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Evidence-led overview

Types of peptides &
what the research shows

Peptides are short chains of amino acids that act as signalling molecules in the body. Below is a plain-English overview of the main categories researchers study, how each works, and the headline results that laboratory and clinical studies have reported so far.

6

Research areas

19

Compounds

≥99%

Purity

HPLC · LC-MS

Verified

For research use only. The figures and findings below are educational and summarise published laboratory, animal and clinical research. They describe what studies have observed — they are not medical advice and are not a claim about the safety or effectiveness of any product for human or veterinary use. Defined Labs products are not for human consumption.

01

GLP-1 · GIP · Glucagon

Metabolic & body-composition peptides

This is the most clinically advanced area of peptide research. These compounds mimic the body's own incretin and growth-hormone-releasing hormones to influence glucose handling, appetite signalling and fat metabolism.

Retatrutide

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Phase 2 trials

≈24% average body-weight reduction at 48 weeks (highest dose)

A single molecule that acts on three receptors at once — GLP-1, GIP and glucagon. A Phase 2 trial in adults with obesity (published in the New England Journal of Medicine, 2023) reported a mean weight reduction of around 24% at 48 weeks on the top dose — among the largest figures seen for any investigational agent of this class. Later-stage trials are ongoing.

Tesamorelin

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FDA-approved

≈15–18% reduction in visceral fat over 26 weeks

A stabilised analogue of growth-hormone-releasing hormone (GHRH) and one of the few peptides here with regulatory approval. Pivotal clinical trials demonstrated roughly a 15–18% reduction in visceral (deep abdominal) fat over 26 weeks in HIV-associated lipodystrophy. It has since been studied for liver fat and cognition in ageing.

02

Healing · Recovery

Tissue repair & recovery peptides

Studied largely in preclinical (cell and animal) models, these peptides are investigated for their effects on angiogenesis — the growth of new blood vessels — and on the remodelling of connective tissue, gut lining, tendon and muscle.

BPC-157

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Preclinical (animal)

Accelerated tendon, ligament & gut healing across numerous animal studies

A 15-amino-acid sequence derived from a protein in gastric juice. Dozens of animal studies have reported faster healing of tendon, ligament and gut tissue, increased blood-vessel formation, and protection of tissue under stress. Robust human clinical data does not yet exist, so these findings remain preclinical.

TB-500

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Preclinical / early trials

Faster wound closure & cell migration in animal models

A synthetic fragment of Thymosin Beta-4, a natural repair protein. Preclinical studies report accelerated wound closure, cell migration and soft-tissue/cardiac recovery. The parent protein has reached early human trials for wound and corneal healing.

03

GH Secretagogues

Growth-hormone pathway peptides

Rather than supplying growth hormone directly, these peptides prompt the pituitary gland to release more of the body's own — aiming for a more physiological, pulsatile pattern of secretion.

Ipamorelin

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Preclinical

Selective GH pulse with little to no rise in cortisol or prolactin

A selective ghrelin-receptor agonist that stimulates a clean pulse of growth hormone with minimal effect on cortisol or prolactin in research models — which is why it's a common reference compound in GH-axis studies.

CJC-1295 / Ipamorelin

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Early-phase human

IGF-1 raised ≈1.5–3× for up to ~6 days from a single dose (CJC-1295)

Combines a long-acting GHRH analogue with Ipamorelin. An early-phase human study of CJC-1295 reported growth hormone increases of several-fold and IGF-1 elevations of roughly 1.5–3× sustained for up to about six days. The blend is studied for complementary, dual-pathway stimulation.

04

Neuropeptides

Cognitive & neurological peptides

Short peptides that cross into the nervous system and modulate neurotrophic factors — the proteins that support neuron growth, survival and plasticity. Several originated in Russian clinical research.

Semax

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Approved (Russia)

Increased BDNF; improved recovery in ischaemia/stroke studies

Derived from a fragment of ACTH. Research has reported increases in BDNF (a key neurotrophic factor) and improved outcomes in models of ischaemia and oxidative stress. It is approved for clinical use in Russia for certain neurological indications.

Selank

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Approved (Russia)

Anxiolytic effects comparable to benzodiazepines without sedation in trials

An analogue of the immunopeptide tuftsin. Studies report anxiolytic (anti-anxiety) activity via the GABA system — in some trials comparable to standard anxiolytics but without sedation — alongside immune-modulating effects.

05

Longevity · Mitochondria

Cellular health & longevity compounds

An emerging field exploring telomere biology, mitochondrial function and the metabolic pathways linked to ageing. Findings here range from animal lifespan studies to active human trials.

Epitalon

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Animal studies

Telomerase activation; extended lifespan markers in rodent studies

A tetrapeptide studied for its effect on telomerase activity and telomere length. Long-running rodent studies, particularly from Russian gerontology research, have reported effects on circadian regulation and increases in lifespan markers.

MOTS-c

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Preclinical

Improved insulin sensitivity & exercise capacity in animal models

A peptide encoded within mitochondrial DNA that acts as a metabolic regulator. Preclinical work links it to improved insulin sensitivity, greater exercise capacity and adaptive responses to metabolic stress.

SS-31

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Human clinical trials

Improved cellular energy output in mitochondrial-disease & heart-failure trials

Also known as elamipretide, this mitochondria-targeting peptide has progressed into human trials for mitochondrial diseases and heart failure, where research has examined improvements in cellular energy production and reductions in oxidative stress.

NAD+

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Active research

Central to energy metabolism & DNA repair; levels fall markedly with age

An essential coenzyme involved in hundreds of metabolic reactions and in DNA repair. Because NAD+ levels decline substantially with age, it and its precursors are a major focus of longevity and metabolic research.

06

Skin · Collagen

Cosmetic & regenerative peptides

Peptides studied for their effects on skin, hair and collagen biology — some of the most extensively documented in cosmetic and dermatological research.

GHK-Cu

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Cosmetic / clinical studies

Improved skin firmness, density & collagen in controlled studies

A copper-binding tripeptide found naturally in plasma. Decades of research — including controlled cosmetic studies — report improvements in skin firmness and density, collagen and elastin synthesis, wound healing and antioxidant gene expression, making it one of the best-studied peptides in skin science.

GLOW (GHK-Cu · BPC-157 · TB-500)

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Blend

Combines the cosmetic & repair peptides above for complementary research

A pre-combined blend pairing the cosmetic and repair peptides described above, researched for potential complementary effects on tissue and skin remodelling.

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Every compound is supplied at ≥99% purity with HPLC and LC-MS testing, and a Certificate of Analysis available on request.

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Products are supplied strictly for in vitro laboratory and scientific research. They are not medicines, supplements, foods or cosmetics, and are not intended for human or veterinary use, consumption, or any clinical or diagnostic purpose.

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