What are peptides?

Definition of a peptide

A peptide is a molecule made up of at least two amino acids joined by a peptide bond. Depending on the number of amino acids in the chain, several types are distinguished:

• dipeptides — two amino acids,
• tripeptides — three amino acids,
• tetrapeptides, pentapeptides, hexapeptides, octapeptides — four, five, six, and eight amino acids respectively,
• oligopeptides — a few to a dozen or so amino acids,
• polypeptides — longer chains, approaching the structure of proteins.

The trade names of many cosmetic peptides contain information about chain length — e.g. Palmitoyl Tripeptide-1 (three amino acids) or Acetyl Hexapeptide-8 (six amino acids).

Peptides vs amino acids — the difference

Amino acids are the single "building blocks" — the smallest structural units from which peptides and proteins are made. A peptide is already a combination of several amino acids in a specific order, which gives it a defined structure and biological function. Put simply: an amino acid is a letter, a peptide is a short word made of those letters, and a protein (like collagen) is a long sentence or paragraph.

This distinction has cosmetic significance: single amino acids in cosmetics mainly act as a hydrating agent (as part of the skin's natural moisturising factor, NMF), while peptides — thanks to their structure — can perform a signalling function, "instructing" skin cells to take specific actions.

Peptides vs proteins and collagen

Collagen is a structural protein made of very long amino acid chains (hundreds to thousands of amino acid residues) that gives skin its strength and firmness. Peptides used in cosmetics are usually much shorter than full-size proteins — this is one reason they can more easily penetrate the epidermal barrier and reach the living layers of the skin.

Collagen peptides form precisely from the hydrolysis (breakdown) of collagen into shorter fragments — more on this phenomenon in the article Bioactive marine peptides, where we describe it using the example of fish collagen.

How are peptides used in cosmetics made?

Peptides used in cosmetics are formed in two main ways:

1. Chemical synthesis — a peptide is designed and manufactured in a lab "from scratch," to precisely replicate a known amino acid sequence with a desired action (e.g. Matrixyl, Argireline).
2. Hydrolysis of natural proteins — long protein chains (e.g. fish collagen) are broken down enzymatically or chemically into shorter, bioactive peptide fragments (e.g. marine peptides in Biopeptide Complex technology).

Both routes lead to molecules of similar size and similar ability to penetrate the skin, but they differ in raw material origin and how the specific amino acid sequence is obtained.

Types of peptides in cosmetics

Cosmetic peptides are usually divided into several main functional categories:

• signal peptides — stimulate collagen and elastin synthesis,
• copper peptides — transport copper ions supporting regeneration,
• neuropeptides — limit facial muscle tension,
• biomimetic peptides — imitate the skin's natural biological signals,
• bioactive marine peptides — obtained from hydrolysates of marine-origin collagen.

A full overview of all categories, with examples and mechanisms of action, can be found in the main guide: Peptides in cosmetics — a complete guide →

Why are peptides popular in skincare?

The popularity of peptides in cosmetics stems from several factors:

• they work at the level of cellular signalling, not just on the surface,
• they're generally well tolerated, making them suitable for a wide range of users, including those with sensitive skin,
• they can be combined with other popular active ingredients (retinol, hyaluronic acid, vitamin C),
• they offer many subcategories tailored to different skincare needs (firmness, facial muscle tension, regeneration).

FAQ

Sources

• General knowledge of biochemistry and cosmetology regarding peptide structure and classification.
• WellU/Larens manufacturer materials (regarding specific technologies, see: Biopeptide Complex).

Content prepared: August 2026.