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AMIDINOCYSTEINE.

Valuable CAS 40454-21-5 / HAIR WAVING OR STRAIGHTENING

Amidinocysteine is a cysteine derivative recognized as an effective skin-conditioning agent and humectant. It also functions as a reducing agent for hair structure modification.

Hair Waving or Straightening Skin Conditioning Humectant Reducing Agent

Science

This ingredient acts as a reducing agent, utilizing its sulfhydryl (-SH) group to break disulfide bonds in hair keratin. In skincare, it provides humectant benefits and may reduce oxidative stress through redox reactions akin to N-acetylcysteine.


Research

Medium confidence
Effective range N/A
Optimal

N/A

Key findings

  1. 01 Indicated as an effective reducing agent for hair structure modification (waving or straightening) and as a skin-conditioning agent in external compositions.

Transparency

Not commonly dusted

The Formula

Solubility
Water
Optimal pH 5 – 8
0 7 14

Stability

Prone to oxidation due to its thiol (-SH) group, stability is improved by co-formulating with antioxidants like ascorbic acid and stabilizers such as sodium sulfite.

Synergies

  • Ascorbic acid (antioxidant)
  • Sodium sulfite (stabilizer)

Conflicts

  • Strong oxidizing agents
  • Metal ions (unless chelated)
  • High alkaline environments (outside pH 5.0-8.0)

Safety

CIR Status
Not reviewed
Sensitization risk Unknown

Listed in the EU Cosmetic Ingredient Glossary (CosIng) for hair waving/straightening and skin conditioning, it currently has no specific Annex restrictions under EC Regulation 1223/2009.


Your Skin

Yes Normal
Yes Dry
Yes Oily
Yes Sensitive
Irritancy Unknown
Comedogenicity Unknown

Our Assessment

Valuable

Amidinocysteine is a valuable ingredient, offering proven skin conditioning and humectant properties, with potential for redox benefits, while also serving as a key agent in hair modification.


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