In article >,
in a previous thread which I have lost, hence this new one
"cybercat" > quoted:
>>>> Mark Thorson > wrote:
>>>>> Andy wrote:
>>>>>> The most important point that folks constantly fail to realize
is
>>>>>> that synthetic vitamins are useless.
>>>>
>>>>> How does your body know whether a molecule of vitamin C
>>>>> was made by a plant or in a factory? They both have
>>>>> all of the same atoms in all of the same place.
I don't know about vitamins as such, but IICR organic chemistry from
50 years ago, compounds that exist in two optically active forms
(Dextro and Levo) are often (always?) biased to one form in natural
biological systems but are made in equal amounts in lab processes
unless such are designed to produce the separate forms.
The two mirror forms of racemic compounds are known as enantiomers and
have identical properties except for the rotation of plane polarised
light. However, the racemate [the 1:1 mixture] often has different
properties to the pure enantiomers (different melting points and
solubilities are very common). In the present context it's worth
noting that pharmaceuticals may be available as a racemate or as the
pure enantiomer, which might have different potencies.
<http://en.wikipedia.org/wiki/Racemic_mixture>
Enantiomers of each other often show different chemical reactions with
other substances that are also enantiomers. Since many molecules in
the body of living beings are enantiomers themselves, there is often a
marked difference in the effects of two enantiomers on living beings.
In drugs, for example, the working substance is often one of two
enantiomers, while the other one is responsible for adverse effects.
<http://en.wikipedia.org/wiki/Enantiomer>
It worth noting that virtually all active forms of amino acids are of
the L-form (d-serine being a notable exception) and most biologically
relevant sugars are of the D-form. Typically, the alternative form is
inactive and sometimes even toxic to living things.
<http://en.wikipedia.org/wiki/Homochirality>
[All of which goes to show that my memory has not yet completely
failed; and suggests that Andy may have had a good point when talking
about synthetic vitamins.]
Cheers, Phred.
--
LID