Molecular Docking Studies of Glycyrrhetinic Acid Derivatives as Anti- Colorectal Cancer Agents

BACKGROUND

In this study, the anti-colorectal cancer (CRC) activities of 40 glycyrrhetinic acid derivatives were proposed and evaluated by the molecular docking method, which allowed the flexibility of both ligand-receptor, with twelve CRC-related targets.

METHODS

The proposed derivatives, which clearly distinguish isomers at position 18 as well as the different tautomers, were divided into five groups, including (1) glycyrrhetinic acid and its oxidation derivatives, (2) glycoside derivatives, (3) 3β-amine derivatives, (4) five-membered heterocyclic ring-combined derivatives, and (5) six-membered heterocyclic ring-combined derivatives.

RESULTS

Finally, four out of twelve proposed targets related to CRC with good binding affinities to the proposed glycyrrhetinic acid derivatives were selected, including Epidermal Growth Factor Receptor (EGFR), Focal Adhesion Kinase (FAK), Lactate Dehydrogenase A (LDHA), and Thymidylate Synthase (TS).

CONCLUSION

From there, 9/40 derivatives for EGFR (pK_d ≥ 9); 10/40 derivatives for FAK (pK_d ≥ 10); 9/40 derivatives for LDHA (pK_d ≥ 10), and 6/40 derivatives for TS (pK_d ≥ 9) were also obtained. The glycoside derivatives showed the best binding affinity (especially the glucuronide derivative 5b), followed by the 3β-amino derivatives (especially the 3β-(phenylamino) derivative 8b) and the five-membered heterocyclic ring-combined derivatives (especially the pyrrole derivative 10a or pyrazole derivative 11.2a), while the six-membered heterocyclic ring-combined derivatives had less potential to inhibit the 4 selected targets.

Identification of chikungunya virus nsP2 protease inhibitors using structure-base approaches

The nsP2 protease of chikungunya virus (CHIKV) is one of the essential components of viral replication and it plays a crucial role in the cleavage of polyprotein precursors for the viral replication process. Therefore, it is gaining attention as a potential drug design target against CHIKV. Based on the recently determined crystal structure of the nsP2 protease of CHIKV, this study identified potential inhibitors of the virus using structure-based approaches with a combination of molecular docking, virtual screening and molecular dynamics (MD) simulations. The top hit compounds from database searching, using the NCI Diversity Set II, with targeting at five potential binding sites of the nsP2 protease, were identified by blind dockings and focused dockings. These complexes were then subjected to MD simulations to investigate the stability and flexibility of the complexes and to gain a more detailed insight into the interactions between the compounds and the enzyme. The hydrogen bonds and hydrophobic contacts were characterized for the complexes. Through structural alignment, the catalytic residues Cys1013 and His1083 were identified in the N-terminal region of the nsP2 protease. The absolute binding free energies were estimated by the linear interaction energy approach and compared with the binding affinities predicted with docking. The results provide valuable information for the development of inhibitors for CHIKV.