Virtual Screening of Natural Products and Drugs as Inhibitors against Aspartate Transcarbamoylase and Orotidine-5'-Monophosphate Decarboxylase in Plasmodium falciparum

Background: Malaria remains to be one of the major health problems in tropical areas of the world. It puts at least one-third of the world population at risk of infection and afflicts over 200 million people worldwide, approximately 7000 of whom are Filipinos. In spite of available drugs, malarial chemotherapy is still insufficient. The increased resistance of Plasmodium falciparum strains to existing antimalarial drugs prompts the discovery of new therapeutic agents for malaria. Objective: This study aimed to uncover, through molecular docking technique, new chemical entities that can be developed as new drugs for malaria. Methodology: In this study, 2,527 approved and 5,755 experimental drugs from DrugBank and 4,687 natural compounds from Analyticon MEGx database were docked against Plasmodium falciparum aspartate transcarbamoylase (PfATC) and oritidine-5'-monophosphate decarboxylase (PfOMPDC), two key enzyme targets involved in the de novo biosynthesis pathway of the pathogen. Results: A total of 39 compounds (1 approved drug, 19 experimental drugs, 19 natural products) had larger binding energy (BE) values than the known ligands 2,3-naphthalenediol (BE PfATC = -7.0 kcal/mol) and uridine 5- monophosphate (BE PfoMPDC = -9.0 kcal/mol). The top 3 hits were natural products: dihydrotrichotetronine (BE PfATC = -21 kcal/mol, BE PfOMPDC = -18 kcal/mol), ginkgolide A (BE PfATC = -19 kcal/mol, BE PfOMPDC = -15 kcal/mol), and ginkgolide C (BE PfATC = -16 kcal/mol, BE pfOMPdc = -16 kcal/mol). Conclusion: Based on calculated binding energy and ADMET properties, dihydrotrichotetronine, ginkgolide A, and ginkgolide C are the best natural product candidates for further development as dual inhibitors for both PfATC and PfOMPDC enzymes. Furthermore, myricetin (BE PfATC = -9 kcal/mol, BE PfOMPDC = -10 kcal/mol) and tolcapone (BE PfATC = -9.1 kcal/mol, BE PfOMPDC = -9.2 kcal/mol) may also be repurposed as anti-malarial drugs.