GINKGO
Source:Ginkgo bilobaL. (Family Ginkgo-
aceae)
Common/vernacular names:Maidenhair
Tree.
GENERAL DESCRIPTION
Monotypic deciduous tree to 40 m; leaves
alternate or borne on spurs in clusters of
3–5; parallel veined, broad fan shaped, up to
12 cm, with notch at apex, forming two dis-
tinct lobes, hence the species name ‘‘biloba’’.
Flowers dioecious; male flowers on pendulous
catkins with numerous, loosely arranged an-
thers in stalked pairs on a slender axis; female
flowers are in pairs on long foot-stalks. The
drupe-like fruits have an acrid, foul-smelling
pulp (likened to dog droppings) surrounding a
single smooth, oval, thin-shelled, semi-edible
nut (seed).
Ginkgo is known only from cultivation;
widely planted ornamental tree worldwide;
limited occurrence in undisturbed forests in
Zhejiang province disputed as natural sponta-
neous specimens or progeny of planted
specimens.
The leaves are used in Western pharmaceu-
ticals; seeds and leaves traditionally used in
China. Leaves are grown on a commercial
scale in China, South Carolina and Maryland
in the United States, and in the Bordeaux
region of France (FOSTER AND YUE).
CHEMICAL COMPOSITION
Leaves and root bark contain terpenoids,
including the monomethyl-mononorditer-
penes: ginkgolide A (3a-OH, 10b-OH), gink-
golide B (1,3a-OH, 10b-OH), ginkgolide C
(1,3a-OH, 7,10b-OH) in the root bark and
leaves; ginkgolide M (1a-OH, 7,10b-OH)
in the root bark; ginkgolide J (3a-OH,
7,10b-OH) in the leaves; and the sesquiter-
pene bilobalide (10a-OH, 8b-OH) in the
leaves. The ginkgolides differ in the number
and position of hydroxyl groups present on
C1, C3, and/or C7 of the spirononane frame-
work.1–3
Flavonoids from the leaves include the
flavones luteolin and tricetin (dalphidenon).
Biflavones including amentoflavone, bilobe-
tin, ginkgetin; isoginkgetin, sciadopitysin, 5^0 -
methoxybilobetin,ginkgetin,andisoginkgetin
glucosides; flavonols including kaempferol,
kaempferol-3-rutinoside, kaempferol-3-O-a-
(6^000 - p-coumaroyl-glucosyl-b-1,4-rha-
mno side), quercetin, quercetin-3-rutinoside
(rutin), quercetin-3-glucoside (isoquercitrin),
quercetin 3-O-a-(6^000 - p-coumaroyl-glucosyl-
b-1,4-rhamnoside), isorharmnetin, myricetin
rhamnoglucoside, and 3-O-methylmyricetin-
3-rutinoside. Catechins include(þ)-catechin,
()-epicatechin, (þ)-gallocatechin, and ()-
epigallocatechin. Proanthocyanidins include
gallocatechin-4,8^00 -catechin(procyanidin)and
gallocatechin-4,8^00 -gallocatechin (prodelphi-
nidin).1,2,4–6
The bioactive ginkgolic acids, 6-(Z-8^0 -hep-
tadecenyl) salicylic and 6-(Z-10^0 -heptadece-
nyl) salicylic acids have recently been isolated
from the leaves and seed coat.7,8
Other leaf components include the ligninZ,
Z,-4,4^0 -(1,4-pentadien-l,5-diyl)diphenol; ster-
oids including megastigmenone, sitosterol
and its glucoside (ipuranol); starch; oil, bal-
sam, benzoic acid, and chromenyl methoxy-
benzoic acid; calcium oxalate raphides; wax
(0.7–1% in dry leaves), consisting of alkanes
and alcohols (75%), esters (15%), and free
acids (10%); pinitol, sequoyitol,D-glucaric
acid, plus shikimic and succinic acids, and
others.1,2
The nut (seed) contains 67.9% starch,
13.1% proteins (globulins, glutelin, and albu-
mins), 2.9% lipids (composed of linoleic,
oleic, palmitic, stearic, linolenic, and a-
hydroxypalmitic acids), 1.6% pentosans; plus
sucrose, glucose, fructose, citric and quinic
acids, fiber, and others.^1
Total synthesis of ginkgolide B has been
achieved.^9Ginkgo 325