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GREENVEIL

  • beauty
  • industrial

L-Thioproline

CAS 2756-91-4

Also registered as 4 other CAS numbers

2928-83-8 · 6070-92-4 · 444-27-9 · 34592-47-7

L-Thioproline chemical structure

Concern score

Not assessed — no hazard data yet.

L-Thioproline in plain language

What it is

On cosmetic ingredient lists it appears as “Timonacic”.

Also known as Timonacic · Timonacic, (r)- · (4R)-1,3-Thiazolidine-4-carboxylic acid · 4-THIAZOLIDINECARBOXYLIC acid, (r)- · 4-THIAZOLIDINECARBOXYLIC acid, l- · L-4-THIAZOLIDINECARBOXYLIC acid

Show all 19 names

Thioproline, l- · Timonacic, (-)- · (4R)-1,3-thiazolidin-3-ium-4-carboxylate · (4R)-4-Thiazolidinecarboxylic acid · (R)-(-)-4-Thiazolidinecarboxylic acid · (R)-(-)-THIAZOLIDINE-4-CARBOXYLIC acid · 4-Thiazolidine carboxylic acid · 4-Thiazolidinecarboxylic acid, (4R)- · 4-thiaproline · L-Thiazolidine-4-carboxylic acid · L-thiaproline · Thioproline · gamma-thioproline

What it does

Used in cosmetics as a skin-conditioning agent.

  • Skin conditioning
Is it a concern?
We haven't assessed a concern score for this ingredient yet. It is listed for cosmetic use in the EU.

Regulation

No restrictions found. L-Thioproline appears in these published regulatory listings.

Recorded in these product areas

  • Found in consumer products
  • Industrial
  • EUCosIngActiveListed in CosIng inventory for cosmetic use.
    • Listed in CosIng inventory for cosmetic use.Source →
  • USEPAcommercial use observedEPA CPDat observed this chemical in 0 composition records across product categories including unclassified products.
    • EPA CPDat observed this chemical in 0 composition records across product categories including unclassified products.Source →
  • USFDAlisted in openFDA substanceopenFDA substance registry classifies this ingredient as chemical.
    • openFDA substance registry classifies this ingredient as chemical.Source →

Expert safety opinions

No expert opinion on file for L-Thioproline. These are the independent scientific bodies that assess ingredients like this one; we show an opinion only when a record we hold cites it.

  • SCCS

    EU Scientific Committee on Consumer Safety

    No SCCS opinion on file.

  • CIR

    Cosmetic Ingredient Review (US expert panel)

    No CIR safety assessment on file.

Evidence & sources

No graded research studies for L-Thioproline yet. This record is compiled from the published data sources below — registries and regulatory listings, not study findings.

6 data sources

Where this comes from

  • CosIng

    regulatory · updated 2026-09-23

    Open →

  • EPA Chemical and Products Database

    exposure · updated 2020-08-31

    Open →

  • EPA DSSTox Identifiers

    chemistry · updated 2025-12-29

    Open →

  • FDA GSRS UNII

    registry · updated 2026-02-26

    Open →

  • openFDA Substance

    registry · updated 2026-05-24

    Open →

  • PubChem Live Enrichment

    chemistry · updated 2026-05-17

    Open →

Suitability

Context-specific fit derived from published classifications and the current ingredient evidence profile.

Fragrance avoidance

Nothing to weigh for this context yet.

No signal in this context

We have no published hazard signal for this ingredient, so we cannot say how it behaves in this context — that is missing evidence, not a clean result.

Where it has been recorded

How often EPA CPDat has listed L-Thioproline in a product composition. These are source records, not Greenveil catalog products.

Named organisations

1

Typical roles

Skin conditioning
See products using L-Thioproline →