Ginkgo Biloba Leaf Extract 24/6

Ginkgo Biloba Leaf Extract 24/6 is the refined and quantified dry extract of the dried leaf of Ginkgo biloba L., family Ginkgoaceae, the only surviving species of its division. The extract itself carries CAS 90045-36-6. Ph. Eur. monograph 1827, ginkgo dry extract refined and quantified, defines the article by a drug-to-extract ratio of 35–67:1 with acetone and water as the extraction solvent, followed by liquid-liquid partition and adsorbent purification. The familiar 24/6 shorthand names the two quantified fractions: about 24% flavonoids expressed as flavone glycosides and about 6% terpene lactones. Both sit inside the pharmacopoeial windows — Ph. Eur. requires 22.0 to 27.0 per cent flavonoids, 2.6 to 3.2 per cent bilobalide and 2.8 to 3.4 per cent ginkgolides A, B and C, and USP Powdered Ginkgo Extract requires NLT 22.0% and NMT 27.0% flavonoids calculated as flavonol glycosides of mean molecular mass 756.7, with terpene lactones at 5.4–12.0% comprising 2.6–5.8% bilobalide and 2.8–6.2% ginkgolides A, B and C. The terpene trilactones are the harder half of the specification and the reason a genuine 24/6 costs what it does. They are bilobalide, CAS 33570-04-6, C15H18O8, MW 326.30; ginkgolide A, CAS 15291-75-5, C20H24O9, MW 408.4; ginkgolide B, CAS 15291-77-7, C20H24O10, MW 424.4; and ginkgolide C, CAS 15291-76-6, C20H24O11, MW 440.4. The flavonoid fraction is quantified after acid hydrolysis as the aglycones quercetin, kaempferol and isorhamnetin, and their ratio is itself an identity check. Ginkgolic acids, the alkylphenols of the raw leaf, are removed during refining and held to a maximum of 5 ppm by both Ph. Eur. and USP; Thovek assays them on every lot and reports the figure rather than a pass statement. Ginkgo extract is one of the most persistently adulterated botanicals in the trade, because the cheapest route to a 24% flavonoid number is to add rutin or quercetin, or to blend in Sophora japonica flavonoid extract, which brings the isoflavones genistin and genistein with it. USP addresses this directly with a limit test for rutin at NMT 4.0% and quercetin at NMT 0.5% in the unhydrolysed extract, and Thovek runs that test alongside an aglycone-ratio check and an isoflavone screen on incoming leaf and on finished lots. The powder is leaf-derived, vegan and vegetarian, non-GMO, and free of milk, egg, soy, fish, crustacean, mollusc, peanut, tree nut, sesame, mustard, celery, lupin and gluten. Sophora-free and soy-free declarations are issued as standard, since the commonest adulterant in this category is itself a legume-family extract and buyers with soy-free finished products need that assurance in writing.