A new binding site and potential novel inhibitors of the respiratory complex III are described. The site is located at the opposite side of the enzyme with respect to ubiquinol binding site (Q site), and distinctly different from both Q, and Q sites (hence designated as NonQbinding site, NQ). NQsite binding pocket extends up close to Phe90 residue, an internal switch (LH switch) that regulates electron transfer between heme bL and heme bH of the low potential redox chain. Docking studies and molecular dynamics simulations of different molecules to the NQsite revealed potential ligands which exhibit a novel inhibitory effect for bc1 complex by switching the LH switch to "off" conformation, thereby shutting down electron transfer in the low potential redox chain. Moreover, the novel inhibitors have lower binding affinity for both Q and Q sites, and hence do not interfere with binding of the natural ligands to those sites. The inhibitory activity of those novel ligands in bc1 complex is suggested to promote the production of reactive oxygen species (ROS) at the Q site. Hence those ligands are potential candidates for designing new "mitocan" drugs.