Macs in Chemistry

Insanely great science

A review of Asteris

Asteris is a new iOS app that arose from a collaboration between Optibrium and Integrated Chemistry Design that allows medicinal chemists to design new molecules on their iPad and then calculate a range of physiochemical and ADME properties. It is the latest app to use a client server model to provide both local drawing tools and access to more computationally intensive operations by accessing a server.

The starting point is the Molecule Designer, here you can draw a new molecule and calculate properties, (click on the “?” in the top right corner for help). Asteris uses Chirys Draw as the chemical drawing package, this is a package I’ve not used before and I didn’t find particularly intuitive. Although I should add that chemical drawing packages are very personal preference. I also often use a stylus and some of the gestures are not compatible, for example a two fingered circle to draw an aromatic ring. There are a few things that make drawing easier, to draw annulated rings first select the bond, then choose the ring size and then draw a circle on the screen and the ring will magically appear, use two fingers for an aromatic ring. You need to make sure that only the atom or bond you want modified is highlighted, I found that sometimes I had several atoms highlighted, fortunately there is an undo option. The most commonly used atoms (C,H,N,O,S) are directly available the rest by opening the periodic table. The ring size is determined by scrolling through the “Number Wheel”. There are no templates or predrawn functional groups to aid drawing.

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Once you have drawn the structure you can calculate properties, and use the “glowing molecule” display to highlight a particular property. All properties are calculated on the Asteris cloud server on Amazon Web Services, there is unlimited access to Core Properties, these include LogP, molecular weight, TPSA and HBD/A. The StarDrop ADME properties have some restrictions, you can calculate properties for 20 compounds each month, free of charge. Additional calculations are available via an in-app purchase.

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The StarDrop ADME properties models were derived using StarDrop Auto-Modeller and are exactly the same models used with the desktop application and are all described online. I found the response from the server to be excellent, calculations were almost instantaneous, in fact it is possible to have the calculations updated continuously as you modify the structure.

For regular StarDrop users the results will be very familiar, you can select which calculated property is displayed in the “glowing molecule”, this is very useful in determining which parts of the molecule contribute most to a particular calculated property.

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The results are shown in a single molecule centric fashion, whilst there are libraries of molecules I couldn’t see how the results could be presented in a tabular form. However an sdf file can be shared that contains all the calculated data.

All communications with the server uses industry-standard SSL encryption, and structures are transmitted as encrypted SMILES strings. No compound structures or data are stored on the server, however if you are concerned about transmitting information in this manner there is an enterprise version that can be installed on your own server. There is an additional benefit in that you can then use your own models as well, Customers can add their own models to the Enterprise server, either built with StarDrop's Auto-Modeller or by interfacing models built with other platforms via a Python API. In my testing I never had any network performance issues but using an Enterprise server may also offer network latency benefits. Users can define the IP address of the enterprise server in the Document settings.

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Sharing files

You can easily share the resulting structures by embedding the file in an email, however there is no Dropbox integration. When you receive an email with an embedded file simply tapping on the file will give you a section of options of applications to open it, as shown below. There is an option to “Share Library” but I think this only works via Airdrop to other local iPad users. The shared file includes the structure and all the calculated properties in standard sdf format.

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You can also print directly to any AirPrint accessible printer.

Support

There are a series of demo videos available on the Asteris support site, these probably provide all the training that is needed.

Summary

For existing StarDrop users this gives them access to familiar functionality on a mobile platform, for those unfamiliar with StarDrop this gives them a great opportunity to try it out. This is also an excellent demonstration of the potential of the mobile platform to deliver computational data.