Vitamin C and Ester-C Metabolism
and Metabolites
VITAMIN
C LITERACY
__________________
Before embarking upon an
investigation into the therapeutic
powers of Vitamin C, a summary
of some of the technical
language and constituents
involved in the formulation
of various products is provided
which may prove useful to
the consumer and professional
alike.
Chemical
formulae and biochemical
pathways are not engraved
in stone upon the brains
of scientists, at least
not upon that of the author.
Even after many years and
advanced courses in biochemistry,
physiology, etc., these
pathways fade from memory
unless in constant use.
And, with the incredibly
rapid advances in knowledge
occurring in science and
medicine, much material
may simply be new and not
have been taught during
one's formal training. These
formulae are presented here
as aids in understanding
as well as a handy reference
tool.
STRUCTURE AND BIOSYNTHESIS
OF VITAMIN C
_______________________________________
Vitamin
C, also known as L-Ascorbic
acid, L-xyloascorbic acid,
3-oxo-L-gulofuranolactone
(enol form), L-3-ketothreohexuronic
acid lactone and antisorbutic
vitamin, has the chemical
formula C6H8O6 and a molecular
weight of 176.12. This 6-carbon
molecule is structurally
very similar to the sugar
D-glucose (Fig. 1), a point
of significance which will
be addressed when considering
the mode of action and mechanisms
underlying Vitamin C's therapeutic
effectiveness with diabetes
and heart disease.
Humans, non-human primates,
guinea pigs, the red-vented
bulbul (an Asian bird),
the Indian fruit-eating
bat, rainbow trout and Coho
salmon are the only animal
species lacking the complete
enzymatic machinery to synthesize
Vitamin C. It has been shown
that humans and guinea pigs
lack the enzyme gulonolactone
oxidase, which oxidizes
l-gulonolactone to 2-keto-l-gulonolactone.
This, then, is the 25-60
million year old evolutionary
accident spoken of earlier
which has deprived humans
and these other animals
of their ability to synthesize
their own Vitamin C. Whether,
as genetic engineering techniques
become more refined in the
future, it may become feasible
to re-introduce this enzyme
back into human cells, must
remain a subject beyond
the scope of this book,
however fascinating and
intriguing an idea.
ASCORBATE SALTS
_______________
Preparations
of Vitamin C are frequently
obtainable as salts of ascorbic
acid, commonly as sodium
or calcium ascorbate. Sodium
(calcium) ascorbate is prepared
from ascorbic acid and sodium
(calcium) carbonate by controlled
precipitation in dilute
acetone or alcohol(184).
Ester-CR ascorbate, prepared
totally in aqueous solutions,
has not, therefore, been
exposed to these toxic chemicals.The
more neutral pH and buffering
power of ascorbate salts
compared with ascorbic acid
is frequently cited as a
superior attribute of ascorbate
products; the heatedly debated
controversy recommending
ascorbate salts over ascorbic
acid and vice versa, and
the advantages and claims
of each of these products
will be addressed in Chapter
11.
METABOLITES
___________
This may
be the magic potentizers
in Vitamin C research today
and in the near future.
Metabolites refer to substances
or constituents which form
part or take part in the
metabolism of a substance.
Other terms could be by-products,
biochemical intermediates
– ie, intermediate
products in Vitamin C metabolism.
Although Vitamin C research
has been going on for over
4 decades, we are still
at the infant stage in really
unravelling exactly how
Vitamin C gets absorbed
and metabolized at the cellular
level. The study of Vitamin
C's metabolites may be crucial
to shedding light at some
of these crucial biochemical
questions, which may lead
to profound and perhaps
powerful breakthroughs in
several areas of medical
science. The metabolism
of Vitamin C into its constituent
metabolites is shown here
(Fig. 3):
ESTER-C
ASCORBATE
__________________
The form
of Vitamin C sold under
Tradename Ester-RC refers
to a composition of Vitamin
C, normally an ascorbate
salt, which also contains
at least one of Vitamin
C's naturally-occurring
metabolites, ie one of the
aldono-lactones or edible
salts of l-threonic, l-xylonic
and l-lyxonic acids(146).
The manufacturing process
of Ester-CR ascorbate is
unique in that all reactions
are carried out with aqueous
solutions (water) and there
is no use of organic solvents
(acetone, alcohol) as in
previous methods of ascorbate
precipitation. The presence
in significant quantities
of metabolites in Ester-CR
accounts for superior absorption
and retention properties
compared to ascorbic acid
and ascorbates(229).
