Multisite Occupancy and Multidimensional Optimization: Design and Evaluation of Piperazine-Thioureidobenzamide Derivatives as Potent HBV Capsid Assembly Modulators

Hepatitis B virus (HBV) capsid assembly modulators are a promising class of agents for chronic HBV infection. Thioureidobenzamide compound 17i exhibits potent anti-HBV activity but suffers from poor water solubility, high cytotoxicity, and limited drug-like properties. Herein, we report the design of piperazine-thioureidobenzamide derivatives via multisite occupancy and multidimensional optimization strategies. The representative compound 35a exhibited potent anti-HBV activity and low cytotoxicity in HepAD38 cells (EC₅₀ = 0.020 μM, CC₅₀ > 100 μM) and HLCZ01 cells (EC₅₀ = 0.024 μM, CC₅₀ > 100 μM). Molecular dynamics simulations revealed that 35a retained critical hydrogen bonds with Trp-102, Thr-128, and Leu-140, while forming new hydrogen bonds with Ser-106, Thr-142, and Asn-136. Multidimensional optimization endowed 35a with improved solubility, ideal LogP and high plasma stability. In HBV carrier mouse models, 35a inhibited viral replication more effectively than 17i, highlighting its potential as a promising candidate drug for further development.