Exploring Artocarpus heterophyllus derivatives as inhibitors of DENV2 NS2B NS3 serine protease through molecular dynamics and biological assays

NS2B/NS3 serine protease is a major target for antiviral medication research, and dengue virus type 2 (DENV2) continues to be a serious public health concern. This study used a combined computational and experimental approach to examine phytochemical substances derived from Artocarpus heterophyllus as possible inhibitors of DENV2 NS2B/NS3 protease. The structural stabilities and binding interactions of four compounds i.e. artocarpanone, artocarpin, cyanomaclurin, and cycloartocarpin were assessed using molecular dynamics (MD) simulations. Cycloartocarpin exhibited the most stable interaction, maintaining a hydrogen bond with the catalytic residue His51 at a distance of 2.7 Å and an angle of 167° throughout the 100 ns simulation. MD parameters confirmed complex stability, with RMSD (root mean square deviation) stabilized at approximately 0.35 nm, Rg maintained at approximately 2.18 nm, and SASA reduced to approximately 145 nm², indicating compact conformational behavior. In vitro enzymatic assays further evaluated the biological relevance, revealing that cycloartocarpin displayed minimal inhibition (< 5%) of protease activity, even at 300 µg/mL, whereas the positive control, aprotinin, achieved ~ 80% inhibition in a dose-dependent manner. These results highlight the discrepancy between computational predictions and experimental outcomes, emphasizing the importance of structural optimization to enhance the biological activity of cycloartocarpin against DENV2 protease.