To enable an assessment of biological relevance, the library was screened in the cell painting assay which interrogates many biological pathways simultaneously. Here, six different dyes were used to stain different cellular compartments; high-content imaging and automated image analysis then enabled extraction and quantification of 579 parameters corresponding to specific morphological features. The biological profile of compounds may be described in terms of fingerprints which capture the changes in these parameters relative to DMSO control. Morphological fingerprints were determined for the 52 screening compounds at 10, 30 and 50 µM, and were compared with those of around 4000 reference compounds (mainly determined at 10 µM). Bioactivity was assessed in terms of an induction value: that is, the percentage of significantly changed parameters (median absolute deviation of the parameter value > ±3) relative to DMSO control. At 30 µM, we identified ten compounds that were considered to be active (induction values > 5%; Panels A, B, Figure ). Comparison of fingerprints revealed clusters of compounds with distinct morphological effects: these effects were similar to those of known modulators of lysosomotropism/cholesterol homeostasis (25-28), DNA synthesis (15b) and mitochondrial stress (22, 23, 29). In addition, two compounds (20 and 30) were not similar to previously-identifed functional clusters (similarity <70%). The fingerprints for the compounds with the highest induction value from each of these clusters (25, 15b, 23 and 20) are displayed as heatmap profiles in Figure (Panel C, left). Crucially, pairwise comparison, based on Pearson correlation, revealed that the morphological fingerprints for these compounds have low biosimilarity (Panel C, right) (fingerprints are typically considered similar if biosimilarity >75% ). These results suggest that our top-down synthetic approach can deliver sets of screening compounds are functionally (as well as structurally) diverse.