Cystine has a Natural Origin Index (NOI) of 1.00 (scale 0–1) per ISO 16128. Obtained by hydrolysing natural keratin (hair/feathers) or by fermentation; both are natural protein-derived routes. An NOI of 1.00 means 100% of its molecular mass is traceable to a natural, renewable source.

Is Cystine natural? NOI 1.00 — Is That Natural?

How we scored it

Whole amino-acid dimer C6H12N2O4S2; keratin-hydrolysate or fermentation derived, no fragmentation needed.

What counts. ISO 16128-2 scores the atoms that remain in the final ingredient. Reagents, solvents, catalysts and protecting groups used during manufacture leave no mass behind and are not counted.

Where it comes from

Commercial L-cystine is mainly extracted by acid hydrolysis of natural keratin from hair or feathers, or produced by fermentation. A minor petrochemical synthesis route exists but is not dominant for cosmetic grade.

In plain English

An amino acid usually obtained by breaking down natural keratin from hair or feathers, or by fermentation. Helps condition hair and can add a light fragrance note.

Structure

(2R)-2-amino-3-[[(2R)-2-amino-2-carboxyethyl]disulfanyl]propanoic acid

PubChem CID 67678 ↗

References

1ISO 16128-1:2016 and ISO 16128-2:2017 — Guidelines on technical definitions and criteria for natural and organic cosmetic ingredients and products. ISO, Geneva.
2Cystine. PubChem CID 67678. National Center for Biotechnology Information. pubchem.ncbi.nlm.nih.gov ↗
3CYSTINE. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
4CYSTINE. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=CYSTINE