A neutral atom consits of a positively charged nucleus surrounded
by acloud of negatively charged electrons; the total charge on
the electrons is equal to that on the nucleus. If an electron
is removed from the atom, the atom is said to have been oxidised.
Of course, we may be able to continue to remove electrons from
the atom, and each step is a further oxidation.
Consider the copper (Cu) oxide, CuO. We may write that Cu2+ O2-,
to illustrate that two electrons have been removed from the Cu,
and given to the O to form the oxide. It was this kind of process
that eventually gave the name oxidation to electron removal from
an atom or a molecule. The atom or molecule receiving the electron
is said to have been reduced. Note that the removal of an electron
from a charged atom which has been reduced, e.g. C1-, is also
A free radical is an electron that is not magnetically paired
up with another electron. Electrons are not only charged, they
are magnetic as well because they possess a spin, an angular momentum.
Two identical bar magnets will attract one another very strongly
if they are next to one another and pointing in opposite directions:
the same is true for two electrons with their magnetic moments
(spins) opposed. A free radical is usually attached to an atom
or molecule, from which it will take its name. The simplest free
radical to consider is the neutral hydrogen atom H. The electron
of thisatom is not paired magnetically with another electron,
but suppose it comes close to another H atom wtih an electron
having the opposite spin direction.
The resultant attractive force between the electron magnetic moment
helps form the hydrogen molecule H2. So this property of a free
radical can make it a very strong molecular oxidation processes.
There are myriads of chemical reactions going on in our bodies
all the time, because we are alive, and need oxygen and food and
water to keep us so. Many of theses reactions will be oxidation
reactions, some mediated by a free radical, and therefore good
for us. But things can go wrong, as we shall see. Consider the
uptake of O by the haemoglobin in the blood. This is clearly vital
for our survival, and an oxidation reaction. But we hyperoxygenate,
by breathing fast and deep without excercising, the physiological
results for us can not only be unpleasant, but possibly dangerous.
Now let us think about cholesterol. It is necessary for us, otherwise
the liver would not manufacture it. There are two kinds of cholesterol,
the LDL and HDL. LDL means low density lipid (lipid is fat) and
HDL means high density lipid. The oxidation of the LDL leads to
a product that clogs arterial walls, and leads to heart disease
and atherosclerosis. The oxidation of LDL is mediated by the so
called superoxide (anion) radical, O2' , where the is used to
indicate that it is a free radical. Anion, meaning negatively
charged, is put in brackets because it is very often omitted in
the discussion of this radical. The charge means that this radical
is very reactive.
So how does such a radical occur in our bodies? One way is through
the 4 - step change of the O2 molecule into water. Apart from
the SOA radical, in this process we have the hydroxyl radical,
which is clearly very reactive and the hrdrogenperoxide molecule,
which is notparticularly stable. Free radical vary considerably
in their reactivity,some are very vigerous in donation (SOA radical)
or acceptance (hydroxylradical) of electrons. this means that
they can interact destructively withmany other chemicals including
those within us. Others, such as some of the radicals found in
wine and other foods, are essentially permanently stable,and provide
a sink for reactive electrons. When a molecule such as a tannin
from wine meets the very reactive SOA radical for example, the
SOA is converted into the more stable (less reactive) hydrogen
peroxide, and the tannin is converted into one of the very stable
(unreactive) free radicals. In this way the bad radicals are converted
into good (harmless) radicals, and the chemicals necessaryfor
our bodies are protected. Such a molecule is called a radical
scavanger or an antioxidant.
The preferred kind of antioxidant is one which removes the unpaired
electron, and stablisises it by delocalising it - that is spreading
the probablilty of finding it over a large area of the molecule
and thus reducing the probalilty of finding at any particular
Antioxidants in wine.
First red wine, made from red grapes. The great storehouse of
antioxidants in red grapes are the skins, which give the wine
its colour,and the seeds, which give the wine its astringent taste.
The antioxidants in both cases are what are called polyphenols.
A simple phenol consists of a hexagonal ring - shaped molecule,
which has at least one hyroxyl group (OH) attached to a corner
of the ring, and some other group, denoted by R, say, attached
to another corner (Fig 2). Even this simple phenolic can act as
a radical - stabilising antioxidant, because the unpaired electron
will partake of some of the electronic motion around the ring,
and so delocalised. A polypnenol may have two or more phenolic
rings joined together by some means (Fig 3), and of course these
molecules can bond together to make larger molecules called oligomers
if only a few of them are involved and polymers if a lot of them
are involved.We have chosen to show a particular shape of molecule
which is common to both the anthocyanins, which do the colouring,
and the flavanoids and tannins, whichgive the astringent taste.
In general red wines are left to ferment on the skins and seeds
after the grapes are pressed. They can also be treated with oak
in many ways: barrels, planks,chips. the oak contains compounds
of gallic acid, also a phenol, which can react with the other
phenols in various ways. It is not necessary to treat red wines
with oak for them to contain antioxidants.
Now let us consider white wine which can be made from red grapes
as well aswhite ones, by immediately seperating the juice from
the skins and seedsafter pressing. It is quite clear that such
a wine cannot contain as many antioxidant molecules as a wine
left to ferment on the skins and seeds. We can, of course, leave
the juice from white grapes to ferment on the skins and seeds,
but this willl not produce a wine having as many antioxidant molecules
as a red wine similarly treated. Nor will the oak treatment of
such a wine give an antioxidant content as greate as that of a
There are at least two works which report that white wines used
in experiments on the antioxidant action of wine in the blood
had a pro-oxidant interaction. Unfortunately, the tannin content
of the wines was not measured in each case, but we can confidently
say that zero tannin concentration will mean little, if any ,
antioxidant action. Indeed, there may well be a threshold concentration
for the antioxidant action to begin.
Recently, some researchers reported that they had to invent their
own white wine in order to observe readily the antioxidant action:
they did this by adding alcohol to the wine being fermented with
skins and seeds. The extra alcohol leaches more tannins from the
seeds, but results in a much sweeter wine. Such a procedure for
a table wine is illegal in many countries! So, to be safe, drink
white wine for pleasure, and red wine for your health as well.
Those allergic to red wines should only drink white wines exposed
to skin, seeds, oak, or even supplement their diet with red grapeseed
extrectsuch as Pycnogenol (R) orActi-Vin. .
The effect of white wine with a nearly zero antioxidant (tannin)concentration
agrees with the work of two independent French researchers on
two different kinds of laboratory animals. First, 10% alcohol
red wine was introduced into their diet, which, it was found,
they could sustain for months without serious damage as compared
to the control groups. Then, the wine was distilled to make a
spirit, "eau de vie", which was then diluted to 10% alcohol, and
included in the diet. Some of the animals became seriously ill.
Finally, very pure alcohol mixed with distilled water, to 10%
dilution, added to the diet. This had serious consequences for
a much larger proportion of the animals.
Where red wine can help us
The disease or health conditions where red wine can help us are
those which are brought about by the action of bad free radicals
- for example cardiovascular and cerebrovascular disease such
as clogging of the arteries, heart attack, stroke and dementia
caused by insufficient blood supply to the brain (ischeamic dementia).
Free radicals are also known to cause inflammatory conditions
and tissue damage, so red wine will act as protection against
these. It is thought that the unexpected effect of wine in at
least delaying the onset of Alzhelmers disease is due to its reduction
of the inflammation associated with the build up of amyloid plaques
which cause the disease in the brain. The combination with moderate
(red) wine consumption of appropriate doses of Chromium polynicotinate
or picolinate, together with appropriate diet and exercise, can
help to get rid of Syndrome X - the initiation of late onset diabetes.
Cr (4+) is an antioxidant which works in synergy with the wine
What about grape juice without the alcohol? Sorry, grape juice
contains 6x as much sugar as table wine, and this clearly is not
good. Besides, the alcohol and the polyphenols work together to
stregthen the heart, and prevent arterial clogging. What about
the antioxidants in beer and stouts? Again sorry. they are simply
not as efficeint as those in wines: and yes, the experimental
work has been done. What about grapeseed extracts, such as Pycnogenol
or Grapeseed 2000? Well, these are certainly better than grape
juice, because they lack the sugar, but the alcohol protection
Eat a Mediterranian diet, rich in fruits and vegetables, low in
red meat, rich in good breads and pastas, and using extra virgin
oil (which contains further phenolic antioxidants) and wash the
meal down slowly with (red) wine in moderation, with the family
and freinds. The sheer enjoyment and the relaxation is part of
the medicine! Oh ... and dont forget the excercise, say 30 mins,
brisk walking 5 days a week!
D.G.Hewitt and G.J.Troup,Chemistry Department and School of Physics
and Materials Engineering Monash University, Clayton, Victoria,