active multi-ingredient patch showed greater eye-wrinkle improvement than a hyaluronic-acid-only comparator. [9]

The positive finding belongs to that tested formulation; it does not isolate the peptide’s contribution.

“Botox-like” describes a marketing comparison and mechanistic theme, not the same material or proven equivalent results. Compared with GHK-Cu’s matrix-related research, SNAP-8 introduces a different starting point for wrinkle-focused product development.

8. BPC-157 — Tissue-Related Research

BPC-157 is a 15-amino-acid peptide investigated in gastrointestinal and other tissue-injury models.

In a rat intestinal-anastomosis study, researchers examined recovery where two sections of the small intestine had been surgically joined. They reported improved tissue-healing observations and greater resistance to leakage compared with saline controls. Assessments included histology and mechanical testing over the first 14 days. [10]

This combination of structural and functional measurements explains its relevance to tissue-recovery research.

It also helps explain why BPC-157 appears in both gastrointestinal and broader recovery discussions. However, an intestinal surgical model cannot stand in for evidence about a different tissue, everyday discomfort, or an athletic injury.

9. TB-500 — Understanding the Material Behind the Name

TB-500 requires particular attention to identity.

FDA scientific materials describe TB-500 as N-acetyl-LKKTETQ, a seven-amino-acid fragment related to thymosin beta-4. Full-length thymosin beta-4 is a different, 43-amino-acid peptide. Their shared sequence background helps explain why the names appear together in tissue-repair discussions. [11]

That relationship does not make their findings interchangeable. The same FDA review describes a scratch-assay experiment in which the specified TB-500 fragment did not promote closure in cultured fibroblasts.

For this name, the useful first step is establishing the sequence and modifications of the actual material. A listing labeled “TB-500” should not automatically inherit every recovery finding reported for full-length thymosin beta-4.

10. KPV — Inflammatory Signaling and Intestinal Models

KPV contains lysine, proline, and valine.

An original study found that the small-peptide transporter PepT1 carried KPV into intestinal and immune-cell models. Researchers observed reduced activity in NF-κB and MAPK inflammatory pathways and lower production of inflammatory mediators.

The same paper reported reduced inflammation in chemically induced mouse colitis, assessed through tissue findings and inflammatory measurements. [12]

These results explain the interest in intestinal inflammatory signaling. They do not establish effectiveness for every symptom described as a gut problem.

KPV and BPC-157 are discussed together because their experimental interests overlap around injured and inflamed tissue. Separate findings do not demonstrate that a combination works better.

11. SS-31 — Mitochondrial Membrane Research

SS-31, also known as elamipretide, is a synthetic peptide studied for interactions with cardiolipin in the inner mitochondrial membrane.

This membrane contains machinery involved in energy production. Investigating its organization and function gives SS-31 a defined research focus.

Its pharmaceutical development has reached a specific clinical use: in September 2025, the FDA granted accelerated approval to Forzinity, an elamipretide medicine, for patients with Barth syndrome weighing at least 30 kg. The approval was based on improved knee-extensor strength, with confirmation of clinical benefit required. [13]

That is an important development milestone. It applies to the approved medicine and conditions—not every research material bearing the SS-31 name.

12. MOTS-c — Metabolic Signaling and Adaptation

MOTS-c is a mitochondrial-derived signaling peptide investigated in metabolism, cellular stress responses, and physical function.

A 2021 study reported improved physical performance in young, middle-aged, and old mice receiving MOTS-c. It also examined muscle metabolism and cellular adaptation. In the human part of the research, exercise changed naturally occurring MOTS-c in muscle and circulation. [14]

These are different forms of evidence: measuring the body’s own peptide after exercise is not the same as demonstrating benefits from administering synthetic material.

Compared with SS-31’s membrane-associated research, MOTS-c emphasizes signaling and adaptation. That distinction makes both interesting without establishing that they are interchangeable or should be used in a particular sequence.

What Are the Main Types of Peptides?

Peptides can be classified by origin, structure, biological function, and product application. This guide uses research interests to organize common names. A peptide may belong in more than one group, so the categories should help navigation rather than imply a fixed, exclusive use.

Why Is the Same Peptide Discussed for Different Purposes?

A biological pathway can operate in several tissues, giving researchers reasons to investigate more than one setting. However, evidence must remain attached to each proposed application. A positive result in one tissue or disease model does not establish an equivalent benefit elsewhere.

Are More Peptides in a Blend Necessarily Better?

No. Ingredient count does not establish better performance. A combination introduces questions about interactions, stability, exposure, and outcomes. Evidence for each ingredient can motivate a combined study, but it cannot replace testing of the actual blend.

Are NAD+ and SLU-PP-332 Peptides?

Neither is a peptide.

NAD+ is nicotinamide adenine dinucleotide, a coenzyme involved in cellular reactions. SLU-PP-332 is a synthetic small-molecule estrogen-related receptor agonist investigated in metabolic and exercise-related experiments. A shared catalog category does not change molecular identity. [15], [16]