Sequel Thread To Holistic Doctors, and medicine

I know I'm not Mod, but I'll attempt an answer anyway.If you synthesise L-Ascorbic acid, then it's identical to the natural form. If you synthesise D-Ascorbic acid (which is the opposite enantiomer) you have a form that has the same physical properties, but rotates the plane of polarised light in the opposite direction. If you did synthesise the D-form, you wouldn't make any money though, because it's biochemically useless.The third alternative is that you synthesised a racemic mixture of the two forms. If you sold this as Vitamin C, you'd be conning people, because only half of it would be biochemically active.

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'I can't even fit all my wife's clothes into a suitcase for travelling. So you want me to believe we're going to put all of the planets and stars and everything into a sandwich bag?' - q3psycho on the Big Bang

Yes. Yes. But there can be more than one stereocentre in a complex molecule (a stereocentre is caused when you have a carbon atom that has four different groups attached to it). In which case you could end up with more that 2 different stereomers.For example, let's say the molecule has two different stereocentres, A and B. Then it will have 4 different enantiomeric forms: RA:SB; RA: RB; SA:RB; and SA:SB (R and S here mean effectively the same as L and D). If only the stereocentre at A is biochemically active, and requires the R form, then both RA:SB and RA:RB could potentially have the same effect.If RA:SB were the naturally occurring form, and you synthesised the RA:RB form, then you will have created a synthetic form that is different from the natural one, but that has the same biochemical effect. From reading Mod's email, it sounds as though this does apply to Vitamin E (although I'm not an expert in vitamins, so I'll just have to take his word for it).

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'I can't even fit all my wife's clothes into a suitcase for travelling. So you want me to believe we're going to put all of the planets and stars and everything into a sandwich bag?' - q3psycho on the Big Bang

As I said, I'm not an expert in Vitamins. My training is more in Chemistry than in Biochemistry. But the Vitamin pages on Wikipedia are quite detailed - you should be able to find out quite a bit from there.What surprises me is that, generally, a Vitamin isn't a particular chemical structure, but a group of related compounds. Only Vitamin C and some of the B vitamins refer to a particular molecular structure.Vitamin A can be any one of a group of related compounds
Vitamin D can be either of two related compounds (but could be one of several other related compounds)
Vitamin E can be one of eight different compounds
Vitamin K, like Vitamin A, can be any one of a group of related compoundsSo it's a bit complicated .

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'I can't even fit all my wife's clothes into a suitcase for travelling. So you want me to believe we're going to put all of the planets and stars and everything into a sandwich bag?' - q3psycho on the Big Bang

Molbiogirl, I'm a trained chemist. Don't patronise me.Vitamin A, Vitamin K, and a good number of the B vitamins aren't even optically active, so how can you have racemic mixtures of them?Note that I said 'a group of related compounds', not 'a mixture of related compounds'.If you'll take the trouble to look up the structures you'll find that, just as I stated in my previous email, most vitamins (Vitamin C is an exception) are ranges of similar organic compounds differing in carbon chain length or substitutions on an aromatic ring.It's not that Vitamin E, for example, is a mixture of different compounds, but that several different compounds can be described as 'Vitamin E'.Edited by JavaMan, : No reason given.Edited by JavaMan, : Changed example to vitamin E, for clarity

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'I can't even fit all my wife's clothes into a suitcase for travelling. So you want me to believe we're going to put all of the planets and stars and everything into a sandwich bag?' - q3psycho on the Big Bang

You do like to argue, don't you? Don't be silly. My original email was perfectly clear. 'Vitamin A' describes one range of compounds; 'Vitamin E' describes another, quite different, range of compounds. Here is the structure of retinol, the most common form of Vitamin A. Show me where the chiral centre is. (For everyone but molbiogirl , there aren't any chiral centres in this molecule, so it can't have enantiomers). If you look closely at the quote you provided, you'll see that they're using tritium and carbon-14 to radioactively tag the molecule. It's the introduction of a tritium molecule at position 15 that creates a chiral centre.Vitamin EThis is Vitamin E (the image is from the Wikipedia page on Vitamin E). As you can see, any one of these eight compounds can be called Vitamin E. Vitamin KAnd here is one form of Vitamin K known as phylloquinone: Now this structure, like retinol, doesn't have any chiral centres, so how come your authors are dealing with a racemic mixture? Let's look at the quote again: Ah, they're dealing with an epoxy derivative of Vitamin K, i.e. it's the derivative that has racemic forms not Vitamin K itself. I don't know why you've included that quote. I'm not interested in dietary supplements - I was just providing PurpleDawn with some neutral advice about vitamin structure. Personally I think dietary supplements are a waste of time .

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'I can't even fit all my wife's clothes into a suitcase for travelling. So you want me to believe we're going to put all of the planets and stars and everything into a sandwich bag?' - q3psycho on the Big Bang

Here's the opening paragraph of the Wikipedia entry on Vitamin A: That seems pretty clear to me. You're responding too quickly. I know that vitamin B12 is optically active. That's why none of my earlier posts claims that it isn't. Generally, I've avoided talking about the B vitamins, because that's a whole other level of complexity; the eight B vitamins are completely different structures, which is why they're given different numbers. My turn to admit a mistake. Yes, vitamin K1 is optically active. Can you see why I missed the two chiral centres? Molbiogirl, can I give you some advice? We're just doing high school chemistry here. There's no need for literature searches. You could have cleared up your own misunderstandings just by looking up the chemical structures of vitamins, and you could have cleared up my mistake about the optical activity of Vitamin K just by pointing to the structure.You might think that the literature searches make you look intelligent and professional, but they actually make you look as though you don't know what you're talking about.Spend more time thinking, and less time trying to look superior.

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'I can't even fit all my wife's clothes into a suitcase for travelling. So you want me to believe we're going to put all of the planets and stars and everything into a sandwich bag?' - q3psycho on the Big Bang

Yes, I guessed. Just teasing .

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'I can't even fit all my wife's clothes into a suitcase for travelling. So you want me to believe we're going to put all of the planets and stars and everything into a sandwich bag?' - q3psycho on the Big Bang