Request for assistance from ORGANIC CHEMISTS:

[kestrel91316]

Some vets on VIN with more time on their hands than me have noted a similarity in the structures of AMINOPTERIN and MELAMINE and hypothesized that melamine is merely a product of the degradation of aminopterin.

http://en.wikipedia.org/wiki/Melamine

http://en.wikipedia.org/wiki/Aminopterin

I am tired and my organic chem was 30 years ago so I welcome comments and speculation from QUALIFIED persons.

[havocmom]

1. Not me, but I will try and kick this through the weekend for ya

:kick:

[AikidoSoul]

2. Recommend and kick up for attention tomorrow

Geez buddy... you started this thread awfully late. It's 10:23 p.m. here.

[PhilipShore]

3. Try Azmira

http://www.azmira.com/">Link

Dr. Lisa Newman, N.D., Ph.D., takes over 20 years of proven, clinical research and real-life applications to show you, “Three Simple Steps to Natural Pet Care – The Holistic Animal Care LifeStyle™”

Have a question about your pet's symptoms or a specific product...
Call our technical support staff at 520-886-1727 or 520-293-6639 to get answers fast...!

[PhilipShore]

9. Note: Azmira-- "Manufacturer of canned foods is “proprietary information”

I have not fed Azmira food to my cat -- nor will I -- until they clarify who exactly manufacturers their food. That statement by them is unacceptable.

http://petsitusa.com/blog/?p=210

Azmira Holistic Animal Care Products (verified by company 3/26/07)

* Manufacturer of canned foods is “proprietary information” but they are not involved in recall.

[Duer 157099]

4. I'm no chemist, but they don't look similar to me

Melamine has a 3-nitrogen ring, and I don't see any of those in aminopterin -- just the terminal ring that has 2 nitrogens and 2 amino groups attached ... similar, but not similar enough imho... hoping a chemist checks in

I just don't think it's a trivial event to get a 3rd nitrogen in a ring like that...

edited to add: ok, now I see the "qualified" part of your post :D

[kestrel91316]

10. I was too tired to even look, frankly, and don't remember much of organic

chemistry except the relief I felt when I finally passed all I had to take, and the upper-level biochemistry, too. 30-32 years ago.

[Der Blaue Engel]

5. Kick and Rec #4

in hopes the right people will see this.

[n2doc]

6. Nope, they aren't connected in that way

If you look at the aromatic ring structures you can see that there is no simple way (i.e. loss of CO2 or NH3) for Aminopterin to be biologically converted to Melamine. Melamine has a ring with 3 N and 3 C, Aminopterin has a dual ring system where no individual ring has such an arrangement. Biology typically uses hydrolytic cleavage (i.e. insertion of water) to break down molecules and not C-N rearrangements.

[w4rma]

7. Yeah, to convert Aminopterin to Melamine you'd have to remove a very strong double bonded ring

(along with all the other junk attached to it) and replace it with a double bonded NH2. To my limited understanding of Organic Chem, it looks like it's an uneconomical reaction.

[kestrel91316]

11. I'll take your word for it gladly. My brain is completely incapable of "doing"

any kind of chemistry anymore, especially organic.

Profound apologies to Skip Wade at Colorado State University all those years ago - you were the GREATEST, but it just didn't stick.

[eridani]

8. What #6 and #7 said n/t

[PhilipShore]

12. Actually Gary Null would love this question n/t

Gary Null
From Wikipedia, the free encyclopedia

http://en.wikipedia.org/wiki/Gary_Null

[Coloradan4Truth]

13. You could register and ask this question in 5 minutes

on Yahoo Ask, in the chemistry section. I'm currently in Chem. II, and I recently asked for clarification of a (to my mind) complicated concept on Yahoo ask and had an answer in five minutes.

C4T

[formercia]

14. The last paragraph may explain it.

Although the use of aminopterin as a rodenticide is widely promulgated on the web and elsewhere, there is no evidence that it has ever been used as a rodenticide either in the United States or elsewhere in the world. The preparation of the molecule is complex and expensive. It is also unstable in the environment due to degradation by light and heat. The apparently mistaken association of aminopterin with its use as a rodenticide likely dates back to a 1951 patent issued to the American Cyanamid Company (then the holding company of Lederle Laboratories) that is commonly cited by a variety of reference textbooks.<8>

[eppur_se_muova]

15. UPDATE!! and HOLY CRAP!! (Posted on this in another thread...)

"Note the common motif of -NH2 groups hanging off of 6-rings with at least two N's in alternate positions. This suggests that these compounds might be sufficiently similar to compete for binding to the same enzyme(s). Also suggests a test for aminopterin might give a false positive if melamine is present." (and I should have said, "and vice versa".)

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=389&topic_id=538952&mesg_id=539467

Aminopterin isn't likely be converted to melamine, but could be "mistaken" for it. Breakdown of aminopterin could (I'm somewhat guessing here, but it's based on "the usual patterns") lead to the molecule being broken roughly in two, with the two fused nitrogen rings (the "base" part) separating from the rest of the molecule (the "amino acid/peptide" part).




Flip this image UPSIDE DOWN and compare to the "left" half of aminopterin. (Any way to do this w/HTML?)

Hope that answers some of your questions. I'm not a biochemist or pharmacological chemist, so I don't know that much *in detail* about how drugs etc. interact with the body, but what I've given above is generally within the range of my expertise.


EDIT TO ADD: One other possible pathway of breakdown occurred to me -- after checking the Merck index, I found it is basically the reverse of the procedure used to manufacture aminopterin! It only involves hydrolysis, i.e. reaction with water, so seems very likely to occur either before or after ingestion -- could even happen on spoilage. The resulting compound would be 2,4,5,6-tetraminopyrimidine, structurally VERY similar to melamine, which could alternatively be named 2,4,6-triamino-1,3,5-triazine, while the other could be named 2,4,5,6-tetramino-1,4-diazine. The similarity in names reflects the very similar structures: melamine has one less NH2 hanging off the side, one more nitrogen in the ring. I google the name to try to find a structure to post, and LOOK what I found: http://www.google.com/search?q=tetraminopyrimidine&hl=en&start=20&sa=N listing after listing of CHINESE suppliers. What are they making all that TAP for?? If they have that much of it, are they using it for rat poison? (It would be MUCH cheaper than aminopterin). This has me wondering: is the toxin in pet food really tetraminopyrimidine (let's call it TAP) rather than melamine? They are very similar, and it would be very easy to confuse them in *qualitative* analysis.

[kestrel91316]

16. Thank you. I took the liberty of posting a link to this at VIN, and

also forwarded the text of your post to Paul Pion so maybe he can get the toxicologists to look into it.

[kestrel91316]

17. Melamine CAN'T be our killer - check this out:

From VIN's melamine info page:

".......As far as we can ascertain, melamine is minimally toxic. In acute toxicity trials in rats and mice, LD50 was >3g/kg. Intravenous injections (0.3mM/kg) and acute oral administration of melamine (125mg/kg) to cats failed to induce any toxicity (Lipschitz & Stokey, 1944, J Pharm & Exp Ther). In chronic dosing studies, rats developed cystic calculi (bladder stones) and consequent carcinomas of the bladder after 6 months of administration. There is virtually no mention of nephrotoxicity in the published literature. It is considered a mild ecological toxin, and generally safe in a work environment (inhalation and dermal or mucosal contact)......"

[northofdenali]

18. You are the BEST - thank you so much for what you've done

for us literal idiots who love animals!!

:hug::pals::hug:

[hang a left]

19. So are we any closer to finding out the culprit poison??