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Natural Products

Hit the Polyamine Pedal, And Hold It

As part of the no-doubt-endless series of head-shaking natural product structures out there, allow me to present the newly described Protoaculeine B, isolated from an Okinawan marine sponge. That side chain looks as if it were inspired by listening to Philip Glass, and it fits well into the category of “I never would have made that in a million years”, which so many natural products seem to occupy. But even freakier things await discovery, of that we can be sure.

17 comments on “Hit the Polyamine Pedal, And Hold It”

  1. Hap says:

    It looks like an oxidatively (and pH) sensitive transfection vector, or an alkaloid misfire.

  2. luysii says:

    It looks like something to test the resolution of your NMR machine on. At physiologic pH (whatever that is in the ocean or the sponge), the change is likely to be extremely extended — the alpha amino acid probably forms the zwitterion leaving the side chain alone. Entropy alone discourages the chain from heading back to ring.

  3. paperclip says:

    Philip Glass — love it! I never thought reading this blog would take me back to the opera class I took as an undergraduate.

  4. Curt F. says:

    I love the natural products posts Derek. Keep ’em coming.

  5. will says:

    Go home sponge, you’re drunk

  6. Hap says:

    Unless you can alkylate DMPU and cleave the cyclic ureas at the end, it looks like time for some good old nosylamide chemistry. Deprotection should be a blast too. At least the left-hand side shouldn’t (!) be horrid to make or manipulate. It’s probably also time for someone to crank out some ninhydrin stain.

  7. Anonymous says:

    Is this a novel amino acid!?

  8. Pig Farmer says:

    Hey! I Like Philip Glass. But the analogy made me chuckle. Not bad!

  9. milkshaken says:

    It must be a boring existence, to be a sponge. So it is occupying its time, by endurance knitting.

  10. great unknown says:

    Are they sure this came from Okinawa and not New Hampshire?

  11. Anonymous says:

    I’d love to see the first reaction to the Mass spectra: “How many times can you protonate this stuff?!?”

  12. T says:

    Hmmm very pretty but is it explosive? Otherwise, my favorite ridiculous natural products are still polyynes like caryoynencin:

  13. myma says:

    I don’t want to know what this thing smells like.

  14. Derek Freyberg says:

    And if it turns out to have some medicinal activity, the next question will be “how many of those aminopropyl groups can we leave off and still have it work?”

  15. Secondaire says:

    Good lawd.
    The repeating NH and propyl chains strangely remind me of an EKG. I’m surprised it doesn’t flatline at the end, which is precisely what my heart would do if someone asked me to synthesize this thing…

  16. I envision a deleted scene from Koyaanisqatsi that takes place in a chemlab. Props on the Phillip Glass reference!

  17. RBW says:

    The structure is interesting but hardly on the wild side.
    Polyamine alkaloids are well known e.g. spider toxins. In this case, you can imagine the indole of tryptophan being acylated or alkylated by a C4 unit followed by generation of an iminium ion and intramolecular cyclization to C-2 of the indole. An unusual motif but biogenetically plausible.

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