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When visiting a botanical garden in Stockholm, I came across the following mosaic tile:

Chemical formula

I tried using MolView, but it does not seem to identify it. Also, I have tried their advanced search (similarity), but that provided no results.

I have also tried searching for it based on SMILES formula on Chemspider.

I am wondering whether there any other tools that can help me to find out what substance it is.

Extra context information: it was next to a DNA structure artwork, so I guess it is somewhat related to evolution, DNA etc.

Question: How can I find out a substance's name based on its structural formula?

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1 Answer 1

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That's betanin, from which beets derive much of their deep purple color, and which may have neuro-protective (Ref. 1) features. The following is the structure retrieved from the wikipedia (on 2019-10-5), which closely matches that in the mosaic:

enter image description here

I used the editor available on the Sigma-Aldritch website to generate a structure and submit a search:

enter image description here

The program identified betanin as the top hit despite my sloppy structure.

The SMILES code is: C(OC(C1O)OC(C(=CC2[N+]3=CC=C(CC(N4)C(=O)O)C=C4C(=O)O)O)=CC=2CC3C([O-])=O)(C(C1O)O)CO

The IUPAC name (retrieved from the wikipedia) is (2S)-1-{2-[(2S)-2,6-dicarboxy-2,3-dihydropyridin-4(1H)-ylidene]ethylidene}-5-(β-d-glucopyranosyloxy)-6-hydroxy-2,3-dihydro-1H-indol-1-ium-2-carboxylate

As noted in a comment, the stereochemistry in the wikipedia image above and that in the mosaic does not match that of the structure in the Sigma-Aldrich catalogue. I used ACD/ChemSketch freeware to generate the following image that does match the one in the catalogue:

enter image description here


  1. American Chemical Society. "Vegetable compound could have a key role in 'beeting' Alzheimer's disease." ScienceDaily, 20 March 2018.

As an aside, it's interesting to note that work on L-dopa, a biosynthetic precursor of betanin, led to a Nobel prize award for Swedish scientist Arvid Carlsson. Also, quoting from the wikipedia:

The 2001 Nobel Prize in Chemistry was also related to l-DOPA: the Nobel Committee awarded one-quarter of the prize to William S. Knowles for his work on chirally catalysed hydrogenation reactions, the most noted example of which was used for the synthesis of l-DOPA.

  1. The structure-drawing engine (and presumably also search engine) provided through the Sigma-Aldrich structure search web service is JSDraw2 (JSDraw V3.2.3) by Scilligence.
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  • $\begingroup$ I am quite disappointed by the actual result (a food dye), but the method is useful. +1. Thanks. $\endgroup$
    – Alexei
    Commented Oct 5, 2019 at 18:49
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    $\begingroup$ Well, I'm guessing that it colors some of the flowers and tubers at the garden you visited, but there might be more to it than that. The family of compunds is pretty interesting if you are willing to look into it. $\endgroup$
    – Buck Thorn
    Commented Oct 5, 2019 at 18:55
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    $\begingroup$ Oh, it makes perfect sense then. An interesting puzzle for a botanical garden. $\endgroup$
    – Alexei
    Commented Oct 5, 2019 at 18:57
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    $\begingroup$ BTW I believe the ACD software, like a number of competitors, can perform structure searches, but the freeware can't. $\endgroup$
    – Buck Thorn
    Commented Oct 5, 2019 at 19:10
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    $\begingroup$ The first image (the one from Wikipedia) is wrong. Its creator mirrored the structure of another image without mirroring the wedged/dashed bonds, inverting the stereochemistry. I've replaced it on the Wikipedia page with an older, correct image. (Also, sadly, the mosaic is wrong for the same reason.) $\endgroup$ Commented Oct 6, 2019 at 14:22

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