Agonist
A molecule that binds to a receptor and activates it, producing a biological response. Peptide agonists are central to most GLP-1 and growth hormone axis research.
24 terms
A
Amino acid
The molecular building blocks of peptides and proteins. There are 20 standard amino acids. Peptides are chains of two or more amino acids linked by peptide bonds.
API (Active Pharmaceutical Ingredient)
The biologically active component of a drug product. In the RUO context, the compound itself - distinct from excipients, carriers, or delivery systems.
Approved indication
The specific condition or use for which a medicine has received regulatory authorisation. A compound may be approved for one indication while being studied for others.
C
C-terminus
The end of a peptide or protein chain that carries a free carboxyl group (-COOH). Many shorter research peptides are defined by their C-terminal sequence - KPV is the C-terminal tripeptide of alpha-MSH.
Certificate of Analysis (COA)
A document from an accredited testing laboratory confirming a compound's identity, purity, and potency for a specific batch. A COA should be requested before any laboratory purchase.
Clinical trial phase
The structured stages through which a candidate compound must pass to reach regulatory approval: Phase I (safety, small healthy volunteer cohort), Phase II (early efficacy, target patient group), Phase III (large-scale controlled trial), Phase IV (post-marketing surveillance).
Copper peptide
A peptide complexed with a copper ion. GHK-Cu (glycyl-L-histidyl-L-lysine:copper2+) is the most studied, with research focused on wound healing and collagen synthesis.
E
Endogenous peptide
A peptide produced naturally within the body. Many research peptides are analogues or fragments of endogenous peptides - BPC-157, for example, is a fragment derived from the gastric protection protein BPC.
Evidence grade
The classification system used in The Compound Index to indicate the highest quality study type completed for a given compound: pre-clinical, Phase I/II, Phase II/III, or clinical/approved.
G
GHRH (Growth Hormone Releasing Hormone)
A hypothalamic peptide that stimulates growth hormone secretion from the pituitary. CJC-1295, sermorelin, and tesamorelin are all GHRH analogues.
GLP-1 receptor
Glucagon-Like Peptide-1 receptor. A G-protein coupled receptor expressed in the pancreas, brain, and gut. The target of semaglutide, tirzepatide, and retatrutide in metabolic and adipose research.
H
Half-life
The time taken for a compound's concentration in the body to reduce by 50%. Critical for understanding dosing intervals in research protocols. DAC (Drug Affinity Complex) modification extends the half-life of GHRH analogues like CJC-1295.
HPLC (High-Performance Liquid Chromatography)
The standard analytical method used to verify peptide purity. HPLC separates compounds in a mixture and measures each component's proportion. A purity of >=98% by HPLC is the minimum standard for research-grade material.
L
Ligand
Any molecule that binds to a specific receptor. Peptide ligands are the active research compounds - the ligand-receptor interaction is the fundamental mechanism studied in most peptide research.
Lyophilized (freeze-dried)
The standard storage form for research peptides. Water is removed under vacuum at low temperature, producing a stable powder. Lyophilized peptides are reconstituted with bacteriostatic water before use in laboratory settings.
P
Peptide
A short chain of amino acids (typically 2-50) linked by peptide bonds. Distinguished from proteins by length - proteins are generally 50+ amino acids. Most research peptides studied here are between 3 and 50 amino acids.
Pre-clinical
Research conducted in laboratory settings (in-vitro cell studies) or animal models before progressing to human trials. The majority of research peptides catalogued here are at the pre-clinical stage for most indications.
Prescription-Only Medicine (POM)
A medicine that can only be supplied on a valid prescription from a qualified prescriber. Some compounds studied in the Index exist as licensed POMs in certain forms - e.g. tesamorelin (Egrifta) in the US.
Purity (%)
The proportion of the intended compound present in a batch, expressed as a percentage. For research-grade peptides, >=98% purity by HPLC is the accepted minimum. Purity is verified per-batch and documented in the COA.
R
Receptor
A protein structure, typically on a cell surface, that binds a specific ligand to produce a cellular response. The receptor-ligand interaction is the mechanism studied in virtually all research peptide investigations.
Research Use Only (RUO)
A regulatory classification indicating that a product is intended solely for in-vitro laboratory research. RUO products are not licensed medicines, not for human or animal consumption, and not evaluated by the MHRA, FDA, or equivalent bodies.
T
Telomere
Protective cap structures at the ends of chromosomes that shorten with each cell division. Telomere length is used as a biomarker of cellular ageing. Epitalon is the most-studied research peptide in telomere research.
Third-party testing
Purity and identity verification carried out by an independent laboratory - not the manufacturer. Third-party COAs are the standard for research-grade material; they are not subject to the supplier's commercial interest.