Formulation and optimization of polymeric nanoparticles loaded with riolozatrione: a promising nanoformulation with potential anti-herpetic activity

Riolozatrione (RZ) is a diterpenoid compound isolated from a dichloromethane extract of the Jatropha dioica root. This compound has been shown to possess moderate anti-herpetic activity in vitro. However, because of the poor solubility of this compound in aqueous vehicles, generating a stable formulation for potential use in the treatment of infection is challenging. The aim of this work was to optimize and physiochemically characterize Eudragit® L100-55-based polymeric nanoparticles (NPs) loaded with RZ (NPR) for in vitro anti-herpetic application. The NPs formulation was initially optimized using the dichloromethane extract of J. dioica, the major component of which was RZ. The optimized NPR formulation was stable, with a size of 263 nm, polydispersity index < 0.2, the zeta potential of –37 mV, and RZ encapsulation efficiency of 89 %. The NPR showed sustained release of RZ for 48 h with release percentages of 95 and 97 % at neutral and slightly acidic pH, respectively. Regarding in vitro anti-herpetic activity, the optimized NPR showed a selectivity index for HSV-1 of ≈16 and for HSV-2 of 13