Virtual Screening and Biological Evaluation of Natural Products as Novel VPS34 Inhibitors that Modulate Autophagy

VPS34 is a sole member of class III phosphoinositide 3-kinase involved in endosomal trafficking and autophagosome formation, making it an interesting target for cancer treatment. Here, we investigated 5,774 natural products using structure-based virtual screening against human VPS34. 10 natural products identified by virtual screening were purchased and tested in VPS34 ADP-Glo assay, yielding several potential VPS34 inhibitors. Amongst, Salvianolic acid A (4) and Ellagic acid (8) inhibited VPS34 with IC50 values of 2.46 and 3.12 mu M, respectively, more potent than the positivity control 3-MA. Moreover, in vitro assays demonstrated that both of the compounds suppressed vesicle trafficking in cell-based assay. Significantly, Salvianolic acid (4) effectively prevented autophagy in Hela cells induced either by starvation or Rapamycin, an mTOR inhibitor. In addition, in silico analysis was done to elucidate the binding mechanisms of the ligand in complex with VPS34. Overall, this study highlights the efficacy of structure-based virtual screening and presents several natural products as VPS34 inhibitors that modulate autophagy.