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Chalconoids and Flavonoids

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infraredz

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There's been a recent development regarding kava. Flavokavain-B has been shown to hepatotoxic and is only found in certain varieties of kava (called tudei). Interestingly, all tudei kava gives a reddish color in acetonic extractions, but not in any of the non-tudei kava (which has no FKB) where it gives a yellow color.

Here is my question for the chemists- Flavokavain A, B, and C are all chalconoids and ring closures (I'm pretty sure they're phenyl rings, but not sure) result in flavonoids which are responsible for a wide variety of plant pigmentation (eg. red vs yellow, for example).
Flavonoids are responsible for a significant amount of color in a plant, and so I'm really interested if the reason we are seeing tudeis (which have FKB, unlike nobles) show a red color vs. the "control" of yellow is because of the conjugation of this phenyl ring which would cause it to to become a flavonoid, which in turn possesses specific color properties. Could the acetone/solvent be doing this? Some sort of other mechanism due to the solvent creating soluble solutes that wouldn't 'normally' co-exist? Chalconoids by themselves don't necessarily have color properties, but they serve as the intermediate in the biosynthesis to the flavonoids that do. Could the color be an actual representation of flavonoids formed from FKB?


I've seen seemingly different representations of FKB





Thanks.
 
Last edited by a moderator:
Can a moderator please change the thread title to the post title: "Chemists- phenyl ring closure?/Chlaconoid => Flavonoid question "

Thanks!
 
There shouldn't be any closure to form a flavonoid in FKB. The molecule is unsaturated across its carbon structure, alternating single and double bonds creates an uninterrupted pi-system across the molecule. This is what is referred to as a conjugated system, and molecules with them tend to be highly colored. This isn't the only determiner of color, though, charge can also contribute color etc. I don't think we could define the color difference between these different strains in a simple statement, you'd have to do some wet lab stuff to really determine that past speculation.
 
Privateer said:
There shouldn't be any closure to form a flavonoid in FKB. The molecule is unsaturated across its carbon structure, alternating single and double bonds creates an uninterrupted pi-system across the molecule. This is what is referred to as a conjugated system, and molecules with them tend to be highly colored. This isn't the only determiner of color, though, charge can also contribute color etc. I don't think we could define the color difference between these different strains in a simple statement, you'd have to do some wet lab stuff to really determine that past speculation.
Click to expand...

Right, that's what I figured but the simple correlation seemed like it might be the possible cause. The fallacious thought I had was that if FKB only occurs in tudei, and tudei is the only strain to test red then tudei contains FKB. I know that correlation doesn't equal causation, but I figured I would ask to see if anyone had any thoughts on the possible mechanism behind the color differences because it seemed possible in my ignorance.

My understanding is that chalconoids go through a bio synthesis process resulting in flavonoids. Would it be plausible to say that FKB causes the synthesis of a flavonoid that is responsible for the color? For instance, normal kava plants aren't yellow (at all, really although the cortex of the root looks off white) and yet they produce this urine yellow color when extracted with acetone. Is it possible that some of these flavonoids are part of the soluble solutes during a solvent extraction but not visible under normal circumstances?
 
Why can't coloration be explained by there being different flavonoids in the "tudei" kava? Occam's razor? It is possible for FKB to convert to a flavonoid or antocyanin type compound, but I think it's more likely to be a plant-produced product rather than a degradation product of FKB.

Could the acetone/solvent be doing this? Some sort of other mechanism due to the solvent creating soluble solutes that wouldn't 'normally' co-exist?
Click to expand...

Switch solvents and find out.

Could the color be an actual representation of flavonoids formed from FKB?
Click to expand...

I somehow doubt it.

Without an HPLC-MS you are going to be stuck doing paper chromatography and scratching your head.
 
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