The novel targets of DL-3-n-butylphthalide predicted by similarity ensemble approach in combination with molecular docking study.

Background: DL-3-n-butylphthalide (NBP) is a drug for treating acute ischemic stroke, and may play a neuroprotective role by acting on multiple active targets. The aim of this study was to predict the target proteins of NBP in mammalian cells.

Methods: The similarity ensemble approach search tool (SEArch), one of the commonly used public bioinformatics tools for target prediction, was employed in the experiment. The molecular docking of NBP to target proteins was performed by using the three-dimensional (3-D) crystal structure, substrate free. The software AutoDock Vina was used for all dockings. The binding targets of NBP were illustrated as 3-D and 2-D diagrams.

Results: Firstly, the results showed that NBP bounded to the same binding site on NAD(P)H quinone oxidoreductases (NQO1) as the substrate FAD, leading to competitive inhibition for the catalytic site with -7.2 kcal/mol. This might break the 3-D structure of NQO1 and bring about P53 degradation, resulting in a decrease of p53-mediated apoptosis in ischemic brain cells. Secondly, NBP might exert its therapeutic effect on acute ischemic stroke via modulating indoleamine 2,3-dioxygenase (IDO) bioactivity after associating with it. NBP could alleviate the depression following ischemic stroke by inhibiting IDO. Thirdly, NBP might modulate the function of NADH-ubiquinone oxidoreductase by competitively embedding itself into this complex, further affecting mitochondrial respiration in cerebrovascular diseases as an anti-oxidant agent.

Conclusions: Three potential target proteins of NBP were identified, which may provide a novel aspect for better understanding the protective effects of NBP on the nervous system at the molecular level.