Converting a spreadsheet of SMILES: my first OSM contribution

I’ve long admired the work of the Open Source Malaria Project. Unfortunately time and “day job” constraints prevent me from being as involved as I’d like.

So: I was happy to make a small contribution recently in response to this request for help:

Note – this all works fine under Linux; there seem to be some issues with Open Babel library files under OSX.

First step: make that data usable by rescuing it from the spreadsheet ;) We’ll clean up a column name too.

library(XLConnect)
mmv <- readWorksheetFromFile("TP compounds with solid amounts 14_3_14.xlsx", sheet = "Sheet1")
colnames(mmv)[5] <- "EC50"

head(mmv)

  COMPOUND_ID                                                      Smiles     MW QUANTITY.REMAINING..mg.
1   MMV668822 c1[n+](cc2n(c1OCCc1cc(c(cc1)F)F)c(nn2)c1ccc(cc1)OC(F)F)[O-] 434.35                     0.0
2   MMV668823      c1nc(c2n(c1OCCc1cc(c(cc1)F)F)c(nn2)c1ccc(cc1)OC(F)F)Cl 452.79                     0.0
3   MMV668824                        c1ncc2n(c1CCO)c(nn2)c1ccc(cc1)OC(F)F 306.27                    29.6
4   MMV668955                        C1NCc2n(C1CCO)c(nn2)c1ccc(cc1)OC(F)F 310.30                    18.5
5   MMV668956    C1(CN(C1)c1cc(c(cc1)F)F)Oc1cncc2n1c(nn2)c1ccc(cc1)OC(F)F 445.38                   124.2
6   MMV668957          c1ncc2n(c1N1CCC(C1)c1ccccc1)c(nn2)c1ccc(cc1)OC(F)F 407.42                    68.5
   EC50 New.quantity.remaining
1  4.01                      0
2  0.16                      0
3 10.00                     29
4  8.37                     18
5  0.43                    124
6  2.00                     62

What OSM would like: an output file in Chemical Markup Language, containing the Compound ID and properties (MW and EC50).

The ChemmineR package makes conversion of SMILES strings to other formats pretty straightforward; we start by converting to Structure Data Format (SDF):

library(ChemmineR)
library(ChemmineOB)

mmv.sdf   <- smiles2sdf(mmv$Smiles)

That will throw a warning, since all molecules in the SDF object have the same CID; currently, no CID (empty string). We add the CID using the compound ID, then use datablock() to add properties:

cid(mmv.sdf) <- mmv$COMPOUND_ID
datablock(mmv.sdf) <- data.frame(MW = mmv$MW, EC50 = mmv$EC50)

Now we can write out to a SDF file. We could also use a loop or an apply function to write individual files per molecule.

write.SDF(mmv.sdf, "mmv-all.sdf", cid = TRUE)

It would be nice to stay in the one R script for conversion to CML too but for now, I just run Open Babel from the command line. Note that the -xp flag is required to include the properties in CML:

babel -xp mmv-all.sdf mmv-all.cml

That’s it; here’s my OSMinformatics Github repository, here’s the output.

3 thoughts on “Converting a spreadsheet of SMILES: my first OSM contribution

  1. Thoroughly enjoyed your blog of 7/1/14. I’m nearing retirement but have a continuing interest in data science/R. Do you know of other non-profit organizations that need work of this sort? How did you get the attention of Ms Williamson? Thanks

    • I know many people in need of statistics, data analysis and visualization, but Mat’s group is the only one I know that openly invites anyone to participate in their science in this way. I’d check out the OSM website as a starting point; when they need help they generally post on Twitter, Facebook and one of their blogs, or at their Github account.

  2. Sensational Neil, thank you. Rescuing the data and making it more understandable/processable has led to us getting the wiki finished:
    http://openwetware.org/wiki/OpenSourceMalaria:Triazolopyrazine_%28TP%29_Series
    Now what we want to do is to try to make sure we’re updating the project’s SD file automatically, but the one you worked on is a huge part of that since it’s all the data we inherited at the start of Series 4. Awesome, thanks again.

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