Effective April 2024, Sigma-Aldrich/TimTec have discontinued MyriaScreen screening library, however 10.000 compounds from original library can be purchased in dry form or as a custom subset, pricing and availability are subject to change.
Redefined MyriaScreen II, a collection of 10,000 drug-like compounds, is a fine choice for an assay that calls for a truly diverse screening library. Diversity is an integral part of this library design. To begin with, MyriaScreen unites handpicked molecules coming from two companies’ large compound pools - Sigma-Aldrich and TimTec screening collections. Diversity characteristic can be put into real numbers and visual examples to add to drug-likeness and chemical-physical properties selection criteria that together go into a screening library design work.
MyriaScreen II structural Diversity score is 0.86899 to be exact or 0.87 to round it. What does the score stand for? Any database diversity sorting produces a number from 1, which means the most structurally dissimilar compounds in a dataset, to 0.0, which means identical compounds in a dataset. Cosine coefficients are used for the calculations of topological areas of molecular fingerprints and can be simplified to this sketch equation: Dissimilarity (D) of the pair of structures A and B is D(A,B)=1-S(A,B), where S is similarity.
For the collection size of 10,000 compounds, 0.87 Diversity score is rather high and one can expect density of singletons and clusters. Going in this direction, clustering calculation reveals 10,000 topologically unique records – the collections is free from structural duplicates. The number of structural clusters in MyriaScreen II is 1,330. The total number of structures in these clusters adds up to 3,948 with the average number of 3 molecules per each cluster. 10,000 compounds minus 3,948 leave 6052 singletons in MyriaScreen II making it objectively diverse screening library.
Zooming from the entire structural fingerprints diversity in to structural scaffolds plane, there are about 4700 large common fragments in the collection out of which 1020 fragments are shared by 2-3 molecules. There are about 100 the most common fragments that show up in more than three structures.
MyriaSreen II largest common fragments 
Fragments showing in structures
Continuing with “de-fragmentation”, there are 1390 heterocycles in MyriaScreen II, 700 of which are found only in one structure. About 450 heterocycles are found in 2-6 structures. Smaller, one ring heterocycles are definitely more common across many structures with furan and pyridine leading the occurrence count showing up in over 500 molecules each. To take down the scaffolds apart, there are 1626 cyclic fragments, 1432 acyclic fragments with 3058 fragments in total.
Complete inventory of the most common fragments, scaffolds, and heterocycles and their correspondence to MyriaScreen ID-numbers is available on request with the orders. Library SDF is available for preview prior to a purchase.
Please contact us if you are considering MyriaScreen II for your next assay.
ChemDBsoft and its modules are used for the calculations.
