Design and development of N-Heterocyclic protease inhibitors for flaviviral infections: a synthetic and SAR-based review.

Dengue, Zika, and West Nile viruses are major global health threats that belong to the genus Flavivirus and demand urgent attention. The viral proteases, particularly the viral protease complex (NS2B-NS3; NS2B: A small cofactor protein that activates NS3, NS3: A large multifunctional protein) complex, play a vital role in viral replication, making them prime targets for antiviral drug development. This review article has included the synthetic approach and Structure Activities Relationship (SAR) of such compounds, emphasizing how structural modifications in N-heterocyclic analogs affect inhibitory effectiveness toward proteases. Synthetic approaches such as click chemistry, cyclization, and bioisosteric replacements have been reviewed in order to enhance the selectivity and bioavailability of such molecules. Furthermore, computational modeling and molecular docking studies have been emphasized that support the rational drug design of reported molecules by predicting key binding interactions and optimizing pharmacokinetic parameters. In summary, this article underscores the importance of N-heterocyclic structures to develop viral protease inhibitors and provides direction for future antiviral drug development efforts. This review also highlights the potential of N-containing heterocycles as promising scaffolds for protease inhibition with an emphasis on their synthetic accessibility and capacity to engage in strong interactions within viral active sites. The present review also focuses on a future for the synthesis of nitrogenous heterocyclic analogs with a greater leadership of in silico approaches, including computational docking, fragment-based screening, and high-throughput synthesis techniques. Recent advances demonstrate that structural optimization of these heterocycles has led to compounds with encouraging antiviral activity, i.e., supported by computational insights. Looking forward, integrating in silico approaches with innovative synthetic methodologies is expected to accelerate development of selective and potent flaviviral protease inhibitors. Together, these efforts may pave the way for effective treatments against emerging flavivirus infections.