Date: Tue, 18 Jul 2000 18:29:30 +0000 From: schlauer@chemie.uni-wuerzburg.de To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2158$foo@default> Subject: Re: Toxic Dionaea and bird dispersal
Dear Barry,
> Jan, your quoted concentrations of toxins in Dionaea are quite low. This
> is interesting to me because I was wondering about the toxin levels in
> "Carnivora", which is an "extract" of Dionaea that some people sell. I
> don't know if the plumbagin survives the extraction process, or if it is
> more concentrated in the extract.
_Dionaea_ is in fact extracted in order to obtain plumbagin (the
main active principle of "Carnivora") from it. Thus, the plumbagin
concentration is higher in the extract than in the plant. Plumbagin
is fairly stable but it diffuses readily. It is solid at normal
conditions but it sublimizes appreciably, so if left unattended, a
bit of it will disappear (or rather appear at places where it is
unwanted) after some time. It is readily soluble in a wide array of
solvents from water to chloroform. If kept in soft plastic vessels,
it will diffuse into the material and stain it in its rich yellow to
orange colour.
The stuff is difficult to manage even for its producers (i.e.
plants). They always keep concentrations low, and larger
accumulations can usually only be found in dead or dying tissues (of
the plants). With its physical/chemcal properties plumbagin is able
to cross all cellular barriers, and the worst thing is that it can
carry electrons across membranes. The quinone can be reduced on one
side of the membrane, cross the membrane by diffusion (the
hydroquinone is almost as amphiphilic as the quinone) and it can be
oxidized on the opposite side of the membrane, just to diffuse back
again. Not good for mitochondria (or chloroplasts), indeed! This is
why cancer cells (but also mice and men, depending on dosage) will
eventually die if exposed to larger amounts of plumbagin.
Kind regards
Jan
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