Common Name(s): Pyrrolidine-2-carboxylic acid,l-proline

CAS Number: 147-85-3

DESCRIPTION

What It Does: Provides hydroxyproline precursor collagen support and osmoprotective nmf conditioning.

Why It's Used: The collagen imino acid — proline and its hydroxylated form hydroxyproline comprise approximately 25% of all collagen amino acids, making l-proline the essential structural amino acid for topical collagen support.

How It Works: Hydroxylated by prolyl hydroxylase (requires vitamin c) to form hydroxyproline — essential for collagen triple-helix stability. nmf osmoprotective function via pyrrolidine ring water interaction. proline-rich repeats in collagen provide gly-pro-hyp triple-helix structure.

Typically Found In: Collagen-support products,nmf moisturisers,anti-aging formulas

TECHNICAL DETAILS

Primary Category: Active ingredient – collagen amino acid

Secondary Functions: Skin conditioning

Application Areas:

Typical Concentration Range: 0.5%–5%

SOURCING & ETHICS

Vegan Status: Conditional - feedstock declaration required

Halal Status: Unverified - feedstock declaration required (plant, animal and petrochemical routes all exist)

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier. [audit 2026-07-29 rev2: origin-dependent: the same inci exists in plant, animal and petrochemical versions and the name does not discriminate. determination requires shariah-panel sign-off.]

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1–2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Proline's prolyl hydroxylase conversion to hydroxyproline is completely vitamin c-dependent: the hydroxylase enzyme requires ascorbate as cofactor. this biochemical interdependence explains why vitamin c deficiency (scurvy) produces defective collagen — hydroxyproline cannot form without vitamin c, and without hydroxyproline the collagen triple helix cannot maintain its structure at body temperature, causing tissue fragility.

Last Verified: 2026-03-12

Primary Sources: Cosing database,cir safety assessment