Prediction of novel inhibitors for Crotalus adamanteus l-amino acid oxidase by repurposing FDA-approved drugs: a virtual screening and molecular dynamics simulation investigation

One of the deadliest enzymes in the snake venom is l-amino acid oxidase (LAAO) which plays an important role in the pathophysiological effects during snake envenomation. Some effects of this enzyme on the human body are apoptosis, platelet aggregation, edema, hemorrhage, and cytotoxicity. Hence, inhibiting the enzyme activity to reduce its degradation effects is of great medical and pharmacological importance. On the other hand, drug repurposing is a process to find the new existing drug for a new medical indication. Since Crotalus adamanteus LAAO has no crystal structure in the protein data bank, first, its 3D structure was constructed by homology modeling using 1REO as the template and then modeled structure was evaluated by several algorithms. We screened the FDA-approved drugs by structure-based virtual screening, molecular dynamics (MD) simulation, and Molecular Mechanics Poisson Boltzmann Surface Area (MM/PBSA) to identify new inhibitors for the snake venom LAAO. Interestingly, docking results revealed that half of the hits belong to the propionic acid derivatives drugs. In addition, MD simulation was performed to assess the interaction profile of the docked protein-hits complexes. Meanwhile, Arg88, Gln112, Lys345, Trp356 form consistent hydrogen bond interactions with Dexketoprofen, Flurbiprofen, Ketoprofen, Morphine, and Citric acid during simulation. According to the results, each of the four compounds can be an appropriate inhibitor of LAAO and since our study was based on drug repurposing could be evaluated in phase II clinical trials.