The SubQFusion Peptide Protocol Library

Letter from SubQFusion

The questions peptide research is trying to answer

Most people hear "peptide" and think trend. Or supplement. Or shortcut.

What peptides actually are: short chains of amino acids — the same molecular building blocks your body uses to repair tissue, regulate metabolism, signal between cells, and produce its own hormones.

Here's the part that matters: as we age, the body produces less of these natural amino acid signals. Growth hormone output declines. Tissue repair slows. Metabolic efficiency drops. The aging process isn't mysterious — it's measurable, and a lot of it traces back to which signaling peptides are still being produced in adequate amounts.

That's the question peptide research has spent decades trying to answer. Can specific signaling peptides — re-introduced — restore some of what time takes away?

This library exists to put that research in your hands. Every peptide profile that follows is grounded in published studies, mechanism diagrams, and citations you can verify yourself. No claims. No hype. Just what the research says.

— SubQFusion

How to read this library

Six fields per profile

• What it is — the molecular identity and category
• Mechanism — how it works at the receptor / signaling level
• Research focus — what published studies have investigated
• Key findings — what those studies have observed, with citations
• How researchers approach it — typical study design parameters in research settings
• Considerations — known limitations and open questions

This is a research reference, not medical advice. None of the compounds in this library are FDA-approved for the uses described.

Section 1

The Growth Hormone Axis

Tesamorelin

SUBQ SKU available · GHRH analog · 44-aa peptide

What it is: A synthetic analog of Growth Hormone-Releasing Hormone (GHRH), a 44-amino-acid peptide that signals the pituitary to release growth hormone.

Mechanism: Binds to GHRH receptors on pituitary somatotrophs, stimulating endogenous GH secretion in a pulsatile pattern that mimics natural physiology.

Research focus: Visceral adipose tissue reduction, body composition, cognition in aging populations.

Key findings: A 2010 NEJM study (Falutz et al.) demonstrated significant reduction in visceral adipose tissue in HIV-associated lipodystrophy with daily subcutaneous administration over 26 weeks. Subsequent NIH-funded research (Stanley et al., 2014) examined cognitive and cardiometabolic markers in the same population.

How researchers approach it: Daily subcutaneous, evening administration to align with natural GH pulse, multi-week study windows. The compound is FDA-approved as Egrifta for a specific clinical indication.

Considerations: GHRH-class compounds increase IGF-1; long-term IGF-1 elevation is a research consideration in any GH-axis investigation.

Citations

1. Falutz J, et al. NEJM 2010;363:1108-1117. "Effects of tesamorelin on visceral fat and abdominal contour in HIV-associated lipodystrophy."
2. Stanley TL, et al. J Clin Endocrinol Metab 2014;99(6):2073-2081. "Effect of tesamorelin on visceral adiposity and cardiometabolic risk."

Sermorelin

GHRH 1-29 fragment · short-acting

What it is: A 29-amino-acid fragment of GHRH (the biologically active portion).

Mechanism: Same GHRH-receptor agonism as Tesamorelin, but with a shorter half-life (~10-20 minutes), producing a single pulse of GH release rather than sustained stimulation.

Research focus: Pediatric growth hormone deficiency (its original FDA indication, marketed as Geref), age-related GH decline, sleep architecture.

Key findings: Vittone et al. (1997, Metabolism) examined GH and IGF-1 response in older adults; Khorram et al. (1997) studied immune and body composition markers in an aging cohort.

How researchers approach it: Subcutaneous administration, often pre-sleep to coincide with the body's natural nocturnal GH pulse.

Considerations: Shorter-acting than Tesamorelin; combined with a GHRP for synergistic study design is common in the literature.

Citations

1. Vittone J, et al. Metabolism 1997;46(1):89-96.
2. Khorram O, et al. J Clin Endocrinol Metab 1997;82(5):1472-1479.

Ipamorelin

SUBQ SKU available · Selective GHRP · pentapeptide

What it is: A pentapeptide growth hormone secretagogue (GHRP-class).

Mechanism: Selective agonist of the ghrelin receptor (GHS-R1a) on pituitary somatotrophs. Unlike older GHRPs (GHRP-2, GHRP-6), it does not significantly affect cortisol or prolactin in published research.

Research focus: Selective GH release without off-target endocrine activation; postoperative ileus in clinical trials.

Key findings: Raun et al. (1998, Eur J Endocrinol) characterized its receptor selectivity profile. Multiple Phase II clinical trials have investigated postoperative gastrointestinal recovery.

How researchers approach it: Subcutaneous, often paired with a GHRH (Sermorelin or Tesamorelin) in research designs that aim to model both arms of natural GH regulation.

Considerations: Receptor selectivity is the defining property — research interest centers on whether this selectivity translates to a different long-term profile than older GHRPs.

Citations

1. Raun K, et al. Eur J Endocrinol 1998;139(5):552-561. "Ipamorelin, the first selective growth hormone secretagogue."

IGF-1 LR3

SUBQ SKU available · Long R3 IGF-1 analog

What it is: Long R3 IGF-1 — a recombinant analog of Insulin-Like Growth Factor 1, the primary downstream mediator of growth hormone action. The "Long R3" modification extends half-life and reduces binding to IGF-binding proteins.

Mechanism: Direct activation of IGF-1 receptors on tissue, bypassing the GH → liver → IGF-1 cascade.

Research focus: Skeletal muscle hypertrophy, satellite cell activation, neuronal survival research.

Key findings: Bell et al. (1995) characterized the binding-protein evasion of LR3 vs native IGF-1. Coleman et al. (1995, J Biol Chem) examined skeletal muscle effects in transgenic IGF-1 models.

How researchers approach it: Subcutaneous, typically peri-workout in studies investigating muscle protein synthesis kinetics.

Considerations: IGF-1 is a potent mitogen — long-term IGF-1 elevation is an active area of research scrutiny. Hypoglycemia risk is documented in higher-dose research designs.

Citations

1. Bell GI, et al. Nucleic Acids Res 1986;14:7873-7882.
2. Coleman ME, et al. J Biol Chem 1995;270:12109-12116.

Section 2

Tissue Repair & Recovery

BPC-157

In KGLOW blend · Body Protection Compound · 15-aa

What it is: Body Protection Compound 157 — a 15-amino-acid sequence derived from a protein found in human gastric juice.

Mechanism: Multi-pathway: VEGFR2 expression upregulation (angiogenesis), nitric oxide synthase modulation, growth hormone receptor expression on tendon fibroblasts (Chang et al., 2014).

Research focus: Tendon and ligament healing, gastrointestinal mucosal protection, vascular repair.

Key findings: Sikiric et al. (2010-2020, multiple publications) — extensive preclinical data on Achilles tendon transection models and IBD models. Chang et al. (2014, J Appl Physiol) demonstrated GH receptor upregulation on tendon explants.

How researchers approach it: Subcutaneous near the site of investigated tissue in animal studies; oral and systemic routes both appear in the literature.

Considerations: Almost all published data is preclinical (rodent models). Human trial data is limited. The compound is investigational.

Citations

1. Chang CH, et al. J Appl Physiol 2014;117:1217-1227.
2. Sikiric P, et al. Curr Pharm Des 2010;16:1224-1234.

TB-500 (Thymosin Beta-4 fragment)

In KGLOW blend · synthetic Tβ4 fragment

What it is: A synthetic fragment of Thymosin Beta-4, a naturally occurring 43-amino-acid peptide that is the most abundant member of the beta-thymosin family.

Mechanism: Actin sequestration — regulates the dynamic assembly and disassembly of the actin cytoskeleton, which underlies cell migration during tissue repair.

Research focus: Wound healing, cardiac tissue repair post-MI, corneal healing.

Key findings: Bock-Marquette et al. (2004, Nature) demonstrated cardiac repair effects in a murine MI model. Subsequent ophthalmology research has investigated corneal applications.

How researchers approach it: Subcutaneous in most preclinical designs.

Considerations: Investigational — no FDA-approved human indication. Often paired with BPC-157 in tissue-repair research designs.

Citations

1. Bock-Marquette I, et al. Nature 2004;432:466-472. "Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair."

Section 3

Skin & Pigmentation

GHK-Cu

In KGLOW blend · Copper-binding tripeptide · Gly-His-Lys

What it is: A naturally occurring copper-binding tripeptide (Glycyl-L-Histidyl-L-Lysine), discovered in human plasma in 1973 and shown to decline with age.

Mechanism: Copper transport, modulation of collagen and glycosaminoglycan synthesis, transcriptional effects on wound-healing and DNA-repair gene clusters (Pickart et al., 2015 — examined effects on >4,000 genes via microarray).

Research focus: Skin remodeling, hair follicle activation, anti-fibrotic action in lung tissue.

Key findings: Pickart L (1973) — original isolation. Pickart & Margolina (2018, Int J Mol Sci) — comprehensive review of GHK-Cu mechanisms and skin/wound-healing literature.

How researchers approach it: Topical formulations in cosmetic dermatology research; subcutaneous routes appear in tissue-repair preclinical work.

Considerations: Copper-bound vs unbound forms behave differently. Most cosmetic-grade research is on topical delivery.

Citations

1. Pickart L, Margolina A. Int J Mol Sci 2018;19(7):1987.

KPV

In KGLOW blend · α-MSH C-terminal tripeptide · Lys-Pro-Val

What it is: A C-terminal tripeptide fragment (Lys-Pro-Val) of α-MSH (alpha-melanocyte stimulating hormone).

Mechanism: Anti-inflammatory action via melanocortin pathway and NF-κB suppression — without the pigmentary effects of full-length α-MSH.

Research focus: Inflammatory bowel disease models, skin inflammation, antimicrobial activity.

Key findings: Brzoska T, et al. (2008, Endocr Rev) — comprehensive review of α-MSH-derived peptides in inflammation.

How researchers approach it: Oral and topical in preclinical IBD and dermatology models.

Considerations: Investigational across all routes.

Citations

1. Brzoska T, et al. Endocr Rev 2008;29(5):581-602.

Melanotan II (MT-2)

SUBQ SKU available · Cyclic α-MSH analog · non-selective MC agonist

What it is: A synthetic cyclic analog of α-MSH.

Mechanism: Non-selective melanocortin receptor agonist (MC1R, MC3R, MC4R, MC5R). MC1R activation drives melanogenesis (skin pigmentation); MC4R is involved in appetite and sexual function pathways.

Research focus: Photoprotection research, erythropoietic protoporphyria (the related compound afamelanotide is FDA-approved for this rare disease), libido/sexual function research.

Key findings: Hadley ME (1996) — original characterization. Subsequent research has examined receptor selectivity and the trade-offs of broad melanocortin agonism.

How researchers approach it: Subcutaneous in research and cosmetic-research settings.

Considerations: Non-selectivity is the defining feature — researchers note GI and cardiovascular effects in the literature. Pigmentary changes (including new mole formation) have been documented.

Citations

1. Hadley ME, Hruby VJ. Trends Pharmacol Sci 1996;17(11):378-380.

Section 4

Metabolic & Body Composition

Retatrutide (GLP-3 RT)

SUBQ SKU available · Triple-receptor agonist · GLP-1 / GIP / glucagon

What it is: A triple agonist of GLP-1, GIP, and glucagon receptors — a "GLP-3" investigational compound under development by Eli Lilly.

Mechanism: Simultaneous agonism of three incretin/glucagon-family receptors. The glucagon arm is hypothesized to drive additional energy expenditure beyond what GLP-1/GIP dual agonists (tirzepatide) achieve.

Research focus: Body weight reduction in obesity trials, glycemic control in T2DM, hepatic fat reduction.

Key findings: Phase 2 obesity trial (Jastreboff et al., NEJM 2023) studied body weight endpoints over 48 weeks across multiple dose cohorts — the trial demonstrated among the largest body composition effects in the published incretin literature.

How researchers approach it: Once-weekly subcutaneous in published trial designs.

Considerations: Investigational — Phase 3 trials ongoing as of 2026. Not yet FDA-approved. GI side effect profile is the primary clinical-trial finding.

Citations

1. Jastreboff AM, et al. NEJM 2023;389:514-526. "Triple-Hormone-Receptor Agonist Retatrutide for Obesity."

Section 5

Cellular Aging

NAD+ (Nicotinamide Adenine Dinucleotide)

SUBQ SKU available · Coenzyme · not a peptide

What it is: Not a peptide — a coenzyme present in every living cell, central to redox reactions, mitochondrial energy production, and the activity of sirtuins (SIRT1-7) and PARP enzymes involved in DNA repair.

Mechanism: Substrate for NAD+-consuming enzymes (sirtuins, PARPs, CD38). Cellular NAD+ pools decline with age in published research (Verdin, Science 2015).

Research focus: Mitochondrial function, sirtuin activity, age-related metabolic decline.

Key findings: Verdin E (2015, Science) — review of NAD+ decline as a hallmark of aging. Multiple human trials have examined NAD+ precursors (NR, NMN); IV and subcutaneous NAD+ research is more limited but expanding.

How researchers approach it: IV infusion is the most-studied delivery route; subcutaneous research is emerging.

Considerations: Bioavailability and pharmacokinetics differ substantially across routes. Direct NAD+ administration vs precursors is an active research debate.

Citations

1. Verdin E. Science 2015;350(6265):1208-1213. "NAD+ in aging, metabolism, and neurodegeneration."

Epithalon (Epitalon)

SUBQ SKU available · Synthetic tetrapeptide · Ala-Glu-Asp-Gly

What it is: A synthetic tetrapeptide (Ala-Glu-Asp-Gly) developed at the St. Petersburg Institute of Bioregulation and Gerontology.

Mechanism: Telomerase activation in cell-culture studies; pineal gland function modulation in rodent models.

Research focus: Russian-origin gerontology research on lifespan extension in murine models, melatonin rhythm in aging humans.

Key findings: Khavinson VK (2002, Bull Exp Biol Med) — telomerase activation in human cell culture. Anisimov VN et al. — multiple rodent lifespan studies out of the same institute.

How researchers approach it: Subcutaneous in original research designs.

Considerations: The strongest published data is from a single research group. Independent replication outside that group is more limited. Investigational.

Citations

1. Khavinson VK, et al. Bull Exp Biol Med 2003;135(6):590-592.

Section 6

Cognition & Neuropeptides

Semax

SUBQ SKU available · ACTH(4-10) analog · 7-aa

What it is: A 7-amino-acid synthetic analog of ACTH(4-10), developed at the Russian Academy of Sciences.

Mechanism: BDNF and NGF expression upregulation in cortical and hippocampal tissue (Dolotov et al., 2006); melanocortin-receptor adjacent activity without significant adrenal effects.

Research focus: Stroke recovery (where it has Russian regulatory approval), cognitive performance, neuroprotection.

Key findings: Dolotov OV et al. (2006, J Neurochem) — BDNF/NGF upregulation. Gusev EI et al. — Russian stroke trials.

How researchers approach it: Intranasal is the most-studied delivery route — bypasses first-pass metabolism, direct nose-to-brain transport.

Considerations: The bulk of clinical data is from Russian research groups. Investigational outside Russia.

Citations

1. Dolotov OV, et al. J Neurochem 2006;97(1):82-86.

Selank

SUBQ SKU available · Tuftsin analog · 7-aa

What it is: A 7-amino-acid synthetic analog of tuftsin (a natural immunomodulatory peptide), also developed in Russia.

Mechanism: GABAergic and serotonergic modulation; enkephalinase inhibition (extends endogenous enkephalin signaling).

Research focus: Generalized anxiety, cognitive performance under stress, immune modulation.

Key findings: Zozulya AA et al. (2008, Bull Exp Biol Med) — anxiolytic effects in clinical research vs medazepam without sedation or dependence.

How researchers approach it: Intranasal, similar to Semax.

Considerations: Same Russian-research caveat as Semax. Investigational outside Russia.

Citations

1. Zozulya AA, et al. Bull Exp Biol Med 2008;145(5):605-608.

Where to go from here

The fastest way to internalize this material

Pick one peptide and read its primary citations directly. PubMed is free. Most of the studies cited above have publicly accessible abstracts; many have full-text PDFs available through institutional access.

If a specific peptide caught your attention, the next step in any researcher's workflow is:

• Read the original paper(s)
• Read the most recent review article in the same area
• Check ClinicalTrials.gov for active human research

If you have a specific research question or want to explore the SubQFusion catalog:

Browse the SubQFusion catalog →