Ginko (Ginkgo biloba)

Other common names: Maidenhair tree
Latin name: Ginkgo biloba L. [Ginkgoaceae]
Plant part: Leaf

The ginkgo tree is native to China. It is the last surviving member
of its family (Ginkgoaceae) and more closely resembles ancient ferns
than deciduous trees. Ginkgo is extremely hardy, and specimens over
one thousand years old have been reported in China, Korea, and Japan.
The seeds have been used therapeutically in China and eastern
Asia for over 2,000 years. Therapeutic use of the leaves has gained
popularity in the past 40 years (Schulz, Hänsel, and Tyler, 2001).
Most of the ginkgo leaf products on the market are concentrated
extracts with a ratio of roughly 50 parts leaf to 1 part extract. This
means that the manufacturing procedure, which uses an acetonewater
extraction and several purification steps, yields one kilogram of
final product from 50 kilograms of dried ginkgo leaves. Standardized
leaf extracts generally contain 22 to 27 percent flavonol glycosides,
5 to 7 percent terpene lactones (2.8 to 3.4 percent ginkgolides A, B,
and C, and 2.6 to 3.2 percent bilobalide), and less than 5 ppm ginkolic
acids. While many ginkgo constituents are purported to contribute to
the herb’s therapeutic effect, some of the constituents have been
linked to specific pharmacological actions. The ginkgo flavonol glycosides
are efficient free-radical scavengers, the ginkgolides inhibit
platelet-activating factor, and the ginkgolides and bilobalide have
demonstrated neuroprotective properties (Schulz, Hänsel, and Tyler,
2001; Foster and Tyler, 1999).

Dementia is a clinical syndrome characterized by losses of cognitive
and emotional abilities that are sufficient to interfere with daily
functioning and quality of life. The American Psychiatric Association,
in its Diagnostic and Statistical Manual of Mental Disorders
(DSM-IV-TR) (2000), defines the diagnostic features of dementia as
memory impairment, deterioration of language function (aphasia),
impaired ability to execute activities despite intact muscles, senses,
and comprehension of the task (apraxia), and disturbances in executive
functioning (the ability to think abstractly and to plan, initiate, sequence,
monitor, and conclude complex behavior). Dementia can be
mild (work and social activities are impaired but the capacity for independent
living remains), moderate (independent living is hazardous
and some supervision is required), or severe (daily living activities
are impaired, continuous supervision is required, and the person
is largely incoherent or mute). Dementia can be caused by Alzheimer’s
disease, vascular disease, human immunodeficiency virus
(HIV), head trauma, Parkinson’s disease, Huntington’s disease, Pick’s
disease, Creutzfeldt-Jakob disease, substance abuse, and other medical
conditions.

Alzheimer’s disease is observed as a gradual and progressive cognitive
decline. Diagnosis of Alzheimer’s disease is often made once
other causes of dementia have been ruled out, due to a lack of laboratory
markers. Cerebrovascular disease can cause vascular dementia
diagnosed by characteristic neurological signs or laboratory evidence.
Symptoms include transient ischemic attacks (ministrokes),
hemipareses, tinnitus (ringing in the ears), dizziness, headache, and
anxiety (Schulz, Halama, and Hoerr, 2000).

Ginkgo has also been tested in treatment of cramping and pain in
the legs while walking, a condition termed intermittent claudication.
This condition is due to mild to moderate peripheral arterial disease
(peripheral arterial occlusive disease), in which narrowing of the arteries
limits the blood supply to the legs. Early stages of the disease
are without symptoms, but later stages are associated with leg pain
and muscle cramps upon walking and, ultimately, ischemic ulceration,
gangrene, and tissue loss. The stages have been classified in a
system according to Fontaine: stage I represents those who are
asymptomatic with isolated arterial stenosis of the lower limbs; stage
II is mild to moderately severe leg pain and muscle cramps upon
walking; stage III are those with pain while resting; and stage IV are
those with ulcerations and gangrene. Ginkgo has been tested in the
treatment of stage IIb, in which subjects have a pain-free walking distance
of 200 meters or less (Peters, Kieser, and Holscher, 1998).