Ginkgolic acid in ginkgo biloba extract: why the limit decides your supplier
Ask two suppliers for ginkgo biloba extract and both will say "24/6". Ask them what the ginkgolic acid figure is and one will answer in ppm from the current lot while the other goes quiet. That gap is the whole story of this ingredient.
The three questions we ask before quoting ginkgo. In our own quotations we ask the extraction facility for the ginkgolic acid figure of the specific production lot, the analytical method behind it, and the lowest limit they can hold on a repeat run — before a price goes to a buyer. A supplier who cannot answer those three is quoting a grade they do not control.
What ginkgolic acid is
Ginkgolic acids are a group of alkylphenol compounds that occur naturally in the ginkgo tree — in the leaf, the fruit and the bark. They are not the active constituents you are buying. They are the ones that give ginkgo its reputation for causing allergic reactions, and they are the reason ginkgo raw material has to be processed rather than simply dried and milled.
A crude leaf preparation can contain ginkgolic acids in the thousands of ppm. A properly refined extract contains single digits. Getting from one to the other is a process step that costs money, which is exactly why the figure varies so much between suppliers.
Why the limit is specified at all
Because of the sensitisation risk, most pharmacopoeial monographs and most brand specifications for ginkgo extract set a ceiling on ginkgolic acid. The limit you will see most often is below 5 ppm, and a significant share of U.S. supplement brands now write below 1 ppm into their purchase specification.
The practical consequence: an extract that meets the 24/6 marker content but carries, say, 40 ppm of ginkgolic acid is not the product you can put on the market — regardless of how good its flavonoid number looks.
A 24/6 label tells you about the actives. The ginkgolic acid figure tells you whether you can sell it.
Why suppliers avoid the question
Three reasons, and they are all about cost:
- Testing is a separate analysis. Ginkgolic acid is measured by HPLC under its own method, and it costs money per lot. A supplier who tests only for flavonoids and lactones has no figure to give you.
- Hitting low limits requires better processing. Reducing ginkgolic acid means more refining, more solvent, more time, and a lower yield. Material at 1 ppm costs more to make than material at 20 ppm.
- The limit is invisible if you do not enforce it. Most buyers check the actives and never test the ginkgolic acid, so there is commercial pressure to test the flattering number and stay quiet about the other.
What to write into your specification
Spell it out, in the specification document rather than in an email thread:
| Parameter | How to state it |
|---|---|
| Total flavonoids | ≥ 24% by HPLC, method named |
| Terpene lactones | ≥ 6% by HPLC, method named |
| Ginkgolic acid | < 5 ppm (or < 1 ppm for a stricter claim), stated as a maximum, measured by HPLC |
| Reporting | The measured figure, not "conforms", to be printed on the batch COA |
The last line matters more than it looks. If the COA is allowed to say "conforms" without a number, you have bought a promise rather than a measurement — and you have no comeback if a retail customer's own laboratory disagrees.
A related problem: flavonoid inflation
Ginkgo is one of the more frequently adulterated botanical extracts. The commercial temptation is to raise the flavonoid figure with cheap flavonoid-rich material — rutin or quercetin from other sources — because a buyer who only reads the total flavonoid line will see a higher number and a lower price.
Two checks help:
- Ask for the full chromatogram, not just the assay result. A pattern that does not match genuine ginkgo is visible in the trace.
- Look at the relationship between flavonoids and lactones. The two move together in genuine material. A product reporting high flavonoids and thin lactones deserves a question.
How a supplier should answer
A supplier who genuinely produces to specification will answer in one message, with a number:
"Ginkgolic acid on the current lot is 1.8 ppm, measured by HPLC, and the figure is printed on the COA. We can produce below 1 ppm on request — allow an additional lead time."
That answer contains a value, a method, a document reference, and a limit of capability. If you collect nothing else from this article, collect that standard of answer — for ginkgo and for every other extract where a secondary limit decides whether the product is sellable.
Need a ginkgo specification checked?
Send us the specification you are working to and we will confirm what we can meet, at what lead time, with which figures reported on the COA.