Research peptide catalogs list dozens of individual compounds, which makes it easy to lose track of which ones share a proposed mechanism and which ones do not. Many labs organize a research program around functional groups instead, treating peptides as belonging to a repair pathway, a neuro pathway, a mitochondrial and metabolic-support pathway, or the separate incretin-receptor pathway that the newer metabolic peptides occupy. This article is a neutral overview of how those groupings work, what each group's compounds have been studied for, and why the metabolic peptides are usually kept in a category of their own rather than folded into the others.
| Group | Representative compounds | Shared research theme |
|---|---|---|
| Repair | BPC-157, TB-500, GHK-Cu | Tissue-protective, actin-binding and matrix-remodeling effects across injury and wound-healing models |
| Neuro | Selank, Semax | Central nervous system signaling effects examined in rodent behavioral and neurochemical models |
| Mitochondrial and metabolic support | MOTS-c, NAD+, SS-31 | Cellular energy production, redox balance, and mitochondrial structure measured in cell and animal models |
| Incretin and metabolic-receptor | LY3437943, NN9535, LY3298176 | GLP-1, GIP and glucagon receptor engagement studied in clinical trial populations |
Why group peptides by mechanism instead of by product line?
A research program that touches several peptides at once benefits from knowing which compounds are likely to interact with the same biological system and which are mechanistically independent. Grouping by pathway rather than by how a supplier happens to bundle a vial makes it easier to design a study around non-overlapping readouts, and it also clarifies which literature is relevant background reading for a given experiment. The four groupings below reflect how these compounds are most often discussed in the published literature, not a formal taxonomy.
What is studied in the repair-pathway group?
BPC-157, TB-500 and GHK-Cu each have separately published evidence in tissue-repair models, though each engages a different proposed mechanism. BPC-157's literature spans gastrointestinal protection and a wide range of other injury models, with a review of the compound's cytoprotective and organoprotective effects summarizing findings across gastrointestinal, tendon, and nerve-injury models in animal research (Sikiric et al., 2020). TB-500's research draws on its parent molecule thymosin beta-4, reviewed for actin-binding and cell-migration effects examined across multiple preclinical wound and tissue-injury models (Goldstein et al., 2012). GHK-Cu's literature centers on collagen synthesis and matrix-remodeling gene expression measured in cultured skin cell models (Pickart et al., 2015). Why these three are frequently paired, and the differences between the two- and three-peptide repair combinations, is covered in why labs pair BPC-157 and TB-500 and GLOW vs KLOW.
What is studied in the neuro-pathway group?
Selank and Semax are both heptapeptides derived from endogenous signaling molecules and studied in Russian and Eastern European neuropharmacology research going back several decades, though each targets a different behavioral and neurochemical readout. A review of Selank's molecular activity summarized its proposed anxiolytic-relevant effects and mechanism at the receptor level in preclinical models (Vyunova et al., 2018). Semax research has more often focused on neuroprotective and cognitive-task readouts in rodent models. A side-by-side comparison of what each compound's literature covers is in Selank vs Semax.
What is studied in the mitochondrial and metabolic-support group?
MOTS-c, NAD+ and SS-31 are grouped together because each is studied for effects on cellular energy metabolism rather than a specific organ or tissue. MOTS-c is a mitochondrial-derived peptide reported to influence metabolic homeostasis and insulin sensitivity measures in mouse models (Lee et al., 2015). SS-31 is a mitochondria-targeted peptide studied for its interaction with cardiolipin in the inner mitochondrial membrane and its reported effects on mitochondrial structure and function in aging-related models (Szeto, 2018). NAD+ itself is a coenzyme rather than a peptide, but it is grouped alongside these compounds because sirtuin and redox pathway research treats NAD+ availability as a shared upstream input to the same cellular energy systems that MOTS-c and SS-31 research examines, a connection reviewed in the broader NAD-boosting molecule literature (Rajman et al., 2018). A full comparison of these three compounds is in mitochondrial research compounds compared.
Why is the incretin and metabolic-receptor group kept separate?
LY3437943, NN9535 and LY3298176 engage GLP-1, GIP and glucagon receptors directly, a mechanism unrelated to the mitochondrial, repair, or neuro pathways above, and their literature comes primarily from large randomized clinical trials rather than the cell and rodent model work that dominates the other three groups. Because the trial infrastructure, receptor targets, and study populations are so different from the rest of the categories on this page, most research programs treat this group as its own separate track rather than folding it into a mixed bundle; background on this compound family is covered in what is LY3437943 and LY3437943 vs LY3298176 vs NN9535.
How should a program decide which group to start with?
The choice generally follows the research question rather than the catalog. A program examining wound-healing or connective-tissue models has more directly relevant published background in the repair group; a program examining central nervous system signaling has more relevant background in the neuro group; and a program examining cellular energy metabolism, redox balance, or aging-related model systems has more relevant background in the mitochondrial group. Reviewing the specific studies cited for a given group before selecting compounds helps confirm that a proposed experimental readout has precedent in the existing literature.
Handling notes
All compounds discussed here are supplied as lyophilized powder for laboratory research. Store per each lot's certificate of analysis and confirm identity and purity before use in an assay. Lot-specific specs for the repair-group blends are posted on our GLOW blend lot page and our BPC-157 and TB-500 lot page.
Frequently asked questions
Is this grouping an official scientific classification?
No. It reflects how these compounds are most often discussed together in the published literature and in research supply catalogs, organized by proposed mechanism rather than by a formal taxonomy.
Can compounds from different groups be studied together?
Yes. The groupings are a starting point for organizing background reading and study design, not a restriction. Some research questions intentionally span groups, such as examining a repair-pathway compound's effect on a metabolic readout.
Why is NAD+ listed with peptides when it is a coenzyme?
NAD+ is grouped with MOTS-c and SS-31 because redox and sirtuin pathway research treats it as a shared upstream input to the same cellular energy systems those peptides are studied in, even though NAD+ itself is not a peptide.
Why isn't the incretin group included in a mixed bundle with the others?
LY3437943, NN9535 and LY3298176 engage a distinct receptor system studied primarily through large clinical trials, which is different enough from the cell and rodent model work in the other three groups that most programs keep it as a separate track.
Where should someone start reading before choosing compounds from a group?
Start with the group-specific comparison articles linked above, then read the individual compound overview for each candidate peptide before finalizing a study design.
References
- Sikiric P, Skrtic A, Gojkovic S, et al. Stable Gastric Pentadecapeptide BPC 157, Robert's Stomach Cytoprotection/Adaptive Cytoprotection/Organoprotection, and Selye's Stress Coping Response: Progress, Achievements, and the Future. Gut Liver. 2020;14(2):153-167. PubMed 31158953.
- Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther. 2012;12(1):37-51. PubMed 22074294.
- Pickart L, Vasquez-Soltero JM, Margolina A. GHK Peptide as a Natural Modulator of Multiple Cellular Pathways in Skin Regeneration. Biomed Res Int. 2015;2015:648108. PubMed 26236730.
- Vyunova TV, Andreeva LA, Shevchenko KV, Myasoedov NF. Peptide-based Anxiolytics: The Molecular Aspects of Heptapeptide Selank Biological Activity. Protein Pept Lett. 2018;25(10):914-923. PubMed 30255741.
- Lee C, Zeng J, Drew BG, et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metab. 2015;21(3):443-54. PubMed 25738459.
- Szeto HH. Cardiolipin-targeted peptides rejuvenate mitochondrial function, remodel mitochondria, and promote tissue regeneration during aging. Arch Biochem Biophys. 2018;660:137-148. PubMed 30359579.
- Rajman L, Chwalek K, Sinclair DA. Therapeutic Potential of NAD-Boosting Molecules: The In Vivo Evidence. Cell Metab. 2018;27(3):529-547. PubMed 29514064.
Research use only. Homegrown Peptides products are for laboratory research and are not for human or animal use. Nothing in this article is medical advice.
