IJT - CIR - February 2024 - 67S

Burnett et al.
67S
The cultured cambial meristem cells are then subjected to
specific culture conditions (details not provided) in order to
produce various secondary metabolites. Finally the cultured
cambial meristem cells are harvested with a filter-press.
Composition/Impurities
Ginkgo Biloba Leaf Extract. Table 3 summarizes the composition
ranges of the major constituents of various extracts
(standardized and non-standardized) of Ginkgo biloba leaves
taken from the published literature. It is not always clear
whether any of these are similar to the cosmetic ingredient
Ginkgo Biloba Leaf Extract. However, according to one
supplier, their raw material is similar to GBE EGb 761®.8
The target levels of the major constituents of the standardized
GBE EGb 761® are reported to be: not less than 6%
total terpene trilactone content, not less than 24% total flavonol
glycosides, and not more than 5 ppm (.0005%) ginkgolic
acids.4 This extract is reported to be a brown powder
with characteristic smell containing not more than 20 ppm
heavy metals and not more than 2 ppm arsenic. The standardized
extract used in National Toxicology Program (NTP)
studies is reported to contain 15.4% terpene trilactones, 31.2%
flavonol glycosides, and 10.45 ppm (.001%) ginkgolic acids.9
According to an analysis ofcrude extracts ofGinkgo biloba
leaves, there are seasonal differences in the levels of certain
constituents, with concentrations of flavonol glycosides
higher in the spring than in the autumn (136.3 mg/100 g vs
46.0 mg/100g) and biflavones higher in the autumn than in the
spring (194.8 mg/100 g vs 44.28 mg/100 g)10
General Ginkgo biloba composition was reported in the
Physician's Desk Reference for Herbal Medicines to be
the following: flavonoids (.5% to 1.8%) including
Table 3. Major Constituents of GBEs (%).†
Class
Identified
Terpene trilactones
Total
Bilobalide
Flavonol glycosides
Alkylphenols
Ginkgolide A
Ginkgolide B
Ginkgolide C
Ginkgolide J
Total
Quercetin
Kaempferol
Isorhamnetin
Ginkgolic
acids,
cardanols
†Adapted from the NTP 2013 report.
‡Van Beek 2009 also reports EGb761® contains 13% carboxylic acids, 7% proanthocyanidins, 2% catechins, 20% non-flavonol glycosides, 4% high molecular
weight compounds, 5% inorganic constituents, 3% water (solvent), and 3% various and 13% unknown compounds.
*Constituent ranges are not specific to the cosmetic ingredient Ginkgo Biloba Leaf Extract but to constituent ranges of standardized and non-standardized GBEs
found in the published literature.
≤.0005
monosides, biosides and triosides ofquercetin, isorhamnetins,
3-O-methylmyristicins, and kaempferol (may be esterified
with p-coumaric acid); biflavonoids (.4% to 1.9%) including
amentoflavone, bilobetin, 5-methoxybilobetin, ginkgetin, and
isoginkgetin; proanthocyanidins (8% to 12%); trilactonic
diterpenes (.06% to .23%) including ginkgolide A, B, and C;
and trilactonic sesquiterpene bilobalide (.04% to .2%).3
The United States Pharmacopeia states that " ginkgo " consists
of the dried leaf of Ginkgo biloba Linne (Fam. Ginkgoacaeae).11
It contains not less than .5% offlavonoids, calculated as
flavonol glycosides, with a mean molecular mass of 756.7; and
not less than .1% of terpene lactones, calculated as the sum of
bilobalide, ginkgolide A, ginkgolide B, and ginkgolide C, both
on the dried basis. This reference also states that " powdered
ginkgo extract " is prepared from dried and comminuted leaves of
Ginkgo extracted with an acetone-watermixture or other suitable
solvents. It contains not less than 22.0% and not more than
27.0% of flavonoids, calculated as flavonol glycosides, with a
mean molecular mass of 756.7; and not less than 5.4% and not
more than 12.0% of terpene lactones, consisting of between
2.6% and 5.8% of bilobalide and between 2.8% and 6.2% of
ginkgolide A, ginkgolide B, and ginkgolide C.
The British Pharmacopoeia states that " ginkgo leaf "
content should be not less than .5% of flavonoids, calculated
as flavone glycosides (dried drug).12
An extraction with 60% w/w ethanol ofdried green Ginkgo
biloba leaves yielded an extract comprised of 3.4% flavone
glycosides, .7% terpene lactones, and 5.5% ginkgolic acids.13
Further fractionation by liquid-liquid partition between water
and heptane yielded a fraction containing .3% flavone glycosides,
.1% terpene lactones, and 24.6% ginkgolic acids.
For use as an herbal medicine in Germany, GBE must be
extracted with acetone/water and contain 22%-27% flavone
Standardized Extract (EGb 761®)
Specification4,‡
6
Standardized and NonStandardized
GBEs*,14,67-69
.07-14.23
.03-8.64
.01-2.90
<.005-1.75
<.005-1.75
.03-.78
24
.18-35.54
<.01-8.34
.02-5.57
.04-1.13
<.0005-9.0
NTP Study Extract9
15.4
6.94
3.74
1.62
3.06
Not measured
31.2
16.71
12.20
2.37
.001

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