free radical is a molecule with one missing electron. Free
radicals are a normal by-product of the body's metabolism
of oxygen. And, normally, these free radicals serve important
functions, such as helping the immune system fight off disease.
However, too many free radicals can start to cause problems
in a cell.
Normally, electrons like to have a balanced
number of electrons; free radicals try to fill their missing
"slot" by stealing an electron from a nearby molecule. This
starts a chain reaction, as the deprived molecules try to
grab electrons from their neighbors, who in turn try to grab
electrons from their neighbors. This process is called oxidation,
and is chemically the same process whereby oxygen rusts iron
and turns peeled apples brown.
In the body, free radicals can attach to
molecules of fat in nerve cell membranes, and thus upset the
delicate functions performed by membranes - such as regulating
the amount of calcium that goes in and out of the cell. Free
radicals have been implicated in the tissue damage in strokes.
They are also implicated in the spread of cancer and in the
effects of aging (e.g. wrinkles and cell death). Nerve cells
producing the mutated form of amyloid protein - the kind that
plaques in Alzheimer's
disease - seem to produce more free radicals.
are substances which are helpful in defending against the
effects of free radicals, either by breaking the free radicals
into harmless substances, or by binding to them and preventing
them from attacking healthy cells.
Article : "GINKGO"
by Catherine E. Myers. Copyright © 2006 Memory Loss and the Brain