Synthesis and phospholipidosis effect of a series of cationic amphiphilic compounds: a case study to evaluate in silico and in vitro assays
In recent years, a large number of in silico and in vitro assays have been developed for safety assessment in early drug discovery. These methods are usually validated using datasets of known drugs with large chemical diversity, while application to homologous series has been rarely explored. Here we report a case study about phospholipidosis (PLD) risk evaluation for a dataset of nine compounds, designed and synthesized to modulate the physico-chemical properties typical of cationic amphiphilic compounds (CADs), representing the main class of PLD inducers. Our aim was to investigate the effect of structure modification on PLD induction according to a number of standard in silico and in vitro methods. As a result, we found that different in silico methods lead to conflicting results when applied to our series of weak PLD inducers, thus the apparently easy-to-use definition of CADs requires special attention. Moreover, when weak inducers are tested in vitro, the revealed PLD effect may vary based on the purity grade of the tested compound and the features of the selected assay. Finally, we have shown that slight modifications on a chemical scaffold can have an impact on the PLD effect. This study also exemplifies that current in silico methods possibly overestimate the PLD induction effect of cationic amphiphilic compounds compared to the in vitro, with the risk of discarding promising compounds based on incorrect safety liabilities.
KeywordsPhospholipidosis Cationic amphiphilic drugs Toxicophore HepG2 cells Fluorescence assays Organic synthesis
The authors would like to thank Prof. Francesco Galli for generously sharing his laboratory facilities for biological analysis, and Dr. Simon Cross for helpful comments and for English revision. Financial support from the Italian MIUR within the “FIRB-Futuro in Ricerca 2010” Program—Project RBFR10×500 is gratefully acknowledged.
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Conflict of interest
The authors declare that they have no competing interests.
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