Formulation and optimization of polymeric nanoparticles loaded with riolozatrione: a promising nanoformulation with potential antiherpetic activity.

Riolozatrione (RZ) is a diterpenoid compound isolated from a dichloromethane extract of the root. This compound has been shown to possess moderate antiherpetic activity . 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 physio-chemically characterize Eudragit L100-55-based polymeric nanoparticles (NPs) loaded with RZ (NPR) for antiherpetic application. The NPs formulation was initially optimized using the dichloromethane extract of , 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 antiherpetic activity, the optimized NPR showed a selectivity index for HSV-1 of ≈16 and for HSV-2 of 13.