Exploring the role of chloro and methyl substitutions in 2-phenylthiomethyl-benzoindole derivatives for 5-LOX enzyme inhibition.

Following the results we previously reported on a series of ethyl 2-phenylthiomethyl 5-hydroxyindole-3-carboxylate derivatives as 5-lipoxygenase (5-LOX) inhibitors, in order to obtain a more selective compound with respect to the previous generation of derivatives, we decided to modify the structure of the core ligand. The first level of structural modification involved the annelation of benzene to the indole, yielding corresponding benzo[g]indole derivatives, systematic optimization of methyl or chlorine groups in meta-, ortho- and ortho/para-position of 2-phenylthiomethyl moiety were applied. The reported results show that extension of the aromatic core led to a great enhancement of activity, especially in cell-free assay, and the accurate structure-based design provided compounds 6f, 6g and 6l that block 5-LOX activity in cell-free assays with IC50 ranging from 0.