Design of more potent squalene synthase inhibitors with multiple activities

Antihyperlipidemic morpholine derivatives ( 1– 6), combining several pharmacophore moieties, were evaluated in vitro and in vivo and optimized towards more active SQS inhibitors ( 7– 12). With the increasing realization that modulating a multiplicity of targets can be an asset in the treatment of multifactorial disorders, we hereby report the synthesis and evaluation of the first compounds in which antioxidant, anti-inflammatory as well as squalene synthase (SQS) inhibitory activities are combined by design, in a series of simple molecules, extending their potential range of activities against the multifactorial disease of atherosclerosis. The activity of the initially synthesized antihyperlipidemic morpholine derivatives ( 1– 6), in which we combined several pharmacophore moieties, was evaluated in vitro (antioxidant, inhibition of SQS and lipoxygenase) and in vivo (anti-dyslipidemic and anti-inflammatory effect). We further compared the in vitro SQS inhibitory action of these derivatives with theoretically derived molecular interactions by performing an in silico docking study using the X-ray crystal structure of human SQS. Based on low energy preferred binding modes, we designed potentially more potent SQS ligands. We proceeded with synthesizing and evaluating these new structures ( 7– 12) in vitro and in vivo, to show that the new derivatives were significantly more active than formerly developed congeners, both as SQS inhibitors (20–70-fold increase in activity) and antioxidants (4–30-fold increase in activity). A significant correlation between experimental activity [Log(1/IC 50)] and the corresponding binding free energy (Δ G b) of the docked compounds was shown. These results, taken together, show a promising alternative and novel approach for the design and development of multifunctional antiatherosclerosis agents.