Two of the four compounds that define a Centella asiatica specification are not extracts in the usual sense at all. Asiatic acid and madecassic acid are isolated single compounds, sold at high purity, and priced accordingly. Buyers who order them against a total-triterpene specification, or who treat them as interchangeable with asiaticoside and madecassoside, end up with material that does not match what their formulation was written for.
Glycoside and genin: the distinction that drives the price
The principal triterpenes in Centella asiatica occur naturally as glycosides — the active molecule with a sugar chain attached. Remove that sugar chain and what remains is the aglycone, known in this trade as the genin.
Each of the two commonly specified glycosides has a corresponding genin:
| Glycoside | Corresponding genin (aglycone) |
|---|---|
| Asiaticoside | Asiatic acid |
| Madecassoside | Madecassic acid |
All four are ursane-type pentacyclic triterpenoids from the same plant — the glycosides are collectively referred to as centellosides — but they are four distinct molecules with different molecular weights, different solubility behaviour, and different market prices. Madecassic acid carries an additional hydroxyl group relative to asiatic acid, which is what separates the two genins from one another.
The practical consequence: a percentage against asiaticoside and a percentage against asiatic acid are not comparable figures. Because the sugar chain contributes a substantial share of the glycoside’s molecular weight, a given mass of asiaticoside does not deliver the same quantity of the underlying triterpene as the same mass of asiatic acid. If your specification was written against one and you receive the other, the numbers on the certificate of analysis may look reassuring while the material is wrong.
What “free genins” means on a specification
Alongside the isolated single compounds, the market offers a free genins grade — commonly seen at 85%. “Free” here means the aglycones present as such, rather than bound up in their glycoside forms. It is a combined specification covering the genin fraction rather than a single named compound.
This is a genuinely different product from either isolated acid, and from a total-triterpene grade. If your specification names free genins, say so explicitly and state the percentage; if it names asiatic acid specifically, do not accept a free-genins grade as equivalent without checking the composition.
Identifiers on the documentation
Each of these compounds has its own CAS number, and because they are distinct molecules the numbers differ between the glycoside and its genin. Buyers working to a chemical identifier rather than a botanical name should quote the CAS number for the specific compound they need, and confirm it against the supplier’s certificate of analysis before ordering — an identifier mismatch between the purchase order and the COA is one of the more common causes of a rejected delivery in this category. SpecNexa lists CAS numbers on a listing where the supplier has declared one.
Commercial grades available
Across SpecNexa’s supply base the genin-side grades are supplier-declared as follows, each reported by HPLC:
| Specification | Grade | Typical appearance | Test method |
|---|---|---|---|
| Asiatic acid | 90% | White powder | HPLC |
| Madecassic acid | 80% | White powder | HPLC |
| Free genins | 85% | White powder | HPLC |
All three sit at the high-purity end of the category and present as white powders. That is worth knowing on receipt: the lower-percentage total-triterpene grades are brown, and colour tracks refinement fairly reliably across this ingredient. A brown powder delivered against a genin specification warrants a query before it reaches production.
Why a formulation specifies a genin
Buyers move to an isolated genin when the specification requires a tightly defined single-compound load rather than a botanical fraction. Ratio extracts and total-triterpene grades vary in composition between producers and between crops; an isolated acid at 90% does not. Where a formulation is built around a defined quantity of one molecule, and where batch-to-batch reproducibility matters more than cost per kilo, the isolated compound is the straightforward answer.
Solubility behaviour also differs between the glycosides and their genins, which matters where the material has to go into a particular carrier system. Confirm behaviour in your own system rather than assuming equivalence with the glycoside you may have used previously.
Assay method and reference standard
These compounds are conventionally assayed by HPLC, and for isolated high-purity material the reference standard matters as much as the method. Two suppliers can both report 90% and be measuring against different standards. Ask which reference standard the assay was run against, and confirm your own quality team can reproduce the method on receipt.
For high-value isolates, the case for independent verification testing is stronger than for a low-percentage botanical fraction: the price per kilo is higher, and the gap between a genuine 90% isolate and an overstated one is commercially significant.
Where the genins fit against a titrated extract
A titrated extract of Centella asiatica — often abbreviated TECA — is standardised to a defined ratio between asiaticoside and the genins, rather than to a single number. If you are working to a titrated specification, the genins are part of what is being titrated, and the ratio matters as much as the total. State the exact ratio and tolerance you require rather than ordering against the abbreviation.
What to include in your RFQ
- The exact compound — asiatic acid, madecassic acid, or free genins. Not “Centella extract” and not a percentage on its own.
- The percentage and the assay method — for example asiatic acid 90% by HPLC.
- The reference standard your specification is written against, if you have one.
- Physical form and particle size if your process is sensitive to them.
- Intended application and destination market — cosmetic, supplement, food — which determines the documentation set and the permitted-use position.
- Annual volume — isolates price very differently at sample scale versus production scale.
- Documentation required — certificate of analysis showing the method, specification sheet, and safety data sheet.
Regulatory note
Centella asiatica derivatives are traded for cosmetic and for food or supplement applications, and the two routes carry different documentation and different permitted-use rules by market. Permitted status, use levels, and labelling requirements vary by destination and are the buyer’s responsibility to confirm for the market being supplied. A supplier specification does not substitute for that check.
Sourcing the Centella genins through SpecNexa
SpecNexa lists Gotu Kola / Centella asiatica extract across the full supplier-declared grade range, from 10% total triterpenes through to the isolated acids covered here. If your specification names a marker compound or percentage not shown, include it in your request and it can usually be quoted.
All specification information is supplier-declared and provided for sourcing discovery. Buyers should confirm the final agreed specification, including assay method, grade, and batch documentation, directly with the contracting supplier.