Rhein has a Natural Origin Index (NOI) of 1.00 (scale 0–1) per ISO 16128. Isolated from rhubarb or senna root/leaf as a naturally occurring anthraquinone; no significant commercial petrochemical synthesis route. An NOI of 1.00 means 100% of its molecular mass is traceable to a natural, renewable source.

Is Rhein natural? NOI 1.00 — Is That Natural?

How we scored it

Anthraquinone carboxylic acid phytochemical; commercially isolated from rhubarb/senna extracts, so the whole molecule is natural (n=1).

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

Extracted and purified from rhubarb (Rheum) roots or senna (Cassia/Senna) leaves, where it occurs naturally. Laboratory synthesis exists but is not the commercial cosmetic route.

In plain English

A plant compound from rhubarb or senna with antimicrobial properties. It's isolated directly from the plant rather than synthesised from scratch.

Structure

4,5-dihydroxy-9,10-dioxoanthracene-2-carboxylic acid

PubChem CID 10168 ↗

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.
2Rhein. PubChem CID 10168. National Center for Biotechnology Information. pubchem.ncbi.nlm.nih.gov ↗
3RHEIN. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
4RHEIN. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=RHEIN